3.2 Air intake Mods
 

How much would a direct cold air intake help a 3.2L basically stock motor breathe? I'm talking about adding an external duct to route cold air directly into the air box.
Car has 1 5/8" headers and is chipped, but other than that stock.

TIA, John

I would worry less about finding a way to try and force air into the airbox (which isn't the major restriction on a stock motor) and concentrate on the intake plenums and throttle body first...

Before:

http://forums.pelicanparts.com/uploa...1162620882.jpg


After:

http://forums.pelicanparts.com/uploa...1162620907.jpg

You can also safely open up the throttle body about 3mm as well...

Once the above is done (which yields a 5-7 horsepower increase), than you can start playing around with different airbox configurations (ie MAF/cut air-box/cone filter, etc) in an effort to try and extract a few more...:)

Ralph

Very nice, Ralph!

Ralph,
Did you do this yourself? Can you explain a little more?

It's a track car and I have an opportunity to run a cold air plenum right into the airbox.

J

What about the sound differance? I have an '05 TRD Toyota Tacoma w/ a Flowmaster exaust. I shortly after put a K&N cold air intake on it and that s@%*&t was more fun than Disneyland. The intake was louder than the exhaust (in a good way). Anyone know what the sound change in the drives seat is (on a 911)?

No, certainly not my handiwork! This is the AFM (abrasive flow machining) process done by Extrude Hone. The ports aren't necessarily being enlarged, but simply cleaned up and made uniform in flow. The CFM's on these plenums can range wildly from cylinder to cylinder and this process brings the variance much closer to uniform.

Before AFM, the hot-set up for these plenums (back in the '80's when the cars were new) was to cut open the plenums, polish/clean up the runners and than weld the plenum back together. The only drawback to this process was the unsightly (for some people) welds that were left as evidence. EVERYONE knew the plenums had been modified versus Extrude Honing where there isn't an external visual clue that it has been performed.

Andial did extensive back-to-back dyno tests in the early '90's and there was no appreciable difference between extrude honing and polishing/welding. They both registered a 5-7 horsepower gain on the dyno in the middle/upper rpm ranges. Whether or not the expense (about $600) is worth it (plus another $150-$200 to enlarge the throttle body) for the relatively minimal power gains or whether these mods are legal for your racing class is up to you to determine...:)

While I think that channeling cold, dense air direct into the airbox is a good idea, I don't believe the airbox is the major restriction and doesn't become the major restriction until the above modifications have been performed...:)

One dyno test is worth 1,000 expert opinions...:)

Ralph

and the 3.2 runners are known to flow inconsistently. EH evens out the runners