I'm in the middle of building an air dam. Here is how it currently sits:



I'll be fastening a vertical plastic sheet to the front just like you've all seen before with an opening for my radiator but I've got a question about the opening. Should I be ducting the air only to the radiator opening? This makes sense to me so I can make the opening as small as possible and reduce drag but what if I don't? Will that create a high pressure zone above the "splitter" and create more down force before pushing out towards the wheels? Making the ducting doesn't seem like the easiest task but I could probably just bend some aluminum sheet for the bottom and 2 sides and be fairly effective.

 

I've always liked the way the C5R Corvettes ducted air from the upper rear quarter panels. I don't have the guts to cut into my car like that (yet) but it's interesting:

 

I look forward to reading about how those vents perform.

My experience, from playing around with a manometer, is that opening the windows drastically reduces interior air pressure. That said, this was over a year ago and I don't recall which location I used as a reference point for that test.

 

Thought some guys are cutting the stock bumper at the crease towards the top if you wrap the ABS in the "EP style"? Then duct from the opening in the wrap all the way to the radiator. Makes it so you can have a more squared off ducting that is easier to fabricate.

 

Found this today. Ferrari uses fans to "pulse" air from the diffuser to the tail lights in the 599XX

 

One of these days I'm going to take my manometer, a ball of yarn, a roll of tape and a gopro with a suction cup out for an afternoon drive. I wonder how many speed limit passes I will be able to make before I get pulled over?

 

Venting lower quarter panels to rear and tail lights? With turbonators? What is the goal of that.

 

I found that Ferrari piece a few months ago and thought about a fan or a R/C electric turbine to help suck the air out of my drivetrain tunnel. But I am looking at running my exhaust the same way as the Ferrari. The goal I have is to reduce the rear drag by pulling as much air out of my drivetrain tunnel as possible.

 

Open



Closed

 

One thing you aero is going to change with that car in front of you, but good pics with the GoPro

 

what do you know, we were right about air being sucked in.

 

:(. No maybe about it. No I need to get a manometer and find out weather that's good or bad. It doesn't look like it effects flow either way from watching the other areas.

 

That's an area where higher pressure would aid in drag reduction and down force. Personally, I'd just leave the vents shut or replace the window.

 

So along the lines of the negative air pressure in the cab... I have slots cut in my trunk lid for an old rear wing mount setup I was playing with. I had been having problems with exhaust gases getting sucked into the cab while out on the track and had tried several things to deal with it.

At the last event, I tried sealing the trunk slots (and all other holes that led into the trunk area) with painter's tape, hypothesizing that was the path for the exhaust getting into the car. That fixed the problem immediately. So, I am not surprised at all about the tufts getting sucked into the rear window vents as shown above.

My exhaust exits past the rear bumper fascia.

 

Yep.

One thing I noticed though, if you look at the row of strings on the trunk lid: with the vents closed some are pointing up/forward but with the vents open they are all laying down flat and pointing backward like they should. You can only see a couple of them in the pic so its hard to be sure, but they may indicate that the laminar flow is getting back down to the trunk lid faster with them open... not that I have any idea why.

 

Ohh yea, that's for sure. I had a buddy who raced a civic hatchback and didn't have the weather stripping on the hatch glass. It would suck in enough exhaust fumes to make you feel light headed.

 

Less turbulent air (some went into the cabin) or just less pressure for the same reason.
Are you thinking about ducting the high-pressure turbulent air to some low pressure zone and thereby make the important air under the wing less disturbed?

 

I'm assuming it's like the base of the windshield or an open truck bed where a high pressure "bubble" (for lack of a better term) is created and the majority of air flows over that high pressure area. Bleed off the pressure and air can follow the shape of the car closer.. but it'll also create a LOT of drag.

Shitty picture I found on google (left side):

 

Do any of you guys with quick disconnect splitters have pictures of your mounting setup that you could post? Specifically the rear mounts. I went back through this thread and the "Splitter height" thread and didn't see much. I made a giant splitter last week and was pretty happy with the mounts I made, but I dropped 2 tires on corner exit Sunday and lost the splitter and destroyed my brackets, so it's time to redesign. My mounting setup didn't fail from aero forces, but from the splitter digging into dirt. I'm going to go from 3.5" static up to 4" and try not go off any more lol.

Losing the splitter alone didn't upset me too much since I expected it to happen at some point and used plywood and kept it pretty cheap, but what I didn't expect was that the aluminum angle pieces I had attached to the splitter as backing for my airdam ended up taking out 2 fresh hoosiers. They didn't puncture the tire enough to damage it, but it was enough force over a small enough area that it caused a giant split in the rubber, down to the belt. Pretty nasty, since I would have likely kept going in a race situation and found out about the tire issue a few laps later. I want my new setup to be completely flat after the bolts tear through the wood, so that if I lose the splitter again I won't have to worry about a high speed tire failure. I've got a couple ideas on how to do that, but still haven't figured out one that retains the quick disconnect for loading onto the trailer.

 

John just built a new splitter and air dam for Crusher. The install was convoluted enough he had to write instructions for me :(

fuzzy cel phone pics FTW