dajogejr Posted December 10, 2007 Report Share Posted December 10, 2007 190psi +4 timing on 98 octane no problems. Static compression is not an accurate meas to gauge what fuel you should run Um...yeah, it's the best way to guesstimate octane at first before tuning. Also...you Aussies have your octane displayed different than us in the states. we use the average of Motor and Research octane for what it's rated at the pump. We don't have 98 octane around here. It's usually 87 to 92, 93 or 94...then right to 100 octane and above for racing fuel. I can tell you a 190PSI motor with +4 timing around here won't last long with 98 octane....our octane readings/display measurement.. Quote Link to comment Share on other sites More sharing options...
Aussie Quad Racer Posted December 11, 2007 Report Share Posted December 11, 2007 i beg to differ, i can alter the exhaust port timing on that motor which will reduce static compression but will result in higher stress on the motor in the top end. therefore requiring higher grade fuel. Fuel should be determined on numerous factors Quote Link to comment Share on other sites More sharing options...
dajogejr Posted December 11, 2007 Report Share Posted December 11, 2007 i beg to differ, i can alter the exhaust port timing on that motor which will reduce static compression but will result in higher stress on the motor in the top end. therefore requiring higher grade fuel. Fuel should be determined on numerous factors I agree...but you can't throw cranking compression out the window as one of the most important factors. between timing and cranking, they are the most important two. Squish band % to bore diameter is another...for example. Quote Link to comment Share on other sites More sharing options...
Bobby Banshee Posted December 18, 2007 Author Report Share Posted December 18, 2007 O.K. fellows, i just put my third set of domes in (22cc +2) and i'm still getting 180psi in each cylinder. What can cause the compression to be this high with stock domes. Keep in mind that they have to be special cut because i'm running a 4mil stroker with a standard rod lenth without a base gasket and the cylinders have been ported. Thanks for any help. Quote Link to comment Share on other sites More sharing options...
jbooker82 Posted December 18, 2007 Report Share Posted December 18, 2007 O.K. fellows, i just put my third set of domes in (22cc +2) and i'm still getting 180psi in each cylinder. What can cause the compression to be this high with stock domes. Keep in mind that they have to be special cut because i'm running a 4mil stroker with a standard rod lenth without a base gasket and the cylinders have been ported. Thanks for any help. Are your domes cut for the 4mill stroker or are you running a base plate? What is the squish? Quote Link to comment Share on other sites More sharing options...
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