I am running a 70 GS 455 with stage 2 SE heads and was wondering what A/F ratio would give me the best MPH top end? I know this is probably determined by a lot of factors such as temp, humidity and altitude among others. I have seen some dyno data on this board lately that was run at approx. mid 13's to around 14.0 and I assume that was where the max power was determined to be. Is this pretty much the ideal place to be? I always thought for some reason it should be like low 13's to like 13.6. Any guidelines to shoot for?
On my FI 455 car, I've found that about 11.5 - 12.1 gives best power. That may change a bit for a carb. -Bob Cunningham
For piston aircraft we manually adjust that mixture during each flight for each alititude( and in turn each density altitude.) On piston aircraft we determine best power by knowing that best power is consistently 50 --150 degrees F on the rich side of peak exhaust gas temperature. (We get that info by looking at a lot of manuf. graphs of hp/ fuel flow /egt.) For protection we dial that in on an EGT gauge for the cylinder that peaks first on a muti probe set up-- in other words for the cylinder that tends to run the leanest. Perhaps that might translate over to auto engines but I have not studied the corresponding curves for auto. engines. I am sure they are available. There is one engine for certified aircraft that was also used in autos. That was a Porsche flat six. As far as I know these principles for adjusting the mixture for best power transfers for a flat six.
