Harmonic Balancers?

[Goforthz28]

So im getting my build under way, and have come to wonder "why dont we have harmonic balancers?"

Im sure that someone is going to chime in "an inline 4 is inherently balance." But that has nothing to do with torsion vibrations from the chuffing of the cylinders.

Have any of the bug race homies snapped crankshafts before? Are there crankshaft preparations that i should pay to have done prior to assembly? Cryo maybe?

Thank you all for the help and support!
~Mark B

[cordes]

The one thing people never have problems with is breaking cranks. I've literally never seen or heard of it from anyone I know.

[85lebaront2]

Harmonic balancers are just that, designed to cancel or negate inherent resonant frequencies in the engine. The problem is worst in an in-line 6. There were two approaches, US manufacturers balanced the engine at low to mid rpm range, and on a lot of the older engines if you approach it's "redline" it will shake like crazy. I had an old (1961) Mercedes 220Sb, on that little (2.2L) in-line 6, the balancing was for higher rpm as the car had 13" wheels and a 4.10 rear, if you got too low on the rpm it would shake like a dog drying off, and if you sat and just slowly brought the rpm up (no tach), a little above a fast idle, the harmonic vibration would set in.

I know the flat 4s are pretty well inherently balanced, and most flat 6s, but Chevy did use a harmonic balancer on the hotter Corvair engines (it was famous for slipping). Biggest issue with the four cyl and automatic is the idle vibration, so much that the higher line K derived cars have rubber mounted lead triangle in the steering wheel to dampen the tendency of it to "dance" at a stop in gear.

[GLHS60]

Our Engines harmonics are efficiently absorbed by the timing belt.

No other is needed as proven by the lack of broken cranks etc.

Thanks
Randy

[boost geek]

I agree with Randy on the timing belts many of us were using cast cranks me included 2.2 TBI crank failures were unheard of even Simon couldn't break one and he could break almost any thing lol

[GLHS60]

Right on Dick!!

The rolled radius on the crank certainly ads strength too.

Thanks
Randy

[boost geek]

Hi Randy!, to correct my post Simon only ran 2.5 not 2.2 was there such a thing as 2.5 forged cranks? watching that heavy van launch was a cool sight to see!

[cordes]

The 2.5 cranks were cast.

[GLHS60]

Both 2.2 and 2.5 feature a rolled radius crank so you're still correct old buddy!!

Forged 2.5 cranks were common in Dreamland but not here on Earth.:eyebrows:

Thanks
Randy


Hi Randy!, to correct my post Simon only ran 2,5 not 2.2 was there such a thing as 2.5 forged cranks? watching that heavy van launch was a cool sight to see!

[Goforthz28]

Ha, its interesting that yall mention the radiused crank. I just notice that when polishing my crank and though “huh, i thought that was a ‘high performance’ thing...guess i was wrong.” When in fact it is!

My next build will be with a 2.5l crank and im thinking about sending it out for cryo after the machine work to hopefully get some extra durability out of her.

~Mark

[contraption22]

Oddly enough, one of the few cracked 2.2/2.5 crankshafts I have seen in person was on one that had been adapted to accept a harmonic balancer.

[135sohc]

That tiny little crank snout... not much there.

[4 l-bodies]

Both 2.2 and 2.5 feature a rolled radius crank so you're still correct old buddy!!

Forged 2.5 cranks were common in Dreamland but not here on Earth.:eyebrows:

Thanks
Randy

Hey Randy,
Here are some pictures from Dreamland. 2.5 forged crank. This crank was made by Velasco not by Chrysler. Honest, they do exist, not just very many of them. Same guy that owns it, also owns NOS Hans Herman head. MP had 2.5 forged cranks in their catalog starting in 1992. Can't imagine to many people popped for them. Then based on early block?
Todd

[Reaper1]

Hey Randy,
Here are some pictures from Dreamland. 2.5 forged crank. This crank was made by Velasco not by Chrysler. Honest, they do exist, not just very many of them. Same guy that owns it, also owns NOS Hans Herman head. MP had 2.5 forged cranks in their catalog starting in 1992. Can't imagine to many people popped for them. Then based on early block?
Todd

There were several different MP forged cranks to change the displacement of the engine for different classes. I would REALLY like to find a destroked 2.0 crank. I think they had them up to 2.7L? I could swear there was one that was longer than the 2.5's 4.09" stroke.

[4 l-bodies]

There were several different MP forged cranks to change the displacement of the engine for different classes. I would REALLY like to find a destroked 2.0 crank. I think they had them up to 2.7L? I could swear there was one that was longer than the 2.5's 4.09" stroke.

The large stroke MP crank was actually a bit smaller stroke at 3.994" vs. the production 4.09". Never heard of anything beyond 2.5 liter cranks. All motor (RIP) had a supposed 2.7 liter engine (circle track N/A car). Crank was a one off according to him. I remember him telling me it cost more than the whole rest of engine. .060" overbore accounts for about .10 liter in displacement, so his crank was around 4.250" stroke. I know of three people that have 2.0 liter forged cranks. All on the back burner as far as builds. I know of two turbo 2.3 liter Chryslers. One by slight stroke, the other by big overbore. Teaser picture of 2.0 crankshaft.
Todd

[Goforthz28]

Those are some awesome pictures. I wish some of these nostalgic MP parts would start surfacing again. Surely there are some folks still sitting on them somewhere. Hopefully they dont get scrapped in estate liquidations...

