has anyone tried an air foil?? just put one in and feels a little more peppy.... what are supposed to be the gains in this...

 

Air foils have been out a long time. If you do a search, you will find many posts about them. The estimated gains vary from manufacturer. I put an expensive one from TPIS on my car and couldn't tell any difference. It's my understanding that what little gain you get is pretty far up the powerband.

Hope this helps.

 

This has been discussed in the aftermarket products review thread, where I had a pretty lengthy explanation. I'll water it down here.

It's been proven that the air foil increases airflow by about 30cfm. Now, unless your car NEEDS 30 more CFM, you wont see gains. Even if that is the case, a 30cfm increase in desktop dyno yeilded 1 whopping horsepower. In my opinion, that is not worth the 40$ you pay for the air foil.

And the statement about the gains varying from manufacturer to manufacturer: The design is all basically the same. I highly doubt that there are differences, if the gain to begin with is so minimal

Some also argue that it smoothes the air out...well, sure it will smooth the air out somewhat...but what happens when the air gets to the runner? Hello 90 degree turn, more turbulence. So basically by the time the air gets to the runners, it doesnt matter if it is just a tad more smooth, it is getting swirled around violently by the sharp runner turn and back under the plenum to the opposite head.

 

Do a porting job along with the Air Foil then you might be putting the air foil to use in the upper RPMs. Beside that I would not spend the money on it IMO. Plus you can find them for like $30 on ebay or somewheres in the cheaper range .