"Warm Air Intake" Apparently increases fuel efficiency?

[Z2TT]

Yes always thought colder air was better, otherwise all cars would have factory unshielded pods

Plonka you mentioned because of the pressure drop occuring after the throttle body, the throttle body could freeze. Is this the reason why coolant runs through it? Or will it only be a problem if you are starting your car in sub zero temperatures?

I was thinking because of the pressure drop which you talked about, would it be a good idea to keep the water lines attached even if your never going to start in sub zero temps? Because of the pressure drop having a potential of freezing the TB? Or in reality would it never happen?

I have heard that many people like to block their TB coolant lines off to stop it from heating up the intake air temperature, wonder if it makes a difference in power or people just remove it simply because it's not needed. MWP?

Thanks.

[MWP]

I have heard that many people like to block their TB coolant lines off to stop it from heating up the intake air temperature, wonder if it makes a difference in power or people just remove it simply because it's not needed

For me its mainly the latter... less coolant lines around the engine bay is always a good thing.

It probably doesnt add much heat to the intake air as the manifold is being heated from the head anyway.
If you had a phenolic inlet manifold spacer, then removing the TB heating would probably make a difference.

[TRDcelica90]

from my personal experience hotter intake air gave me an extra 15-25kms per tank in my old 184 celica..

i used the standard airbox with a gay&N panel filter for about 7 months.

then changed to a open pod and that tank instantly bumped up my economy!! sounded awesome too so i gave it a little more stick lol.

but yes u lose power, we dynoed pod vs stock airbox and the stock airbox won by 2.5KW at the wheels, wasnt noticeable while driving.

[Robbo]

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.

22R's do not run a cold start valve.
these engines and alot of older 80's -some 90's spec Toyota EFI engines run a cold start injector ,(located in the intake plenum ,usually in the middle,as to give even spray.) running off a thermotime switch thats located in the thermo housing.

[white_sandshoe]

I do believe, in theory, warm air intake will "increase fuel efficiency"... at the detriment of power.

If the air is nice and warm, the mass will be less than cold air of the same volume, so that same volume will need less fuel... That will of course come with the added bonus of less power.

But i suppose then one would be more inclined to put the boot into it to get the darn car to move, meaning larger volumes will be allowed past the throttle body... hmmm...

oh, THAT's why i don't look at these technical questions late at night when i'm drunk. gotta love a good circular argument.

[woggin]

I have been studying this type of stuff since my missus got her Yaris last year, read the following, it explains how a WAI works, i still dunno if i believe it....all i can say is "I FU$KING HATE FLY BY WIRE THROTTLE BODIES!!!"

Taken from the Ecomodder website and the hypermiling website:

A garagir warm air intake or WAI is a system to decrease the amount of the air going into a car for the purpose of increasing the fuel economy of the internal-combustion engine. This term may also be used to describe a short ram air intake, a totally different intake modification.

All warm air intakes operate on the principle of decreasing the amount of oxygen available for combustion with fuel. Warm air from inside the engine bay is used opposed to air taken from the generally more restrictive stock intake. Warmer air is less dense, and thus contains less oxygen to burn fuel in. The car's ECU compensates by opening the throttle wider to admit more air. This, in turn, decreases the resistance the engine must overcome to suck air in. The net effect is for the engine to intake the same amount of oxygen (and thus burn the same amount of fuel, producing the same power) but with less friction losses, allowing for a gain in fuel economy, at the expense of top-end power.

Opposite principle of a cold air intake (CAI) which significantly differs by collecting air from a colder source outside of the engine.

In the extreme, a warm air intake can eliminate the need for a conventional throttle and thus eliminate throttle losses

[mattysshop]

a guy called 'barry' on the magna club has proven that replacing the plastic fuel rail spacers in the fuel rail with turned ally ones, thus allowing the cylinder head to transfer it's heat into the fuel rail, give you better economy... using the factory cold air duct feed from infront of the radiator (cool ambient air) and a warmer fuel mixture apparantly give better atomisation

and another reason for the throttle body to be heater is to help with the gumming up that crank case ventilation to the throttle body does.

[Sam_Q]

I am with Plonka, I thought that with the warmer air needing the throttle much more open it significantly reduces pump losses due to the reduction of pressure difference between the chamber and the crankcase.

[Hiro]

22R's do not run a cold start valve.
these engines and alot of older 80's -some 90's spec Toyota EFI engines run a cold start injector ,(located in the intake plenum ,usually in the middle,as to give even spray.) running off a thermotime switch thats located in the thermo housing.

You can still run a cold-idle valve _and_ a cold-start injector, as the cold-start injector only fires on cranking when the engine is below a certain temperature, whilst the cold-idle valve is open as long as coolant temp is below a certain amount (the infamous wax pellet in a lot of cases) bumping the idle up higher until the engine is warm

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.

The EFI Toyotas I've had have used the coolant for the cold-idle valve, not the TB itself (the coolant runs into the valve below the TB, not the TB itself), this includes 4AGE, 7AFE, 3SGE and 5SFE.

[MWP]

The EFI Toyotas I've had have used the coolant for the cold-idle valve, not the TB itself (the coolant runs into the valve below the TB, not the TB itself), this includes 4AGE, 7AFE, 3SGE and 5SFE.

It still heats the TB though.
Engines that dont have a cold-idle valve still run coolant to the TB.

[wizza_101]

All warm air intakes operate on the principle of decreasing the amount of oxygen available for combustion with fuel. Warm air from inside the engine bay is used opposed to air taken from the generally more restrictive stock intake. Warmer air is less dense, and thus contains less oxygen to burn fuel in. The car's ECU compensates by opening the throttle wider to admit more air. This, in turn, decreases the resistance the engine must overcome to suck air in. The net effect is for the engine to intake the same amount of oxygen (and thus burn the same amount of fuel, producing the same power) but with less friction losses, allowing for a gain in fuel economy, at the expense of top-end power.

i remember reading this a while ago. it would seem to run true. however this has also been a very common factory piece of equipment across the years. right back into the carby days where the intake pipe into the factory airbox came from a bolted on intake to the exhaust headers.

[JP]

with an aftermarket ECU, in the intake air temp compensation table you usually have to remove fuel as the intake air temp gets hotter to maintain the same AFR, otherwise it goes rich...

Hotter/less dense air with the same injector pulsewidth runs richer.

[Z2TT]

Yeah lots of the carb cars did have air inlet from near the exhaust manifold, why do EFI cars not have this anymore but just a permanent cold inlet?

[RONA]

Cross flow heads.

[ra28_miles]

gotta remember when a gas is compressed eg twice its volume metric size, it doubles in heat. SO when a gas is compressed 8 times the heat, say atmosphere temp 20c, becomes 160c in the camber. Add turbo boost and you get the picture. So by raising it just 5c can equal 40c = melted piston tops!

In boosted situations inlet temp can rise to 90c. But 90c is easy to be cooled by an aftercooler.

In diesel the air needs to be heated to get the air to "combustion" temp before diesel will self ignite, but haven't seen it in petrol.

Don't believe me? stick your hand on a compressor and tell me how hot it gets.