110/90 mix

Edited by White70JavelinSST - Mar/22/2023 at 5:20pm

White70JavelinSST wrote: X2 on what BU1 said. I've never seen unleaded av fuel. It may exist but who knows where... BTW, don't let the fuel police see you putting leaded fuel in your street driven car. It is against the law and carries a pretty hefty fine. I'm not sure how it affects race cars. Below is something I found on the web that states it quite eloquently. It's no longer legal to put leaded gas in your car though, whether it's a classic or not. Don't even think about trying to do it on the downlow either. If you're found to be driving a car with leaded gas in the tank, you could well wind up slapped with a hefty $10,000 fine for your ingenuity.

A couple things.  Lead response, the increase in octane per gram per gallon of lead is not linear.  It doesn't take a lot of lead to increase the octane of unleaded premium a lot.  It is not arithmetic.  Lead response varies depending on the base fuel.  Lucky that the lead response of catalytically cracked fuel is high. Also lucky that cat cracking is how we get high-ish octane fuel without lead.  Typical race gas, the 110-112 stuff has 4 grams per gallon of lead.  If you mix 1 gallon of race gas with 4 gallons of unleaded 93, you will end up about 100 octane.