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air intake foil?

Paul G

Well-known member
Joined
Aug 27, 2001
Messages
200
Location
Griffith, IN, USA
Corvette
96 CE LT4 Convertible
My 88 had one on it already when I got the car. When I cleaned the throttle body I left the air foil off for a while. I did not feel any difference either way. I put it back on. It cant hurt.

Paul
 
R

racecar

Guest
I have used these and they do add something. I think you will feel a small seat of the pants improvement.
A 10 HP increase is just enough of a gain that you can feel it when you run it through the gears. One word of caution,
the instructions tell you to use Locktite on the screw, my friend tried it without, the screw fell out and you can guess how much damage that did to the valve seat and piston. :bang
 

Highway Man

Well-known member
Joined
Oct 30, 2010
Messages
110
Location
West Plains, MO.
Corvette
1992 Black on Black Coupe
Air foil response

I've got a 92 LT1 that is stock except for a K&N air filter with opened up air box and Magnaflow exhaust and my car runs better without the foil than with it.
When I put the foil in I experienced a drop in my throttle response and my fuel mileage dropped also. If you are determined to try using the foil I've got one just like new that screws into the throttle body that I'll sell you for $25.00. Just be sure when you install it that you use high strength thread lock on the screw so it doesn't come out fall into the intake and do damage to your engine. According to some posts this has happened to people who didn't bother to use the thread lock. I'm not saying the foil won't work for you I'm just saying it didn't work for me.:w
 

boomdriver

Well-known member
Joined
Dec 18, 2008
Messages
1,888
Location
texas
Corvette
87 z-51
I've got a 92 LT1 that is stock except for a K&N air filter with opened up air box and Magnaflow exhaust and my car runs better without the foil than with it.
When I put the foil in I experienced a drop in my throttle response and my fuel mileage dropped also. If you are determined to try using the foil I've got one just like new that screws into the throttle body that I'll sell you for $25.00. Just be sure when you install it that you use high strength thread lock on the screw so it doesn't come out fall into the intake and do damage to your engine. According to some posts this has happened to people who didn't bother to use the thread lock. I'm not saying the foil won't work for you I'm just saying it didn't work for me.:w

Pure Placebo effect......

how can it possibly work when it wasn't tuned (shaped for cfm) for that particular engine? It can't.

sugar pill That cost $50.


Theres another 'scare' story about these junk add on's....having the screw or a piece of the foil itself crack and break off and jam the throttle plates. Even at 1/4 throttle, when it happens unexpectedly, it gets ugly fast.

Its never a good idea to stick things in the engines induction that the factory did'nt put there.........there is a reason.
 

catbert

Moderator
Joined
Aug 26, 2004
Messages
3,487
Location
Tobacco Road, NC
If it added anything, the factory would have installed it. They aren't THAT stupid.
 

Hib Halverson

Technical Writer for Internet & Print Media
Joined
Jan 10, 2001
Messages
13,453
Location
CenCoast CA
Corvette
71 04 12 19
Pure Placebo effect......

The ole "boomdriver" gets the Monday morning "Beacon-of-Reality" Award.

"Air foils"....

:chuckle

Actually they are a "fairing" or a streamlining device and not an airfoil.

They offer no practical improvement to performance on a stock or near-stock L98 engine, however, on engines which have substantial modifications (ie: aftermarket camshaft, headwork and changes in induction system volume and length) such that the throttle body becomes a restriction to airflow, there will be a slight to modest improvement in performance because of this fairing causing a decrease in air flow restriction due to it's "blending", "smoothing" or streamlining of airflow around the divider and just ahead of the throttle plates.

Thing is...on a highly-modified engine, you're more likely to install a throttle body with larger bores and that far greater reduction in restriction may negate the value of the "air foil" in that application as well.

As for people "feeling" the difference on a stock L98...

Sorry but i think "boomdriver" has it right. They've fallen victim to the "placebo effect."

On the gas mileage thing, it's highly unlikely they improve fuel mileage. Don't get me wrong. I'm not doubting people may note an increase, however, I do question the accuracy of their mileage testing. Conducting fuel mileage checks is very difficult for the average enthusiast to do accurately. "Real" mileage checks are done with the car's fuel system connected to a calibrated fuel supply and not the vehicle gas tank and with the car either operated by a computer on a chassis dyno or by a professional driver who can drive the car the same way, two different times, over a special drive route.

Duplicating that accuracy by simply filling the tank, driving a ways on the highway or around town then filling the tank again and noting the fuel added is impossible.

