Jan AMG

Have you dynoed your car?
If so, what hp/tq did you get?
I sent my E55 to dyno and got these results..
Hp: 341.8
Nm: 455

I later found out the gear mode selector was switched to W mode. Can this be the reason why the performance was slighly limited?
Everything else on the car is close to factory/mint condition.

Jan AMG

Yeah and I used Natural 95 RON petrol this time so the lowest octane rating possible (you can buy 98 RON or 100 RON in Europe).

CharlyE500

We only have 91 in California... not much choices.

Jan AMG

Hi, thanks for your input. Californian 91 AKI equals European 95 RON.

https://en.m.wikipedia.org/wiki/Octane_rating

I will try another dyno with 100 RON and see difference it makes.

Jan AMG

IanB

Starting in "W" mode would only mean the trans would start off in 2nd gear, rather than 1st. I assume you'd be doing your dyno run in 4th gear, so that shouldn't make any difference to your results.

As your dyno results would be "at the wheels" you would expect there to be driveline loss to the tune of 20% or so for an auto (just a guess), if that figure is in the right ballpark that would put your HP if stock at just over 280hp. Your figures are much stronger than that, so you're either pretty heavily modified, or there's been some "tinkering" with the dyno calibration to get the figures you're seeing, perhaps trying to convert to a flywheel hp level (as the engine is rated from factory).

Great pics on the dyno btw, car looks amazing!

Jan AMG

Hi Ian, thanks. You made me learn more about it.

The driveline loss is calculated by the dyno system. It should be 15% (auto + RWD).
If you would add this to my current output I'd have over 400hp and my car is bone stock so that is not possible.

The dyno guys told most of the atmospheric engines eg. M273 500 V8 should have 388hp but they measure around 350hp, even 330hp. On the other hand, most of turbo charged engines get exact factory values, even up to 10% more.

I will do another test run in the next week, this time with a better fuel.

IanB

I think you'll find the actual driveline loss on these cars is much higher than 15%, I'd believe that for a manual transmission. Our cars are likely more like 25%. These transmissions are pretty beefy, they use them behind the V12's as well, but I think they suck up a lot of the power in the process of getting it to the wheels. Here's a great link I found:

http://www.superstreetonline.com/how...in-power-loss/

NAFT1

20% is the accepted figure, but it's not exact. The 722.6 (with different clutches and converters across the range) had to put down power in everything from the C320 all the way up to the SL73 and McLaren SLR, so it is massively overbuilt to contain the torque and sucks up more of the HP than many other auto gearboxes. Stock should dyno at about 270-290 rwhp from what I've seen out there, and depending on the type of dyno. Winter mode changes the reverse gear ration (we have 2 reverse gears), locks out 1st gear, and I believe also changes the lockup point in some of the gears to limit torque to the rear wheels at low RPM. If they used 15% as the correction factor, you are at about 296 whp, which is healthy for these cars unmodified.