bmwe21.net forums

Maybe this will help, got it from a german e21 test article from a magazine



Martin

well I don't understand these numbers very well, but I understand that they are getting better with a spoiler than without one

Great stats!!! Love it

yeah , +1, but still I don't understand, can anyone explain the terms ?
Do these mean that overall aerodynamics of the car (which I think was never the most powerful part of the E21) is getting a bit better with the spoiler? (This should have a positive impact on fuel economy as well, shouldn't it?...)

Drag coefficient tells you (with a bit of extra maths) the force of the air pushing back against the car at a given speed.
A 10% reduction in drag coefficient gives a 10% reduction in drag force at a given speed.
With less drag your engine effectively will have more power left in reserve to accelerate the car.

Lift is a measure of the reduction in the static axel weight due to aerodynamic effects.
Less lift means more weight on the tyres which means you can achieve higher accelerations (braking and cornering. Accelerating too if you're traction limited at speeds where the aerodynamics have a noticebale effect as with an F1 car)
None of these spoliers produce downforce as such, they simply reduce the amount of lift that the e21 body shape generates.

I wonder what the difference is in the real world and what's more beneficial...

A) The weight saving from having no spoiler
B) The benefits of drag and lift with a spoiler

Did you notice a change when you removed yours Tom?

In any case, the spoiler's weight is not very significant, when I held the BBS with my hands I noticed it is no more than the weight I should loose (I think it weighs less than 7-8 kilos if I am right, I have to loose more than this) so from tomorrow I am on a diet, and when I loose the weight I gt the spoiler on

interesting figures.

I'm thinking of fitting E30 Mtech 1 boot spoiler on my E21.
It's obvious I will not have as much benefits of it as it suposed to give on E30 but...
did anybody did it already? any pics?

i happy that the BBS comes in close second to the kamie one

On the back im guessing the hartge one comes up top because of the hartge rear ground effect deviece

Well, I have always been thinking that the Kamei spoiler was just rubbish, I never knew it's the best from aerodynamics point of view...

It'd be nice to know what speed those lift numbers were generated. I've got spoilers front and back and you can still feel it lighten up once you get up towards 90 mph. I guess it's got 50 kg pushing the rear axle up. I'd hate to feel it without the spoiler!

Cheers

Mihajlo wrote:I'm thinking of fitting E30 Mtech 1 boot spoiler on my E21.
It's obvious I will not have as much benefits of it as it suposed to give on E30 but...
did anybody did it already? any pics?

some wanker on here done this...




J

who would make that rediculous choice

someone with a long white stick?

anyway jimi will tell ya..... it offers lots of down force while its parked up in his garage!
the spoilers probably for sale now anyway as he's raping his car for owt worth a quid.....