Shouldn’t the question be what is the limiting factor in producing engine power given that fuel delivery into the combustion chamber and the air ingested through the throttle plate (considering the ECU aims to achieve low pollution levels in the closed loop control model our engines run under)? Is it the density of air (oxygen) or the density of petrol that is more important?
I thought we only deliver enough fuel into the combustion chamber to burn fully with the oxygen we have available from the air our NA engine actually suck in…
I‘d think (guess) the ECU could measure fuel rail temperature and adjust injector timing to also compensate for the changed fuel density but such just isn’t done. I haven’t seen a fuel rail temp sensor in any car I’ve owned and guess it isn’t done for a reason.
I‘d guess the reason that such fuel temp sensor don’t exist is because it wouldn’t really be beneficial because petrol engines are run under closed loop control where the amount of oxygen getting into the combustion chamber provides the overriding limitation to power production (which is why we see power fall and engines get sluggish as air temp gets above 30 and nearer 40C; o2 is reduced and timing is retarded as a result).
Unfortunately there isn’t much we could do in a practically sense to change air density in a NAT engine. So fuel density ends up being of little to zero concern since the ECU can‘t really compensate for less oxygen other than to squirt less fuel into the combustion chamber… the amount of o2 past the throttle plate is what it is…
Guess we could use an ac system to cool the air and thus could squirt in more fuel (regardless of the fuels temperature) but manufacturers won’t ever do that and for the most part vehicle owners wouldn’t see any benefit associated with the extra cost if the manufacturers did such…
Don’t know, maybe I’ve misunderstood the issue but for EFI EPA compliant cars, I don’t see the point of spending money in cooling fuel when cooling the intake air
may will provide a bigger benefit