Join Date: Mar 2001
Location: Tucson, AZ, USA
The 9.5 to 1 depends on the cam and the quench area...if your quench area is .08" or bigger, your swirl and turbulance is in trouble and so is the burn rate and thus flame travel...this promotes detonation...
Choosing a proper cam as well as using aluminum heads as well as maintaining as small a quench area .04" is good...will all help keep detonation from occuring..
NOW..you CAN make more power with higher octance.... With higher octane, it allows you to get more over-all advance and allows you to re-set the distributor curve...thus pulling in more torque when it's needed...
Newer cars with computer control have a knock sensor in the block which signal the computer to RETARD(pull-back) the timing..thus loosing some low end torque..So using a higher octance doesn't ADD power..it allows the motor to be at it's best without reducing the timing due to detonation.. Lower compression motors generaly make MORE heat than higher compression, the lead in the fuel is to help the exhaust valve better disipate the heat..this helps prevent the seat from getting soft from too much heat..which leads to the seat dropping into the head from the pounding of the valve..
Also note that the LEADED fuel WILL cause permenant damage to the catalytic converter..