SL60 AMG rolling road rests.

[SavMan]

I think I am right in saying that you would be wrong to look at the transmission losses being a percentage of the flywheel power output. These losses are speed related not load related so as the torque at the flywheel increases the actual percentage losses reduce (Assuming the peak torque is measured at the same speed). The rolling road should calculate the losses within the transmission as it winds down after the power run, thereby giving you the flywheel torque measurement (probably more accurately described as an estimate).

The problem is whether the run down is accurate (or more likely enhanced) so I prefer the manufacturers published drive train loses.

I no longer chase dyno numbers but how to make consitent power without causing unnecassary strain on the components.



I am no expert but after 10 rolling road sessions this year on my car I now only ask for the following

1. BHP and Torque graph and figures at the wheels
2. AFR graph
3. Boost pressure graph
4. IAT graph
5. Exhaust back pressure and Intake Vacuum graphs


And finally the conditions of the day


What I look for is how consistent the graphs are and areas that can be improved or have been made worse since my last changes.


By doing this my top line power and torque figures are going up a little but more important I can run the 1/4 mile almost 0.6 secs faster and I am almost 7 mph faster crossing the line.

 

[Dieselman]

I think 20% transmission losses is too high, more like 15-18%...but that doesn't make people feel good...

Transmissions do lose more power depending on the load exerted.

 

[Bobby Dazzler]

I'm a 15-18% transmission loss kind of guy too, which equates to 412-427 bhp which is exactly what I would expect from a healthy to very healthy SL60.

 

[Darrell]

Ill do a thread soon mate...

Jay, can you do an album of all your Mercs because I am seriously losing track of what you have got.

 

[andy27168]

Hi,
I had my C43 on the rolling road with the original 43 engine, published BHP figure 306, at the wheels 224BHP, another forum member had his low mileage FSH C43 done at the same time and this was 225BHP at the wheels, which equates to 26-27% lost through the drive train.
Thought this info might be of some use to establish power loss in the transmission/drive train.

 

[SavMan]

W211 E55 AMG has a stated 19% loss according to Mercedes, this is used to calculate there offical power figures.

 

[Dieselman]

Hi,
I had my C43 on the rolling road with the original 43 engine, published BHP figure 306, at the wheels 224BHP, another forum member had his low mileage FSH C43 done at the same time and this was 225BHP at the wheels, which equates to 26-27% lost through the drive train.
Thought this info might be of some use to establish power loss in the transmission/drive train.

That indicates that either the readings or method were incorrect or both engines were under performing somewhat.

 

[SavMan]

That indicates that either the readings or method were incorrect or both engines were under performing somewhat.

Or that the official BHP were not accurate

 

[SavMan]

Hi,
I had my C43 on the rolling road with the original 43 engine, published BHP figure 306, at the wheels 224BHP, another forum member had his low mileage FSH C43 done at the same time and this was 225BHP at the wheels, which equates to 26-27% lost through the drive train.
Thought this info might be of some use to establish power loss in the transmission/drive train.

That does sound a lot, most would be closer to 240bhp but again it all depends on the dyno.

 

[Dieselman]

Dyno's are almost a waste of time for anything other than taking live data with the engine under load and adjusting timing and fueling while running
A much better way to measure performance is use a flat piece of road and a stopwatch..which is what they do at drag strips, isn't it...?

 

[SavMan]

Dyno's are almost a waste of time for anything other than taking live data with the engine under load and adjusting timing and fueling while running
A much better way to measure performance is use a flat piece of road and a stopwatch..which is what they do at drag strips, isn't it...?

Fully agree with you

 

[Martyn_n]

Transmissions do lose more power depending on the load exerted.

I personally cannot see why this is correct. Apart from the additional torque acting on helical cut gears creating additional logitudilal loading against thrust bearings and ultimately heating those bearings where is the energy going? Even if they do I cannot see it being completely linear with the increse of input torque, therefore my argument that using a percentage transmission loss when calculating flywheel torque improvements is innacurate. Of course I am open to a good explaination why this is incorrect.

 

[Martyn_n]

Dyno's are almost a waste of time for anything other than taking live data with the engine under load and adjusting timing and fueling while running
A much better way to measure performance is use a flat piece of road and a stopwatch..which is what they do at drag strips, isn't it...?

I cannot disagree with you there DM.

 

[Dieselman]

Even if they do I cannot see it being completely linear with the increse of input torque,

I don't recall saying it was linear, I think you will find losses are more likely to be exponential due to the load attempting to force the gears apart and loading the bearings more.

 

[Martyn_n]

I don't recall saying it was linear, I think you will find losses are more likely to be exponential due to the load attempting to force the gears apart and loading the bearings more.

If it is not linear, and I agree you never said it was, then even if we agree than an increase in losses do happen it still becomes something which is not useable when trying to calculate flywheel torque (which is the point I was making). It all kind of compounds the fact that using a rolling road as a tool for wagging your gentleman friend in the pub is a bit sad, as a tool for mapping your fuelling / ignition requirements it is superb in the right hands, which is why it seems strange that the op did the run but was reluctant to remap.

 

[Pauljay]

Where's the Dyno graph?

Let us see the line curvature please!