Which KB Hyperutectic Pistons?

[AMXguy]

I'm building another 440 six pack and I've been very happy with the 237 KB's in the  other one I have.   but when I went to order them I see there are a couple step head ones I've never looked at before.

I'm looking to stay around 10.1 compression on a street engine which all 3 of them  will do with 906 heads.   I know it's about the quench but I've never really understood the concept .  with 906 heads should I go with the 237's or one of the step pistons?

[jimynick]

The concept involves having an area of the heads and pistons come together in close contact- the generally accepted gap is .040" so that when they come together, they cause a high speed gush of air or "quench" to carry the flame kernel better across the combustion chamber and promote better flame propagation and overall smoother combustion with less chance of detonation. Google a guy named Feuling; he's dead now, but he really was an innovator in this and I'd say he was the father of the bathtub style of combustion chamber. I think it was Popular Hotrodding that had an article about his heads years ago. Does that help? Personally, I'd call the piston manufacturer and speak with them; they'll know their own stuff and what it'll work with. Godd luck 

[1 Wild R/T]

None of KB's current step head pistons will give you effective quench without machining the cylinders heads.... They use to sell one step head piston with a step head that you didn't need to cut the heads, instead you had to machine the step head to shorten it....

The get effective quench with open chamber heads & KB pistons you'll spend more time & money than by doing it the right way....

Open Chamber heads & 1000+ gram pistons are not the way to build a performance engine....  Rethink your build...

[moper]

you are MUCH better served by ignoring quench and running the 237s again than trying to mess with the step domes and open chambers. You have to spend a lot of time, and usually a little more money in order to make them work like 1 Wild notes. The gain in static ratio means very little. So if the plan is open chamber iron factory heads, ignore quench and just build it for 9.5:1 or whatever a zero deck comes to. 

[Chryco Psycho]

I agree with Wild , rethink the build , Quench is important so I would use a forged piston & a closed chamber cylinder head like the stealth or new trick flow