cracked hypereutectic piston caught just in time

[Dan Timberlake]

http://www.jalopyjournal.com/forum/thre ... t-11665730

Not my engine, but it still gives me the shivers.

[cgarb]

Wonder what kept it from blowing what looked like a torch cut out like mine did?...Last cast piston engine I put together. Mine was a KB piston, and it was a NOS miscue. Maybe a forged would have made it, but probably it would have got tight on the pin or some other problem. I learned from that little mishap...That being said, the KB's are pretty tough pistons for a street car or bracket engine, as long as you don't abuse them.

[Tuner]

I think that piston crack might be hydraulic damage.

[mag2555]

How does that cylinders Rod bearing look?

[pdq67]

I have said this before that I will use a stock type, steel-strutted, cast piston over a hyper due to the strut holding them together if they crack whereas hyper's usually turn to "aluminum gravel"!

And I have seen stock steel strutted pistons break a skirt off one side and keep on running towards home!

pdq67

[pamotorman]

how does GM get away with hypereutecic pistons in the 460 HP 6600 RPM corvette engines ???

[Cogburn]

Lucky,

Usually hypereutectic pistons shatter like glass.

I also do not use them and prefer cast aluminum or forged.

Once, long ago I had a 1971 400 that I beat pretty hard. I literally had a piston fall apart in my hand when I took it apart and 5 pistons were cracked(cast).

[F-BIRD'88]

The only time you will have any trouble with any piston is if and when you
Exceeded the laws of physics.

If the piston (ANY PISTON) broke or burned up , You just did that.

[Geoff2]

The piston could have a defect in the material, wrong heat treatment, percentages of ingredients are wrong, poor machining, etc.

[MadBill]

Or it could have been operating exactly as designed but not for the conditions it was exposed to.

[peejay]

how does GM get away with hypereutecic pistons in the 460 HP 6600 RPM corvette engines ???

Very low duty cycle?

I have seen far too many pictures of ventilated LS1/LS2 engines that were used on trackdays. Looks like the piston comes apart and then the flailing rod destroys the block.

The funny thing is, I see this a lot in swapped RX-7s out of some misguided sense of added reliability. A rotary at 400hp will run for days at WOT provided that it has adequate cooling system and wasn't tuned by a moron.

[peejay]

Or it could have been operating exactly as designed but not for the conditions it was exposed to.

Beautifully succinct. I'll have to remember that.

[novadude]

I'm running those speed pro ACP pistons in my engine. Wonder what killed it?

[FuelieNova]

Did anyone catch the guy with a broken piston was his pcv line with a orifice on the other breather for a crankcase vacuum pump on his engine? Interesting concept for those of us who don't have room for a vacuum pump...
Tom

[FC-Pilot]

about 15 years ago my brothers and I tore down an engine that my dad had built a decade before. When we pulled out the TRW forged pistons 3 or 4 of the pistons had skirts that broke off in our hands. All we could figure at the time was it was from being overheated in Phoenix stop and go traffic too many times over the years. Never seen anything like it since.

Paul