Thread ideas.

[David Bohrer]

O.K.

How about this. A thread for "CAST PISTONS CRACKED AT ???WHP?" or "T2 RODS FAILURE AT XXXWHP?" etc,etc. That way we can actually SEE pics of the failure by dyno plot and remnants and finally have the ability to draw the line on "when" the component hits its stress limit. I think the t2 rod limit is well over 500whp by a good measure. Anyone care to volunteer? I think Larry can if he still has the plots.

Just trying to get this section started!


DaveB.

[cordes]

Are there too many variables to eliminate here? For the cast pistons it seems as though we would need to quantify detonation rather than HP from what I have read about them.

I have run 22PSI on cast 2.5 pistons for a good length of time with no ill effects.

The rods and crank might be a different story. I think Russ Jerome may have been the first to find the HP limit of the stock common block cast crank.

[8valves]

Yes- cast pistons WILL live at high HP levels if there is zero imperfections in the tune. Now, I'm sure overall longevity is reduced, but look, Bryan Lugert made 334 whp at 34 psi on a stock longblock. It's possible, yes.

T2 rods I think might be questionable. I don't know if people have figured out a diehard set in stone "they're going to break at this level" figure. I could be wrong though.

Aaron Miller

[Tony Hanna]

The only problem I can think of is that there isn't any "diehard set in stone they're going to break at this level" figures. Some parts are going to fail sooner than others of the same part due to any number of variences in the manufacturing process and/or stress from previous use. Some may fail quite a bit under the average while others may put up with quite a bit more than they should.
With that said, it would still be pretty neat to get an average.
Tony

[turbovanman²]

Not a bad idea but theres too many variables.

[David Bohrer]

Granted there are alot of variables but let's at least get a "window" of when the compenents fail. It would give newbies a idea of when to upgrade. And it would at least clear some questions on component strength.

I have seen t1 rods hold up to 333whp on a 8v and make 150 or so runs down the eighth mile before the car got retired.

I, personally have rolled 352whp and 392 wtq on cast 2.5t pistons and T2 rods. I sprayed a 50 shot on top of that for quite a while before a nitrous backfire claimed all four pistons the intake gasket, a few wires and warped the hood. THAT is a nice video to watch!

Anyway this was just an idea to condense a massive search into one thread. No harm intended.

DaveB.

[Tony Hanna]

Anyway this was just an idea to condense a massive search into one thread. No harm intended.

DaveB.

I don't think anybody intended to make it seem like a bad idea. Personally I think it would be really neat to see, and it would be good for a guideline for newbies just as long as they realized that nothing is definate.
Tony

[moparzrule]

I broke 3 mahle 2.2 pistons at 225 WHP levels, but I swapped to a G head and at 300 WHP levels and 20+ PSI only broke 1 piston due to a bad gas fluke. It's all in the tune.

[Directconnection]

Yes- cast pistons WILL live at high HP levels if there is zero imperfections in the tune. Now, I'm sure overall longevity is reduced, but look, Bryan Lugert made 334 whp at 34 psi on a stock longblock. It's possible, yes.

T2 rods I think might be questionable. I don't know if people have figured out a diehard set in stone "they're going to break at this level" figure. I could be wrong though.

Aaron Miller

I will say that Gary mentioned that once he was running low 11's in his K-car, that he kept peeling the tops of the stock 2.5 Mahles. I know he had some detonation issues due from overboost with the intercooler upgrade, but I think he was stating a HP level in his case. I would bet a 2.2 Mahle would be able to survive 10's easier.

[8valves]

I will say that Gary mentioned that once he was running low 11's in his K-car, that he kept peeling the tops of the stock 2.5 Mahles. I know he had some detonation issues due from overboost with the intercooler upgrade, but I think he was stating a HP level in his case. I would bet a 2.2 Mahle would be able to survive 10's easier.

