I guess I've been doing it wrong, I thought it was like this......

414 *multiplied* by .18 = 74.52 add that to the original 414 rwhp & you get 488.52....That's the way I was tuaght anyway, please explain better if I've been wrong thanks

Edit: I see what your are doing but I don't know which is correct they both make sense....
Your way 505 multiplied by .18 = 90.9 add that to 414 = 504.9

Guys, in the end, we're still faster after they've had years of more R&D.

What you're doing is:

414 * 1.18 = 488.52. That's not the same taking 18% from the crank HP number. You're adding 18% of the RWHP number to the RWHP. 18% of a smaller number is of course smaller than the 18% of a larger number.

I like your way better! my rwhp rwto = a beastly C6!! Dynoed 350rwhp 360rwto bone stock.....


400 * .18 = 72 + 350 rwhp = 422 Crank HP C6 w/ 432 crank torque though I'd like to believe this I don't think it's true....Hope so though!!

She is damned quick! they did report the new Z06 was underrated from GM so maybe ...mine to..

there is not a production automatic on earth that can do 18% driveline loss. the best auto does 20, avg is 21%. front engine RWD sticks do 17%, and rear engine RWD do 15%. this 17-18% garbage everyone has been saying here for ever is WAY off. No auto short of a dragracing race auto tranny can pull that low of a drivetrain loss and even that im skeptic. 20-21% is correct. Benz engine HP numbers are conservative just as their 0-60 numbers so don't try and match it to the manfucaturers claims or you will always use too low of a conversion factor. use 20%

LOL my Dyno results are already being used in other posts. It's only been a couple of hours and remember that this was a CLS63 not an E63. I don't think it makes much of a diff but it probably does.

What you really want to do is:

414/507=81.6%

100% - 81.6% = 18.3% loss from crank to wheel which is what is to be expected. I have heard of others getting 425 after about 3000 miles. This car only has 900 miles on it.

I don't think they would under estimate my ponies to that extreme, I've allways heard it was 15% for manual and usaly 18% Auto...

It's a good dyno for ref, sorry for borrowing it for our discussion

I do not "know" that the E63 does not make 507 crank HP anymore than anyone else "knows" it does. We don't "know" what it makes, because it has not been run on an ENGINE dyno, as I stated. However, Mr. bench racers, we do "know", that for every WHEEL HP dyno we have seen, it makes several HP less than the 469 HP rating of the Kompressor (on average). Don't even start with me, or I'll sick Improviz on you. The discussion is about the accuracy of HP ratings, not 63 VS 55, and even if you consider them equal, either the 55 makes more than 469 HP, or the E63 makes less than 507.

Is there a dyno graph of a stock 55 available anywhere?

Many. Your CLS is right in line with many stock E55's. Again, the numbers don't seem to make sense if the 55 is at 469 and the CLS is at 507.

MB has understated E55s HP numbers.

SL55 was rated at 493HP and E55 was rated at 469HP.

I have dynoed ten SLs and over 30 E55s - on the Dynojet, both cars are in mid420s RWHP.

I usually like to use 17% drivetrain loss. So to find out flywheel HP from wheel HP, I simply divide WHP by 0.83.

So if CLS63 is making 415 at the wheels, than we have 414/0.83 = 499HP. Considering that CLS63 still has 900 miles, IMHO AMGs 507HP rating is right on.

Shi*t yeah......that means when my C6 was BONE STOCK it was making 421.6 crank & 433.73 torque

This deffinitely falls in line w/rumors of GM understating Z06 HP w/Stock C6 Z06 rwhp of 445-465 on dynos I've seen at the Vette forum, that = 536-560 crank HP stock ohh damn! no wonder there so kick-***

Edit there even higher I forgot to lower the drive line % loss due to the Z06 is manual...

There are just too many variables to narrow this down to within 10hp I reckon ...

lets see...

Drivetrain eficiency
IAT
Ambient
AC on / off
Alternator Load
Fuel Octane
Fuel Mapping program
Dyno Type
Tyre grip on dyno
S/C Belt slippage (if present)
Gearing differences / tranny and diff.

And there are probably loads more ...

I totally agree...there is more to the hp issue than a simple dyno test. Bottom line; E55, or E63, they're both great cars