reducing drag

[IPD]

i have a buddy who is looking for ways to improve is road car. (sti). rules stipulate that he has to run with the front windows open on his car; and he MUST have windows in place on the rear & back windows. he's considering cutting holes in the trunk to allow for the airflow to pass through without creating excessive drag.

has anyone done this with a track car? any input?

[J. Fast]

I have a couple of friends that have CF rear side window inserts with holes punched in them. They are blocker panels that set on top of the windows and have reinforcement tiebacks and holdowns tied to the cage crossmembers. The rear windows roll up 1/2 way. The rules don't say anything about using filler panels so that's what they're using They are Evo's and not STI's though. I'll see if I can get them to shoot me some pics of the panels. They also have some pretty elaborate undertray and front and rear splitter setups. Not sure what class they are running but their Aero is pretty wicked.

[J. Fast]

Okay, one has a 8 ply carbon fiber inlay that's molded to the physical door frame with rated fasteners in these collars.

The other physically welded a blank plate to the upper 50% of the door framed window opening. He cut the plate to match the contour of the window and then welded a saddle to contour the window and accept a weather gasket. Then he punched several holes in the plates and blended them in with the car paint.

[J. Fast]

EDIT: Same kind of porhole in an armored car

[J. Fast]

They both look just like this Rexspeed one installed at Lancershop... with a little less window opening. One is CF, the other is painted the same as the car.

[DocWalt]

I was going to suggest those window vents as well.

[J_Parker]

Can he simply just unbolt the trunk lid and remove it for the duration of the race? I've seen that done a couple of times here.

Even with the window vents I can still see a large amount of drag/pressure building up in the area between the rear window and rear door windows. taking the back seat out and coming up with some sort of ventilation would probably be optimal.

Perhaps cutting the lower portion of the trunk lid off and rigging something up that would ensure it could be bolted back on and seal-able would be the best route, definitely time consuming, but worth it in my opinion.

[STiedVR4Guy]

Back seats are really easy to remove in the back of an STi and the only thing behind that and the trunk is a plastic panel that can also be taken out. I'm not the most educated in road course but that would just make sense to me if putting holes in the trunk or removing the lid completely.