PDC

General consensus is that the auto tranny and driveline on our E55s pulls about 17% from the power numbers at the flywheel. Theoretically, a car that makes 469 hp at the flywheel will show about 390 ponies at the tires. That means it takes about 80 ponies to turn the driveline. BUT --- an E500 with the previous generation 302 hp V8 by these calculations would only require 51 ponies to turn the SAME auto trans and driveline. Does it really take 30 additional ponies for a more powerful motor to do the same work? Shouldn't the amount of power necessary to turn the driveline be a set or constant number? I know somebody out there can 'splain it in simple, layman's terms. Thanks!!

stevebez

I am curious if Torque Convertor that locks up fully has this level of loss once locked up ???

Grumpy666

The amount of power loss in a drivetrain is also a function of how much torque is applied. An engine that produces more torque will have higher fritional losses and will therefore have a higher drivetrain loss. This is why dynos that measure deceleration tend to measure/correct higher than other dynos - they can only measure the rotational losses and do not take into account the extra losses due to increased torque.

Once a torque converter locks up, the transmission input shaft is directly coupled to the engine, so theorectically, no more TC losses. But there are still losses due to the front pump in the tranny.

jangy

The E500 and E55 do not share the same tranny and other drivelines. A more powerful car will need more rugged components, which will make more drag.

Vadim @ FD

Typically, W211 E55s make around 420RWHP on Dynojets. Other dynos seem to be all over the place.

An SL55 puts down the same numbers - 420-425RWHP, which indicates that E55s are under rated by the factory.

If we use 17% as a loss and plug it in 420/0.83 we get 506HP which puts us very close to fatcory rating of 493HP (SL55).

500s (Including CL, SL and E) are typically in 250RWHP range on Dynojet. Again plugging in the numbers yields 250/0.83 = 301HP.

So as you can see the loss is not a fixed number, but a percentage.

PDC

Thanks guys! It does make sense that the more torque you twist through the driveline, the more resistance you generate - resulting in a percentage relative the input as opposed to a set, fixed number. The nearest Dyno to me is a Mustang, which I have heard is a very pessimistic machine that consistently rates about 10% less than the identical car on a Dynojet. We'll see.

Vadim @ FD

You are welcome!

See if you get to a Dynojet, even if it takes a bit of time to get it. Dynojet numbers will be a lot easier to compare.

Good Luck and enjoy the car.