>>>*One thing to remember is that 150# of crank speed pressure actually is a lot. The only reason we can even run that much at all is the fact that the head is aluminium which bleeds off heat, plus control systems that allow it by tightly controlling the flame front (when all is right.)

*Noting a fair amount of pinging suggests that something isn't quite right, that is why the dyno run and a computer analysis can be a benefit. We see systems that have just that typically "tipon to the throttle" crackle or "ping" with crank numbers of 180# and up.

Properly quenched (piston to head clearence) the engine will create less ping at higher compression than it will at lower compression, also. Interesting stuff, I remember when the 9 to one rule came along for the 5.0L Chevies, lord we had hot engines until we figured out the cam changes and what to do with the combustion chambers. Those designs had crank compression numbers of around 120# and put down 550 H/P. I remember the 355" we had in the number 43 car, she had 105# crank pressure and that one made right at 700 H/P. Static compression ratio was 13.8 to one, still only 105#, big duration camshaft of course..

The late 22RE combustion chamber is very efficient, the problem with very efficient is the engine then becomes extremely sensitive to ignition timing and valve timing. I keep saying just right is just right and everything else is just wrong.

In the old days we increased the compression ratio through the roof, then advanced the timing until she rattled. At that point we jacked up the octane of the fuel and went racing. The pistons all had huge domes and they ran so close to the head at temp that the chambers left marks in the tops of them.

Now it is flat top pistons, tight chambers, close quench and we also have to be concerned about what comes out the tailpipe.

Nearly always when we hear a report of soft crank compression and pinging, with mileage a bit lower than it should be, I start suspecting that the piston is down the bore a bit too much at TDC. If that part is right, next we look to see how much total advance she has at each step.

One part of our world fights the other, can't have emissions so she needs to run at stoichiometric, at that point power fades since power means fuel, bumping the fuel curve to around 14.5 to one increases the power but now the tank goes dry too fast, advancing the valve timing brings the power peak in early, but then she pings so the system backs off the timing..Then we realize that heat means power but heat means NOX, so we bolt on an EGR valve to dilute the fuel/air mix to cool the heat.....*LOL**...

*Everything is a balance...and a compromise......*EB