The Big Rod Discussion!

[Subliminal]

Carillo owns K1.

The rods at TU are made by K1 (which is now owned by Carillo)
The rods at FWDP are made by Carillo, not by K1 (which is now owned by Carillo.

:)

[turbovanman²]

K1 rods will meet or exceed any thing you can throw at them. :thumb:

[JamesL]

K1 rods will meet or exceed any thing you can throw at them. :thumb:

And for a little less money Eagles will hold up to 650 HP.

[turbovanman²]

And for a little less money Eagles will hold up to 650 HP.

That too.

[Austrian Dodge]

why do you guys rate rods by HP? it's not a certain HP level that makes a rod fail.
Can't remember who, but someone did a very good post containing the tech. info whats the most stress on rods.

[mpgmike]

why do you guys rate rods by HP? it's not a certain HP level that makes a rod fail.


It's like rating cylinder heads by flow numbers. It quantifies them and puts a number on them. (So does dyno testing, but I digress.)

Mike

[8valves]

RPM is usually the most related to rod failures, although brute power can break a rod, key word being break. The bend is more of a signifier of more rpm than it was capable of. That's a pretty simple way of looking at it.

Are your Carrillo's going to be their A beam design, or something else?

[TurboGLH]

.....Having said that, Carrillo wouldn't buy just any rod company. Couple that with Tom’s credentials and you can trust he has a solid product. Feel free to email him Tom Molnar at K1 tom.m@k1technologies.com or Susan Williams susan.w@k1technologies.com if you have any questions. He is a very amiable individual. Kudos to TU for getting this companies product to the TD market first! Perhaps the TD community will benefit further with pricing should K1 find the need to increase production.

I know that the bad feelings between both companies will never subside, but cudo's for being a professional. I'd like to see this more often, but I'm practical and would settle for less public animosity from both sides.

[Directconnection]

RPM is usually the most related to rod failures, although brute power can break a rod, key word being break. The bend is more of a signifier of more rpm than it was capable of. That's a pretty simple way of looking at it.

Are your Carrillo's going to be their A beam design, or something else?

I think you got it the other way around. Compressive forces aka power is what bends rods including heavy detonation like what we saw with Larry's
T-III a few years back. High rpms is what breaks rods like overrevving, or revving too high for a heavy piston, rod and more like high piston velocites. But in the big time drag racing engines (V-8s with 700+hp) they usually toss rods at the big end due to letting out of the throttle. I hear this alot from the guys that race. Running WOT at max rpm through te traps, then lifting is when a rod goes boom. It's the stretching of the rods and same principle for people that engine brake alot as well.

The eagle h-beam I mentioned about that broke was due mostly in part to the heavy bobweight combo of the piston and piston velocity and the fact that the guy was severely overrevving his engine (windowed one of those nice aluminum Indy Max blocks as well)

Sorry to get off topic again, James. Rating the rod for a given HP is not a bad thing. Easier for people to understand vs. a large techinical breakdown of max. rpm vs stroke vs rod ratio vs piston, pin, ring weight etc vs modulus of elasticity analysis of rod bolt in question etc...:)

[8valves]

I think you got it the other way around. Compressive forces aka power is what bends rods including heavy detonation like what we saw with Larry's
T-III a few years back. High rpms is what breaks rods like overrevving, or revving too high for a heavy piston, rod and more like high piston velocites. But in the big time drag racing engines (V-8s with 700+hp) they usually toss rods at the big end due to letting out of the throttle. I hear this alot from the guys that race. Running WOT at max rpm through te traps, then lifting is when a rod goes boom. It's the stretching of the rods and same principle for people that engine brake alot as well.

The eagle h-beam I mentioned about that broke was due mostly in part to the heavy bobweight combo of the piston and piston velocity and the fact that the guy was severely overrevving his engine (windowed one of those nice aluminum Indy Max blocks as well)

Sorry to get off topic again, James. Rating the rod for a given HP is not a bad thing. Easier for people to understand vs. a large techinical breakdown of max. rpm vs stroke vs rod ratio vs piston, pin, ring weight etc vs modulus of elasticity analysis of rod bolt in question etc...:)

You bring up good points for sure. The few rods failures I have seen in person, none in the TM scene, were rpm related and caused a bend. I will also state that two of the failures were an aluminum rodded hemi pulling truck engine, that could also alter the situation.

Ah well. Simplicity is the way to go probably :thumb:

[Chris W]

Kudos to TU for getting this companies product to the TD market first!

:faint:

Thanks for the compliment James:thumb: Happy Easter to you and your family:amen:


it's not a certain HP level that makes a rod fail. Can't remember who, but someone did a very good post containing the tech. info whats the most stress on rods.

I'm not sure where that post is, but, unless the rod is grossly under designed, it will not break due to HP. Because power is produced from the expanding gasses pushing down on the piston, there is a compressive (pushing) load on the rod. If a rod broke due to power, it would be crushed. The fact is, rods are broken due to being pulled in two. This high tension (pulling) load is highest at TDC on the exhaust stroke when the piston is trying to go through the cylinder head and the crank tries to pull it back down. The reason it is highest at this point is because the other time the piston is at TDC is on the compression stroke and the piston is being pushed back down by the gas loads of the compressed air/fuel mixture. To the best of my knowledge, there is no power being created on the exhaust stroke so rating rods by power is simply not applicable. Most people including most rod manufacturers do not realize this. Fortunately for us, turbocharged engines do provide "some" backpressure on the exhaust stroke reducing that stretching force on the rods.

Chris-TU

[Frank]

Moved posts from the various threads in the vendors section. This is too be a nice collimation of posts and lets keep it awesome! Thanks!

[turbovanman²]

lets keep it awesome!

:wow1: :faint: :bolt:

[Directconnection]

You bring up good points for sure. The few rods failures I have seen in person, none in the TM scene, were rpm related and caused a bend. I will also state that two of the failures were an aluminum rodded hemi pulling truck engine, that could also alter the situation.

Ah well. Simplicity is the way to go probably :thumb:


Did the rod bend due to over-revving and the piston crashing the chamber?

[TurboJerry]

The most stress is when the piston has to go from TDC and be *yanked* down by the rod during the overlap period. Boost takes some of this stress away in a forced induction engine. Too much cylinder pressure at a low rpm (below 3000 rpm) in most cases will bend a rod from the force involved. Like hitting a high hp nitrous system at low rpm will bend a rod for sure in most cases. Also the rod bolts are usually first to go at high rpm. properly prepared rods usually won't crack.

[turbovanman²]

The most stress is when the piston has to go from TDC and be *yanked* down by the rod during the overlap period. Boost takes some of this stress away in a forced induction engine. Too much cylinder pressure at a low rpm (below 3000 rpm) in most cases will bend a rod from the force involved. Like hitting a high hp nitrous system at low rpm will bend a rod for sure in most cases. Also the rod bolts are usually first to go at high rpm. properly prepared rods usually won't crack.

Thats what I have heard and read. I won't let anyone dyno my bike or vehicles that goes to WOT then just pulls the clutch in, :wow1:

[Ondonti]

well a stronger rod can mean the difference between detonation bending a rod and simply needing to replace a bearing. I know we would all like to have a "perfect" tune that never has a hiccup but....thats not always realistic.

[Chris W]

The most stress is when the piston has to go from TDC and be *yanked* down by the rod during the overlap period. Boost takes some of this stress away in a forced induction engine. Too much cylinder pressure at a low rpm (below 3000 rpm) in most cases will bend a rod from the force involved. Like hitting a high hp nitrous system at low rpm will bend a rod for sure in most cases. Also the rod bolts are usually first to go at high rpm. properly prepared rods usually won't crack.

Exactly!! Sounds like an echo of the words I just wrote above Jerry:thumb:

I can think of one instance where horsepower will definitely bend a rod and that's if a cylinder is hydro locked.

