DIY Warm-Air Intake

[bnmorgan]

I'll shortly be working on an '88 festiva, carb 1.3L as my first project. I noticed that on the intake hat, there is a tube running to the fender, and a smaller metal tube running up to a valve of some sort, the other end attached to a heat shield on the exhaust manifold. If i force this valve to remain open, is that going to give me intake air that is too hot? Is hot air gonna help that much, and how much will it hurt what power there is? 70 mile per day commute through rural Mississippi.

[nubbzcummins]

"Version 1.0, 3-years ago, drew the air from between the heat shield and manifold. IATs were way too high -- 180F in the Winter! The faster warmups were nice, but detonation wasn't. v1.1 moved the tube to its current location, which is far enough away, but never broke 90F. Removing the shield allowed "v1.2" to reach 100-110F on cold days, 140F on 40F+ days (fall is a bit unpredictable). This is in combination with a rad-block and has worked well since."

RH77: Have you tried changing the gap, heat range, type of spark plugs being used to fix the detonation due to high intake temps? I had a supercharger on a toyota tacoma and the discharge temps of the s/c was so hot that it caused detonation that could only be cured with timing adjustment and/or colder heat range plugs. Just an idea.....

[swoody]

I tried this same setup in my Civic, but for some reason it dropped my MPG. I just removed the flexible piping, and now I just have a large hole in the side of my intake where the cool air tube and resonator used to be, and I get much better mileage now. I figure it's pulling in warmer air from the engine bay, but not getting the extremely hot air from the headers. Seems to be a great compromise for my car

[nemesis]

so what kind of gains did you guys get from wai??

[Davinator61]

I'm seriously looking at replacing the Cold Air Intake I've currently got on my 1991 Jeep Cherokee Laredo 4.0L (Spectre Industries Modular Tubes with Original Factory Bellows-Elbow and Amsoil Synthetic Dry Media Cone Filter) with a Donaldson G070020 Sealed Cylindrical Air Filter Housing and plumb a heat resistant duct to my replacement APN Exhaust Header in order to improve colder weather fuel efficiency. I'll try to post pics once its done.

[13B_88FC]

I don't quite get this mod.

Warmer air is less dense, I get that. Therefore the car would run leaner if it thought there was mroe air coming into the engine than expected based off the air flow meter. However, if I'm not mistaken, most cars have BOTH an air flow meter and an intake air temperature sensor that sends information to the ECU. So, if that were the case for this specific car, I don't see how this would help since the ECU would just correct accordingly and inject less fuel anyways.

Optimally you would want cold air going into the engine(to an extent) and the ECU to know how cold it is and how much there is to inject the correct amount of fuel.

Is there something I'm missing?

[H-Man]

Heat. The engine will run richer with cold air because the ECU adds more fuel to make it so that it can burn the fuel properly since cold fuel is hard to ignite.
The hondas seem to like it at 120f, it manages the same MPG gain as lean burn if memory serves.

[13B_88FC]

I'm not sure I quite buy that. An engine that is already at an operating temperature of 200 degree or more is not going to have problems igniting the charge from a "cold air" intake because by the time is actually gets to the engine, it's plenty warm. Maybe this wouldn't be true if temps are down below say 40 degrees, but still I'd have to see really solid data showing good gains to believe this is beneficial.

Cold air intakes are good for both power and mpg. A denser charge is a good thing.

[H-Man]

Originally Posted by 13B_88FC

I'm not sure I quite buy that. An engine that is already at an operating temperature of 200 degree or more is not going to have problems igniting the charge from a "cold air" intake because by the time is actually gets to the engine, it's plenty warm. Maybe this wouldn't be true if temps are down below say 40 degrees, but still I'd have to see really solid data showing good gains to believe this is beneficial.

Cold air intakes are good for both power and mpg. A denser charge is a good thing.[Citation needed]

My Prizm has seen a 4 MPG boost from the WAI and my average temperature is in the 70's.
When I put the CAI back on, I see it drop back down to 33 MPG.
Half the problem is that the engine has a hard time getting up to operating temperature quickly.

[13B_88FC]

Originally Posted by H-Man

My Prizm has seen a 4 MPG boost from the WAI and my average temperature is in the 70's.
When I put the CAI back on, I see it drop back down to 33 MPG.
Half the problem is that the engine has a hard time getting up to operating temperature quickly.

Is that in primarily city or highway driving?