Cant dyno a merc?? Hmmmmm

[E55BOF]

That may be the way the way people approximate power at the flywheel on AMGs, but that's a drive train loss of 15.25% if you believe that the power at the wheel is 414 BHP and power at the flywheel is 488.52 BHP

Starting with the wheel horsepower as the baseline skews the figures, which is precisely my point. Thank you.

It doesn't matter where you start from, 'correcting' a loss of 18% by adding 18% of the 82% left after the loss cannot possibly give an accurate figure. It may be the way everyone does it, but the final figure will still be wrong.

But I don't much care; I'm quite happy to do as everyone else does. I don't care what the power actually is; I just want to know if it is a standard map, or not.

Thank you AMgeed; mine was in fact putting out 415.4 hp, but only 458 ft-lb of torque, at the wheels. Swings and roundabouts, I guess. Interestingly, using the arithmetically correct method to calculate the flywheel horsepower, but with 14% as the notional loss, gives 483 bhp, which is much closer to stock than 504. Hmmmm.

I'll wait to see if a few more posters can offer unmodded figures, but it looks like a Star session will be needed. I wouldn't want, even unwittingly, to give my insurers duff gen.

 

[AMGeed]

Thank you AMgeed; mine was in fact putting out 415.4 hp, but only 458 ft-lb of torque, at the wheels. Swings and roundabouts, I guess. Interestingly, using the arithmetically correct method to calculate the flywheel horsepower, but with 14% as the notional loss, gives 483 bhp, which is much closer to stock than 504. Hmmmm.

I'll wait to see if a few more posters can offer unmodded figures, but it looks like a Star session will be needed. I wouldn't want, even unwittingly, to give my insurers duff gen.

Bear in mind that some of these 55k AMG engines have left the factory with over 500BHP as standard. I believe Cyclone has a CLS55 that dynoed over 500 at MSL before being mapped, so even if yours is up to 20 odd HP above stock, don't assume its been mapped. You may just have a cracking engine
That said, I don't blame you wanting to be absolutely sure. Insurance companies can be notably zealous if there is a chance not all is what it seems to be come claim time.

 

[Mrhanky]

Debate of the figures aside for a second, I take it we are all now safe in the knowledge you can actually dyno a auto Mercedes, and Celtic Tuning need to brush up on their skills.

 

[st13phil]

It doesn't matter where you start from, 'correcting' a loss of 18% by adding 18% of the 82% left after the loss cannot possibly give an accurate figure. It may be the way everyone does it, but the final figure will still be wrong.

But I don't much care; I'm quite happy to do as everyone else does. I don't care what the power actually is; I just want to know if it is a standard map, or not.

I think you've grasped it.

People often confuse precision with accuracy. The fact that a particular dyno records (say) 507.16 wheel horse-power (WHP) is certainly precise, but whether it's accurate or not is another question entirely. Using a factor to scale that up to crank (or flywheel) horse-power may or may not improve the accuracy, but it will always be an approximation.

The absolute numbers recorded on any given chassis dyno are subject to so many variables that they are only meaningful for comparative purposes on the same dyno, under the same conditions. And the peak value obtained is just that: a peak value which on its own doesn't give a very good indication of how the car will perform.

I doubt you'd be able to determine if a particular car was mapped or not just by looking at peak WHP on a random dyno unless the operator had records of runs with the same model in a known condition, or there were some very obvious deviations to what could be expected within a "normal" range of deviation from the published performance parameters.

 

[Leabrooks]

Looks like the only Fail is from your total lack of understanding of Power losses through drivetrain ....

:

Really? And its 18% even though your first statement says is not measurable and then ignores that very fact? So whats the tyre loss at the wheels in your car (not transmission/drivetrain but the tyre contact)?

 

[ChrisA]

Really? And its 18% even though your first statement says is not measurable and then ignores that very fact? So whats the tyre loss at the wheels in your car (not transmission/drivetrain but the tyre contact)?

Apologies for my previous post, I sounded a bit of a tw@t

So many grey areas when it comes to working out total losses.

I go for 18% total broken down to 12% drivetrain and 6% tyre loss.

For the record, we use the dyno often to give us an idea of gains after each mod, same dyno, same environment. This gives as good as your going to get figure to work out the progress or lack of

The real figures are on the drag strip/runway

 

[acej]

Apologies for my previous post, I sounded a bit of a tw@t So many grey areas when it comes to working out total losses. I go for 18% total broken down to 12% drivetrain and 6% tyre loss. For the record, we use the dyno often to give us an idea of gains after each mod, same dyno, same environment. This gives as good as your going to get figure to work out the progress or lack of The real figures are on the drag strip/runway

I would use a different word Chris and guess what it begins with ;-)