Chris-TU

[Tony Hanna]

I can think of one instance where horsepower will definitely bend a rod and that's if a cylinder is hydro locked.
Chris-TU

I've seen this first hand.:(
Doesn't take much, you can do it with the starter.

[2.216VTurbo]

So does anyone have any first hand experience with the Mechart rods? I have a set of them in a spare 8V motor that was built many years ago... Not sure if I should pull them at some point and press them back into service on another motor or not:confused: I've heard they were crack prone but again, only what I heard, never seen any break.

[zin]

A simplistic way to diagnosis a rod failure is as follows: a separated rod will generally be related to RPM and/or rod bolt failure. If it separated at the small end, then the stresses where too much for the design of the rod and/or a flaw or stress riser in/on the rod, be that too heavy a piston, too much RPM or both, it will literally be pulled in two. This mode of failure also has the unpleasant effect of creating what I refer to as "a rotary hacksaw", that tends to try and saw the block in half! The other mode is when the big end comes apart, this is generally due to rod bolt failure, not the rod itself. A bent rod is most commonly due to more compressive force than the rod was designed for, be it cylinder pressure, water in the cylinder, or other debris (valve heads, etc). I don't know how deep people want to get into rods and their part in an engine, so I won't get into rod length, etc. :D
Hope this is helpful to at least one of us!

Mike

[8valves]

Did the rod bend due to over-revving and the piston crashing the chamber?

No damage to the head in that particular case, but the piston was visibly shorter at TDC than the rest!! Took it out and it had a nice obvious whoop to it halfway through.

Like I mentioned, this is an aluminum rodded motor that I saw this on. That could make a difference I suppose.

[Sloride]

So, to quantify our rod selection and help me make an informed rod choice. we have...


A) Stock Refurbished (400ish hp 700 grams)

B) Eagle H-beam ("up to 650hp")

C) K1 H-beam ("Anything I can throw at them")

D) Carrillo H-beam (The ZEUS of our rod world)

X) GRP Aluminum (+/- 453grams!!! not a street rod :( )

Could someone fill in the approximate rod weights + recommended power/stress levels (rpm please :) )

info on other rod choices is also welcome

[GLHNSLHT2]

So if you have a 2.2 and you want to make maybe 600hp and run 8k rpms or more what rod would be the one to use?

[turbovanman²]

So, to quantify our rod selection and help me make an informed rod choice. we have...


A) Stock Refurbished (400ish hp 700 grams)

B) Eagle H-beam ("up to 650hp")

C) K1 H-beam ("Anything I can throw at them")

D) Carrillo H-beam (The ZEUS of our rod world)

X) GRP Aluminum (+/- 453grams!!! not a street rod :( )

Could someone fill in the approximate rod weights + recommended power/stress levels (rpm please :) )

info on other rod choices is also welcome

Ok my list-

My TII rods that I removed the parting line and had them balanced-692 grams
Stock TII rods, untouched-710 grams
Eagle EDZ SRT rods-573 grams :wow1:
TU Billet K1 rod-600 grams

Stock std Mahle 2.5 8 valve piston-366 grams
Sealed Power .020 2.5 cast piston-362 grams
Wisco .040 forged 2.5 slug-368 grams
My 2.5 JE's with rings and a small hole-404 grams
TIII std Mahle piston-418 grams

Stock Dodge pin-125 grams
Wiseco wrist pin-122 grams

Std rod bearings-43 grams



So if you have a 2.2 and you want to make maybe 600hp and run 8k rpms or more what rod would be the one to use?

I would say K1 or Carrillo's at $1400, ;)

[Mario]

Per Chris W:

TU Billet Rods- 600grams

[GLHSKEN]

2.2L Wiseco Pistons 432-434 grams. (I've bought 4 sets.

[sdac guy]

So does anyone have any first hand experience with the Mechart rods? I have a set of them in a spare 8V motor that was built many years ago... Not sure if I should pull them at some point and press them back into service on another motor or not:confused: I've heard they were crack prone but again, only what I heard, never seen any break.
I bought a set of the MP Mechart rods about 10 years ago at the Mopar Nats. I heard some stories about them after I got them. At SDAC-8, Jerry Mallicoat was one of the folks on the tech discussion panel. Since he was around Shelby when these were introduced I asked him about them. He said that while he might use them in an N/A application, he would never use them in a turbo motor. While very strong, they are just too brittle. He said when they break, and they do, they take a lot of the block with it. His words were something like "one of these broken spinning around can cut a block in half."

The recommendations on them I have now heard over the years is, have them magnafluxed before using them to be sure they are sound before they are installed. Don't use them in a forced induction app, and more recently, if used in competition in a N/A app, change them out every year.

I have a friend who races SCCA with a N/A 12.5:1 cr motor, which he spins to 8500 rpm on a regular basis. He uses the Mecharts. He has two more sets and wants to buy my set as spares because he is going to start changing them out yearly just to be safe.

A prettier rod was never made though!

Barry

[2.216VTurbo]

Thanks Barry, never heard that they were brittle and not well suited for boost. They were on a ~250 whp motor for like 10K miles, I was either lucky or living on borrowed time:o

[Mario]

Glad I didn't buy them when I had the chance! Thanks Barry.

[sdac guy]

Thanks Barry, never heard that they were brittle and not well suited for boost. They were on a ~250 whp motor for like 10K miles, I was either lucky or living on borrowed time.

When I quoted Jerry, I didn't really mean to imply that dozens of those rods haven't been used successfully by many folks, including use in turbo motors.

So I don't know if the "borrowed time" is accurate. But what cooked it for me was that Jerry did say, "If it was me, I certainly wouldn't use them in my turbo motor."

Barry

[turbovanman²]

2.2L Wiseco Pistons 432-434 grams. (I've bought 4 sets.

Weird, wonder if the 2.2's are a heavier construction?

Did you take out the wrist pin? :lol:

[csxtra]

Weird, wonder if the 2.2's are a heavier construction?


Could it be because 2.2 pistons aren't tuna cans like the 2.5s are? :nod:

[MiniMopar]

Yep, longer skirts on the stockers.

[TurboJerry]

Exactly!! Sounds like an echo of the words I just wrote above Jerry:thumb:

I can think of one instance where horsepower will definitely bend a rod and that's if a cylinder is hydro locked.

Chris-TU

I should make it a habit to read others posts before I post! DOH!!!!

[GLHNSLHT2]

Quote:
Originally Posted by GLHNSLHT2 View Post
So if you have a 2.2 and you want to make maybe 600hp and run 8k rpms or more what rod would be the one to use?


I would say K1 or Carrillo's at $1400, ;)

Would the K1's live? Simon is the only one with an opinion on this?

[Mario]

Would the K1's live? Simon is the only one with an opinion on this?

GRP Aluminum rods. If you're going to be making that power from an 8V 2.2, and spinning that high, you'll obviously be running this at the track, or just making 5th gear pulls on the highway.

You really should start a thread and tell us the recipe for 600HP and a powerband that goes to 8,000 RPMs from a 2.2 8V. I'd really be interested.

[turbovanman²]

If race car only then yeah, Aluminium, if not, then either K1's or Carrillo's.

[Frank]

If race car only then yeah, Aluminium, if not, then either K1's or Carrillo's.

Whats that based on? Where is the facts behind it?

While I dont like Eagles, even they can handle most anything we can throw at it. I would prefer K1 and know they could handle alot of power as seen on Supra and 4G63 cars.... of course that is just what I read nothing more.

[turbovanman²]

Whats that based on? Where is the facts behind it?

While I dont like Eagles, even they can handle most anything we can throw at it. I would prefer K1 and know they could handle alot of power as seen on Supra and 4G63 cars.... of course that is just what I read nothing more.

ACK, time and time again were told NOT to use aluminium rods in a street car, you of all people should know that.