How much do yall think we are talking for a custom crank? $1500? $2500?

i would think billet main caps and a main girdle solution would be more important.

thanks all,
~Mark

[Reaper1]

The large stroke MP crank was actually a bit smaller stroke at 3.994" vs. the production 4.09". Never heard of anything beyond 2.5 liter cranks. All motor (RIP) had a supposed 2.7 liter engine (circle track N/A car). Crank was a one off according to him. I remember him telling me it cost more than the whole rest of engine. .060" overbore accounts for about .10 liter in displacement, so his crank was around 4.250" stroke. I know of three people that have 2.0 liter forged cranks. All on the back burner as far as builds. I know of two turbo 2.3 liter Chryslers. One by slight stroke, the other by big overbore. Teaser picture of 2.0 crankshaft.
Todd

I have an offset ground crank I had done back around 2001 with a 3.75" stroke. It was supposed to be used with 6" rods and custom pistons. I have the whole set-up, but never put it together. :(

[Reaper1]

Those are some awesome pictures. I wish some of these nostalgic MP parts would start surfacing again. Surely there are some folks still sitting on them somewhere. Hopefully they dont get scrapped in estate liquidations...

How much do yall think we are talking for a custom crank? $1500? $2500?

i would think billet main caps and a main girdle solution would be more important.

thanks all,
~Mark

I think custom cranks are going for about $3500 nowadays.

Billet caps exist.

Personally, I think deck sealing is more important. Nobody really breaks bottom ends from too much power. There's typically some underlying reason for bottom end failures with these engines, even with "big" power (less than 600), not part design or strength.

[tryingbe]

The one thing people never have problems with is breaking cranks. I've literally never seen or heard of it from anyone I know.

Not mine.
https://www.facebook.com/groups/shelbydodge/permalink/3435495396520003


https://scontent.fphx1-2.fna.fbcdn.net/v/t1.0-0/s600x600/121000666_10217634145914625_8698225521775306077_o. jpg?_nc_cat=100&ccb=2&_nc_sid=b9115d&_nc_ohc=zxkhH_CbQFYAX_r_Zof&_nc_ht=scontent.fphx1-2.fna&tp=7&oh=1b4daffae37ef230d079f7288788d582&oe=5FBE6392

- - - Updated - - -

Same post, different owner/car

https://scontent.fphx1-1.fna.fbcdn.net/v/t1.0-0/s261x260/121030467_2780734878866874_1700084246309882427_n.j pg?_nc_cat=108&ccb=2&_nc_sid=dbeb18&_nc_ohc=slLLr1ATxHwAX_sxZh8&_nc_ht=scontent.fphx1-1.fna&tp=7&oh=b6758f69c771e297bcd47069d00c4b55&oe=5FBF191E

[Warren Stramer]

I think custom cranks are going for about $3500 nowadays.

I broke the nose of a cast 2.2 crank. Also As a personal favor Randy Winberg Himself https://winbergcrankshafts.com/ did this crank for me, cost $1750. What I got for that was cryo treatment, nitride hard surface, ground journals, equalized and indexed stroke, shot peened and balanced.
I did all the sculpting of the counter weights before I shipped it to him. This is a factory forging.....65199 You can get a really nice crank for less than $2000.

[cordes]

Not mine.
https://www.facebook.com/groups/shelbydodge/permalink/3435495396520003


https://scontent.fphx1-2.fna.fbcdn.net/v/t1.0-0/s600x600/121000666_10217634145914625_8698225521775306077_o. jpg?_nc_cat=100&ccb=2&_nc_sid=b9115d&_nc_ohc=zxkhH_CbQFYAX_r_Zof&_nc_ht=scontent.fphx1-2.fna&tp=7&oh=1b4daffae37ef230d079f7288788d582&oe=5FBE6392

- - - Updated - - -

Same post, different owner/car

https://scontent.fphx1-1.fna.fbcdn.net/v/t1.0-0/s261x260/121030467_2780734878866874_1700084246309882427_n.j pg?_nc_cat=108&ccb=2&_nc_sid=dbeb18&_nc_ohc=slLLr1ATxHwAX_sxZh8&_nc_ht=scontent.fphx1-1.fna&tp=7&oh=b6758f69c771e297bcd47069d00c4b55&oe=5FBF191E

I guess I meant broken at the rod or bearing journals. Do you have any information about the power levels of the engines in which those cranks failed? I'm skeptical that it was due to too much power.

[jrod1231]

For those not on facebook: The post says it was crank number 2 that broke like that. Power is probably not the underlying cause...

[tryingbe]

Do you have any information about the power levels of the engines in which those cranks failed? I'm skeptical that it was due to too much power.

Negative.

[Steelpanther]

That picture that tryingbe posted is from my omni. 2.5l it makes good power indeed. But not a record maker buy any means. The 1st crank the key was clearly moving around and cracked the snout. The 2nd crank did almost the same thing. I had. I've confirmed crank bolt is not bottoming out. And have now had the crank pulley balanced (tone wheel missing a tooth for megasquirt) well see if it lasts...

[cordes]

So you broke two of them which had the modified pulley for use with megasquirt installed on them?

[Steelpanther]

The 1st crank snout did not have megasquirt tone wheel on it. I noticed my alt belt getting beat up and not keeping adjustment. The 2nd snout started wobbling enough to start hitting my crank sensor.