Hyper Piston Disaster?

[Nick Micale]

After having hundreds of turbo Buick engines apart, this engine was sent in for a rebuild and it seemed ok except for one piston?

Cylinder pressure was great enough to actually crack the piston. The crack is hard to see in the photo, but the marker outlines where it runs down to the pin boss.

We have seen lots of piston damage with forged pistons, but the usual cause is pre-ignition and the associated heat, and that is not the case here. There is no sign of detonation on this piston or any of the others.

We have never used a hyper piston in any new build and never will, as this illustrates why they are not reliable in a turbo engine build.

 

[PSID6]

Just out of curiosity, what kind of power was she making?

 

[Undercover87T]

So was this from too much boost or just seeing boost in general for a lot of miles? Glad I no longer have them.

 

[Chuck Leeper]

Nick, what is the piston to wall w/ these pistons?
Cracked from the wrist pin... Broken when the piston was pressed, and not noticed??

 

[cruzn57]

when done correctly ( installing pressed pins /pistons on the rods)
there is no force placed upon the piston, the rod small end is is heated, and the pin is slid into
the rod with very little (or no) pressure,
still , it could have been over looked at install,

 

[Chuck Leeper]

there is no force placed upon the piston, the rod small end is is heated, and the pin is slid into
the rod with very little (or no) pressure,

Could well be, if the shop is using the press fixture....

 

[87GN_70GS]

Why is it not cracked up to the top ring land? Unless the crack started from the pin hole

 

[gunzandgearz]

Yep hyperutectic meaning hi melting point, problem with these pistons is they have a lot of silicon content which makes them hard or not very malleable like a forged piston. The good, you can run them in n/a engines up to about 400 horsepower and they have tight piston to wall clearances, like a cast factory piston. the bad as I said before is they are not good for boosted or high cylinder pressures. A little better than cast stock piston but nowhere near a forged piston.Probably just cracked from high cylinder pressure from pin boss up.Anyway good picture nick, and another reason not to skimp on parts when building a mid to high horse engine.

 

[34blazer]

What is the opinion concerning max power allowed with a hyper piston? To be reliable, that is.

Must be more power than a high 10 lap full weight.

 

[gunzandgearz]

In my honest opinion about 400 horsepower n/a. Here is the deal you can buy a set of forged pistons for about 200 dollars more now they might be the cheaper sealed powers or one of the other cheaper brands but they are still a lot better piston. The piston that Nick was showing in photo I personally think the guy just got lucky he didn't grenade the motor, because if he had that 200 bucks he just saved just cost him a short block, you do the math.Again this is just my opinion but I don't like taking chances.

 

[Nick Micale]

I would rather use an original stock cast before a hyper piston. It is never going to be "reliable in a turbo Buick is my opinion.

The other issue with the hyper piston is the dish is larger than a stock piston so you will end up with less compression.

 

[34blazer]

Cool, thanks for the feedback!

 

[gunzandgearz]

Anytime, again this is my professional opinion, others may disagree.