[Frank]

I should slap you. You missed what I was saying. Why do you say you must have aluminum in a race car? On what basis does everyone say you must have aluminum? Its not like you can buy super light pistons and pins....

[turbovanman²]

I should slap you. You missed what I was saying. Why do you say you must have aluminum in a race car? On what basis does everyone say you must have aluminum? Its not like you can buy super light pistons and pins....

You could try, ;)

I missed nothing, your response was nothing but innuendo. I didn't say you must have aluminium but did you read his goals, 8000 rpm, to me, that would make a need for light rods? yes/no?

Eagle makes a great rod, we all know that, I would tend to believe that K1's are miles ahead, would you also not agree? if the goal is ultimate life, etc, I would say based on company reputation, then Carrillo would be the top choice, again, would you not agree?

[Frank]

Not the point. Aluminum rods while lighter and in tern allow you to rev easier have less strength. At 8k rpms, if I can't buy a light weight piston and pin, whats the point of an aluminum rod if I run the higher chance of breaking the rod compared to keeping with our common forged piston and say K1's.

My problem is someone tells someone to run aluminum without looking at the system as a whole when next to no one has run aluminum at those RPMs is not wise. It could very well be fine, but until you consider all aspects of the system even if they turn out to be null and void....

Frank

[turbovanman²]

Not the point. Aluminum rods while lighter and in tern allow you to rev easier have less strength. At 8k rpms, if I can't buy a light weight piston and pin, whats the point of an aluminum rod if I run the higher chance of breaking the rod compared to keeping with our common forged piston and say K1's.

My problem is someone tells someone to run aluminum without looking at the system as a whole when next to no one has run aluminum at those RPMs is not wise. It could very well be fine, but until you consider all aspects of the system even if they turn out to be null and void....

Frank


Exactly, his engine build up is vague at best, throwing out idea's, thats what we are here for and since only you and I have answered, his info is limited at best.

[Speedeuphoria]

Pauter Billet Rods are another option
http://www.pauter.com/billet_rods.htm

they run ~$700-800 a set

they normally have them in stock for the SRT4(so any Dodge 2.4) I have the weights that I'll post later on when I find my info

[Mario]

Bottom line IS if he has the cash for this "600HP" 8V, he has the cash to go with whatever rods he chooses, whether it be titanium, aluminum, steel, or lead (joke, haha).

I really wasn't being all that serious, I just thought I'd throw something out there. As Frank said, it really depends on the application.

Isn't titanium, really the best though?

[8valves]

Isn't titanium, really the best though?

Once again, totally application specific.

I'd venture to guess that above 7500 rpms in our engines, 2.5 need not apply, playing with geometry is probably a better bet than all out weight savings. Get a slightly longer rod with a rasied wrist pin location to let it want to live a little better up high.

[Directconnection]

That's my view on it.

[GLHNSLHT2]

ok, sorry for being vague. While aluminum rods would be much lighter I do plan to drive this thing whenever I want. Engine specs, 2.2 Forged crank Commonblock, JE pistons, scraper/windage tray blah blah all the other block tricks. For the head, 16v Maserati head, ported, lightweight valvetrain components (titanium retainers, dual race springs lighweight buckets etc.) and oversize valves, The exhaust valves are inconel, not sure on the intake. Ported exhaust manifold (flows over 700cfm according to the guy porting) I know it made the stock head flow 15cfm more just by bolting the stock exhaust manny on mmmmmmm. Ported intake stock intake manifold with bigger plenum and larger TB. GT35R turbo with 4" exhaust, external gate etc. Right now planning on going with a water/air i/c with 3" plumbing. As soon as aftermarket cams are available they will be bolted in.

Rods are the only unknown variable right now. I was thinking of using the masi crank as the rods are beautiful but the crank is too heavy and the bearings aren't as wide on the big end. I'd like something that will meet my goals while being as cheap as possible. The money I can save might be better spent elsewhere ya know.

I've looked at Pauter and they look really nice. And at about half the price of Carrillo's that'd be nice too. Are SRT4 rods longer or shorter than T2 rods? I was also thinking that having a slightly longer rod (would .050 be too much?) would be benificial and not hurt the strenth of the piston.

I also would like to stick with a steel rod. Aluminum is nice but only if you're gonna tear the motor down once a year. Titanium is a bit out of my price range . I'm not going to be tooling around town. When it get's driven it's gonna be driven hard :) Might even be a competitor for SCC's Ultimate Street Car Challange if I can get enough tire under it. Thanks guys.

[Mario]

Ahh, 16V.

[turbovanman²]

The SRT rod is the same length as our T2 rods, the Eagle version weights like 150 grams less, check out my FAQ on weights. Use need to use SRT rod bearings but the wrist pin end is .866 so you need custom pistons like I am having done or remove the bronze bushing and run metal on metal, which would be fine too.

I would see if you could get lighter pistons made and maybe use some titanium or casdium? wrist pins, there 20-40 grams lighter than our steel ones.

Rods, not an expert but maybe give Pauter a call, for $700-800 bucks, sounds like a good deal.

[TurboJerry]

Put a 3.250" stroke in it and it will make really good top end power. (or at least make the stroke the same dimension as the bore)Aluminum rods are not weaker, they just have a limited life cycle. You can put 5000 hp on them, but when the life cycle is up, they will break. I prefer steel rods only because of street use. Steel is much heaver then aluminum, so there is a big weight savings. Any exotic metal rods have a limited life span. Eagle rods would be fine for 99.9% of applications. Running a rod and pin steel on steel will start to gall if run for a longer periods of time.

[glhs727]

agreed, on the Eagles do NOT remove bushing and run the wrist pin as Simon suggested.
Rebush the small end and open bushing for new pin.
later,
Cindy

[turbovanman²]

agreed, on the Eagles do NOT remove bushing and run the wrist pin as Simon suggested.
Rebush the small end and open bushing for new pin.
later,
Cindy

I have talked to some of my hipo shops that build insane motors that live and they say it won't be an issue. There is also not enough material on the small end to safely make it bigger for .901 pins.

[2.216VTurbo]

Ahh, 16V.

Ahh, MASI 16V:D

Jay Joined the 'club' a few months ago:partywoot:

[Reaper1]

I know that it is REALLY expensive...and most of us would never try this, but what about titanium rods? Lighter than steel, stronger than aluminum, and less bunky than aluminum. Also, you don't run in to the "life cycle" issue.

I've asked about using aluminum rods on a street motor. It *can* be done. You just have to be careful. The big issue was back in the day the aluminum wasn't as good of anb alloy and would work harden over time, making it brittle as well as making it so you had to allow for a lot of stretch for high rpm. Nowdays the newer alloys are much better and have quelled these issue to an extent. Would I suggest this for a DD? NO! But for a weekend warrior that has fun and drives it once ina while to work and such..no biggie....

[8valves]

I know that it is REALLY expensive...and most of us would never try this, but what about titanium rods? Lighter than steel, stronger than aluminum, and less bunky than aluminum. Also, you don't run in to the "life cycle" issue.

I've asked about using aluminum rods on a street motor. It *can* be done. You just have to be careful. The big issue was back in the day the aluminum wasn't as good of anb alloy and would work harden over time, making it brittle as well as making it so you had to allow for a lot of stretch for high rpm. Nowdays the newer alloys are much better and have quelled these issue to an extent. Would I suggest this for a DD? NO! But for a weekend warrior that has fun and drives it once ina while to work and such..no biggie....


I think people are looking at this the wrong way possibly. Steel rods are not obsolete whatsoever, and just because he wants to run up to 8K doesn't mean that all the weight in the world needs to be done away with.

Taking stroke into account, a steel rod can live to much higher than 8K. Heck, a stock B16A Honda turns 8600, and stock motors with removed limiters will go as high as 9400.

