Warm Air Intake (WAI) insanity

[Bill in Houston]

WAI definitely improves mileage, as long as your ECU doesn't do something like richen the mixture to prevent pinging. It seems to me that you just want to get the air temp into the 100-120 degree range. Any car should be able to run at that intake temperature. It's like a hot summer day...

[landspeed]

A WAI sounds like a good idea, *if* you are careful and make sure you don't get pinging. A lot of people here also block radiators, and do 'engine off coasting', with 'bump starts' to start again. This could be considered bad for the oil circulation in the engine

Restricting the air intake will save fuel compared to flooring the accelerator pedal, however, it will cause increased pumping losses. Diesels run with no throttle plate at all, one of the reasons for their much better economy!

However, as some people here get 250% of the EPA rating in their car, I suppose it is worth it if done carefully . I actually save $400/month by driving economically, so I could probably get a lot of engine repairs done if needed!

P.S. My non-intercooler turbo air intake pipe is burning hot to the touch when driving gently anyway so I suppose I already have a warm-air intake . I suppose this is why my ECU is programmed to enrich at 30-40% throttle too!

[zpiloto]

Originally Posted by 1bolt

I've never registered for a forum just to reply to a thread I found web searching (or a couple threads here to be more precise). So I can guess how this "first post" will go over but I have to point out a couple things for those doing "warm air intakes" hopefully before they pre-ignite holes in their pistons.

1) If you're bent on causing your engine to run at sub optimal performance, then the correct way to lower the amount of air getting into your engine is with an artificial restriction.

It's completely baffling that anyone would force heat into their intake path to reduce air density when simply restricting the normal intake tubing will do a MUCH better job of it, up to a complete 100% lack of air at full blockage.

Whats more blocking the intake path is FAR more predictable, and is less likely to cause your engine to detonate itself into the road beneath your vehicle.

2) heated air outside the design parameters of your ECU is a fast way to pre-ignition and/or detonation either of which WILL KILL your MPG's and shortly their after your engine.

3) The need to use 93 octane to compensate for the hellish pinging and detonation you're causing should be a huge red neon flashing warning sign. MOST "ping" happens before and after you actually HEAR it. Most of what you HEAR when your engine is pinging is generally a result of your valve train "complaining" (so to speak), when the valves are being hammered by explosions that aren't supposed to happen at that time (or that quickly).

WAI is just so wrong on so many different levels. Never mind all of the above; unless your commute is dead flat; the decreased power will cause you to compensate by putting your foot down further and longer, slowing down and losing momentum will cause the need to speed up more often and you all surely know that acceleration is bad for economy.

Lugging up hills and when loaded, will cause knock which will force most ECU's to retard the timing, which will further cut your fuel efficiency AND performance.

So before you peen your engine into an early demise, consider: Engines cost much MUCH more than what you will save with a 1 or 2 MPG increase. Even over a few years.

just my 2c

1bolt just wanted to say welcome to the site. I hope you hang around.

[Hockey4mnhs]

repete dont do a wai i think that it is killing my fe! It robs of low end tourque and it makes ur car louder. I want to get rid of mine bad but idk how to put the stock one back on

[rh77]

The point of the HAI/WAI is to get the intake temps up to the level the ECU needs to run leaner -- this is especially best in Winter. I've run past the 200*F mark and saw no improvement in my application. Tests have shown that for my Integra ECU, about 90*F is ideal to satisfy the leaner requirements.

Since ambient temps are getting closer to that, a switch-out of the HAI into something cooler is needed: with temps of 70*F outside, the under-hood and IAT temps are pusing 125*F at times, which will start to move things in the other direction, efficiency-wise.

Nearly all computerized cars need to warm-up both with air and coolant temps to become most efficient (that's why drawing HAI/WAI on startup is important). Tests (by yours truly) with restrictors, super-high IATs and even CAIs have yielded some good data for my application. Make no mistake that I haven't even come close to understanding the nuances of engine air management, but for my car, the data has concluded highest efficiency is attatined with a consistently "Warm" temp, free-flow, and a stock-length and diameter tube.

RH77

[mrmad]

The best data I've seen is on Metrompg's website and he didn't see a great difference with a WAI, which he attibuted to the fact that he believed the Metro's ECU wasn't adjusting the AFR due to the intake temp. While in theory, hotter intake temperatures may reduce pumping losses, I would think any gains made from this would be offset by the loss of power, which would then result in a larger throttle setting.

[VetteOwner]

yea.. my chevettes motor control flap in the snorkel (flap that controls where the air comes from either from around the exhaust manifold, or the front of the car) that flap was stuck up all the time and boy did my mpg hit the fan...im talking liek 20's froma 4banger 4speed...so i just took that temp sensor out because thats what causes the flat to go up and so its always down now...

[GasSavers_nathan]

VetteOwner, with the flap down does it draw cold air? i remember mine failing before so i just pulled the vacuum line to it. i disconnected the tube that pulls the air from in front of the rad though so its getting warmer air from the engine bay.

[rh77]

Originally Posted by mrmad

The best data I've seen is on Metrompg's website and he didn't see a great difference with a WAI, which he attibuted to the fact that he believed the Metro's ECU wasn't adjusting the AFR due to the intake temp. While in theory, hotter intake temperatures may reduce pumping losses, I would think any gains made from this would be offset by the loss of power, which would then result in a larger throttle setting.

This is a true YMMV mod. Most Honda OBD-II vehicles like the warmer air; whereas, vehicle's like Metro's Suzuki-clones do not see a huge improvement. Personal testing of your own vehicle can only tell.

I'm pretty confident that warm air on startup helps in most cases: carbed or injected.

RH77

[VetteOwner]

Originally Posted by nathan

VetteOwner, with the flap down does it draw cold air? i remember mine failing before so i just pulled the vacuum line to it. i disconnected the tube that pulls the air from in front of the rad though so its getting warmer air from the engine bay.

yea ive tried that in the winter just so it would start and be runnign and not sucking in super cold air... yes the flap is constantly down now.