"Warm Air Intake" Apparently increases fuel efficiency?

[Z2TT]

Hi,

All the time i've believed that colder intake temps result in more power and economy because colder air is easier to compress?
However I have been reading on ecomodder and read the following on this page :

http://ecomodder.com/forum/fuel-econ...ifications.php

"Higher intake charge temperature has been found to increase the flame speed, the combustion reaction rate, the uniformity of the fuel-air mixture and reduce the heat transfer rate though the cylinder walls. This all adds up to the engine using more heat for physical movement and less being wasted.

The downside to this is that hotter air also tends to retard ignition timing and cause engine pinging. Different engines will react differently to warm air intakes and testing will need to be done to see if it will work for your specific vehicle. Saturns are known to react well to warm air intakes."

Any truth to this?

[jimmmayyy]

load of shit.

[celicapain]

maybe on a old carbied crapper, due to the extra heat helping fuel vapourisation.
On a new car it would just reduce the power slightly, with no increase in fuel economy.
fuel efficiency is just an umbrella for engine efficiency, which is influenced but internal friction,head/ combustion chamber design, fuel delivery type etc etc, and without major mods its nearly impossible to improve and engines fundamental efficiency.
Basically when you heat up the air you reduce its mass for a given volume, which reduces the engines effective power output,and its fuel consumption. but its alot easier just to stay off the pedal.
Alot of very old cars(1900-1940's) utilized intakes heated by the exhaust systems but that was because people were engineering around seriously poor fuel systems(crap pumps, carbies), Instead of any intrinsic benifit from a heated intake charge. I just felt like sharing something tonight, lol.

[Z2TT]

About the carby and fuel vaporization, I have noticed on a friends carbied car when cold you can see fuel dripping from the top yet into the carby, But when it's hot it sprays. Is it normal for it to drop when cold?

Float is fine and all no flooding after turning car off.

[auto351]

Hi,

All the time I’ve believed that colder intake temps result in more power and economy because colder air is easier to compress?

This is were you have may your mistake, if you cool air, it will become a liquid (when it gets very cold) which can’t be compressed.

load of shit.

I’m with jimmay, these facts are to general to prove or disprove.

If you want economy buy a donkey (LOL)

[Hiro]

This is you have may your mistake, if you cool air, it will become a liquid (when it gets very cold) which can’t be compressed.

You have to cool air (mostly nitrogen and oxygen) to ridiculously cold temperatures for them to become liquid - I think Z2TT got confused with cold air being denser than warm air, and thus already partly "compressed" and taking away some of the work that the engine does. Cold air, being denser, means that the engine draws in a greater mass of air for the same volume, and as long as extra fuel is given to match the air, more power will be made.

[neal]

Ever wondered why there is coolant going into your Plenum, it is to maximize fuel/air atomisation.

[Billzilla]

If you want a bit of an interesting journey, for better or worse do some research on Smokey Yunick's Adiabatic Engine.

[Norbie]

Ever wondered why there is coolant going into your Plenum, it is to maximize fuel/air atomisation.

No, that is to prevent the throttle plate from jamming due to ice formation. Not an issue for most of us but in colder climates it can happen quite easily.

[Hiro]

No, that is to prevent the throttle plate from jamming due to ice formation. Not an issue for most of us but in colder climates it can happen quite easily.

And the coolant lines to the throttle-body are usually for the cold-idle valve, not for heating the T/B

[Steve M]

And the coolant lines to the throttle-body are usually for the cold-idle valve, not for heating the T/B

That depends on the engine.
22R-s have the TB heated and the cold start valve is mounted else where (it may be run from another source of heat information.

[Hiro]

That depends on the engine.
22R-s have the TB heated and the cold start valve is mounted else where (it may be run from another source of heat information.

Hence the word _usually_.

[Duk]

It's an exstreem example but the principle is the same (turning chemical energy into heat energy).
The Reheat furnace at our Rolling Mill, at ONESTEEL, uses pre heating of the draught air. This has a huge impact on the amount of fuel (Coke Ovens gas and Natural gas) that the furnace requires. No pre heating = lots more fuel. I was told the percentage increase in fuel use and it was quite substantial, but I just can't remember atm.

Higher inlet air temperatures probably will have less ignition advance and result in less amount of power for a given amount of throttle percentage. So that should increase the amount of throttle require to maintane a given cruise speed. The increase in amount of throttle should help slightly reduce induction pumping losses (slightly less vacuum in the inlet manifold). Tho that's all a pretty big 'maybe'. The slight reduction of puming loss may or may not overcome the slight loss of power from the slight reduction of ignition advance.

Most people forget that there is a pressure drop across a TB (unless at full throttle). This pressure drop causes cooling of the air. So even in ambiant air temperatures higher than 0*C, there is the potential of freezing of the TB.

Without accurate testing it is wrong to write off an idea/concept as being BS. Assumptions really are teh mubba's of all fark upz.

[MWP]

Hence the word _usually_.

Nope, not usually... most.
Every Toyota EFI engine ive come across runs coolant to the TB to stop it iceing up.

Ive always blocked it off on my cars.

[quadthrottle]

No its actually true, it does increase MPG. Thats why there are so many pod filters on peoples cars that aren't sheilded. Aren't they the smart ones.

Lol