[Lasse]

We don't yet have MPG-forum or topic. Ok, we have that 34:1 topic, but that is not the same thing, so I assume anybody don't resent if I start one. I'd like to hear what you others will make for engine to improve MPG.

I have one idea. I'd like to hear what you think.

When we are driving at low constant speed, we don't need very much horsepower, but our engines are making maybe 5 or 40 times more horsepower @ WOT.
That is situation where your engine is extremely too powerful at low speeds. So when you drive low speed, you have to somehow limit power or car is accelerating. What we do is we lift right leg from gas pedal and close throttle. And what happens? Volumetric efficiency drops very low and car goes constant speed. In side effect compression pressure drops very low. That can't be good for fuel economy, right? Next question is how much fuel car will consume if it have so small engine it just gives enough horsepower @ WOT to drive constant speed at let's say 50 mph? I think it is much efficient, because of good compression pressure.
Next you think I will suggest to put two engines in car. That is one solution, but not very practical. What I suggest we make conditions for big engine allmost same that in small engine. Ok, lean burn engine is doing that, but there is limitation in mixture leaness. Conventionally we try to atomize fuel to small particles and we put it in chamber and pray it will mix homogenous with air and burn efficiently in very low combustion pressure. My idea is what if we vaporize fuel and mix it air before even it is entering to intake manifold. Vaporized fuel will take very much volume of air, so you don't have to put so much fuel in mixture, because mass of air entering in the engine is low. So you don't have to lean mixture to it's limits for getting good combustion pressure.

Another idea is to heat air so hot it expands much and therefore you don't have to put so much fuel in it to satisfy engines AFR limit. I don't know if it is good to combustion at high compression pressure, but that might be tradeoff.

Maybe fuel can also be for example propane so it vaporized very easily and takes volume of air.

I repeat, my english is not best possible, I hope you understood my idea. And I am very unexperienced hobbyist, so I really like to hear your opinions for my theories.