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Different octane rating

Understanding AFR

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Hello everyone,

for now, im tuning my engine with 11.1v afr with 26 psi at 9000 rpm with gasoline (petrol) unleaded RON95.

if use other fuel that have similar stoich with petrol, 14.7v, such as Avgas 100 Low Lead, can i use leaner AFR like 12.5v?

since octane rating is higher and leaded fuel helps eliminate knocking?


If you want to run leaner for more power you should probably be running egt probes so you have a good idea of how hot everything is getting. Lambda 0.85 will likely make more power but I don't think many engines can run sustained load at those equivalence ratios on non oxygenated fuels as things get too hot.

Thank You very much Michael. i will try 0.82-0.85 and feel the acceleration.