normal_post in maximum compression in Engine, Transmission & Rear End Author Topic: maximum compression  (Read 219 times)

Offline GoMangoBoys

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maximum compression
« on: April 15, 2020, 07:23:28 AM »
We are going to run 906 heads on our 383 stroker (either 432 or 489).  What is the maximum compression we should build for in order to stick with pump gas?  I know these are not as good as the aluminum or the closed chamber heads in regards to quench, but I got a good deal on them and I am trying to control cost.
Thanks

Linkback: https://forum.e-bodies.org/engine-transmission-and-rear-end/4/maximum-compression/15765/

Offline 1 Wild R/T

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Re: maximum compression
« Reply #1 on: April 15, 2020, 07:30:06 AM »
9.5ish is about the max

Offline HP2

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Re: maximum compression
« Reply #2 on: April 15, 2020, 07:40:48 AM »
Keith Black makes some decent quench dome pistons with reasonable compression ratios for standard stroke cranks. I haven't looked at them lately, but with the proliferation of strokers, I bet they are keeping up with that demand too.

I typically don't build to a set ratio but try to achieve a cylinder pressure of around 180 psi for pump gas. Figuring out cylinder pressure is tougher to do as doing so can also takes into account altitude and camshaft event timing.  However, doing this can also allow you to maximize the compression and best utilize  what you have. Depending on the cam you are thinking of using, that 9.5:1 ratio could perform like a 7:1 which is why, IMO, its worth considering valve events to chose compression ratio.

One I've used for a long time is here:
https://www.rbracing-rsr.com/comprAdvHD.htm

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Re: maximum compression
« Reply #2 on: April 15, 2020, 07:40:48 AM »

Offline Chryco Psycho

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Re: maximum compression
« Reply #3 on: April 15, 2020, 08:22:11 AM »
Cam profile is a big factor , I have seen 7:1 motors ping badly & 10 ;1 not ping , quench is very important
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Offline Cudamike

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Re: maximum compression
« Reply #4 on: April 15, 2020, 08:24:58 AM »
I have Stage V heads at 9.9:1 with 93 octane.

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Re: maximum compression
« Reply #4 on: April 15, 2020, 08:24:58 AM »

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