CAI to WAI?

[XanderWiFi]

For simplicity and convenience sake, I would like to convert my CAI to a WAI on my 3400. Does anyone have this setup, and if so, could you tell me what length piping and filter fits the best?

Thanks.

Second question: I read that a WAI can draw hot air into the engine which can damage it. Any validity to that? I do have the aftermarket headers in there.

[a.graham52]

I had a cai in my car. Removed all of the cai except for the part between the maf and tb. Then stuck the filter on the maf. Boom wai. I've never ever herd of hot air damaging an engine though

[AleroB888]

Originally Posted by XanderWiFi

For simplicity and convenience sake, I would like to convert my CAI to a WAI on my 3400. Does anyone have this setup, and if so, could you tell me what length piping and filter fits the best?

Thanks.

Second question: I read that a WAI can draw hot air into the engine which can damage it. Any validity to that? I do have the aftermarket headers in there.

I don't think it's likely to damage your engine. There will be a loss of power if the upper intake manifold does not have a source of cooler air from the filter tubing. A stock PCM will also reduce timing for higher intake temps. Easiest would be put the stock unit in with a paper filter. However, omit the section that fits inside the fenderwell, and keep the stock section that goes to the fender.

[wws944]

The air filter will keep out any bad stuff. However cold(er) air is all about power and fuel economy. Back in the olden days of carbs and compromised mixtures, warmer underhood air was probably desireable for general drivability. Especially in the 1970s and early 1980s, when they were going with leaner mixtures, so put the little heaters on exhaust manifold to thermostatically have a controlled source of warm air. But with closed-loop computer-controlled fuel injection, that is no longer an issue. The input air temp is monitored, and the mixture adjusted as appropriate.

[a.graham52]

Originally Posted by wws944

The air filter will keep out any bad stuff. However cold(er) air is all about power and fuel economy. Back in the olden days of carbs and compromised mixtures, warmer underhood air was probably desireable for general drivability. Especially in the 1970s and early 1980s, when they were going with leaner mixtures, so put the little heaters on exhaust manifold to thermostatically have a controlled source of warm air. But with closed-loop computer-controlled fuel injection, that is no longer an issue. The input air temp is monitored, and the mixture adjusted as appropriate.

the colder the air the worse your fuel economy but the better the power, the denser the air, the more fuel added to keep a good fuel mixture going, the warmer the air the "leaner" the air mixture will be so fuel is subtracted.

and with carbs, the "thermostaticaly controled hot air" was used to help the engine run good (driveability) in cold temps. a cold engine will not like cold air. you realy noticed this on a wheeler or bike thats carbed and you try and crank on the throttle when its stone cold... falls on its face.

i run the WAI for fuel economy.

[AleroB888]

Originally Posted by a.graham52

the colder the air the worse your fuel economy but the better the power, the denser the air, the more fuel added to keep a good fuel mixture going, the warmer the air the "leaner" the air mixture will be so fuel is subtracted. ....

Warmer air is less dense, but the O2 sensor compensates for colder air and still brings the AFR to 14.7.

With more power available, the engine can run at a slightly lower rpm, which works to balance out the extra fuel added.
Hot enough air will cause the PCM to reduce timing, which can also adversely affect economy, and require a higher rpm to make the same power, which can increase wear.

Most savings with warm air are when the engine is started cold, then there is definitely fuel saved and lower emissions. Not so much after fully warm, especially in hot weather.

Driving habits and how the PCM is tuned, high-flowing exhaust all make a difference.

[a.graham52]

i agree with you say but IMO i think your being a bit too technical for a DD. plus the O2 sensor doesnt determin how dense the air is. thats the job of the MAF/MAP sensor.

[Redog]

Search button.

I did a write up on this years ago

[wws944]

Well... if a WAI gave better MPG on fuel injected cars, the car manufacturers would still be providing them. On old cars with carbs, it probably cost them a couple of dollars per car to add the stove and 'thermac'.

It is a good point about cold starts though. Goal is to get the cat lit and the O2 sensor warm ASAP so that the computer can go into closed loop mode. I haven't monitored it on my Alero yet. But on my 2002 Rendezvous, which has the same engine, it takes less than a minute for the computer to switch to closed loop. A WAI wouldn't help this much.

One of the really amazing things when cars switched to EFI was how well the engines ran when cold. I bought my first EFI car ('81 Audi 5000S) in 1983 and never looked back.

[a.graham52]

Wws: u are aware that a warm air intake just takes air don the engine compartment and not from the fender like a cold air right? The warm air intake only has engine bay ambient temp. It's not "heated" like the older cars on a cold start up. And intake temp is not going to heat the cat or O2 sensor rather its hot or cold. Hot air goes in engine, comes out hotter... Cold air goes in engine and come out just as hot. What helps heat the O2 sensors are build in heaters. Plus the extra fuel In the exhaust heats the cat

[wws944]

Underhood air is certainly warmed by passing through the radiator, and also from the engine itself. Of course the engine actually has to be warm for this to occur.

Last night I timed a cold start on my Rendezvous. It took 30 seconds, on the nose, to switch from open to closed loop. And yes, heated O2 sensors definitely speed the process up.

So I am not sure I see the point of a WAI (on a car with modern EFI). Unless, of course, one simply wants to run something like a cone filter in the engine bay so that you can hear all the intake hiss and drone.

[a.graham52]

both WAI and CAI let more air in and faster over stock setup making them more efficent. however CAI lets in colder air and usualy cost a bit more

[MMGT1]

A CAI also gives you a longer intake runner. What this will do is allow airflow to stabilize before passing throught the MAF and will result in better throttle response and a little better fuel economy overall. There is just too much turbulance with a WAI and even your "ass dyno" will feel the difference