Aero opinions?

[zigm89]

Our next Lemons race will be @ Carolina Motorsports Park full course.... Some corners are 70mph+.

Setup:
- no fsb
- boxed rear swingarm
- Front 400, Rear 320 springs
- Dunlop Star Spec 14" tires
Car still has a bit of understeer to it.

Does a front air dam help the handling of a MK2?

I built a diy air dam for a race last year but never really got to test it out.
Any opinions on whether the car will behave better or worse with the air dam?

Without:



With:

[chois]

The air dam will help with engine and brake cooling and will reduce drag, though that does not seem to be much a concern in this series. Make sure all the air hitting the front has to go either through fluid coolers, brake ducts or around the car. Can make a 10-20 degree difference in coolant and oil temps.

You can add downforce with a front splitter effectively, but again, may not work well with the scrutineering process in LeMons.

[flyinglizard]

Zig, Do you have my book?
The rear bushing cut, will take out a lot of push. 5mm rear toe out will help also.
Iuse a splitter to get air to the brakes and grill. Water cooled brakes help if the track is brake heavy.
MM

Ps the high pressure area is near the center of the nose. ( your ducts are at the edge, where the air is moving across the car.
I toe out the tire that helps the most, IE the LR. This gets the car dogged tracked some and unloads the LF. More is better until the car wont turn left. ( For right turn road racing).


For oval track,I toe out the RR about 1in. (and toe inthe RR).

[chois]

I also recommend using some flashing to cover up ALL air flow paths from the front of the car to the engine compartment that are not through the radiator/oil cooler. Cover those empty light buckets.

[zigm89]

Thanks for all the feedback!

The headlight buckets are blocked off with same flashing that I used for the air dam. (painted flat black, so a bit hard to see in the pictures).

How far would a splitter have to extend forward from the dam to be effective? How high off the ground can it be? My gut tells me it is not worth the effort, and is likely to get mangled in heavy Lemons traffic.... there will be ~89 cars on the 2.2 mile track.

Mike:
I do have your book, and have made the dsr mod. (Bought one of the 1st drafts. Is there a newer rev since 2010?) The track is mostly RH turns, so we do have the LR toed out a bit via a shim on the axle stub.... need to recheck how much we actually have.

Any benefit to putting lexan over the rear 1/4 windows?

[flyinglizard]

Good Zig.
Looking at the pics; The car is too high in the front by about 1in , and 2 or3 in the rear.

I use the Hubs to rocker for RE.


Drop the rear until the axle touches the body, flatten the contact area, and clear the brake line.
Smash some tire clearance /cut the wheelarches.
Dropping the rear increases castor, decreases windshield angle, reduces total aero shadow.
It also tightens the car up some, so more spring and or air pressure is needed.

Maybe try a little more front camber, a little more rear air pressure. 40ish or more. .

Chumpcar has no stock body rules, does Lemons?

[flyinglizard]

http://gallery.oracool.net/v/album82...e+003.jpg.html

Spliitter pic

[zigm89]

We are maxed out on front camber; will have to look at slotting the strut housing holes to get more. I think our rear hot pressures were ~39psi, so adding a bit more should help free up the back end.

Below is a pic of the car on a straight at VIR.... If we cut the front springs any more, the lower control arms will droop past horizontal - I thought that was a definite no-no?

Lemons has some basic rules about body/sheet-metal, but we've decided as a team to not go any more extreme on weight reduction. She's a bit fat at 2,050lbs no driver, but mercifully dry in the rain.

[flyinglizard]

Ihave reduced my Chumper camber to 2.5 front. from 3. It was eating the inner too bad.
Reducing the rear height about one inch. is what i was talking about. The front looks about right, maybe 1/2inch. I run my arms just up a little. Lower for Daytona, up some for Sebring.

I have orange snowflakes also..

[enginerd]

Make a front splitter from a sheet of plywood and some aluminum struts. $50 and good for a second + a lap on my MKIV track car at limerock. You would be amazed at what this can to to fix high speed understeer. It doesn't even have to be that low to work. ~ 5" off the road still works. You should make it protrude 4-5 inches forward from the bodywork. any further wont net much for downforce. just make the supports very strong so you can stand on it.

some rubber sheet as side skirts might help your aero on the sides but its soo high off the ground it probably won't do much unless you really extend it down.


On a rabbit i have used crash bolt in addition to the stock camber bolts for extra camber.



http://www.facebook.com/photo.php?fb...&type=1&ref=nf

[johndeniel]

Yes, it would definitely work. It increases the performance of the vehicle. If you install it at the chassis then it reduces lifting of the front end of the vehicle. The front end air damp provide aerodynamically support to your vehicle. I have tried on my car.