It's not the material, it's the geometry. Pauter, Crower, and I believe Carrillo will make you any rod you want, you just have to wait for a bit and give them dimensions... if they're wrong that's your problem. They're not out of this world expensive either. If you're going to such extents I would invest in a strong set of steel rods and go with the longer rod. Take or send a stock piston to a manufacturer such as Wiseco who will make a custom piston and ask how much higher can the pin go without sacrificing strength. That answer plus a stock rod will give you your new rod length. Voila, same displacement, less bottom end torque, more top end HP.

[Frank]

Eactly! Geometry is everything... it determines how fast the piston must slow down, how much bending the rod must endure on the down stroke, and how fast the piston must slow down.

[Directconnection]

I have talked to some of my hipo shops that build insane motors that live and they say it won't be an issue. There is also not enough material on the small end to safely make it bigger for .901 pins.


I have not seen one metal on metel full floating setup here in this shop and would advise against that idea as well. You would need to find a bushing for a different application which fits in the small end's bore that has alot of material in it so you could bore/hone the bushing to the new smaller size.

[Directconnection]

I know that it is REALLY expensive...and most of us would never try this, but what about titanium rods? Lighter than steel, stronger than aluminum, and less bunky than aluminum. Also, you don't run in to the "life cycle" issue.

All out lightweight STEEL rod is the Crower Maxi-lite. Not sure of the forging material, but it is the cat's meow of steel rods in the circle track region. Not Ti though and is very strong and light (and $$)

[Directconnection]

Proper geometries keep piston velocities lower which can help rpms and also high rpm hp due to minimizing mass of the rotating assembly which increases exponentially as the rpms go up. Short strokes allow the use of longer rod which give you great rod ratio and all it's advantages and using a shorter piston = lighter. It's a quadruple edged sword.

[turbovanman²]

I have not seen one metal on metel full floating setup here in this shop and would advise against that idea as well. You would need to find a bushing for a different application which fits in the small end's bore that has alot of material in it so you could bore/hone the bushing to the new smaller size.


I thought the same thing and thats why I just had the pistons altered. There small end is well, small, and if you ream out the rod for a larger bushing, theres nothing left. It would make for a very weak wrist pin area.

[Directconnection]

I thought the same thing and thats why I just had the pistons altered. There small end is well, small, and if you ream out the rod for a larger bushing, theres nothing left. It would make for a very weak wrist pin area.


I was thinking backwards.... really tired and sleep deprived like I usualy am come friday:) .

[Birddog]

I'd like something that will meet my goals while being as cheap as possible. The money I can save might be better spent elsewhere ya know.

This is not an area where you want to be cheap... IMHO I'd pop the dough for the Carillos and not have to worry as much about it...



All out lightweight STEEL rod is the Crower Maxi-lite. Not sure of the forging material, but it is the cat's meow of steel rods in the circle track region. Not Ti though and is very strong and light (and $$)

2 choices with Crower Maxis. 4340 steel or 6al4v AKA Titanium. More or less the same as Pauter rods.

[turbovanman²]

I was thinking backwards.... really tired and sleep deprived like I usualy am come friday:) .

You had it right, ;)

[GLHNSLHT2]

This is not an area where you want to be cheap... IMHO I'd pop the dough for the Carillos and not have to worry as much about it...




2 choices with Crower Maxis. 4340 steel or 6al4v AKA Titanium. More or less the same as Pauter rods.


Well if a less expensive rod (pauter/crower/K1??) will be more than I need then it'd just be overkill for the Carillo's.

I'll be running JE's that raise the compression from the stock 7.3:1 to 8.3:1 so I'll have to see if I can have the pin raised up a bit.

[glhs875]

You really should start a thread and tell us the recipe for 600HP and a powerband that goes to 8,000 RPMs from a 2.2 8V. I'd really be interested.[/QUOTE]

Personally, I think peak power @ 8000rpm and 600HP would be asking alot from an 8V. It would definitely require some serious port work, opening up the cross sectional area of the ports to work well in that rpm range. Along with a cam that could breathe up there as well. Both of which can reduce throttle response and low end torque. In other words, it would most likely be very peaky engine like the small high revving Honda's, maybe even worse. I measured the cross sectional area of a stock G head (smallest area of the port is the choke point not largest) and got around 1.43 square in. On a 2.2, 1.43 sq. in. gives an rpm choke point due to velocity speed limitations around 5800rpm. That's pretty much where a well setup stock headed combo will pull good too. The ports on my highly ported G head measure around 1.78 sq. in. The rpm choke point of that area on a 2.2 is around 7200rpm. And that's where my engine seems to pull good too even with a stock cam. The area of the port would have to be over 2.0 sq. in. to work well to 8000rpm on an 8v and even a 16V. It's easier to get the area needed on a 16V with more valve area and a larger port entrance then what is usually on our 8V heads. 2.0 sq. in. is a big port on a 2.2! One could use smaller ports and a long duration cam and spin to 8000rpm, but peak HP won't be as high as if a larger port were used. Or destroke the crank lowering the cu. in. of the engine would help also. But I like displacement over very high revving capabilty on a street/strip combo. When it comes to making good power high the R's the area of the port needs to be large enough to do so even if the port flows really well. Upping the flow of the port while keeping the area of the smallest part of the port basically the same as stock will definitely make more power, but within the same basic rpm range as when stock. That's my opinion. And seems to hold true on my combo. And of course lighter parts (like rods,pistons, etc.) and longer rods (higher rod ratio) can further enhance upper rpm HP.

[puppet]

That holds true for everybody really. Smaller cross section combined with short runners equal better low end response/torque while larger cross section combined with longer runners equal better upper end response. (providing that your stuff can flow) There are formulas to get close to the ideal length and shape but you need to pick an engine speed and be happy.You can't have it all without some sort of dual runner affair. Then you have the additional drag associated with the extra plumbing and then the air/fueling issues. PITA without some major investment in R/D.

One thing that maybe hasn't been experimented with enough is injector placement. I know that the farther away you get from the intake valve the better fuel atomization is ... supporting better power. What we have now is probably a nice compromise between good mileage, emissions, etc. There are calculations for injector placement too. Working in this area might provide some nice results for the right engine ... and it's simple.

I know Warren runs ITB's ... I'll bet he has nice throttle response because of it too.

[GLHNSLHT2]

Not sure if post #67 was directed at me in any way but I'm not not even thinking about this on an 8v. Read post #49 for the recipe. I don't need to make peak power at 8grand but was more thinking that'd be my shift points at the track. So peak power at 7k-7500?? With a nice flat power curve? Anyway Back to rods. Want rods that will live at that RPM or more.

Choices so far are Pauter/Crower/Carrillo/K1. $1400 is a big chunk of change to throw out there for Carrillo's. Pauter's seem to run $800ish. and Crower who knows. Will the K1's live?

As for length I think the Masi uses an .866 pin. Same as SRT4? And I'll have to see how far I can raise the pin. Anyone (Frank/Aaron/etc) have an idea on the rod length I should be shooting for? I'll so some more research on pin size to find out.

thanks guys

[Directconnection]

I decided I am going with aluminum rods (my own custom design). I got them in yesterday and already hung up my pistons so they're ready to rock 'n roll. Here's a pic:

[Directconnection]

Ok...cat's out of the bag.... they're actually for a 5hp Briggs and Stratton I was working on yesterday. As you can see, it's a race motor for a go-kart. Reportedly going to make alot more than just 5hp. I had to deck the block and the piston so it had a deck height of .005" out of the hole which is the max spec you are allowed. You can't see it as I covered it up in the pic and forgot to uncover for the 2nd pic, but the rod bearings have an actual oil hole and get semi pressurized oil fed in through a slinger. On the very bottom of the cap, it's a knife/wedge shaped part that on this engine extends about 2-1/2". At the very end, the sliger is supposed to splash oil up to the rod bearings and piston, etc...this one does that, but is also drilled all the way up to the cap. Kinda neat looking. Old car engines used the slinger, but I never saw them have the oil feed hole.


