Warm air intake

[MeteorGray]

The Jeep 4.0L straight six had both the exhaust and intake manifolds on the same side of the engine. Some models even had a problem or two from overheating the injectors due to exhaust manifold heat. The factory's fix for that was to insulate the affected injectors.

Although that old-school cast-iron six proved to be a great engine for pulling through the mud with all four tires spinning, alas it didn't do very well in regards to fuel economy. Pushing a square box through the air will do that.

The factory obviously didn't buy into the warm air intake being better for the Jeep. They located the air filter intake on the cool side of the engine. I guess heating up the intake air when you're doing three miles an hour in the muck might not always be seen as an advantage.

[teoman]

I have an car now that i cannot do extensive modificatios to.

So i stuffed some cardboard in front of the radiator. And i removed the cold air intake so it should now suck warmer air from the engine bay.

[cRiPpLe_rOoStEr]

Originally Posted by teoman

I have an car now that i cannot do extensive modificatios to.

Why can't you do extensive mods to it?

[teoman]

It's my grandmother's car. She doesn't use it much, but she will want it back eventually.

[Magician]

This Winter season was brutal cold in Omaha... my MPG last tank was 46.32 MPG. It was nice having the new larger 13.5 gallon tank vs the old 10 gallon. This Summer will likely give me 900 mile tanks.

[teoman]

What if the intake was modified to suck air through the radiator. Its relatively thermo regulated.

[Magician]

You get warm/hot air much quicker off the exhaust manifold.

[ECONORAM]

Originally Posted by teoman

What if the intake was modified to suck air through the radiator. Its relatively thermo regulated.

I was doing that for a while until my electric fan gave up the ghost. On my truck it was worth a 30*F increase. I pulled air right from the upper radiator hose entrance.

[teoman]

I am very much in to control systems, but i still have not figured out the optimal temperature parameters. Or the means to create a feedback loop (sensor information by which to control the temperature) for optimal fuel efficiency.

One thing that comes to mind (for steady speed) is increasing temp untill gas peadal is to the floor or advance decreases, or detonation begins or fuel injection time starts to increase (to cool things)... but unfortunately as of yet i am unable to conjure up the formula to create a system.

Academic papers are contradictory. Some say lower temps increase efficiency, some say they decrease it. In reality it is both, as intake temps decrease engine efficiency goes up, as butterfly valve opens up more, punping losses decrease, as intane air temp goes up vaporisation increases, hence more complete combustion...

One paper says 80 dec C is optimal, but that is for a HCCI engine.

So if you guys have any ideas, i would be willing to discuss yss.

[ECONORAM]

Tvago did some testing with his dodge 4.7L, and found 130F was about the upper limit for improvement. I couldn't let mine get above 100F, or my engine's PCM would retard timing and that didn't help anything...