Improving top speed on a road car?

djones · Post 03 Dec 2006, 18:08

Theoretical question...

This is not my car, but is like a friends. If we were to cover the headlights, gap between bumper, number plate and all the other sticking out bits with vinyl to make it smooth would it help the top speed at all?

Spyker MF1 · Post 03 Dec 2006, 18:18

Theoretically it should reduce the drag coefficient( not sure if I have got that right but cause less drag) this should allow the car to get a faster top speed. Although I would of thought it would only be by a few MPH maybe 10 max.

djones · Post 03 Dec 2006, 18:21

Even if it was 4 mph that would be fine!

We are going over to Germany again in the New year and last time we went we hit 156 MPH (on the GPS) with a bit of a tail wind.

The aim is to try and get 160.

Spyker MF1 · Post 03 Dec 2006, 18:51

Did you pull the wing mirrors in last time because that would reduce the drag a fair bit. Also aerials and such that could be removed would help as well

Tom · Post 03 Dec 2006, 20:21

All these things would reduce drag so little it would scarely make 2mph gain at 150mph. The best thing to do would be to wait for a porsche or something to fly past and dive into its slipstream, use the best fuel available and some redex or similar product, that should make that magic 4mph, plus a bit more.
Also consider inflating the tyres a couple of psi, not too much though!

Also for the love of god make sure everything you do is legal, the police will no doubt be able to reach over 160mph and if they can't then they'll just use a chopper.

West · Post 03 Dec 2006, 20:39

If you want a quick fix, and enough money, buy a low-drag front end. Dunno if they make them for beemers tho.

djones · Post 03 Dec 2006, 20:40

mmm, maybe not worth it then.

It's perfectly legal in Germany to do 150 MPH on the de-restricted autobhans. Indeed you can do 250 MPH if you could.

Tom · Post 03 Dec 2006, 21:33

yeah, but is it legal to cover your lights and numberplate with tape while you do it?

djones · Post 03 Dec 2006, 21:35

ah, see what you mean. No, it would be clear vinyl.

wazojugs · Post 03 Dec 2006, 22:18

sorry bit i thought all mercs and bmw's were electronically limited to 155mph ish.

I would have the limiter taken off then you should easily hit around 165mph

f1.redbaron · Post 03 Dec 2006, 22:40

wazojugs wrote:sorry bit i thought all mercs and bmw's were electronically limited to 155mph ish.

I would have the limiter taken off then you should easily hit around 165mph

Yeah, I was just going to say that. Most cars like that have governors which limit their top speed. I'm not sure what it is on a BMW, but I know that mine is set at 141mph.

Might be a stupid suggestion, but have you thought of taking everything that you don't need, out? Spare tire (I know!), the jack, seats...that should lighten the load.

djones · Post 04 Dec 2006, 00:10

It's not got a 155 limiter as the car is geared in such a way that the standard rev limt in top gear is 153 MPH. The rev limit has now been upped by 500 RPM so thats no longer a problem.

Does weight effect top speed by much?? I was under the impression top speed was more down to power and aero and weight does not come ito it (within reason) ?

Tom · Post 04 Dec 2006, 00:12

Weight should have no effect on top speed really, except that it's more effort for the engine to pull, but it won't make much difference, it has more effect on the acceleration than anything.

Carlos · Post 04 Dec 2006, 02:30

You might cardboard closed the radiator grille opening and that "smiley face" on the bottom of the front fascia -- for a few miles -- while watching the temp gauge -- and the road -- and maybe this is a foolish idea -- hmmmmmmm

Post 04 Dec 2006, 05:15

http://mark8.org/lod/bonneville.htm

good read on my car

Pay attention to how they gained the last few mph