Here's a pic of a Venolia aluminum rod sitting out so I had to snap a pic of that as well. Didn't know Venolia made aluminum rods. I would go BME for aluminum rods since they are the top choice out there in top fuel and others. Really nice polished finish on them and they now offer a new finish that is like a light shot-peen. One set of BME's went on a 388" SB Chevy that was going to make some serious power in a mud buggy (1,000+ hp n/a)

[TurboJerry]

I think the Eagles will live. There are 1900 hp V-8's with Eagle rods and show no signs of letting go any time soon..... The K-1's should be even better though.....

[2.216VTurbo]

Ok...cat's out of the bag.... they're actually for a 5hp Briggs and Stratton I was working on yesterday. As you can see, it's a race motor for a go-kart. Reportedly going to make alot more than just 5hp. I had to deck the block and the piston so it had a deck height of .005" out of the hole which is the max spec you are allowed. You can't see it as I covered it up in the pic and forgot to uncover for the 2nd pic, but the rod bearings have an actual oil hole and get semi pressurized oil fed in through a slinger. On the very bottom of the cap, it's a knife/wedge shaped part that on this engine extends about 2-1/2". At the very end, the sliger is supposed to splash oil up to the rod bearings and piston, etc...this one does that, but is also drilled all the way up to the cap. Kinda neat looking. Old car engines used the slinger, but I never saw them have the oil feed hole.


Here's a pic of a Venolia aluminum rod sitting out so I had to snap a pic of that as well. Didn't know Venolia made aluminum rods. I would go BME for aluminum rods since they are the top choice out there in top fuel and others. Really nice polished finish on them and they now offer a new finish that is like a light shot-peen. One set of BME's went on a 388" SB Chevy that was going to make some serious power in a mud buggy (1,000+ hp n/a)

I'm looking at that pic thinking to myself, why the heck would he run a cast piston with high dollar rods:confused: ;)

[Directconnection]

I knew some people would spot that... hehe. it's a new super forging cast proccess called hyperueforged.

[TurboJerry]

I knew some people would spot that... hehe. it's a new super forging cast proccess called hyperueforged.

I believe it's actually Hyperueforgedit........:D

[turbovanman²]

I'm looking at that pic thinking to myself, why the heck would he run a cast piston with high dollar rods:confused: ;)

I thought the same thing, great minds think alike, :eyebrows:

[Directconnection]

I have not seen one metal on metel full floating setup here in this shop and would advise against that idea as well. You would need to find a bushing for a different application which fits in the small end's bore that has alot of material in it so you could bore/hone the bushing to the new smaller size.

Murphy's law. Saw my 1st set like this today. Stock SB Chevy rods that someone honed out to become full floating. Funny thing is that the small end looked fine along with the pins, but they are being tossed in favor of full floating rods.

[BadAssPerformance]

Did somebody say "big rod" discussion? I like my 'big' FM rods :D

http://mm-racing.com/alumpistonrod.jpg

[turbovanman²]

Did somebody say "big rod" discussion? I like my 'big' FM rods :D

http://mm-racing.com/alumpistonrod.jpg

Damn dude, sexy, :thumb:

[BadAssPerformance]

Damn dude, sexy, :thumb:

Thanks, LOL... you dig my rod! ;)

[Ondonti]

Can someone explain this superior geometry a bit more in depth because most hondas i know of have Rod ratios's in the 1.5's
I think some people here are juts a bit too paranoid about failures that nobody seems to ever have (RPM related failure).

[BadAssPerformance]

Wow, only 1.5? which engine? you got the stroke and rod length?

[Reaper1]

The 1.6L SOHC engine (B16A??) and the 1.8L S&DOHC both have rod ratios in the 1.5's....1.56 IIRC. The thing is that the bore is so small that side loading isn't a huge factor here(among other things).

The issue isn't particilarly with rpm related failier. We most likely won't really see that too much due to our overall engine design. Some of the DOHC guys *might*. The thing that is in question is efficiency. As with everything, even rod ratio is a compromise. Some say a little lower ratio becuase the pistons will spend more time at BDC giving better cylinder filling. Others say a little higher rod ratio to slow the piston down and give it more dwell time at TDC. The "magic" number is 1.78:1 from what I've been told by several people that have been around engines longer than I've been alive and who remember when slide rules were the only pocket calculators! Side loading is only part of the story here. A higher rod ratio puts less stress on the side of the piston while it is traveling the cylinder bore. This helps with efficiency, heat, longentivity, and power(all to varying degrees). The thing that opens MY eyes and makes me want to hit that number more than almost anything else is this...if the piston is moving down too fast at a given rpm, the flame front from the combustion process has to chase the piston down. When it is chasing, it isn't exerting force on the piston and so no additional power is being made. High octane fuels only make this probelm worse because they burn slower! For us, this engine speed is around 6500rpm on a 2.5L. I don't really know what it is on a 2.2L, but I'd imagine around 72-7500rpm.

Now, you're going to ask about those Hondas again...again the answer is bore size! There's less space for the flame front to take up, so they can get away with having a higher piston speed and not outruning the combustion event....it expands at the same rate regardless of the engine...less space to fill=less filling time=more psitons speed is acceptable!

Another bennefit to rod ratio is that it can allow better cam profiles to be used and can also make the engine easier to tune. There's a whole bunch of reasons for this, but I honestly have put more energy in to studying the piston speed than anything else.

There was a whole other thread on this on the "other" site a while back that had a LOT of good info in it.

[Ondonti]

I would bet the k24 has a low rod ratio too.

[BadAssPerformance]

yeah, bore and also small displacement (read: less mass)... how small are the pistons in those F1 engines that run to 18k rpm? ;)

[TurboJerry]

If you want an engine to run 200,000 miles, then a longer rod will *help*. But the smaller and lighter the reciprocating parts are, the less stress on the engine. Of course a 2.5 has a crappy ratio, but they run 200,000 easily. But 2.5's can get very noisy because of all the side loads from the short rod ratio. So there's exceptions to everything.......

[Reaper1]

Most of a 2.5's noise comes from piston slap due to worn out pin bores that comes from the pistons accelerating and declerating under very high G-forces and wearing themselves out...alkong with a little psiton rock due to worn out side skirts(what little there is on a 2.5 piston!)

[GLHNSLHT2]

yeah, bore and also small displacement (read: less mass)... how small are the pistons in those F1 engines that run to 18k rpm? ;)

18k? They're limited to 19k this year, and where hitting 21k last year. If they hadn't changed the rules they would probably be closer to 22k. They're 2.4 ltr V8's the last 2 years as well with a very short stroke compared to bore. 3 years ago they were 3.0ltr V10's making upwards of 200hp more. Best part. Even with 200hp less and crappier tires to try and slow the cars down they're very close to the qualifying records previously set by the more powerful V10's. Also a the higher you rev a V8 the worse the harmonics become to where it want's to shake itself apart. Where the V10's would vibrate from 10k to 16k but above that would smooth out. So think about 21k in a V8 that starts having bad harmonics at 10k. It's amazing those motors don't just nuke at 17k.

[EXTRME PSI]

old thread revisited !!! i have been told that the srt-4 rods are now being used in the 2.2 block, i am building a very high hp t3 600hp + and want the best rods available
what if any of this info since 2007 still holds true or has it changed

[turismolover22]

Yes, an srt rod will work in the 2.2 family. Use srt-4 crank bearings and have the pin end bushed out for larger wristpin. Srt is .875, 2.2 stock is .901 iirc. Then venolias are .912, last I remembered

[Chris W]

Yes, an srt rod will work in the 2.2 family. Use srt-4 crank bearings and have the pin end bushed out for larger wristpin. Srt is .875, 2.2 stock is .901 iirc. Then venolias are .912, last I remembered

And we have the last remaining SRT-4 rods made by K1 right here:

http://www.turbo-mopar.com/forums/showthread.php?73266-****EXCLUSIVE-T-M-Neon-Caliber-SRT-4-Billet-H-Beam-Connecting-Rod-Sale-275-00!!!****

Remember to order the piston wrist pins to match the rods.

