JMB

A simple spreadsheet you can use to calculate power needed to reach a desired speed, or the opposite, speed you can reach with a specified power.

The spreadsheet doesn't have into account rolling losses, so it is not accurate at low speeds, but with speeds above 120Km/h almost all the power goes to fight against the air.

You can find offical data for BMW E60, and two examples of different F1 configurations, one for Monza circuit where the aerodynamics of the car are prepared for maximun speed (long straights, low drag) and for Monaco where you need a lot of downforce (resistance to air very high, high drag). You can see that a F1 car needs much more power to achieve the same speed our cars reach...




EDIT: Oppppsss... I'm not allowed to upload a spreadsheet file

Alex.br

Please don't forget to check the tires speed rate before the Vmax test ...

olli_535d

Sorry, Tiago, no. The rpm were my least worry at that speed on a slightly bendy dual lane Autobahn.


[/quote]Please don't forget to check the tires speed rate before the Vmax test [quote]

Good point. You think I shouldn't have done it on my H-rated winter tyres then ?
Joking aside, you are absolutely correct, you need at least a Y rated tyre.

AlexFW

Don't drink when you post on the internet ... (= even the 535d is capable of 275 kmh)

Tiago

I don't drink. I just have a few years of experience about chipping cars and know that both (tuners and customers) usually increase the numbers that they actually got. But i chipped my 535d this afternoon and i already made a vmax test this night. I didn't know that the head-display speed stop reading at 260 km/h :thumbsdown: . At least i checked the max rpm that it had made and it was between 4100rpm and 4200rpm in 6th gear. Can you tell me how much speed it made?

PS: my car was chipped for about 350/360hp and it was been removed the two speed limiters. Most of the tuners only take out the first speed limiter. He also said that in about 50.000km the DPF will failure because it won't be able to clean such a higher level of exhaust gases. Did anyone know this problem?

dlevi67

4150 rpm in 6th on a stock transmission and tyres (225/50 r 17 or 245/40 r 18) is 289 km/h.

This implies ~ 370 bhp at the crankshaft. If that is the case, your tuning is better (or delivers higher power - "better" in my view is a subjective judgment including smoothness, driveability and reliability) than anyone else's I have seen advertised by about 30 bhp.

Tiago

The car has better smoothness and driveability now. It feels that the car made a +500kg diet. I only need now to use half of the throtle than full throttle before to get the same reaction. About the reliability, i think that it will depends on the attitude of the driver. I use generally the car between 2000 and 3000rpm with half of throttle course, if i need to smash the throttle i never do it below 3500-4000rpm's in higher gears, and everytime i push it a little harder i let the engine running for about 1 min (to cool down the turbos) before turn it off.

They set the bigger turbo to 2.2bar (they said that it makes 1.8bar from stock). Is there anyone running at 2.3bar?

PS: I have oem M135 wheels with 245/40-18".

AlexFW

ROTFL!
Then explain me why this stock 545i, that has only 330 hp, :

http://video.google.com/videoplay?docid=-2...6796&q=545i

would defeat you .

dlevi67

Uh? Sorry, but I seem to miss the point. The car in the video is accelerating 0-200 km/h. The whole thread here is about top speed.

Quite how either of these is relevant to normal driving conditions, also escapes me, but never mind

quad_m

if you have extra hp/power/powerchip on the car and would like to see your 100% Speed rate
I reccomend that you can try it with a GPS system(aftermarket one). GPS will tell your exact speed even your speedometer does not continue after the 260km/h. One more thing you can get the stainless steel wire wound Vitek Spark plug wires to optimize your power (also you can try your real engine power by buying 100+ Octane race gasoline)

just my 0.02..

best regards,
Tony