Splitters, Canadrs and Wings

Real tech discussion. Not pansy-ass-bitch questions about the power a CAI will give.

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Splitters, Canadrs and Wings

Postby crzyone » Sat Jan 19, 2008 10:09 am

Aerodynamics and downforce don't get discussed much aside from hood vents.

As far as I know, nobody has ever put a front splitter on a fiero. I would think to do this properly you would need a closed chin spoiler first and then add the splitter underneath. For those of you why do not know what a splitter is, here is a picture.

Image

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It works by forcing air over the car instead of letting it go underheath. The fiero nose with its upward angle is really bad for forcing air underneath the front end. Its probably the biggest cause of front end lightness at speed. With a chin spoler and splitter, there might not even be a need for a hood vent, but the more air you can get up and over the car the better.


Canards would also help with front end stability and downforce but I think they might be a bit overboard for a mostly street driven car. Most people would associate canards with a ricer although they are on quite a few road course cars.
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Hood vents work well on a fiero. Instead of forcing hot air under the car from the radiator, you can vent some or most of it out of the hood. I think most hood vents on fieros are too small to get the most benefit, but everything helps.

Driven Visions (www.drivenvisions.com) makes one of the better aftermarket fiero hood vents I've seen. Its deep and has good size vents.
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I'm not sure if a traditional wing will work effectivly on a fiero. It would probably have to be 12-15" high to be in a clean air stream to work. The fiero rear window created a big low pressure area and a bunch of "dirty" air. The IMSA "whale tail" spoiler is another option but I'm also unsure on how effective it is. Its design looks like it prevents air from flowing up the back side of the car into the low pressure area. Anyone else have insights on any testing?

IMSA spoiler
Image


The major aerodynamic flaw of the fiero is the flat rear window, but it also serves a purpose. It promotes airflow through the engine bay by creating a low pressure area which sucks out hot air.

There is lots you can do to make a more stable car and help with handling. Maybe I will make my car a guinea pig and start adding some of these parts and report back on road feel.
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Postby Shaun41178(2) » Sat Jan 19, 2008 10:52 am

The only way to do this with real scientific data is in a wind tunnel. Ass meters are worthless.

Don't pull a JScott and start slapping on cut up front bumpers and stapling it to the rear of your car.

On the imsa car I am sure that wing served a good purpose and was tunnel tested.

Just remember you start bolting things tot he front of the car, and your road clearence will suffer, and it will probably get ripped off going up a driveway or somethign with normal city driving. The people on naziland have done several front chin modifications only to have them busted up going up driveways into shopping centers.
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Postby crzyone » Sat Jan 19, 2008 12:13 pm

I'm not talking about cutting up body parts and trying to do anything. I'm talking about extending the nose downwards enough so it does not shove a bunch of air under the nose. A splitter just goes one step furthur and promotes airflow up over the nose.

The front of the car needs the most help and I'm sure these mods would help. They are not needed on a street car that never goes above 70mph, but if you plan on taking a fiero to a road course they would definitly help.

The Fiero Warehouse sells the IMSA chin spoiler. I'm sure they didn't add it to the car for looks. The race cars needed better aerodynamics than the stock fiero front end.

Looks like the IMSA chin spoiler uses a bit of a splitter at the bottom edge. Not just a flat piece, it curves outward to send air up the nose.
Image

Maybe not the best for city streets. I wonder how many fiero owners actually wreck their add-ons by parking too close or running into a curb.
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Re: Splitters, Canadrs and Wings

Postby The Dark Side of Will » Mon Jan 21, 2008 10:39 am

crzyone wrote:The fiero nose with its upward angle is really bad for forcing air underneath the front end. Its probably the biggest cause of front end lightness at speed. With a chin spoler and splitter, there might not even be a need for a hood vent, but the more air you can get up and over the car the better.



Some amount of air MUST go under the nose/through the front intake because you need flow through the radiator. A significant amount (maybe more than half) of the radiator air goes under the stock nose as opposed to through the stock duct/hole. C5 Corvettes, for instance, are also bottom breathers.
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Re: Splitters, Canadrs and Wings

Postby Aaron » Mon Jan 21, 2008 11:46 am

The Dark Side of Will wrote:Some amount of air MUST go under the nose/through the front intake because you need flow through the radiator. A significant amount (maybe more than half) of the radiator air goes under the stock nose as opposed to through the stock duct/hole. C5 Corvettes, for instance, are also bottom breathers.


But in conjunction with a hood vent, it may work out to be even better for the cooling system, as there would certainly be more flow across the radiator.

Not to mention with the hood vent, the air from the radiator is released on top of the car, not underneath like the factory setup.
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Postby Kohburn » Mon Jan 21, 2008 1:30 pm

crzyone wrote:Looks like the IMSA chin spoiler uses a bit of a splitter at the bottom edge. Not just a flat peice, it curves outward to send air up the nose.
Image

Maybe not the best for city streets. I wonder how many fiero owners actually wreck their add-ons by parking too close or running into a curb.


i had the open mouth version and a hood vent. it made a significant change to the front end handling of the fiero at anything over about 75. without the hood vent there was enough air ramming into the nose that if a semi passed me going the other way at 55 the headlight doors would pop up. hood vent fixed that up to the highest i ever took it of 140.

and yes its not curb friendly. but i learned my lesson, repaired it with kevlar and flexible body filler and never had a problem again.
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Postby crzyone » Mon Jan 21, 2008 5:07 pm

Even with a front spoiler there would be sufficient air flow through the radiator. The IMSA race cars used them under the hardest conditions.
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Postby Indy » Mon Jan 21, 2008 9:09 pm

I'm taking fluid mechanics this semester. Maybe by the end of the year I'll know enough to do some modeling of a Fiero in a CFD program...
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Postby crzyone » Tue Jan 22, 2008 7:47 am

That would be awesome. Would also like to see what a rear diffuser would do for the fiero.
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Postby Series8217 » Tue Jan 22, 2008 1:12 pm

At its best (aerodynamically) my silver Fiero had a large hood vent, an underbody tray, and was lowered... a lot. It had no wing and had the 88 Coupe/Formula body. I got it up to ~130mph before I ran out of guts. It tracked perfectly straight and stable at that speed. When completely stock it was pretty scary at 110.
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