200mph+ for less?

[ruzman]

Inspired by the 5% Pocket Exotic thread and the fact that I've just bought an SL55 - I wondered how little you need to spend to top 200mph+ in a production car?

I'm not talking about a Ford Escort with a Rover V8 running on nitrous, but a standard production car.

An SL55 can be had for about £12k, and a pint to the right man can get the 155mph limit removed, to top out at 202 or 207mph depending on who you believe (it could be argued that isn't standard anymore).

What do you need to spend to get into the 200mph+ club?

Utterly pointless, of course, unless you live in Germany.

[ruzman]

Great information all. I was originally thinking standard - no remap or hardware. Seems the front runners (albeit with some mods) are unsurprisingly the Germans. Mercs - 55s, 600, 63s. BMW V10s. Audi Ss (I think RSs are out on price). And of course the bike.
Apologies if I missed any other good options.

[ruzman]

popeyewhite said:

PurpleAki said:

I'm dubious of all these stock M5's and M6's claiming 200mph. A 560bhp Gallardo LP-560 only just cracks 200mph with a much smaller frontal area. Same with the Ferrari 458. McLaren 650's with 640bhp top out at 205mph I believe. I just don't buy the BMW's being able to do it with 500bhp.

Yup, no way a saloon will manage the 200 on 500bhp. Here's an MRC tuned RS6 with 730 bhp and <1000lb/ft. And it only manages 198 mph (verified), 205 on clock.

To be fair. Top speed is about power and drag. Many Ferraris, Lambos, McLarens etc have aero aimed at producing downforce which despite pointy front ends increases drag.
Not saying that a boxy saloon will have a lower drag co-efficient but a slinky SL does. Just dont expect to take a corner over 150.

[ruzman]

stevieeg said:

traffman said:

lucido grigio said:

Isn't it true that well known Mc F1 owner drove his car regularly at very high speeds in the 90s on his commute in Germany.

Forgotten his name.

ETA....Tomas Bscher....also seen at LM24.

Edited by lucido grigio on Thursday 16th March 15:50

Yup he was a Swiss Banker..if i recall. When Maclaren plug his car into there machine they had to check it wasnt an error.

The anecdote he told in CAR magazine was to the effect that he sent telemetry data to McLaren via modem (Probably a 14.4k one). They subsequently contacted him and asked him to bring his car. They thought it's data logging hardware malfunctioning as they were seeing regular speeds in excess of 200mph... to which Bscher responded that it was correct and he was just driving to work.

For the life of me I can't find my copy of the magazine but I must have read that article about 100 times when I was 17.

August 1996. Found it surprisingly easily in my pile of Car mags. I too read that many times and recounted it many times since. (I was 17)

Edited by ruzman on Thursday 16th March 21:54

[ruzman]

turboteeth said:

W211 not W201 actually!

Seems quite a few agree with you, even to the point of 200mph

http://www.pistonheads.com/news/general-pistonhead...

[ruzman]

Sergio DS said:

Found this http://phors.locost7.info/phors06.htm Nice breakdown of the Physics involved... So which cars can beat the 200mph, without 600+ bhp?

Excellent. Thanks for that. Many things mentioned in there that we've forgotten. Especially in the debate of a saloon vs supercar. So a supercar requires a lot more power not just because of the downforce generating drag, but the high rolling resistance of some great fat tyres. Also add in some of some cars are permanent 4 wheeldrive (911 turbo) so add in additonal drive train losses compared to 2 wheel drive.

So same power the saloon will go a lot faster than a fancy super/hyper car

BTW - open admission - I have a physics degree - please don't think less of me!

[ruzman]

liner33 said:

Summed up by "it has less impact that other factors but far from no impact"

WARNING: NERD HAT ON
I didn't set out to prove anyone right or wrong - but the physicist in me was curious. The below is a good paper on rolling resistance.

http://geosci.uchicago.edu/~moyer/GEOS24705/Readin...

Rolling Resistance
The formula for rolling resistance Power Requirement is Power = Crr m g v (rolling resistance * mass * gravity * velocity)

The paper shares the median rolling resistance of tyres from 2005 (Crr = 0.0099)

Thus the power required to overcome rolling resistance at 200mph in a 2000kg car is =
= 0.0099 * 2000 * 9.8 * 89.4 = 17.3kw ~ 23hp
Half the weight to a 1000kg car and you need about 11hp less to maintain 200mph.

Aero
Aero power requirements are given by: Power = ½ρA v3Cd

All else equal the top speed will be governed proportionally by the Cd –

So out of interest I compared a Lambo and the SL55
SL Cd = 0.29
Lamborghini Gallardo Cd = 0.34

A 560hp Gallardo (LP-560-4) has a top speed of 202mph
Which means that the SL55 power requirement to hit that same speed = 0.29/0.34 * 560 = 478hp.
Actual SL quoted power – (476-512hp)

So the SL55 from a simple comparison looks as if it can top 200mph.
(I expect the Lambo has a greater frontal area and is also 4 wheel drive so will have even greater frictional losses)

[ruzman]

CraigyMc said:

Are we assuming the Gallardo and the SL55 have the same cross-sectional area?

Yes

In reality I doubt there's much difference but I'd also be prepared to believe that the muscular Lambo has a bigger area.

Having found the formulas I was just messing around and surprised the result aligned so closely with real world test results.