Back to the machine shop...

Back to the machine shop...

Not trying to ruffle any feathers or be contentious, but 1st and 2nd gen Hemis have 360 degree squish and quench, and 3rd gen Hemis have two large quench and squish areas on the sides of the combustion chamber. I have had (or still have) all three generations of Hemi engines and run them.
So I respectfully disagree with the assertion that Hemi engines don't have squish and quench. Besides the wonderful unshrouded valves and direct, cross flow, the large squish and quench are what make the design so effective.

Second, head material does make a large difference in detonation tolerance. Most aluminum head engines can tolerate at least a point higher in static CR.

Also, smogger low compression 440's pinged like crazy with very low compression ratios, reason... no quench and squish.

Just my 2 cents derived from experience and study.

I respect your opinions and am in no way trying to discount your assertions.

Thanks,
Mark

yellow rose said
Ok, so I went back and looked at your first post so I could figure out WTH is going on.

In the first post you didn't say a thing about the CR. All you said was you were going to do all this work to get quench.

Two entirely different and unrelated topics for sure.

So...if you need to stick the piston out of the hole .050 I don't care. If (and it's a big IF) you are doing it to get the CR where you want it.

Nothing wrong with that. But to do all that work to get quench is worth nothing.

At your elevation, 10.56:1 may be low. I'd get it to 11:1 and make sure the rest of the engine combo is set up for it.

The material the head is made of makes ZERO diffence regarding detonation resistance, compression ratio or any other voodoo bull crap the magazines push.

I'm running 11.1:1 on pump gas with iron heads, running full timing (36 total) and I can't make it rattle unless I'm just being stupid.

My next build will be 12:1 on pump gas, maybe a bit more.

And I don't calculate my CR based on an online calculator and and the piston manufacturers advertised numbers so I'm 100% sure where my CR is at. And I'm about 800 feet above sea level. I know, because I was talking with my mentor the other day and this discussion came up so I verified my altitude.