Even if you use the same gas station, the same pump, park in exactly the same position, fill the tank to the same levgel, then use the same drive route, have similar atmospheric conditions and the same driver, it's still difficult to accurately measure gas mileage.

Consequently, i suggest that any nonscientific comparison of gas mileage to support the idea that "airfoils" improve mileage might be questionable in its credibility.
 
Joined
Oct 7, 2007
Messages
719
Location
Amherst, NY
You should not fall for those 10 extra pony claims if you have a stock TPI engine.
As Hib points out, there is value on modified engine that can take advantage of higher cfms.
Here is a dyno run by TPIS on a stock TPI showing a few extra HP:
AirFoil.jpg
 

boomdriver

Well-known member
Joined
Dec 18, 2008
Messages
1,888
Location
texas
Corvette
87 z-51
I think Ted and Hib nailed it...

if the engine is not set up to utilize more CFM, then by making more CFM available can possibly defeat the pressure waves (vac/charging) flow thru the entire intake system....people forget that the few CI of air thats in the cylinder as the valve closes did NOT just get pulled thru the t-body...it was waiting in a semi charged state in a pulse or a wave somewhere in the plenum or runners. It would take a 350 cubic ft engine to inhale a single breath (cycle) thru a GM TPI and get any of it in a cylinder....
Anyone interested in doing some complex math calculations can calculate the vol of a 350 single cyl, the plenum, runners vol and see exactly how many waves (cycles) it takes to make the trip...

Same reason why compression test require 3 -4 puffs...thats about how many waves there are between throttle body and cylinder.

Myth...........BUSTED :beer
 

Hib Halverson

Technical Writer for Internet & Print Media
Joined
Jan 10, 2001
Messages
13,453
Location
CenCoast CA
Corvette
71 04 12 19
Ok...I've thought about it. I need to clarify my earlier statement on fuel mileage testing.

While it's true that "lab grade" fuel economy testing uses a calibrated fuel supply system other than the stock gas tank, a computer-operated chassis dyno or a professional test driver on a special route, you can come close in accuracy to those methods using real world practices, but you have to be careful of a few things

1) Use fuel from the same source and refuel under similar atmospheric conditions.
2) Refuel with the car on level ground.
3) Refuel to exactly the same level each time...in some cases with a late model car having an unleaded gas restrictor in the filler neck that will be difficult. For example, with a C4 you may need to make a fuel "dip stick".
4) Drive exactly the same route, in similar atmospheric conditions and in the same manner.
5) Check your odometer accuracy before the test.

If you observe those procedures you can make reasonably-accurate gas mileage comparisons.
 
F

FForward

Guest
I installed one of those airfoils on my '89 because a fellow Vette owner suggested it to me. I didn't feel anything in the seat of my pants except for being lighter by the $ I paid for it. I also added a power coupler which replaced the accordian type which was stock with the smooth one. I also opened up the air intake box, none of these made any difference I could feel. I beleive the only thing they do is smooth out the air flow to the plennum. That may help improve things a little, but not that I could tell. My gas mileage didn't change either. I've also read of guys cutting the screens out of the MAF for more air flow. I haven't done that and personally wouldn't even try. With the open air box, power coupler, and air foil installed my throttle responce did seem smoother, but thats about all I noticed.
 

boomdriver

Well-known member
Joined
Dec 18, 2008
Messages
1,888
Location
texas
Corvette
87 z-51
What people need to undrrstand with these onboard mods, is that they do not ADD power to the engine, they simply change the way the power is delivered. They change the way the engine performs.
Better throttle response is an acceptable upgrade.
 

muddywaters

Well-known member
Joined
Aug 25, 2002
Messages
765
Location
wilkes-barre,pa.usa
Corvette
1988 white 4+3 coupe 99 Torch Red 6spd. coupe
I installed one of those airfoils on my '89 because a fellow Vette owner suggested it to me. I didn't feel anything in the seat of my pants except for being lighter by the $ I paid for it. I also added a power coupler which replaced the accordian type which was stock with the smooth one. I also opened up the air intake box, none of these made any difference I could feel. I beleive the only thing they do is smooth out the air flow to the plennum. That may help improve things a little, but not that I could tell. My gas mileage didn't change either. I've also read of guys cutting the screens out of the MAF for more air flow. I haven't done that and personally wouldn't even try. With the open air box, power coupler, and air foil installed my throttle responce did seem smoother, but thats about all I noticed.
I agree with that. I got the same results.
 

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