Chris-TU

[glhs875]

Weird, wonder if the 2.2's are a heavier construction?

Did you take out the wrist pin? :lol:

The compression height is shorter on a 2.5 piston making it lighter than a 2.2 piston. I would like to have some good 6.18" rods made up and then have some custom 2.5 style pistons made up to use for a 2.2!

[Reaper1]

I'm using BC Pro rods for a SRT-4 in my build. I think those aught to do the trick. BTW, using the smaller wrist pin saves some weight and if the pistons you are using are lighter than stock you gain even more. The old thinking was to use a larger diameter pin for piston rock, but I think most people have found the weight savings by sticking to the stock size or even smaller is of more benefit.

[glhs727]

old thread revisited !!! i have been told that the srt-4 rods are now being used in the 2.2 block, i am building a very high hp t3 600hp + and want the best rods available
what if any of this info since 2007 still holds true or has it changed

we have BC (Brian Crower) custom make 2.2/2.5 H-beam rods for us. We have them on the shelf ready to ship with either the .901 pin or the .912 pin. These are rated for 800hp and have the ARP2000 rod bolts. These use the 2.2/2.5 rod bearings as well

[Ondonti]

I'm using BC Pro rods for a SRT-4 in my build. I think those aught to do the trick. BTW, using the smaller wrist pin saves some weight and if the pistons you are using are lighter than stock you gain even more. The old thinking was to use a larger diameter pin for piston rock, but I think most people have found the weight savings by sticking to the stock size or even smaller is of more benefit.

6g72's have piston pins bend at high power levels, and I noticed when searching up the diameter (.866) that the next generation 6g75 motor went larger diameter (.905) even though the rods were MUCH thinner.
6g72's with stock pin size often end up going with tool steel thick wall pins at higher HP levels (over 100hp per rod).

[glhs727]

6g72's have piston pins bend at high power levels, and I noticed when searching up the diameter (.866) that the next generation 6g75 motor went larger diameter (.905) even though the rods were MUCH thinner.
6g72's with stock pin size often end up going with tool steel thick wall pins at higher HP levels (175hp per rod).

That's a valid point! I haven't seen any issues with the .912 pins under 400hp, but I know several guys in the 400+ range that were trashing the pins and needed to move up on the pins to a thicker wall version. I know one guy was using the srt .866 piston pins and his were in a bad shape with only one season of racing.
We do sell the upgraded pins for people that plan to make mega hp, but they aren't cheap!

[Ondonti]

That HP level I mentioned is completely wrong. I meant people going over 100hp/rod. That matches up with what Cindy is saying for a similar size pin. Some of that will depend on the width of the small end of the rod and the width of the piston pin bosses. Making the pin carry more load is bad even if you are saving weight.

A lot of people can get away with 100hp/cylinder but the more torque you make (low rpm hp) the more stress you put on those pins. The guys changing just above those levels are running E85 and trying to build high torque setups for fun street use with big power. High torque is the worst thing for a motor on the edge of compression strength.

[EXTRME PSI]

we have BC (Brian Crower) custom make 2.2/2.5 H-beam rods for us. We have them on the shelf ready to ship with either the .901 pin or the .912 pin. These are rated for 800hp and have the ARP2000 rod bolts. These use the 2.2/2.5 rod bearings as well
to be honest im hoping to be over 800hp in the next few years and don't want to buy rods again in the near future after much research i am thinking of using Pauter rods

[EXTRME PSI]

received this pm, "i wont say who but i do agree 100% "
Unless the rod is grossly under designed, it will not break due to HP so anyone referencing HP does not know enough about what causes rods to fail. Piston/rod weight combined with RPMs is what causes rods to fail. Because power is produced from the expanding gasses pushing down on the piston, there is a compressive (pushing) load on the rod. If a rod broke due to power, it would be crushed. The fact is, rods are broken due to being pulled in two. This high tension (pulling) load is highest at TDC on the exhaust stroke when the piston is trying to go through the cylinder head and the crank tries to pull it back down. The reason it is highest at this point is because the other time the piston is at TDC is on the compression stroke and the piston is being pushed back down by the gas loads of the compressed air/fuel mixture. To the best of my knowledge, there is no power being created on the exhaust stroke so rating rods by Horsepower is simply not applicable. Most people including some rod manufacturers do not realize this. Fortunately for us, turbocharged engines do provide "some" backpressure on the exhaust stroke reducing that stretching force on the rods.

[Ondonti]

received this pm, "i wont say who but i do agree 100% "
Unless the rod is grossly under designed, it will not break due to HP so anyone referencing HP does not know enough about what causes rods to fail. Piston/rod weight combined with RPMs is what causes rods to fail. Because power is produced from the expanding gasses pushing down on the piston, there is a compressive (pushing) load on the rod. If a rod broke due to power, it would be crushed. The fact is, rods are broken due to being pulled in two. This high tension (pulling) load is highest at TDC on the exhaust stroke when the piston is trying to go through the cylinder head and the crank tries to pull it back down. The reason it is highest at this point is because the other time the piston is at TDC is on the compression stroke and the piston is being pushed back down by the gas loads of the compressed air/fuel mixture. To the best of my knowledge, there is no power being created on the exhaust stroke so rating rods by Horsepower is simply not applicable. Most people including some rod manufacturers do not realize this. Fortunately for us, turbocharged engines do provide "some" backpressure on the exhaust stroke reducing that stretching force on the rods.

Sounds like somebody quoting some books I have read that focus on naturally aspirated engines or lightly turbocharged engines in a chapter that is trying to scare people away from high rpm setups. That almost sounds like the introduction to Corky Bell's Maximum Boost. The whole point of that intro is teach people that turbocharging does not necessarily mean the death of your engine, therefore, lets go have fun with it (aka, "you are not wasting your time reading my book").

His "best knowledge" is inadequate and wrong when it comes to extreme turbo setups. Extreme turbo setups bend rods and it usually doesn't happen at high rpms (which totaly blows the quoted stuff above out of the water as far as part weight goes).

I have never seen a properly assembled rod come apart on a 6g72 (which rods are smaller/weaker then 2.2/2.5 big rods except the fasteners are probably superior) BUT stock rods bend all the time when pushed to over 100hp/cylinder. In reality, HP is not exactly what is killing the rods, but it is peak combustion pressure which is happening at peak torque. So to simply think of it, torque per cylinder bends rods but most mild rpm turbo setups make similar HP as torque and many dynos with bad rpm pickups don't give out torque numbers.

The next thing that fails is the pins bend or the main bearing caps start separating from the block etc etc etc.

So if we want to go into full douche mode,
================================================== ===============================

Peak combustion pressure bends rods, E85 actually decreases peak combustion pressures so equal torque #'s the E85 shortblock will survive more abuse. E85 extends the high compression levels throughout the combustion stroke so it still makes the same power but the decreased peak combustion pressure means less shock load on the rod, less bending.

Simple proof would be looking into new Nissan GTR's that bend rods on gasoline with stock turbos but similar power E85 setups usually don't. I think the combustion pressure difference was something like comparing 1300psi on gasoline vs 1000 on E85. I don't want to look it up for someone sending condescending PM's.
================================================== ================================================== ==

If you are planning on very high rpms then you are going to have to look at the weight of your parts, your rod ratio, and balance that with your peak combustion pressure needs. Most good rods just need improved fasteners to handle ridiculous rpms. Tool steel connecting rod fasteners are the next step up (ARP 625+ for example). IMO, aluminum rods are more important for how they absorb shock loads that would hurt crankshafts/bearings etc than any weight savings people worry about. Lots of guys run them when they have bearing problems. Other people run them because it seemed like a good idea at the time. I don't like their short cycle life but if I had bottom end problems they make sense. If you are running 800whp (200hp/cylinder) its possible you will have bearing problems and its a good chance that aluminum rods would solve that. I would skip them and only try if you can't keep a bearing in your motor. 800whp is when 4g63's start having rod bearing problems.