This is true, 2.5 pistons are known to be more prone to breaking due to the design, specifically the ringland area iirc. But in reality, there should be no reason for the piston to fail if there isn't a cause, such as minor detonation at those HP levels. That's my theory, I could be totally wrong though. Maybe there is a HP level (specific cylinder pressure perhaps) that they're not a stable item anymore?

Aaron Miller

[David Bohrer]

I don't think anybody intended to make it seem like a bad idea. Personally I think it would be really neat to see, and it would be good for a guideline for newbies just as long as they realized that nothing is definate.
Tony

I have played long enough to know when someone is just trying to protect the information from some end-users who may not understand what is being said. And when then blow up the car and even worse, themselves, and then blame us because they "read it on the internet". No harm no foul. I didn't even think of this when I brought up the idea!

So, for all reading this thread the upper limits are achieved on perfect tunes and set ups! No half arsing! Even then you are playing "rock, papers, scissors".:eyebrows:

So as it stands:

2.5 mahles upper limit is @ 450whp ;) perhaps a little more?

2.2 mahles lower limit is 225whp (with a bad tune) upper limit is 334whp

Any input on the T2 rods?

I know that the T1's can handle 334whp.

Any others with info to share? I think this thread is going great!


*** These stated figures are actual real-world results found with mass produced (albiet strong) stock components which have a great range of quality and inherit casting variances that make for a wide range of power making capabilities. These figures should not be used as a "Chiseled in STONE" data for comparision to your car. Because it is quite possible that on that day at the foundry someone threw a Schlitz beer can in the aluminum vat and you ended up with it as a piston.

Dave B.

[moparzrule]

Any cast piston can be broken even under 200 WHP, there is no lower limit. And as stated before, 2.2 pistons can handle more than 2.5's due to the design.
I don't think anybody has done 450 WHP on stock 2.5 mahles.

[Tony Hanna]

*** These stated figures are actual real-world results found with mass produced (albiet strong) stock components which have a great range of quality and inherit casting variances that make for a wide range of power making capabilities. These figures should not be used as a "Chiseled in STONE" data for comparision to your car. Because it is quite possible that on that day at the foundry someone threw a Schlitz beer can in the aluminum vat and you ended up with it as a piston.

Dave B.

ROTFL :lol:

Well said.:thumb:

[TylerEss]

It was this guy. I saw him working at Mahle that fateful day in '86.
http://www.fenestrated.net/~macman/pics/MonkeyBeer.jpg

[cordes]

It was this guy. I saw him working at Mahle that fateful day in '86.
http://www.fenestrated.net/~macman/pics/MonkeyBeer.jpg

In their defense, those pistons have zero problems in the aplication for which they were origionally intended. Moreover, they do quite well in a hevily moded motor. That picture is funny none the less though.

[Directconnection]

A 2.5 Mahle s a good piston, but due to it's design limitations.... it can't support as much HP as the 2.2 Mahle. So...I wouldn't say that 450whp on a 2.5 Mahle is a good #. Maybe the most I have heard of would be around 350whp tops...but that is just my guessing. I don't have my calculator handy.


The Hypers... not anywhere's near as good as the stock Mahles(as we all know). I have a friend that ran these (forget which brand..Federal Mogul..spell check) in his 2.2. at 23psi on pump gas with the fwd s5 computer. There was a good amount of fuel pulled at the afpr to keep the a/f ratio happy, and it was still on the fat side. Basically, one summer's worth of driving and then they let go. I'd steer clear of these.

[Tony Hanna]

I was under the impression that the power output wasn't near as critical to piston life as state of tune.:confused:
Has anybody actually witnessed a stock piston failure that was due to power output and not running lean or detonation?

[moparzrule]

I was under the impression that the power output wasn't near as critical to piston life as state of tune.:confused:
Has anybody actually witnessed a stock piston failure that was due to power output and not running lean or detonation?


Well here's the thing, power level makes a difference but isn't necessarily what breaks the piston. For example, at 250 WHP, 1600 degree EGT's are normally completely safe...but at 400 WHP, 1600 would melt a piston in a millisecond!