What makes piston high compression?

[mouse]

??

[scotty-2-forty]

Either more height to the piston dome or a longer stroke rod.

[mouse]

Lets say for example I have the KA24E, how do you know what is too much compression? And what does higher octane gas do?

[IvoryJ30t]

octane is a measure of a fuels ability to resist preignition.

a higher octane fuel requires more energy to ignite it. therefore you can compress it harder and get the charge hotter before it will spontaneously combust.

also, a higher octane fuel contains less energy per unit than a lower rated fuel.

[Ubernoober]

http://www.repairfaq.org/filip....html

[mouse]

thank you.