suggest to me ideas for airflow with rear lexan windows (e30 rallycross car)

Thinking of doing a rear-window delete and putting lexan there on the e30, if only to save 15-20lbs in glass/window mechanism in a car that could do with some additional weight loss. My one pause is that when driving the 3-4 hours to events I usually put the windows in the back down to get better airflow (no a/c). What are my best options for venting in Lexan windows? Keeping in mind that this car sits outside all the time (so they have to be leakproof) and also runs in the winter (so I have to be able to close them). And that it's a street car, so the windows can't just be "pop-in" since I want to be able to lock the car and have it secure if parked overnight at a hotel (er...motel) at events, etc.

I had thought of possibly just drilling a bunch of 1" holes along the top edge and having a backing panel or something, or using some kind of pre-made race-style vent, but would like suggestions or ideas.

Eventually I'll do the back windshield as well, and will put a couple "pop-open" vents on there, but that's for next season maybe.

"Snap vents".

thanks, found some of those for $17/pair at an aircraft supply place.

Not that lexan side windows will save me a TON of weight (there are other things I could do), but just looking to do some kind of little project on the car since I don't have any "big" projects in the works, lol.

I suppose you already know of this company. http://www.acwmotorsportplastics.co.uk/bmw-e30-3series-4dr-saloon.html

thanks for the info on snap vents, i'll (hopefully) be getting around to installing the lexan 1/4 glass in the 323 this summer and had planned on going with a felt lined horozontial slider setup, the snap vents definitely seemed like the better way to go

Hntsvl_E30 wrote: I suppose you already know of this company. http://www.acwmotorsportplastics.co.uk/bmw-e30-3series-4dr-saloon.html

Yeah the main issue there is shipping...$100+ for just a pair of rears!

As of Jan 2014, ACW no longer ships to the USA. Ask me how I know...

LanEvo wrote: As of Jan 2014, ACW no longer ships to the USA. Ask me how I know...

Yeah, they don't list it on the site either. They do ship to Canada though....still about $100+ for two.

I ordered a 36x36" piece of Lexan off ebay for $65 (cut in half it will do both rear windows), and four of the pop-out vents from the aircraft supply place, so hopefully for around $100 total I'll have these done. And finally get to use the new drill press...

I like this idea

If you formed the louvers properly, water would never get in

I like that idea too, but don't think I have that kind of skill, lol.

In reply to Keith Tanner:

Bookmarked!! These would work well on the LS.

And with lovers dust would still get in, there's always dust.

What's wrong with the glass? It doesn't scratch, it doesn't leak, and who cares about 15-20lb? You need that weight up high and back to help you rotate. (WHY do you think wagons drive so much better? It's not because they look cool! Well not JUST because they look cool)

Anyway, that aside, airflow in a rallycross car is bad. Suck it up during the run and sit with the door(s) open in grid. Better to be hot than to have bloody eyes and mud streaming down your face from all of the dust.

He wants the airflow for the drive to and from events, not for during runs

How about hinging it and making it a rear popout vent window?

captdownshift wrote: He wants the airflow for the drive to and from events, not for during runs

you win at reading comprehension. Knurled does not

Knurled wrote: What's wrong with the glass? It doesn't scratch, it doesn't leak, and who cares about 15-20lb? You need that weight up high and back to help you rotate. (WHY do you think wagons drive so much better? It's not because they look cool! Well not JUST because they look cool) Anyway, that aside, airflow in a rallycross car is bad. Suck it up during the run and sit with the door(s) open in grid. Better to be hot than to have bloody eyes and mud streaming down your face from all of the dust.

I don't really care about scratches, and the lexan windows will be sealed, so leaking isn't an issue (aside from the fact that the car leaks in other places anyhow, lol).

As to who cares about 15-20 lbs? IDK, most people who race do last I checked I certainly do. Locally the other top MR cars have far more power than mine, so my only advantage is lightness and handling (and mine does out-handle all of the other MR cars locally, no question). I have to make compromises for weight on this car to keep it street legal/travel-functional (headlights, bumpers, etc), and my only real "dead weight" right now is a roll bar (which I use for my harness) and a passenger seat (a necessary evil for a few reason, though it may come out this season). So I need to lose weight where I can without it affecting the car's functionality/legality. Offsetting the weight of the rollbar (also high in the back of the car) is top priority. This is one of those ways. If I feel the need for weight later at some point, ballast is easy to add.

And I'm sure you've figured out by now that I like to tinker, and that the build for me is just as much fun as the actual racing. There aren't many budget-friendly things I can do to the car at the moment, but I still want to do something.....

Rotating this car has never been a problem, and this season we're running on gravel courses, so it will be even less of a problem

And as mentioned, the airflow is for transit, not for competition. Though correctly-routed airflow won't result in dust in the car necessarily. Considering I run a black car in 95-degree summers (oh, I own 4 black cars...), I don't think I need to be told to suck it up, lol

15- 20 lbs in the right place makes a huge difference.

My MINI had a Lexan windshield, and the weight difference high in the vehicle was very noticeable in the handling.

If these turn out well, I'll plan to do the rear windshield at some point this year. Front windshield will stay glass since this is a street car, as will front door windows (to retain roll-down functionality that would scratch the hell out of Lexan).

well, I made one side, using the pop-out vents. They should work fine for my purposes.

just enjoying how clear it is right now, since it's gonna get scratched beyond recognition on a rallycross car, lol.

will post up another pic once they're installed. It's too cold out right now to actually work outside the garage tonight...

Looks good. This is going in a four door, correct?

yup, just in the back doors for the moment. Trying to partially offset the weight of the rollbar, so it was the logical next part of the car to take a bit of weight off of.

Looks great, I can't wait to be working on my rally-x project again. This was on the (incredibly long) to do list

I took a hole saw to the rear clip where the license plate used to be and "ventilated". I also removed the rubber trunk seal but left the standoffs so there is a 1/2 air gap all the way around.

The object is just to relieve pressure - you don't need to put the holes in the window.

Shelby GT350 style?