Air Dams

[lag waggon]

I am about to build an air dam for my gas coupe and i was just looking for what would be the right thickness, im going to use aluminuim and was thinking of 2mm would this be suitalbe to hold up to the high air pressure on the dam?

What height should it be off the ground i want it close but not to close as to act like a grader blade?

any help would be great thanks.

[Dr Goggles]

Dave Partridge ( #232) who runs an RX7 and is responsible for a few unwelcome ear-aches on the lake had a fibreglass front dam which was said to be the same as the one that Moffat used on an RX7...under wind pressure at speed it buckled backwards and down and caught the salt at which point it broke , closing the track and ending Dave's year .Obviously you want the bottom of it to be above the lowest point of your front suspension but it might be worth taking note of Dave's problem and making it very rigid.

[David Leikvold]

Don't use aluminium, it will bend under load and do exactly what Doc just described. Do it with several layers of woven mat fibreglass (not chopped strand) but add some Kevlar as well.
My only practical experience with Kevlar was a sprint kart seat a mate of mine from Alabama made for me. It was much lighter than plain fibreglass (no advantage to us) but it was incredibly strong, so much so that it couldn't be bent at all and even made the kart handle better!

[momec]

The G.O. is to use aluminium down to about 30mm from the ground then use flexible kevlar material as a stiff skirt down to the ground as a scraper. The aluminium needs to be well mounted and tough at least 2mm and the kevlar viewed as sacrificial. The stuff they use for rally car mud flaps is what would work.
This is what l intend to run on the ute next year.
Bob Ellis has had no problem with aluminium and its been like a snow plough on the return road sometimes
Chris

[lag waggon]

thanks for the comments guys chris i think we are on the same page here.

[David Leikvold]

I had another look at Bob's car and I understand it better now. Mounting the aluminium solidly is the trick, if it bends under wind load it'll just let air under the car. I'd be looking at ways of encouraging the airflow out to the sides of the car to relieve some of the pressure. Maybe an air inlet for the turbo right in the middle where the pressure is highest. If you were concerned about sucking junk into the turbo you could always run a couple of FOD screens before the final air filter.

[BOB ELLIS]

Back in town! been up in the sticks awhile. Aloominum is the G.O.(as Mr Hanlon said) The air dam on the falcon is 3/16" (4mm to the young fella's) . and as Chris noted . it has bulldozed a bit of lumpy salt now and then.Remember the air dam is to be verticle (unless it is OEM in certain classes).David , can do tech for you , need about 2 weeks notice. Nathan , still have to look at your car when you're ready. Cheers Bob. #66 C/GCC.

[momec]

Hello Bob