Ernie J

Hi all, just back from Sebring testing with the 944S2. The car stuck like glue. I have raced there 10 times and I could say the car worked the best ever. faster everywhere. You guys, buy a anemometer and you will see which way the air goes. Until you are in a windtunnel you are guessing as to what's going on. BTW, I did take a Aero course with SAE. The 944 is a race car, its been in the tunnel and tested 100 times approx. Each time I have changed or added something, each time surprised at the result. Patrick, the rules I have to follow are a bit more restrictive than yours.

I , now have acheived aero balance and downforce fr/r. Still working on more front down force.Why , because thats the hard part. Anyone can bolt on a rear wing and get downforce. The front end is much more difficult to make work.

We are also building for customer, a LS3 engine TT car, so your car Patrick is a model for us.

Sterling Doc

I found a 60" predator wing with 944 uprights for $500 - so it's a start.

ZB, yours came close, and thanks for the offer, and good luck.

Interesting stuff in this thread. Lots to think about over the winter!

67King

Anyone have any more info on any of these wings? AJ Hartman has a downforce/speed/angle versus drag chart on theirs, and their chord length is 14". I know that the Raptor that GT Racing sells has a 10.5" chord. Anyone have any info on the Good wing, chord or downforce/drag data?

Also, does anyone who has an SP3 legal setup have any data they'll share on downforce their splitter generates?

Cyril

Data for the Goodaero Raptor wing (65" wing, 14" span)

Sterling Doc

Interesting this came up again - I am deep in off-season aero research and development:

The Turbo Miata forums are a wealth of info on budget aero:

http://www.miataturbo.net/race-prep-...s-63769/page4/

http://www.miataturbo.net/race-prep-...-thread-70612/

This bit of CFD aero analysis prompted me to look into and "EP" style nose for the Franken44:

https://hanchagroup.wordpress.com/20...esign-is-best/

These are early pics of the work:





I'll get up to date pictures later - it has made making effective ducting super easy (nice flat surface) vs. OEM.

As far as the wing, my Predator wing bows a bit (can be seen in the pic below), and I'm sure it's less efficient that either option listed above, but it has been helpful!



Next up is work on a flat bottom, and diffuser.

Sterling Doc

Here are some updated pictures of the front end with openings for radiator ducting, and brake cooling, I can seal in and route the ducting much better with this arrangement. I still have to reinstall the upper radiator shroud (exposed now).
I also plan on making the lower lip height adjustable by cutting off the lower 2" or so, and slotting the attachment points, to make the splitter height adjustments easier.



I have also adapted a "boom tube" style exhaust (another ex-Nascar Ebay part), to keep exhaust heat away from the trans, CV joints, and gas tank, which had been causing some issues.



This is flat enough to allow a flat bottom, without having to take the penalty in NASA ST for a through the body exhaust. Lots of heat management required - it will be wrapped, and high temp heat reflective material used, as the exhaust will now be in an enclosed space.

I also had to re-route fuel line to keep it away from the exhaust - always a cascade of implications to one change on a racecar!

mark kibort

the hood vent is huge, as long as it is in the correct position. did you see the charts i had for the 928? do you have some for the 944... might be similar... and that vent should take alll the air cooling the radiator to mitigate the low pressure in that section of the hood. basically removing most of the lift on the front of the car. the undersection will be mainly to reduce drag, unless you are doing some venturi tunnels.


as a note on your link... I picked #4 as #4 and 6 seem to be best. but, i would bet that #4 is best, WITH a hood vent. the flat plate in front has less value, than a properly routed curved nose with a hood vent.... without it... sure.... but it looks like you are doing it, but still have the #6 approach...

the hood vent, will toss more air upward, and get that air from going under the car. (see the dark blue flow).. that way, you increase the high pressure zone at the base of the winshield.... more flow to the rear wing if you have one and reduce the low pressure area on the middle of the hood, which is lift. (not shown by the heat map air pressure charts... but its there)

Sterling Doc

Huge hood vent? If you mean the intake in the bumper, yes that is large. It will be easy to block some off with Gorilla tape, and find out what the optimal aperture is over time. Pretty simple to make further versions of this, so I started off big to ensure adequate cooling

Pressure diagrams I've seen of the 944 have a low pressure area in the front part of the hood, so an extractor duct with a little Gurney was placed there as a start.

Sterling Doc

333pg333

Eric, I'm guessing Mark is talking about the hood vent in the first of your 3 latest pics. Although it's not there in the 3rd pic. Assume the top pic was taken at a later date than the bottom one. Adding a front gurney or raised louvre to the front of that vent (as shown in pic) will also help draw out the air. I agree with Mark that this is a good option aerodynamically.

Sterling Doc

Thanks - it's didn't seem "huge" but the rest makes sense.

Your implementation of that vent is what I would like to match. More metalwork to come!

You also have a ton of louvers! Once the flat bottom & diffuser is done I'll look into venting the wheel wells and hood more.

The bottom pic was from NASA Championships. That was a hand-me down fiberglass hood that I vented where the old 924 GT style hood scoop used to be. Less than ideal, but a quick solution. I ran one class higher for better class counts, and needed the weight loss there to get close power to weight wise.

This year I have a new cam in to make the power when I need it, and a restrictor when I don't (depending on car counts in ST2 vs. ST3). For now, working with the metal hood is easier, but long term, I need to get a good/new lightweight hood, and work with that when the budget allows. The old FG hood is too tired to cut any more holes in!

How low is your splitter? It looks huge, and like it would be hard to keep off of the ground!

333pg333

Yes, those f/g hoods only stand so many holes cut in them until they just want to fold into pieces. Good thing is that they're cheap to replace. We have gone somewhat 'vent crazy' but bear in mind that we have a turbo car (Lots of heat!) and no cool air inlet for the engine bay (gets EXTRA hot!!), so the vents help in extricating both pressure and heat. Also venting at the rear of the front fenders is a worthwhile mod to make. Even a basic hole of sorts is better than not. The more you can relieve around the rear of the guard the more the underhood air that is bouncing around the wheelhouse can escape more efficiently.

67King

You could make that a lot better if you changed the uprights. That wing is off of memory right at 60" wide. I'd try to place the uprights somewhere near 15" inboard from each end. Without actual CFD data, you are left with simple statics, which would tell you that you'll place the load evenly on each side of each upright doing that. It won't be perfect, as you'll get a little more force on the middle of the wing since it will be at a slightly higher angle of attack to the airflow (presumably, anyway). The end caps will likely help a lot wiht preventing the low pressure air underneath from moving upward, and vice versa, which would make the ends less effective. As for the effectiveness, the shape of that wing looks more like ones I've seen with Cl's closer to 1.5 at max Cl/Cd. The best ones I see out there are about 2.1-2.2. That combined with the shorter chord, and I'm guessing you are getting about 30-35% less downforce than the Good or Hartman wings, albeit wiht less drag (not proportionately less).

I have been planning on putting a 968 Turbo RS style duct on my hood for cooling, but I can't find who sells those things, grr..... Hartman sells a hood vent, but the shape of it may not work for me.

Thanks for the CFD on the Miata. Air dams are free. THis may change what I do there.

333pg333

Harry I bought a 968 rs duct (copy) some years ago. Can't remember where from. Might have been Mike at IFC come to think of it. If I can find it in my garage you can have it for the cost of shipping.
Here you go: http://www.allporscheracing.com/Racing.html

Personally, I think you can make something that has a more efficient shape. Pretty sure the 968 one was largely based on packaging.

Sterling Doc

Good info. There are hard points on the wing where it attaches now, and the hatche gets in the way, but I'll see what I can do. I really need a longer wing!