Saturday Night Racer

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Saturday Night Racer >> RACE TECH >> KB Hyper explosive pistons
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Message started by dirtmopar44 on 08/23/15 at 7:57pm

Title: KB Hyper explosive pistons
Post by dirtmopar44 on 08/23/15 at 7:57pm

Lets here you experiences with the failure of these pistons, And your theory's about why they brake the top ring land? Recent sbc that I built had 3 piston's fail after only one race. I have build many engines using these pistons with no issues and I know about the increased top ring gap factor of .007 x bore which = .028. and the total timing of 34 deg. With all that being said I always run even more top ring gap .035 and they still broke. We have a comp ratio of 10.5 to 1 and use 94 octane fuel and water temp was 215 0r less. Timing marks were checked before the heads were installed.
Now my theory: The total advance is set at 34deg but it has dam near that at idle about 24* to 26* which I feel is to much when hot idling causing detonation at this low rpm. Thoughts?

Title: Re: KB Hyper explosive pistons
Post by hogracer3d on 08/25/15 at 11:46am

Vortec heads?
If so they are fast burn technology, and don't like more than 32° timing.
Not that it's the problem, but you never know.
We've learned that pump gas isn't good enough for sustained high RPM, so we mix it 50/50 with 110 in our crate

Title: Re: KB Hyper explosive pistons
Post by dirtmopar44 on 08/25/15 at 7:46pm

Not vortic heads.you think that makes a difference?

Title: Re: KB Hyper explosive pistons
Post by hogracer3d on 08/26/15 at 10:42am

we burned/detonated 3 pistons on 3 different occasions before we figured it out, but was forged stuff and 15.75:1.
better fuel and less timing and never had another issue

Title: Re: KB Hyper explosive pistons
Post by dirtmopar44 on 10/18/15 at 7:15pm

Update: We put 3 new pistons in the sbc and didn't change anything except the initial timing. Now at idle 1000rpm's it is about 10 deg and 34 total at 3200. We ran 163 laps at OSS without any engine issues. So im thinking all the initial timing we had before (24-28deg @ 1000rpm because of the very lite dist springs was the cause.