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View Full Version : HP question....at the wheels or at crank


Aronis
May 8th, 2007, 03:17
I was at a local BMW dealership and was told the M5 has 507 hp AT THE WHEELS and the 3.0 turbo has 300 hp AT THE WHEELS. That would make the output at the crank much higher, no? So which is it? Anyone know?

My understanding is that the RS6 has 450 hp at the crank...and the New S6 V10 has 435 at the crank, so how does the AWD car, heavier than the M5 with supposedly much less HP at the WHEELS even keep up with the M5?

I think the salesman was not quite correct?

Any thoughts?

And if this is true the 335 convertible at about 55k should be more than a match for the S4 convertible which is similarly equiped at the rediculous price of 94k. I thought this price difference is just INSANE for Audi to try to pull off.

????

Mike
42TT
May 8th, 2007, 07:22
Mike

Manafacturers quote flywheel HP so all those figures are at the engine not the wheels
GeCcO
May 8th, 2007, 12:02
I don't think i have ever heard of a carmaker that states whp. Crank hp is much more and looks more impressive. But then again, whp is what counts in the end.
42TT
May 8th, 2007, 15:36
As a point of reference the standard M5 V10 makes 290rwkw and a standard RS6 makes 260rwkw

42TT
skiwi
May 9th, 2007, 02:33
sae or din standards are used for the calculation of kw/bhp. btw, the "b" in "bhp" means "brake" and indicates not flywheel hp, but power with the engine in situ, fully connected with all normal ancillaries. there is a difference between sae and din, but only a few %

if you are going to go down the "power at the wheels" line, i suggest you use "power at the road" which takes account of wheel size and drag...
42TT
May 9th, 2007, 02:36
Most dyno's takein account wheels size but not sure about "drag"

42TT
AuditudeA642
May 9th, 2007, 21:35
NO!!! All HP figures released by Car companies and dealers are crank hp no wheel hp. IF that was the case the 335i should be faster than a 911 turbo b/c 300 wheel HP is about 415 crank hp.

PS: The Audi S4 convertible is 56k not 94k. I dont know who told you that number.
AuditudeA642
May 9th, 2007, 21:40
http://www.audiusa.com/audi/us/en2/new_cars/Audi_A4.html S4 cab starts at $55,700.

http://www.audiusa.com/audi/us/en2/new_cars/Audi_A4.html 335i cab starts at $50,000
Aronis
May 10th, 2007, 03:05
You know I ran the numbers twice with the S4 convertible..not believing my eyes, and it was 94......now I went back and it's not that high loaded.....perhaps a web site calc error....anyway, it still ends up being significantly more than the BMW.......

Mike

Yes, the dealers like to give missinformation as the salesman stressed the "At the Wheels number."