What would happen if........

[xroadrunnerx]

What would happen if I built a 440 engine with 10.5:1 compression ratio and just used regular 87 octane pump gas? Would it damage the engine in any way at all? What else could it do? Thanks.

[PapaBato]

wouldn't it ping or knock like a mofo?

[451Mopar]

10.5:1 static compression, built with aluminum heads, they disipate heat quicker and usually have better designed combustion chambers so it would be more like running a 9.5:1 compression engine.

If you build the engine with the Keith Black Quench pistons, or flat tops and a closed chamber head to get proper quench you may be able to cheat an extra 1/2 point of compression.

A big cam also helps reduce cylinder pressures in the lower RPM ranges.

Using a EGR valve can also be another way to reduce combustion chamber tempatures.

Then there is the old stand-by, backing off on the ignition timming

If you are driving at high altitude, you can cheat with even more compression.

Want proof, look at most of the new car engines, most are running about 10:1 compression or more, even with using mild cam timming (usually less than 220 @ 0.050" duration.)