335i Drivetrain loss factors - wkw to Kw@FlyWheel

[Baracus]

Thought some of you guys might find this useful? Below are the drivetrain loss factors for a 335i. I found these posted by DINAN (maker of x35i tuning software in the USA) on E90.

quote: "The percentage of drivetrain loss has been a talking point among tuners and the numbers have been fluctuating from 10% to over 17%. What most tuners do not know is that drivetrain loss is not a constant factor; it is determined by the frictional losses throughout the engine and drivetrain which differs throughout the entire rev range. As the car goes faster (MPH goes up on the speedo) the gears, bearings and seals are moving at a higher speed and friction increases"

It seems you can get a pretty reasonable estimate of KW's at the Fly by multiplying your dyno wheel KW readings by the relevant factor. Not sure how acurate these are though? i.e. 200 wkw @ 5600 RPM x 1.121 = 224.2 KW at the fly.

Think us JHB guys will still also need to multiply by 1.05 (extra 5%) to compensate for altitude

RPM Loss Factor
2500 1.085
3000 1.090
3300 1.093
3500 1.100
3700 1.102
4000 1.105
4300 1.108
4500 1.110
5000 1.115
5500 1.120
5600 1.121
5700 1.122
6000 1.125
6500 1.130
7000 1.135

 

[Raybimmer]

What oil is used in gearbox and differfential ?
A engine oil change from mineral oil to a full synthetic can be beneficial for a dyno test , so what about the g/box and diff ?

 

[Twinz]

interesting indeed...a good find :thumbsup:
@Baracus, hope to see you smiling on Tuesday. :thinker:

 

[Baracus]

interesting indeed...a good find :thumbsup:
@Baracus, hope to see you smiling on Tuesday. :thinker:

Thanks Twins, cant wait to get the JB3 installed
How long do you reckon I give the ECU to adjust before starting data logs for Terry? Also, through what gears do you think I should run when capturing data?

 

[Rennzport]

baracus.. We'll take that offline.
Be in touch tuesday

 

[Twinz]

Baracus...Just sent you an email with my ideas for next week....have fun :thumbsup:

 

[STREETRACER]

What oil is used in gearbox and differfential ?
A engine oil change from mineral oil to a full synthetic can be beneficial for a dyno test , so what about the g/box and diff ?

Im with Ray on this one! Different oils, tire pressures, wheelbearing heat, oil heat, every thing makes a difference on losses! If you do 10 runs direct after each other they will all be different! power figueres!

But i agree 100% saying your losses is not a constant %.. it does differ on different engine speeds!
Easiest way is just work out your losses on your peak power RPM!
But as Oom Pieter De Weerdt owner of dastek says! There is only one acurate way to work out engine power! and that is to take out your engine, drive down to the coast and put it on a engine dyno!!

 

[Twinz]

"...take out your engine, drive down to the coast and put it on a engine dyno!!

Oom Pieter is the man.:thumbsup::thumbsup:

 

[lebofa]

Thought some of you guys might find this useful? Below are the drivetrain loss factors for a 335i. I found these posted by DINAN (maker of x35i tuning software in the USA) on E90.

quote: "The percentage of drivetrain loss has been a talking point among tuners and the numbers have been fluctuating from 10% to over 17%. What most tuners do not know is that drivetrain loss is not a constant factor; it is determined by the frictional losses throughout the engine and drivetrain which differs throughout the entire rev range. As the car goes faster (MPH goes up on the speedo) the gears, bearings and seals are moving at a higher speed and friction increases"

It seems you can get a pretty reasonable estimate of KW's at the Fly by multiplying your dyno wheel KW readings by the relevant factor. Not sure how acurate these are though? i.e. 200 wkw @ 5600 RPM x 1.121 = 224.2 KW at the fly.

Think us JHB guys will still also need to multiply by 1.05 (extra 5%) to compensate for altitude

RPM Loss Factor
2500 1.085
3000 1.090
3300 1.093
3500 1.100
3700 1.102
4000 1.105
4300 1.108
4500 1.110
5000 1.115
5500 1.120
5600 1.121
5700 1.122
6000 1.125
6500 1.130
7000 1.135

Interesting, just had a dyno today and at 4500rpm I got 128KW and 431Nm. I was a bit disappointed about the figures because my car has the BMW MPP kit installed and was expecting to see 140KW. Now when use the conversions I see that the 128Kw translate to 142KW at the flywheel :ty: