Cold air VS Warm Air Intakes - what's the difference?

[Xist]

Somehow I feel that the WAI idea is academic for me here in Arizona, although it is not 120° everyday...

[ChadB]

The 94 ranger has one of these "manifold stoves" except it's controlled by engine vacuum instead of temperature.

[jeff88]

Bringing up an old thread, but a good one!...

I was thinking, which steffen707 started to talk about, what if I did a "T" or "Y" bend, so that during engine warm-up, it used warm air, during acceleration or high engine revs (say over 2,000ish RPM), it switched to cold air and at cruising, switched back to warm air. I feel like this would give me the best of both worlds and help increase my FE better than a WAI or CAI alone. How would this be done? It would need some sort of "computer" to know certain variables (engine temp, revs, etc.) in order to switch back and forth appropriately.

Also, somebody mention fuel temp. Would preheating the fuel, in the fuel line before the injectors help with power and/or FE? What about the safety risk? Would there be a higher chance of vapor pre-ignition (e.g. inside the fuel line, well before the engine)? How would this be done? Re-route the fuel line close to the exhaust manifold (again, sounds dangerous)? I can't think of any other ways to preheat the fuel, though.

P.S. I don't have it yet, but I am planning on buying a Ford Escape Hybrid. Don't know if hybrids change the equation or not... Also, the FEH engine at cold start-up, automatically stays on until the engine is at operating temp, so the sooner it gets hot the better, because it will switch to battery sooner.

Soooo many questions!...

[RH77]

Originally Posted by jeff88

Bringing up an old thread, but a good one!...

I was thinking, which steffen707 started to talk about, what if I did a "T" or "Y" bend, so that during engine warm-up, it used warm air, during acceleration or high engine revs (say over 2,000ish RPM), it switched to cold air and at cruising, switched back to warm air. I feel like this would give me the best of both worlds and help increase my FE better than a WAI or CAI alone. How would this be done? It would need some sort of "computer" to know certain variables (engine temp, revs, etc.) in order to switch back and forth appropriately.
...
P.S. I don't have it yet, but I am planning on buying a Ford Escape Hybrid. Don't know if hybrids change the equation or not... Also, the FEH engine at cold start-up, automatically stays on until the engine is at operating temp, so the sooner it gets hot the better, because it will switch to battery sooner.

Soooo many questions!...

If the Escape Hybrid's algorithm is like the Pruis (or perhaps similar in design to the Insight 5-door), there may be a few levels of "warm-up", based on coolant temp (perhaps transmission fluid temp as well), battery State of Charge, etc. Operation could inlclude the use of the electric motor assist/charge even immediately after cold-soak starts. Others can likely offer more details.

Regarding the T- or Y-junction for intake air temp control, I had a scheme dreamed-up a few years ago for this exact scenario. You can go as complicated as fully automated gate with servo controls, using a circuit to use voltages and/or resistance values from Coolant Temp and engine RPM to calculate required gate movement to achieve a targeted IAT condition (monitored on a feedback loop). Another easier (yet manual) solution could be to use a knob to control the air source with a simple vaccum or electric gate. I opted for the latter and tried to find an existing part from a separate vehicle that was already built for this sort of task -- but struck out. EDIT: See this post for an air box with the assembly fit for the task (Volvo). I suppose to decide on wild or mild and go from there...

RH77

[radioranger]

I think a hot air intake would definitely help the short trip driver mainly because of much faster warm up times, Also on an older non mass air setup like my ranger, warmer days are much better for smooth operation, nothing like a warm foggy night to smooth out an older car, or truck . my experience anyway. the idea of a heated fuel rail setup sounds interesting or heating the fuel line itself, dont know if any engine measures the fuel temp before injecting it.

[RdRnr]

Wouldn't warmer fuel and/or air (up to a point) be better for FE because it contains more energy? I just made that up, so don't believe it.

[gone-ot]

Originally Posted by RdRnr

Wouldn't warmer fuel and/or air (up to a point) be better for FE because it contains more energy? I just made that up, so don't believe it.

• COLD air for horsepower.

• WARM air for fuel economy.

[euromodder]

Originally Posted by Old Tele man

• COLD air for horsepower.

• WARM air for fuel economy.

Except on a diesel, which will rather take the cold air.

[gone-ot]

Originally Posted by euromodder

Except on a diesel, which will rather take the cold air.

...or, turbocharged, without an intercooler.

[radioranger]

what we need is a separate throttle body to feed warm air into the air cleaner housing from a heat stove heated by the exhaust, that can be closed for high load operation to allow the factory cold air system to function normally , might not be that tricky. or high tech but would probably help a lot, my escort hates cold weather, at least for FE, also the MTL trans lube although far quieter has cost me about 2 mpg, or could just be the colder weather also. anybody insulating their trans case ?