[Reaper1]

I agree that 99% of rod failures have to do with high rpm, and a lot of the time it's right as the throttle is lifted (the engine is compression braking or freewheeling). That is not to say that rods don't bend or break under power. Rods (aka pillars or columns) are typically better in compression than in tension. However, when you induce angles to the loads, then you start introducing some bending moments as well. Those bending moments can be on more than 1 axis, hence why H-beam rods are popular as they resist those types of loads much better than say a round cross section.

I find it interesting that people have problems bending wrist pins. I can understand what may be causing this, but even in hydrolocked engines where the rod is bent/broken due to a compression load much greater than it was ever designed for I've found it not that common for the pin to be bent. Given that the piston is aluminum I'd expect the pin bore to elongate due to work hardening the aluminum before the pin bending. Of course the material and thickness of the pin will have a large impact on what actually happens, plus it has to be considered that the pin is in single shear while the piston is in double shear.

From the descriptions of what people are doing when they have these issues it almost sounds more like a tuning problem given that the reason stated for this phenomena is peak cylinder pressure. There is a larger chance of things not being happy when that happens close to TDC. It almost sounds like a little compromise on torque by retarding the timing a bit would help this. Of course I'll admit that I have a lot of theory background, but my real-world is lacking...a LOT. :(

I just did a basic search for bend wrist pins (for all kinds of applications), and it really doesn't seem that common. Thickness of the wall seems to be the main culprit, then material, then pin length. There are a LOT of applications that run the .866 (22mm) pin size. From the limited search I did it seems about 600whp is around where people start to see problems with the stock .866/.150 thick pins in DSM's. The one upgrade I found was an increase in pin wall thickness to .225. It looks like an upgrade to 9310 steel is also very common, though not cheap (probably the alternate upgrade being offered by out vendors), the one site I finally found a price for pins alone were just over $100 for a set.

It also sounds like beyond the reduced fatigue due to the constant deformation of the pin that lubrication plays a large factor in pin failure. Once the pin is scored, it is doomed. That stress riser will kill the pin.

One more factor I found, and honestly didn't take into account due to I was thinking about the bore deforming, was that when a pin bends, it is also putting stress on the piston and can lead to a broken piston as well. That would be pretty nasty.

Anyway, the pin diameter doesn't seem to be the issue. It's the wall thickness and material.

[EXTRME PSI]

has anyone used Pauter rods ?

[Pat]

I believe Bruce Bender ran Pauter rods in his car for years. Not sure if he's on here much these days though.

[2.216VTurbo]

[QUOTE=EXTRME PSI;1046906]has anyone used Pauter rods ?[/QUOTE



Lots of the air cooled Volkswagon ProMod guys use the Pauter's. Several of those cars are above 800HP level.

[Ondonti]

Chris, I don't exactly know where you are going with your post. The person private messaging, whether its your or anyone else, needs to research boosted engines and ignore information about other engines.

99% of rod failures among all engines regardless of application has nothing to do with rod failures in the type of high boost engine that we are looking at (and I would bet most failed rods are caused by oil starvation and owners who continue to drive the damaged engine). I know your background is not in turbocharged engines and the stuff you are interested in is actually not turbocharged (no matter how many turbochargers you want to put on your own car.) You have to admit this. I know what you follow. The ONLY thing I follow are boosted engines and people who build/break them.

Research. I have seen the evidence, I am not conjecturing which you are admitting to above. My stock engine build program is planned around the idea of limiting torque output and increasing rpms to achieve higher HP without losing a stock rod.

In highly boosted compressions The compression loads on the rods are extreme and no matter how well designed they are, when you run 300-500% more horsepower through and engine then designed, its no wonder pins and rods have problems.

I mentioned the pins as a very useful bit of advice because its a fact that many people here have no exposure to extreme turbocharged engines since basically nobody on this site has one. If they do, they probably know all the ins and outs thanks to unmentioned failures or their engine builder does.
I have custom wrist pins in my built block and they are done with a tapered inner bore (venolia). I don't know what my custom ones are capable of since they are lighter than stock and are an unknown material but .220 tool steel pins for me cost over 200 dollars.

Decreasing peak combustion pressure will just hurt HP. When you are at that level you can't make the mistakes you did when you were slow. Detonation introduces huge combustion pressures but when I am talking about bending rods I am referring to knock free motors and the rods bending from knock free combustion pressure. The number of cycles they will live becomes very short when exposed to so much more power then they were designed for.

If people want to go build motors for an RPM they will never see or obsess about weight loss on parts that ONLY matters in restricted racing classes where every advantage is needed...........go ahead. Waste your money and your time. I don't understand why people try to mimic things they see on professional racing engines (that are not even turbocharged) that are regulated into NOT doing what is best for the budget for nearly the same results. Most upgraded rods are lighter then stock for motors that have strong factory rods. No worries about adding weight there.

2.2/2.5L Chryslers are already blessed with a large piston pin so even the guys making big power might never have noticed a problem. If you go with .866 pins I don't see your goals working out, especially a compound turbo setup (rod killer).

[boostedsohc]

Sounds like somebody quoting some books I have read that focus on naturally aspirated engines or lightly turbocharged engines in a chapter that is trying to scare people away from high rpm setups. That almost sounds like the introduction to Corky Bell's Maximum Boost. The whole point of that intro is teach people that turbocharging does not necessarily mean the death of your engine, therefore, lets go have fun with it (aka, "you are not wasting your time reading my book").

His "best knowledge" is inadequate and wrong when it comes to extreme turbo setups. Extreme turbo setups bend rods and it usually doesn't happen at high rpms (which totaly blows the quoted stuff above out of the water as far as part weight goes).

I have never seen a properly assembled rod come apart on a 6g72 (which rods are smaller/weaker then 2.2/2.5 big rods except the fasteners are probably superior) BUT stock rods bend all the time when pushed to over 100hp/cylinder. In reality, HP is not exactly what is killing the rods, but it is peak combustion pressure which is happening at peak torque. So to simply think of it, torque per cylinder bends rods but most mild rpm turbo setups make similar HP as torque and many dynos with bad rpm pickups don't give out torque numbers.

The next thing that fails is the pins bend or the main bearing caps start separating from the block etc etc etc.

So if we want to go into full douche mode,
================================================== ===============================

Peak combustion pressure bends rods, E85 actually decreases peak combustion pressures so equal torque #'s the E85 shortblock will survive more abuse. E85 extends the high compression levels throughout the combustion stroke so it still makes the same power but the decreased peak combustion pressure means less shock load on the rod, less bending.

Simple proof would be looking into new Nissan GTR's that bend rods on gasoline with stock turbos but similar power E85 setups usually don't. I think the combustion pressure difference was something like comparing 1300psi on gasoline vs 1000 on E85. I don't want to look it up for someone sending condescending PM's.
================================================== ================================================== ==

If you are planning on very high rpms then you are going to have to look at the weight of your parts, your rod ratio, and balance that with your peak combustion pressure needs. Most good rods just need improved fasteners to handle ridiculous rpms. Tool steel connecting rod fasteners are the next step up (ARP 625+ for example). IMO, aluminum rods are more important for how they absorb shock loads that would hurt crankshafts/bearings etc than any weight savings people worry about. Lots of guys run them when they have bearing problems. Other people run them because it seemed like a good idea at the time. I don't like their short cycle life but if I had bottom end problems they make sense. If you are running 800whp (200hp/cylinder) its possible you will have bearing problems and its a good chance that aluminum rods would solve that. I would skip them and only try if you can't keep a bearing in your motor. 800whp is when 4g63's start having rod bearing problems.

