jungle
New Reader
6/10/10 11:34 a.m.
I was part of a team building up a 1995 VW Golf for Chump car...
http://team-short-bus.blogspot.com
The rules say no glass except for the windsheild. That being said, we did what many other teams do....simply pull the rear hatch off the car. Great, less weight, and less of the "parachute effect" (air coming in the front windows and having no place to go).
However we found our selves getting fumigated.......and almost sick after being in the car for hour long stints. I assume what is happening is the exhaust is coming back in where the hatch would be, since it is a low pressure area.
So what can we do about that?
Some ideas kicked around thus far:
-put the hatch back in w/o any glass
-put the hatch back in w/ lexan to replace the glass (the we have the parachute effect going on again)
-put a wing on the roof of the car forcing air down the back of the car (much like old station wagons and suburbans
-put a wing on the lower portion of the car, where a closed hatch would normally go (just above the rear bumper).
-put turn downs on the muffler?
...tia!
Route the exhaust out the side ahead of the rear wheel?
In all seriousness I'd suggest re-hatching the car. You could also build a sheetmetal barrier just along the back of the car between the taillights. It may only need to be as high as the tail lights to keep the exhaust gases out of the car.
I drove ChumpCar in a 92 Escort wagon without a hatch. My team got around your problem by cutting off all the upper body work past the front doors. It looked like a pickup truck but it didn't suck exhaust gases into the cabin.
At least try with the hatch "skin"- w/o the window, but putting enough to make sure that the flow is out of the back instead of just circling.
With enough holes, the hatch won't weigh that much.
I agree with relocating exhaust.
perhaps you could cut into the floorboard and make some sort of rear spoiler, sucking air from under the car...
tuna55
HalfDork
6/10/10 12:25 p.m.
I'd try relocating and/or extending the exhaust. Adding a hatch back to the car sounds like it would take some time to fabricate yourselves especially with the aforementioned aero losses.
Our Dodge Shadow ChumpCar had a plastic rear window for the hatch that we made from recycled material. Didn't seem to hurt our top end that much when we went toe-toe with a SHO Taurus.
Also, our exhaust dumped on the side of the car with a turn down at the end.
A 944 team had no rear hatch and seemed to do fine with their exhaust exiting the rear of the car. Then again they looked a bit like a pickup that way, so that probably helped a bit.
Nashco
SuperDork
6/10/10 1:28 p.m.
We ran sans hatch with our Impreza Wagon. With all of the other windows removed, the HVAC vents letting air pass towards the driver, and a helmet on, you could smell the fumes but it was barely noticeable. IMO, if the fumes really bother you and having the vent fan cranked on high doesn't fix it, then you guys should try rerouting the exhaust (add lightness at the same time!). If that doesn't work, then lexan to the hatch is the next best plan.
Bryce
route the exhaust straight up thru the hood in 4 individual stacks of awesomeness.
Test it in a wind tunnel?
What about a roof vent, they use them in rally cars to keep the dust out, would the same thing work for your problem?
Andrew
