How effective are the "is" aerodynamics

[bastianshaw]

I believe I read that the is was 2mph faster top speed based on the spoiler.
Is this true, or does that figure include skirts and, more notably the lip spoiler?

Would like to hear from maybe spec e30 or swapped guys that have installed after they bought their cars, or driven both, can you feel it at higher speeds?

[agent]

I know I can't tell the difference between 120 and 122.

[DÌEGØ]

Its a small difference. barely worth it

[bastianshaw]

Anyone know the actual drag coefficient for a late model 325i OR is?

[jlevie]

My opinion, based on experience with race cars, is that the front spoiler makes no difference.

[bastianshaw]

http://forums.bimmerforums.com/forum/showthread.php?t=290933&page=2

looks like the 87is wins

[bastianshaw]

My opinion, based on experience with race cars, is that the front spoiler makes no difference.

always liked that valance

[nando]

the trunk spoiler is supposed to reduce drag by about 2%. don't know about the front spoiler. it might do something but the difference is probably small. They did actually wind tunnel test them.

for drag I've seen anywhere between .33 and .35, but remember the E30 is a small car with a smaller frontal area (area X coefficient of drag = total drag). Modern cars have slightly lower drag coefficients but they're also fucking HUGE.

[TobyB]

Anyone know the actual drag coefficient for a late model 325i OR is?

=> brick

t

[nmlss2006]

Really? 0.33 to 0.35? That seems exceptionally low given the age of the project... and it's true, the important part in figuring out the aerodynamic drag in an E30 is that the S part of SCx is small, compared to an E46.

[Wild Ride]

I talked to a couple pro3 guys at PIR. (portland international raceway). The class only allows for certain OEM parts and mods to be used. Several of them claimed 5mph faster at the end of the front straight using front and rear IS spoiler and lip vs no trunk spoiler and i lip. I have no evidence to substantiate this however.

[djmossm42]

I would assume the front spoiler is to keep less air from getting under the car which could reduce drag at high speed as opposed to an expensive full under car diffuser not sure if that's the right term but you know when the bottom of the car is one smooth surface and air can be directed out the back

[Driftin]

I talked to a couple pro3 guys at PIR. (portland international raceway). The class only allows for certain OEM parts and mods to be used. Several of them claimed 5mph faster at the end of the front straight using front and rear IS spoiler and lip vs no trunk spoiler and i lip. I have no evidence to substantiate this however.

If anything, the spoilers are reducing lift, thereby allowing a higher exit speed out of the corner and a higher top speed on the straight. Easiest way to reduce drag and increase top speed is to reduce the frontal area of the car. Do this by lowering it. (yes I am including the air below the front spoiler as frontal area since air packs up there at high speeds)

[Bimmerguy91]

Really? 0.33 to 0.35? That seems exceptionally low given the age of the project... and it's true, the important part in figuring out the aerodynamic drag in an E30 is that the S part of SCx is small, compared to an E46.

I agree I find that extremely low given the design and age of the car.. I mean its like a brick.

[nando]

Volvos are bricks. E30s are basically bubble cars in comparison. :p