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Home made airdam


RebekahsZ

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There is still access to cool airflow for the radiator (no ram air - just fan driven air) and for the air filter via the fenders.  That aluminum panel comes off if I still have trouble with cooling, but the old-timers seem to think I will be fine. The idea is to limit air from entering the engine compartment and from going under the car.  I plan to warm the engine enough to get the temp gauge in the "normal" range, then to shut off the car until I am directed to start my run.  This thing is heavy (60# including the dam, belly pan, and support structure).  Together with the headlight covers, I hope to close the gap between my current record of 167mph and the max the cage is certified to: 175mph. I have no idea if this thing will clean the car up even at all!  It's just my first whack at getting faster before changing gearing or adding power. If I ever exceed 175, this hobby is going to get (more) expensive, as the safety requirements really sky-rocket.

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Nice work, but it does sound heavy especially hanging that much weigh, that far out in front of the tires. But it may not have a huge problem while drag racing. However, too much down force could be an issue along with what everyone else said about air flow to intake and cooling. 1/4 mile at a time it might be fine. Trial and error will tell. I really like the Z reflection on the hood in the third photo. I am sure you planned it that way.

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I agree, that does sound really heavy for what it is, and it's in one of the worst places it could be. You should definitely be able to take some weight out of it. Maybe take a hole saw to some of the metal structure, and just make a 2 piece FG airdam and splitter? Looks like your airdam is FG over wood, which won't be light. And as 310z mentioned, I think you may want to balance out that front end downforce with a rear spoiler. This one should help: http://www.thezstore.com/page/TZS/PROD/classic02a01e/50-1606

Edited by rturbo 930
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I will post my results next week in this thread and the aero forum. I hope to do a rear wing comparison next summer-I hope to compare those two wings against each other, and against no wing. So far, down force isn't my priority, rather drag reduction is-the little splitter lip was just a "while I'm at it...". Traction and manners were excellent at 167mph without the airdam. I guess there IS a chance that this could screw that up...this is a prototype, and a 2-piece unit is definite in order. Inhave all the supplies on hand for version two, except motivation, but that will return with sleep.

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Preliminary feedback:

 

The 3" wide splitter 3" off the ground has been cut off. First run-174.2. Car wandered a bit between 150 and 175. Put in impound for a bit because car has no chute. Got to pits and found that airdam had contacted the ground! That means that it built up enough downforce to compress 225# springs 3-inches. Second run-174.2. We had raised the front 3/4" and dropped the rear 3/4" yeilding a splitter height of 5". Car ran great and straight under power but drifted hard right under braking, straightened when brakes lifted, then drifted left when braking resumed. Used full track to stop-was pretty scary. After that, I wasn't going back out in the car. After a while, my courage recovered (I gotta tell ya: 174 is a hell of a lot faster than 150 or even 167, especially when you car isnt going where you point it). We cut the splitter completely off the airdam and re-glasses it in the pits. Put the from ride height back down and checked toe-in. 1/16" out at static. In the morning I'm setting it to about 1/4" in and gonna give it another try. I really want to have it handling well enough to test a couple rear spoilers next year.

Edited by RebekahsZ
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You also need a lot more spring (450 to 550).  A friend ran a splitter a little larger than that and grounded it from 4 inches doing 160 on the straight at Thunderhill. This would allow you to lower to keep more air from going under.

 

Cary

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Survived and heading home. I do think the splitter contributed to the grounding, but I hit the airdam in the ground today at 167 mph (with 12 mph headwind) so it is either from downforce on the hood or just excessive bump travel. That screwed up my hypothesis of blaming it all on the splitter, cause I cut that shift off! I'm definitely in agreement on the higher spring rate. Thanks for the recommendation - I was thinking at least 400, so you confirmed my suspicions. We are moving into a suspension thread, but lets go with it till somebody makes us move. What about a corresponding rear spring rate change ( currently at 225F/250R)? Keep it soft or up rear rate too? Getting good at adjusting toe, so that bubble has been burst. Car drives better with 1/4" in. Still having to really drive the car (finger tips) from 150 up, and holy shit, don't hit the seam in the midfle of the track -that launched me across the lane at 155 mph. But I'm not swerving from one side of the track and back on braking from 170-ish anymore. I'm also thinking about losing all my front camber (ran at -3 because of upcoming track day) and turning that into more caster if possible. I'm thinking of taking the airdam to Memphis for the track day(I think 150 is doable on the long straight-away) to put some tell-tale zip ties on the struts to see just how much movement I'm getting. Hate to fill the back of my truck with airdam instead of tires.... Tried increasing from compression and car behavior was not affected. Dropped front and rear tire pressure from 55 and 40 to 35 on all corners. Car drove better. Maybe the sidewalls were giving, allowing the suspension to stay more still?

Edited by RebekahsZ
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