Thread: Hypereutectic Pistons for Y-block

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What are the benefits or drawbacks if I use hypereutectic pistons in this new 292? The supplier says this about the pistons "...16% silicon. No lead fuel alloy, better ring groove life, 15% less thermo expansion. 1.5mm top and 2nd ring, 3.0 mm oil. 40-60% savings in parasitic ring friction."
My other piston option is a run of the mill Cast unit with 5/64 compression rings and 3/16 oil ring.
Is the life expectancy going to equal standard pistons? Can clearances be tightened up?

Mike

For toughness, hypers are sort of "middle of the road" between cast and forged. Piston to wall clearance is tight and critical.

As far as ring thickness, I prefer the thicker rings for a low rpm street motor. I guess there would be a reduction in friction by using a 0.059" ring as opposed to a 0.078" ring, but in my opinion the thicker ring will seal better, so it's 6 of 1 and a half-dozen of the other.

The main reason I like KB hypers is for the nice, flat crown that mates up with the squish pad on a Chevy head. Even the dished ones have the crater offset to match up with the chamber and a nice flat crown for squish. You just can't get a nice, clean squish with those 4-relief, run-of-the-mill Chevy pistons. The crown just is not flat on them.

Now, I realize you are talking Y-block here and I have no idea what the chamber configuration is in that motor.

That is some good and appreciated info. Richard. This will be a motor I'm trying to build for mpg. Static compression will be approx. 9.1:1 with very very mild cam (stats on cam are due back from analysis this week). Minimum Y quench of .040 is another objective. Gave up on trying to mate up the Jahns popups that are on hand to this application. I will go out and take a picture of the chambers and post them in a couple hours.
It sounds like the hypers are just an unnecessary expense for me.

Mike

Here is a link to a picture of the CCs. The head is a model 113, maybe the best the Y's offered. The motor will use this model, with chambers of 69 cc instead of the stock 72cc. The picture shows hardened seats for 1.78 intakes, but they originally came with 1.92. Just an FYI.

The link didnt work. Maybe I can get a picture into a post.