They recommend that during a 6G72 rebuild with intentions of greater than 400whp to replace wrist pins with stronger wrist pins due to the torque that is exerted on the connecting rods. They also recommend running thicker H-Beam rods if you plan on going over 500whp, however the rods can bend easily in a 6G72 engine.

[EXTRME PSI]

ok we are NOT building a 6g72 engine i am building a t3 2.2 16 valve engine the block has been upgraded to 4 bolt mains and im going to run venolia pistons ,the head has been race ported and i have custom designed cams, i have not decided on fuel or turbo yet

[Reaper1]

Chris, I don't exactly know where you are going with your post. The person private messaging, whether its your or anyone else, needs to research boosted engines and ignore information about other engines.

99% of rod failures among all engines regardless of application has nothing to do with rod failures in the type of high boost engine that we are looking at (and I would bet most failed rods are caused by oil starvation and owners who continue to drive the damaged engine). I know your background is not in turbocharged engines and the stuff you are interested in is actually not turbocharged (no matter how many turbochargers you want to put on your own car.) You have to admit this. I know what you follow. The ONLY thing I follow are boosted engines and people who build/break them.

Research. I have seen the evidence, I am not conjecturing which you are admitting to above. My stock engine build program is planned around the idea of limiting torque output and increasing rpms to achieve higher HP without losing a stock rod.

Brent, you are absolutely correct that it appears I need to do more research about modern ultra high-boost builds. :nod: (BTW, it is not me that is PM'ing in case others were wondering). I was going after the fact that bending rods and wrist pins isn't that common in our community (2.2/2.5) and things to consider when these issues are discussed.

For those that don't know me well:
I have personally never built a non-boosted engine for my own vehicles. My background, more accurately what I'm interested in, is not only about making good power, but also getting to it and being able to use it. Transient response, or how quickly the engine can transition between rpm's is a big interest of mine as well as making that power as efficiently as possible (reducing parasitic losses). So in that regard, yes, I do worry about weights of parts that most people wouldn't even bat an eye at. My own build isn't even on the level I would like it to be, but I've got to start somewhere! :ballchain: LOL A lot of the thinking and train of thought that goes with transient response does come from the N/A world. The discussion of bending wrist pins, or even rods for that matter isn't something that comes up too often on the non-boosted side of things. So, this is an area that is not directly translatable.



If people want to go build motors for an RPM they will never see or obsess about weight loss on parts that ONLY matters in restricted racing classes where every advantage is needed...........go ahead. Waste your money and your time. I don't understand why people try to mimic things they see on professional racing engines (that are not even turbocharged) that are regulated into NOT doing what is best for the budget for nearly the same results. Most upgraded rods are lighter then stock for motors that have strong factory rods. No worries about adding weight there.

So, decreasing peak combustion pressure will decrease torque at a given rpm. Rev it a bit harder and you just gained that horsepower back (horsepower is a function of torque). While I typically will strive to stay at a low rpm for many reasons, there are times, and this may be one, where it makes sense to take a small hit down low to keep things alive. Besides, in these extreme builds, especially with our cars, we are talking torque numbers that are usually close to the power number, which is something that isn't typical. There are guys that have tried to kill low end torque (though I'm thinking even more could be done). The fact is that while it's cool to brag about huge torque numbers for a 4-banger, the exact issues we are talking about, and the driveability factor all indicate that taking a hit on the torque number down low and winding the engine out a bit might be a better way to go...especially for the 16V guys since the valve trains in those heads were designed with higher rpm in mind to begin with.

In any kind of racing or competition, any legal advantage that can be taken should be. Why would you want to leave something on the table? In our world there are no restrictions, so beyond simply building a brick sh*thouse for an engine that can withstand a nuclear holocaust I still think that finding those areas that can make gains in performance, whether it's making 10hp more, or getting the engine to recover from a rpm drop .100 seconds faster are all worthy of investigation. There is a point where the sacrifice between that performance gain and engine longevity will have to be weighed (no pun intended).



2.2/2.5L Chryslers are already blessed with a large piston pin so even the guys making big power might never have noticed a problem. If you go with .866 pins I don't see your goals working out, especially a compound turbo setup (rod killer).

I agree that these engines were built very robust and that might be part of the reason this problem hasn't really surfaced before. There's nothing wrong with .866 pins. It's WHICH .866 pins to use that is the key. ;) :thumb:


ok we are NOT building a 6g72 engine i am building a t3 2.2 16 valve engine the block has been upgraded to 4 bolt mains and im going to run venolia pistons ,the head has been race ported and i have custom designed cams, i have not decided on fuel or turbo yet

Correct. You aren't building a 6Gxx or a 4gxx or a 426 or a B18.... you are building a mechanical device that you are intending to make a certain power. Regardless of the manufacturer, model designation, displacement, number of cylinders...whatever, a reciprocating engine is required to abide by the same physics. Lessons learned by somebody else can help you either avoid pitfalls, or find an edge that others haven't figured out yet.

[EXTRME PSI]

what rods are the big guys running turboshad, Brian Slowe, etc

[Reaper1]

In the BSX update thread pages 8-10 there is a pretty intense connecting rod discussion because Brian fragged a GRP aluminum rod on the dyno. I know he went with a steel rod, but I don't know the manufacturer as it's never really stated ( was only skimming because the thread is 79 pages long! :eek: ), but if I had to guess he went with Pauter rods. No telling what pin size.

The discussion starts here: http://www.turbo-mopar.com/forums/showthread.php?23007-BSX-progress/page8&highlight=connecting+rod+rods+BSX

[Force Fed Mopar]

NASCAR Cup engines all seem to run a .787" pin now. Just an observation, I know they aren't turbocharged :p But they do make 800-900 hp and spin 9500 rpm. However, they also spend most of their time at a high rpm, and don't see the low-rev loads of a boosted street car.

[Chris W]

NASCAR Cup engines all seem to run a .787" pin now. Just an observation, I know they aren't turbocharged :p But they do make 800-900 hp and spin 9500 rpm. However, they also spend most of their time at a high rpm, and don't see the low-rev loads of a boosted street car.

Smaller pin= less surface area and less friction.

Chris-TU

[Reaper1]

I figured people might want to know the specifications of the steels used for wrist pins that are upgrades.



H13
Hardness (Rockwell C): 28-54
Ultimate Strength: 289,000 psi
Yield Strength: 239,000
Elongation at Break: 9%
Poisson's Ratio: 0.30
Shear Modulus: 11700
Density: 0.282 lb/in^3
Alloy Makeup
Carbon: 0.32-0.40%
Chromium: 3.13-5.25%
Iron: >= 90-95%
Molybdenum: 1.33-1.4%
Silicon: 1%
Vanadium: 1%



9310 (these are the typical upgrade pins)
Hardness (Rockwell C): 40
Ultimate Strength: 179,000 psi
Yield Strength: 143,000 psi
Elongation @ Break: 15.7%
Poisson's Ratio: 0.29
Shear Modulus: 116,000 ksi
Density: 0.284 lb/in^3
Alloy Makeup
Carbon: 0.08-0.13%
Chromium: 1.2%
Iron: 94%
Molybdenum: 0.12%
Silicon: 0.28%
Nickle: 3.25%
Phosphorus: 0.025% max
Sodium: 0.025% max


I got confirmation today that my Venoilia pistons (custom ordered) are made of H13 and have .866 OD with a .155 wall thickness. Seeing as H13 is used for matched metal press dies (we have these at work...up to 1500 TONS), I'm thinking I should be OK :thumb:

I'm going to look up some other steels that have been sighted as being used for wrist pins and post those as well.