SundayDriver

They also run the best data aq company around for amateur racers, IMO. They did my Motec system and offer amazing help and customer support.

Kevin Mitz, very active with sports racers, worked for Rennwerks and I think he has a lot of Porsche specific expertise. There is a LOT of crossover between the sports racer and Porsche world.

Bryan Watts

Looks like aero designed for slower speeds and larger yaw angles, which makes sense for the road rally the car is participating in. Also, every setup must be considered within the budget and ruleset it is built to.

mark kibort

that seems to be the latest trend. lots of folks, especially in open classes , like SCCA SP and ITE, are doing the dive plane thing. lots of downforce, in addition for what can be provided by splitters. lots of hood venting, dive planes/canards, etc. all this puts tremendous pressure on the front of the car, but at a cost of substantial drag. But if you the HP, this certainly will make you stick better!

PPo

You guys got it all wrong... look at what a local Ice Racing competitor built with a power steering pump.

http://www.youtube.com/watch?v=ttpi4pJtNck

FYI... These cars might get up to 40mph on a good day since most cars run without studs. Most cars are valued under $500 also...

Bryan Watts

I'm not sure that you can say that they cost substantial drag.

With a well designed venting sytem, you aren't necessarily adding downforce but removing trapped air that's creating lift. You may get a net gain in downforce while also making the car more efficient. Especially if you use ducting to control exactly where air is allowed to go as it passes through your bumper, through coolers, and out the hood. And the vented wheel wells definitely result in less drag.

Dive planes probably add some drag, but in some cases they also remove some drag caused by an exposed front tire and can even be used to create vortexes.

Actually, my experience has been that dive planes have a very minimal benefit (at least in the size seen on a typical club racer car). I can't necessarily "feel" when they aren't there, but you could probably see it in data with a well controlled test.

mark kibort

venting systems dont, but dive planes do. their gains are not as great as a wing, as it is just raw downforce. you can calculate what they can provide, and your right, its not a lot. thats why the cars that are serious about downforce, will use rows of them. each one if at 1 sq ft of area, at .1psi surface pressure, at near 100mph, would have near 14lbs pushing on it in theory. lift/drag ratios for flat plate wings are near double of that of a wing.

and then this goes back to my original point. I dont think we all could tell if we had 3 different wings, all with the same downforce at some speed that there was any difference between the 3. the differences are going to be very subtle. (flat wing, crawford and GTC300)

Mahler9th

Well... I have known Dave and Ellen for a while... Dave even helped me buy the MacBook Pro laptop on which I type now... my wife did some landscape design for them. I wish she would have done their new place... I could have probably bartered for some nice data acq. stuff, but alas, too far away

I know all of the Rennwerks folks-- the founders are PCA guys-- I even got to instruct them a little back when they started. Anyway, I know Kevin and he is not a Porsche expert. He is a racing expert. I hope to visit with him to say hi next week. His place is 5 minutes from SmartRacing Products/Jerry Woods Enterprises... I suppose Scott and I will have to stop in there to say hi as well. Maybe we can examine some 962 or 935 wings.

The fellow building Scott's car is a Porsche and racing expert. Unquestioned. He uses a Predator.

In this picture, you can see I run an adjustable double splitter on my g-type nose and some carbon fiber dive planes I made in my garage. Works well at Sears Point on my car.

Scott took this picture.

I will have to go drive the car on the freeway today or tomorrow-- the sun is out for the next few days... perhaps I will take Scott for a ride.

Mahler9th

Picture:

mark kibort

Wow, better wake up the DTM guys that they are doing it all wrong.

Bryan Watts

What are you talking about?

Or do you not see the differences between a DTM car and a "club car" on a rally stage (with regards to budget, rules and power, nevermind the actual differences between the aero on the two cars)? Hint: They aren't the same.

Johninrsf

I just wound up using a Getty wing --first a 60" and later a 72" wing. I have no specs on it, but after much testing and racing and screwing around with all the variables (the wing, shock settings and cannister pressures, sway bar sizes and settings, front splitter sizes, tire sizes and pressures etc.) it all seems to work pretty well and the car is pretty well balanced. I really have no idea how effective the wing is in this entire equation. I did do some tuft testing and at all track speeds the air flowed smoothly at whatever AOA i used.
The only bad part is maneuvering around the back of my car inside the trailer with the 72" wing!

Mahler9th

Thanks Johninrsf. I figured something like that.

DTM.. I have seen some stuff on DTM aero in Racecar Engineering magazine. I'd sure like to learn more technical details on those cars... the what, why, how and so on.

I think Scott is on the right path now...

Talk to pros... or those that can connect you with pros...

Interestingly Scott's car is being built to compete in a spec class, and the fastest car/driver already in the class is "managed" by a pro, with recent experience in Grandam (Brumos DP). That pro also has a lot of other racing experience and knowledge and I am sure an amazing network of technical colleagues. He is also a really good guy.

I might just get the same wing that is on that car... but heck, maybe there is an advantage to be had... dunno.

No matter where you go, there you are.

mark kibort

I see stuff like the long end plates on the wings. is that what you are talking about?

stownsen914

DTM and some of the aero stuff they do may not be a very good comparison with a typical club racer. DTM, like many other professional racing series, probably has strict limits on wing size, size of underbody diffuser, etc. Those are usually the first places race aero designers look for downforce when allowed by the rules, since they tend to give the best lift to drag ratio. Since DTM cars are pretty fast and powerful, and limited in their aero, it looks like the designers have gotten creative with aero add-ons to get downforce, even at the expense of drag. I guess this is comparable to all the funky winglets and add-ons that we've seen on F1 cars in recent years.

Of course, DTM and F1 designers no doubt spend a lot of time with CFD and wind tunnel testing to come up with these tricks. They may not transfer over to other applications as readily as something like wing.

Scott

Cory M

There is a relavent article in the current issue of Racecar Engineering. They look at a former ALMS RSR and change the wing used (span and profile) as well as the mounting height and location and get some serious gains (see attached). In the previous article they showed big improvements at the front and overall balance with a simple splitter (see here https://rennlist.com/forums/porsche-...p-front-2.html). Simon McBeath is the author of the articles and runs his own aero consulting/wing manufacturing firm. If you are serius about getting the a better wing than the off the shelf options you might make a phone call to the UK...

Interesting to note that both wings tested have approx 15% camber to chord. The predator wing on the other hand has much less camber and is nearly flat on the pressure side (top), while the suction side (bottom) has pretty extreme curvature (too much? flow separation?). Some of the newer racecar wings I have seen, like the factory Corvette GT1 and GT3 cars, have even more camber.

There is local company called "Kognition" that makes wings for a lot of time attack cars that also feature significant camber. The wings look pretty nice and they have some basic CFD numbers on their website to review. It's hard to judge with the time attack cars though because most of them look like they produce a ton of drag, but they have high-strung turbo engines with enough power to overcome it. Worth a look anyway.