help me with 944 aero

[aftermath]

Hi, I have a 84 944 ( with mostly 951 running gear and 400HP). This year I am racing on a big track, with a 1km or .6mile and a .8km or .5 mile straights. This is my first year on good rubber Nitto NT-01 275's. Im looking for easy improvements. Aero advice specifically.

I have a rear diffuser from a 951 I can install on the car. Should I do that?

I want to make a front splitter, any one have recommendations on how to make one that is actually going to work?

Any other aero tricks I should consider? I am on a time crunch getting the car ready so Im looking for something quick, but I have budgeted time for some sort of splitter and installing the diffuser.

Yes I use the mirrors and I have a mirror bar in the car, but I could consider something cheap for the flag mirrors if that would help. Im looking more for grip than reducing drag.




I have done little to remove weight the car other than remove the door windows and motors. This year I will gut the hood and doors and I bought a 5lb lithium battery ( battery already located in passenger rear of car ). So after I ligthen the car and deal with the wider tires I am left with the easy aero mods. Dropping the weight a bit is relatively quick and easy. Down the road is lexan and maybe FG parts.

[Cocacolakidd]

There was recently a big discussion here with one of the Aerodynamic Engineers from Porsche who actually worked with the 944 and it's design. What was brought up during the discussion was that the 944 is very aerodynamic it's self. The addition of the rear Turbo Lower air foil/diffuser does indeed add down force even though it is modest. The biggest thing that was brought out was the under motor shields that help with cooling the motor and under car aerodynamics, they are a must. A small wedge type front splitter is slightly beneficial, but there again modest. The turbo/S2 front bumper cover is slightly more aerodynamic than the Std. NA. Most of the greater aerodynamic additions were drastic changes to car length (like 3' or 4' backwards).

I did a quick search to try and find the mentioned thread, but did not find it. I do not remember what the original title was of the thread so the search for it could be a lengthy one - it's out there someplace.

[aftermath]

Under the car all I have left is ducting to the rad. There is a LS1 engine in the car so any factory aero parts under the car are long gone. Im having heat issues where my header is cooking my starter but I could consider making something that works like the factory parts. I just have to find some pics of whats under the factory motor.

[ernie9944]

^^ There you go alluminum undertray of an early 944 (late car had the plastic one).I wouldn't try to frabicate one, but finding one from somebody parting an early car will be your best bet

[Rasta Monsta]

Can we go back to the 400 HP part? V8 or 951 powerplant?

[aftermath]

Rebuilt LS1. I have a long way to go to make the car faster. Im learning as I go, got the push way down from where I started, fixed the brake bias problem I had ( came with 951 brakes with no proportioning valve ), fixed the engine up, etc. Grip is my problem with the car, brakes are pretty good now that I have brake cooling and the balance fixed.

So simple aero mods and making the car lighter are the relatively free things I want to do for the July 16 race coming up.

PS:Rasta, I have a eagle talon awd turbo that I really hope I can bring to PIR for a chump car race next year. Need to rebuild the transmission first as we finished the last race with only 4th gear.

[SolReaver]

+1 on the motor plate if you currently race without one

Rear spoiler delete. Increases your rear field of vision as well. The spoiler is stylistic and counter productive. Especially at stock ride height. Can't see if you have a spoiler from the pic.

924 fenders? Beyond that, you would tape up the seams and such.

It is a fairly aerodynamic car to begin with.

[petrolhead611]

Put lexan door windows in. Running without door windows screws the aerodynamics.

[Porsche-O-Phile]

Agreed to all of the above. Pick up an early car undertray - they're cheap enough. I see some opportunities on your car to reduce drag if that's your goal - the fog light recesses and sidemarker light recesses should at least be taped over or infilled and made smooth (or put ducts).

I like the 931 hood - are you using the air captured by the NACA scoop for anything?

Plexi windows would definitely help if allowed in your class. The rear under-bumper spoiler that the 951 uses does make some downforce at higher speeds as has been said - it's probably worth looking into.

Good luck - I'd like to hear more about this car!

[aftermath]

The front splitter is still what Im interested in making, no one has any suggestions on that?

We are not allowed to run with door windows up in the race series I run in.

The naca scoop isnt doint anything but allowing air to enter the engine bay

The drivers signal light opening is what lets air into where the air filter is located. The fog lights are connected to ducting for the brake cooling. But I do know that I can close off some openings which should help. Might just use some good racers tape for that this year.

I dont know if a undertray will fit with the LS1 installed in the car , does the undertray fit over or under the engine crossmember? If its over it wont fit because the oil pan drops around the cross member a bit.

I will install the rear diffuser since everyone seems to agree it helps. My understanding is that the 951 aero is better than the 944 so it makes sense.

PS: With the battery in the back, I do have factory weight distribution even with the ls1. I always get that question asked.

I just missed out on something.....A add for a 944 with a fiberglass body, no engine, interior or drivers door for $400. I would have grabbed it as the fiberglass hood is probably worth that much when you factor in shipping costs. Darn.

[Porsche-O-Phile]

The 951 also has sideskirts under the doors which probably help a little too. Should be a more-or-less bolt-on.

[North Coast Cab]

For a big track you want the least amount of drag vs. downforce.
Tape or smooth over all those light holes in the front bumper/fascia - go to a 951 bumper or better yet a GT Racing or Broadfoot one
Fold in the mirrors or remove them
Lower the car
Splitter or undertray is helpful
If the splitter comes out front much and creates downforce it will make the car loose and require rear downforce which will add drag

[aftermath]

Got the rear 951 diffuser off my other car and managed to find a aero tray that goes under the engine, it will even fit with my LS1. I will tape up some holes in the front bumper.

This leaves me with a front splitter to consider. I looked at my friends 951 and the splitter he bought actually sits 2 inches lower than the factory bumper. I probably have time to make a sheet of wood or plastic to secure to the car.

I measured 6 inches from the front bumper ( in front of wheel ) to the ground. Im guessing my car isnt that low after all. Do I want to fab up a splitter that gets lower to the ground? If so Im going to have trouble getting in\out of trailer. How far forward should the splitter protrude? Im guessing 2 inches is lots.

This race has 50 cars ranging from 160hp to 800. Im keeping the mirrors on as its a busy track and I would rather have them. Its amazing how fast a 800HP full tube chasis car with 13 inch slicks comes up on you

[v2rocket_aka944]

Originally Posted by SolReaver

Rear spoiler delete. Increases your rear field of vision as well. The spoiler is stylistic and counter productive. Especially at stock ride height. Can't see if you have a spoiler from the pic.

NO.

The spoiler absolutely improves your aerodynamics, it is not just a pretty add-on. There is a reason the factory added them starting with the turbo 924; it cleans the flow of the air up significantly coming off the back of the car which helps with fuel economy and top speed. A 924's back end puts off "dirty" air, which is why even with a small engine and lighter weight it gets almost bad fuel economy.

Hell, go drive on the freeway, two runs. Once with your sunroof popped open, and once with the roof closed. You will be able to notice the rear end is more skittish with the roof open, it is throwing air off from hitting the tail.

[RedDragon]

I made an excellent front undertray/splurged for my Evo time attack car. Get a sheet of divinYcell foam andwrap it in fiberglass. Use the front bumper for a template and trace a few inches infront to get a lip. Paint it black for a carbon look. 8 dzus clips around the lower edge of the bumper and 2 on the crossmember brace to make it eazy to take on an off. Cut areas close to headers so it won't burn and your done.

[mistertate]

Originally Posted by v2rocket_aka944

NO.

ha ha, +1