|
The compression that you can run depends on a whole myriad of things. From stuff like ignition timing and fuel octane rating, to combustion chamber shape and cam grind, to cooling efficiency, and more.
The real problem with high compression isn't blowing the head off the motor, it's pre-ignition. AKA "pinging", "detonation", or "knock", that is where the mixture lights off in the combustion chamber before you want it to. The high temperatures and uneven burning can lead to hot spots on the valves, or on the pistons, or on the head, and those can over time lead to parts failure. I've seen pistons with holes burned right through them from detonation.
Most modern cars have knock sensors and will retard the ignition if they detect detonation. Most older cars do not, so they tend to leave more safety margin before knock would occur--so you can make more gains in them by increasing the ignition advance or increasing the compression than you can with the newer cars.
-soD
|