air fuel ratio

[Skating_rob]

got a quick question i got a apexi afc neo controller and never could give it a street tune cause i never had a air/fuel ration gauage but it coming in this week does any no what the air/fuel for a vq35de should be im no poor to put in on a dyno atm

[SmoothZ]

A quick search got me this:

QUOTE

For gasoline fuel, the stoichiometric air/fuel mixture is approximately 14.7 times the mass of air to fuel. Any mixture less than 14.7 to 1 is considered to be a rich mixture, any more than 14.7 to 1 is a lean mixture - given perfect (ideal) "test" fuel (gasoline consisting of solely n-heptane and iso-octane). In reality, most fuels consist of a combination of heptane, octane, a handful of other -tanes, plus additives including detergents, and possibly oxygenators such as MTBE (Methyl tert-butyl ether) or ethanol/methanol. These compounds all alter the stoichiometric ratio, with most of the additives pushing the ratio downward (oxygenators bring extra oxygen to the combustion event in liquid form that is released at time of combustions; for MTBE-laden fuel, a stoichiometric ratio can be as low as 14.1:1).

[westpak]

a naturally aspirated Z runs best around 12.5 at wide open throttle, any richer and it loses power any leaner and it doesn't make more

[Skating_rob]

ok thank you