I'm rebuilding my engine now and got Federal Mogul hypereutectic pistons in my engine kit, my machine shop has already pressed them onto my rods. Today I was talking with a guy at work who works closely with many professional racing teams and he said that I should think twice before using these pistons. Has anyone heard of or had problems with these?

If I decide to get new heads I will probably be at around 425hp, with my factory heads it'll be more like 375hp maybe.

Thanks.

 

They're fine for a street build with no nitrous. I'm driving around a set of them right now.

Open up the top ring gap a little; typically you'd use about .004" - .0045" of gap per inch of bore, open that up to about .006 - .0065" of gap per inch of bore.

They are a very hard material, which makes them last a long time, but also makes them brittle. They do not tolerate detonation at all, which is why they're not real safe wih nitrous.

 

Well, I do my co-op at Federal Mogul. They make great pistons for many apps, but have yet to try anything performance oriented with the small block chevrolet. It's too bad too, cuz they really make a lot of awesome parts for our european counterparts.

 

Interesting take on things, considering that they're the parent compnay of the Sealed Power / Speed Pro, and TRW brands....

 

I'm going on my 4th season with a set of Federal Mogul H631P hypereutectic 2 valve relief pistons, no complaints here.

11 road course track days, more dragstrip passes than I can remember, periodic work commutes, etc.

No nitrous, carefully tuned spark map.

However...next time I'll likely go with SRP forged pistons. They're made from high silicon (but they don't call it hypereutectic??) alloy, clearance specs are tighter than the other forged pistons I've looked at, and not too expensive.

 

"High" is a relative term. The content may not quite be at the point beyond saturation, or "hypereutectic". In any event, extra silcon in the bauxite is a good thing.

Extra Credit Question: Anyone know who pioneered the "high" silicon/aluminum casting process?

 

I've got 11-12k miles on the forged flat top Federal Mogul pistons in my car, and so far so good.

 

Put a set into a 400 small block that went deep in the 12s N/A and was REGULARLY abused. Never a wimper from them. I think they were purchased from PAW since they were the cheapest Hypereutectics money could buy and the budget was real tight. Was surprised at the relatively high quality for the dirt-cheap price.

 

I don't "know", but I'll hazzard some guesses:

1) Your alma mater.
2) GM, for the Chevy Vega engine.
3) Porsche.
4) Sheffield University in Scottland (or is that the same as #1?).