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Old 04-05-2010, 01:27 PM   #21
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6 seconds is HUGE
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Old 04-05-2010, 01:32 PM   #22
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The car is impressive. I still say the wing looks stupid because it does. Hopefully they can improve on it if that isn't outlawed by whatever league they plan to run it in.
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Old 04-05-2010, 02:06 PM   #23
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that was a good article. one I don't quite agree:

it said to not vent the hood (not sure the exact wording). that just don't sound right to me.
Thats what had me confused on the article too. As I understand it, the thinking there is that by reducing pressure under the hood, you also make it easier for air to go under the splitter and this you actually increase lift relative to having a bit of a high pressure area under the engine bay.

Thats my understanding of it, but that thinking does not make sense to me: If you have high pressure under the hood, you have lost the battle and you are getting front end lift. Reducing this is good in and of itself. You might get more air under the splitter, but thats where setting up the splitter properly is important. No matter how you slice it you are reducing lift and getting cooling in the bargain too.

Maybe they were thinking along the lines that many cars actually have high presure zones right around the cowl, meaning that an 'extractor' hood will actually get air reversion into the engine bay?



GRM is on the very short list of mags I actually read cover to cover every time. Note the lack of OEM worship they have. I love that.
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Old 04-05-2010, 02:52 PM   #24
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This month was an "aero" spectacular. Got my new GRM and the new Top Gear magazine the same day. You guys saw the GRM article. In top gear they had pics of the new Audi A4 GTM race car. It wasn't an aero article but that car itself is pretty much a lesson on aero all on it's own. Those two were followed by Car & Driver with a nice write up on the new Ferrari 599xx. A track only version of the 599. Lots of great aero info in that article too.

Here's the back of the Audi A4 GTM. It takes aero add ons to the extreme.



I was a dissapointed the GRM aero article didn't apply what they were talking about to a test car. I wish they would have taken a basic car and done some testing. Splitter, wing, diffuser, vents and the results of each.
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Old 04-05-2010, 05:43 PM   #25
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Those two were followed by Car & Driver with a nice write up on the new Ferrari 599xx. A track only version of the 599. Lots of great aero info in that article too. .
in that issue, they talked about how the Ferrari 599xxx extractor hood helped with down force.
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Old 04-05-2010, 05:58 PM   #26
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BW, I loved the smooth bottom of the 599xx combined with the winglets to move air toward the rear spoiler and "puffs" of air to separate the turbulence as air leaves the back of the car. 1.5 Million for a track day/time trial toy. Amazing.

I have to reread the GRM article. I can't believe they wouldn't advocate vented hoods for aero. 80mph on the freeway I can see my unvented hood trying to lift. Allowing that pressure to escape is a well proven aero enhancement. Had to be a mistake in editing if they said that.

Last edited by cueball1; 04-06-2010 at 02:25 PM.
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Old 04-05-2010, 08:36 PM   #27
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Very good read. Everyone should read it
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Old 04-06-2010, 10:40 AM   #28
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BW, I loved the smooth bottom of the 599xx combined with the winglets to move air toward the rear spoiler and "puffs" of air to separate the turbulence as air leaves the back of the car.
+1

I'm waiting for the first track Miata guy to try mounting a Chaparral-style fan in his trunk to suck air from underneath the car.
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Old 04-06-2010, 10:49 AM   #29
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I never read the top gear magazine. I might do sometime!
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Old 04-06-2010, 01:26 PM   #30
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The car is impressive. I still say the wing looks stupid because it does. Hopefully they can improve on it if that isn't outlawed by whatever league they plan to run it in.
he's running redline time attack and the super lap battle series. both unlimited fwd. it would be stupid if they outlawed it, wouldn't be unlimited class if they did.

i think this front splitter looks ridiculous, but i wouldn't drive that car without it.

http://images.search.yahoo.com/image...sigb=13i6hts62
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Old 04-06-2010, 02:59 PM   #31
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I actually like it. This late April fools has gone to far.

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Old 04-06-2010, 04:17 PM   #32
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I'm waiting for the first track Miata guy to try mounting a Chaparral-style fan in his trunk to suck air from underneath the car.
I have considered it This thing is, even with ridiculously effective side skirts, they needed a lot of power (45 HP snowmobile engine) to drive the suction fans in order to get a good vacuum. Good article here
http://antholonet.com/EngineersCars/...aparral2J.html
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Old 04-06-2010, 06:43 PM   #33
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(Flame suit on)

Is there any merit to the idea of running a ducted system through the trunk and out either the trunk lid or the trim plate around the license plate? The ducting would go down in front of the gas tank mre or less. So the vacuum at the back of the car naturally pulls air out from under the car to reduce both lift and drag.
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Old 04-06-2010, 06:59 PM   #34
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No flaming. There's a whole lotta stuff to be tried. Without a wind tunnel at your disposal it's a whole lot tougher to quantify improvements. You can use lap times but only if you are super consistant and able to push 10/10ths all the time. You can also do high speed coast down runs in 2 directions on a known stretch of road but at the risk of police intervention.
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Old 04-06-2010, 07:17 PM   #35
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What about a small fan-like deal with a magnetic pick-up based RPM signal, like they use on a bike speedometer?

The faster it spins, the more air you have going through that area. All you need to do it calibrate it roughly to get an idea of what RPM corresponds to what speed, which you could do by strapping the thing to the roof.

Crude, but possibly effective. If you get similar velocity through the duct that you do on the roof, then good things are happening.
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Old 04-06-2010, 07:24 PM   #36
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Quote:
Originally Posted by Sparetire View Post
(Flame suit on)

Is there any merit to the idea of running a ducted system through the trunk and out either the trunk lid or the trim plate around the license plate? The ducting would go down in front of the gas tank mre or less. So the vacuum at the back of the car naturally pulls air out from under the car to reduce both lift and drag.
That is basically what a diffuser does. Different than what you described but essentially does the same job in the same area. I'll be building one myself one of these days for the track car.
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Old 04-06-2010, 07:29 PM   #37
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What about a small fan-like deal with a magnetic pick-up based RPM signal, like they use on a bike speedometer?
You mean an anemometer. Here is an example though they come in different sizes.
http://salestores.com/lacros111.html

Speaking of measuring airflow I thought that flowing paint trick mentioned in the article was a nice idea. I like it because it is cheap, easy, and can be used on just about any surface on the car. I wish they had described the recipe in more detail (x parts of paint, x parts of 3-in-1 oil, x parts of alcohol). But it should be not too hard to figure out with some searching and/or trial and error.
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Old 04-06-2010, 07:29 PM   #38
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True. I was wondering if there would be any advantage of introducing the air higher up on the tail of the car, but its most likely more work that its worth. Good idea for a snowmobile motor/pull fan though

Thanks for the link too, sweet.
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