Great race aero article in GRM
 

If you do not have it already, pick up a copy of the May 2010 issue of Grassroots Motorsports. There is a good article on aero methodology targeted at low budget race cars (no discussion on how to set up your F1 car) in normal GRM style. You do not need a PhD in Fluids to understand it. It echoes some of what has been discussed here and elsewhere.

There is also a section with pictures of several cars, with different setups, talking about what is good and what is bad on each one. They have a picture of the aero setup on a high-end Pikes Peak car; the splitter is insane.

Good stuff. I am really beginning to like this magazine a lot. It is very similar to Roadracing World (for the motorcycle road racing crowd) in that it is oriented towards the club racers.

Get a subscription if you haven't yet, it's well worth it.

My only problem with that article was the comment about the car with the wipers parked in an up position, creating extra drag. If you look at the pic, there are puddles on the ground and drops of water on the car. I suspect the wipers were not "parked in an up position" (how would you even do that?), but were actually turned on to keep the windshield clear.

Yep, got one when I recently signed up for NASA. Just waiting for it to kick in.

HA! Yes when I read that I thought :facepalm:. Maybe it was tongue-in-cheek.

Eh, you might be right. If so, they got me.

I'm also thinking of subscribing to Classic Motorsports. Obviously, not as much direct application to Miata ownership, but lots of good info on restoration and track prep as well.

I can switch my accessories off (heater and wipers) independently of the main ign circuit. So if you're bored and time it just right, you can park the wipers in the up position. Good for baller effect, bad for aero.

I need to read that article. It looked good, but it was long and didn't have any miatas, so I skipped over it.

I'll never have that issue with my car....no wipers at all, solved!:giggle:

Good stuff. But they disrespected me in the project car section. They said tr wheels are cheap!

And the Scion Tc time trial car is super dumb. I've been looking for video of it.

GRM is a great mag. I have learned more tricks from there than any other source. I need to renew my subscription. I have been buying it lately from the news stand, which is preventing me from getting all the editions. I wonder how much I have missed.:facepalm:

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.

Are you talking about Chris rado's 1000whp tc with the frt. Wing? If so, there's gotta be 100's of em on youtube.
Grm is a great, and dsport is all I buy mag wise. Dsport has cover cars that have scratches on them because they're actual track cars. Time attack,drift,drag. They have excellent tech articles, product reviews, and every editor races in some type of motorsport.

The only things I found so far are drag racing and promo videos of his other scions. I'm looking for a straight up in car or something. No music no master editing. Its no big deal.

Wy is the TC "Super Dumb"? I have quite abit of respect for Chris. He is trying somethin that no one else is doing at this time.

On top of that that car halls ass. I was in turn 1 at Cal Speedway and he ripped past me like I was on the side of the highway about 3 car withs higher.
I talked to him a few years ago and he said that he had to turn down the boost since he had no traction due to the lack of down force. When he is supported by that many people why not try something different if it works.

I am shure there have been a few people that have done a few turbo installs that people thought were dumb and turnd out to be bad ass. It is always hard to be the first one to do something different, but if it works then you can laugh in their faces.

By the way the article was interesting to read.

Have a great day,
Jared

I'll have to look at it again for context but yeah that is not right IMO either. It is pretty clear that hood venting/extracting works well, and not just on LeMans cars. In fact I am about to install the 18x10 Carbontrix extractor/vent on my LS1 track car hood. And, Bbundy (IIRC) was indicating recently how effective his extractor hood was on the track, and not just for cooling, but for downforce as well. Here it is https://www.miataturbo.net/forum/t45256/#post544424

Oh wait... snap... OK for anyone racing in the Tx Miata Challenge. Hood extractors suck, and I do not mean literally. Don't get one! You WILL go SLOWER! :giggle:

I'm currently getting 2 copies... I failed to realize that I got a 1yr sub for joining NASA before I sent in my own sub. Sorry, extra copy already spoken for!

It was a great article... hope the owners can handle the critiques..
As far as the vented hood, well in some cases you just have to choose the lesser of the 2 evils. Lower aero factor (if true) vs. skyrocketing underhood temps... I'll choose taking care of the later, thank you very much GRM...

Here's one: YouTube - Passion - Chris Rado

http://www.youtube.com/watch?v=Mr90cQOyRVw

Thats the promo shit I was talking about.

My only thing is the wing. Does it make the car faster? I just want some video to show how that front wing improves the car. Why be progressive and not explain your ideas to get the word out. Thats like the biggest point of racing, selling ideas, selling cars. Maybe its just a ploy to make the car stick out, that'll sell some Tc's!

Yes, the wing makes the car faster. Since he can put down more power and has more traction he can be on the power sooner, longer and brake later. As we all know this will make the times drop.

Not explaining what and why teams are doing thins has been going on since the first race. No team likes to give up their secrets. I think what he is selling is himself beeing on the podium. However he manages to do it within the rulls is all that matters.

I thought I had already explained that he had to turn down the boost because he was unable to keep from spinning the tires. In a front wheel drive car a wing on the rear will not help traction for the front/drive tires. Hence the front wing. He was only able to put down something like 350hp at buttonwillow. If he is putting down 1000hp now that can only be done by getting a ton of down force. A splitter and canards are not able to produce any where near enough down force. I don't think that he would allow them to release any speciffic info on what has learned at this time. It's not hard to imagine what the front wing is doing for him.

Have a great day,
Jared

Love GRM. They have a good forum as well. They also have a $100 10 year subscription. I got it for my birthday one year, so I'm set!

grass roots is great mag i actually won my subscription for free.

All you gotta do is look at his lap times before and after the frt. wing to see that it is working. He dropped 6 sec. If I remember correctly when he first put I on. Can't remember which one but I remember reading the article. It's just like the first time a team used a wheelie bar on a fwd. I think it was ed bergenholtz crx. Everybody laughed. But within a month every single team in pro fwd class was running one.

6 seconds is HUGE

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.

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?

:2cents:

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.

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.

http://www.carzi.com/wp-content/uploads/new_dtm.jpg

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.

in that issue, they talked about how the Ferrari 599xxx extractor hood helped with down force.

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.

Very good read. Everyone should read it

+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.

I never read the top gear magazine. I might do sometime!

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

I actually like it. This late April fools has gone to far. :giggle:

http://www.wainfan.com/chrisoncar.jpg

I have considered it :giggle: 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

(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.

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.

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.

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.

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.

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.