[ponchjoe]

Thanks, KBd would be a last resort for me. I’ll probably just go heavy Speed Pro

Originally Posted by chiphead

You guys still think Hyper pistons are a viable alternative? What about resistance to detonation and ring butting? Hyper pistons are high silicon content. They are dimensionally stable, but are brittle. Heavy detonation can crack them.
Some designs (particularly the KB hypers) tend to put a lot of heat in the top ring. In high power, nitrous or boosted engines, they tend to butt the top ring and tear the top of the piston off. They also cannot have dished milled in the top to lower compression. For a low compression, lesser than 400 HP builds, they would be an option. But if you get the bug for more HP, the hyper pistons quickly become a limiting factor to power production.

I used a set of Ross 2618 pistons in a long rod 400 nitrous street/strip motor. It ran for 10 years and about 15K miles. My only complaint was the piston slap when cold. Upon teardown, the pistons were good, even though the rings and bearings showed signs of being unhappy due to years of being run hard. The looser bore clearance makes some noise when cold and can shorten ring life. At least in 2004, the Ross pistons had limited options for customization. I sold those used Ross pistons to somebody here, they were still perfectly good.

Since I like to make the max power on pump gas and use nitrous, I have to use good pistons and rings. That 434 got the Autotec pistons and a $350 set of AP stainless LS style rings, torque plate honed, 6.8 BBC rods, the whole burrito. For a cruiser, the only pistons I would NEVER use would be a hypereutectic or the 8-eyebrow cast monster. Just be sure to consider the compression, camshaft choice, RPM range, gearing and risk of detonation with less expensive pistons and ring packs.

[chiphead]

Originally Posted by ponchjoe

Thanks, KBd would be a last resort for me. I’ll probably just go heavy Speed Pro

That should be fine. A TRW piston with moly top ring, ductile iron 2nd and standard tension oil rings will be fine. I assume aftermarket 6.625 rods with press fit pin?

The next concern is compression. What heads are you using to get 9:1?

[ponchjoe]

Originally Posted by chiphead

That should be fine. A TRW piston with moly top ring, ductile iron 2nd and standard tension oil rings will be fine. I assume aftermarket 6.625 rods with press fit pin?

The next concern is compression. What heads are you using to get 9:1?

Ported 7k3, zero decked

[Formulajones]

Originally Posted by ponchjoe

Thanks, KBd would be a last resort for me. I’ll probably just go heavy Speed Pro

It's not a bad choice, just be aware as Cliff mentions you'll have to shave a bit off the deck to get them at or near zero. I've used these pistons before in builds some 25+ years ago before we had all the nice choices we have now. Those engines are still together today, quiet as a mouse and running fine, but as mentioned, the blocks needed decked to get them up to the top.

That's not necessarily a bad thing as every single engine I've ever touched needs decked anyway simply because they are so far out of spec, and Pontiac is one of the worst with that deal. You'll find them lop sided many times having to take as much as .007-.0010 more material off one end compared to the other end to get them square. So it's not like it's the end of the world using the speed pros anyway. Probably my bigger gripe with them is the large tractor ring package they come with. That's pretty antiquated these days as smaller ring packs have proven themselves to be a better deal all around with better sealing abilities, lighter weight, less drag, all equals more HP.

The price differences aren't really enough to even consider a decision maker in my opinion anyway, I'd just go with a nice modern forged full floating deal with a small ring package and call it a day.