w/a 383. The motor has 800 miles on it. Can i spray her? How much can i get away with. Thanks, Brian Kaiser

i wouldnt, did a 355 with them, they crack under nitrous. split a KB on a 125 shot. use forged pistons. they are strong pistons, on N/A apps, but not with nitrous.

Did the pistons crack becasue of the pressure or becasue of pre-ignition?

i would say pressure, because it didnt detonate, it ran hard, then went pop.

Hyperutetic pistons tend to shatter when exposed to detonation. We have used them with great success, all the time with 150 shots. Get the octane up and the timming down.

My friends car just made almost 500 hp and 600 ft lbs rear wheel hp and torque on a 150 shot with "rebuilder" hyperutetics.

Next day he went 11.39 with a 1.55 60 footer.

as Andy said.... when set up correct( ring gap and piston to wall clearance) they will live a long life on a mild dose of gas. My KBs have seen as much as 175 HP and see a regular 125 hp.

yep went 11.38 @118 , 1.55 60'on the 100 shot with a 3.07 gear We sprayed the 150 on the dyno but held back (for now) on the 150 kit.

I use 92 in the tank and 118 in the seperate system. Timing was 33 deg. total.

How are Keith Black pistons compared to their Silv-o-lite line?

i pulled the dyno sheets, and looked at the EGTs and A/F ratio, i was getting into detonation. sorry for the mix up. i always run ross custom pistons in my motors. i'd say u could spray them with 150, but wouldnt do any more, i'd go with a light weight alum. piston. good luck, and remember nitrous isnt for babys, its like insurance, in case bad **** starts to happen, or to prevent it

And that's the difference.


The forged can and will take short term abuse ( detonation). The hypers may not live through the first one.

I have no problem at the 150 level and at 200 you better have it right on hypers, but with a forged piston you can spray well beyond that. I knew 200 would be the MOST i would spray to the cast crank 2 bolt main, so i went with the hypers. As it turns out looks like the 150 will achieve my goal.

Thanks for clearing that up bills77.

Soo if i wanted to do a 100 shot would i blow my motor. I would install the kit and then take it to a performance shop to look over before i do anything with it? I had the pcm tuned and the timing was advanced. I dont know exactly how much, but i might be going to a gm847 cam soon also. Thanks, Brian Kaiser

I'd retard the timing 4 degrees, use 93 preimum, and maybe install colder plugs.

Having the timing advanced is not a good thing in this case, but as long as the stock knock programs are still active, as well as the knock sensor, the computer will prevent engine damage. Don't leave this to chance, verify with a scan tool and look at the plugs.

You could dump in race gas and nix the plugs and retard.

DITTO to what Andy said....

Spray that baby and be prepared to be HOOKED!!

KB hypereutectics are a great lightweight piston. You'd be safe with a 100-125 shot and possibly even a 150 shot but I'd play it safe.