Modded 35is, Rolling Road Results

jleckenby · Post by **jleckenby** » Sat Apr 01, 2017 4:15 pm

Hey all,

Following on from my thread on mods (viewtopic.php?f=23&t=95078), I have been to a rolling road today to see what she's making.

So yeah, pretty pleased with that

Lynchy · Post by **Lynchy** » Sat Apr 01, 2017 4:28 pm

438 BHP! Wow !

flimper · Post by **flimper** » Sat Apr 01, 2017 4:38 pm

nice

Z4M-2006 · Post by **Z4M-2006** » Sun Apr 02, 2017 8:08 am

That will be quick

Proper sleeper

jabber · Post by **jabber** » Sun Apr 02, 2017 8:48 am

Am I reading that graph correctly loosing 137 bhp through drive train?

jleckenby · Post by **jleckenby** » Sun Apr 02, 2017 11:06 am

Yep, thats pretty normal though I think!

Chris_D · Post by **Chris_D** » Sun Apr 02, 2017 11:09 am

295 @ the wheels is the figure that counts.
How heavy are you? If >=100Kg then knock off 50 bhp at the wheels

jleckenby · Post by **jleckenby** » Sun Apr 02, 2017 11:22 am

Hehe, safely under 100 for now!

R.E92 · Post by **R.E92** » Sun Apr 02, 2017 12:07 pm

There's something wrong with the dyno if you are making 438 at the crank but only 295 at the wheels. That's a 30% drivetrain loss!
Did they do something stupid like calculate the power using the manual gear ratios not the DCT?

The crank figure is about right though. I would expect 440bhp from a stage 2 car.

AFAIK BHP is a measure of power at the output of the engine, WHP should be used for the wheel figure so there's another thing not quite adding up with the dyno chart.

Rockford · Post by **Rockford** » Sun Apr 02, 2017 12:18 pm

Thought the same, whp seems way down on what I'd expect. Nice headline figure though, must really get a move on.

jleckenby · Post by **jleckenby** » Sun Apr 02, 2017 12:46 pm

It was done using a coastdown run, did it a few times. Does seem on the high side, but with the drivetrain drag measured, headline should be pretty accurate. Worth noting I did a stock run on same dyno and got 340bhp.

R.E92 · Post by **R.E92** » Sun Apr 02, 2017 1:13 pm

I'm a little confused how they managed to get the WHP figure so wrong though. Doing a little reading I have found a few topics across the web that state it's normal for Maha dynos to over-report drivetrain losses as they also factor in the losses at the roller into the calculation.

Your wheel horsepower is more like 380. 13% loss is typical for our cars from what I've seen at other sources.

If you have your COBB to hand you can do a few logs and enter them into VirtualDyno. I think you should get a figure similar to 380 (VirtualDyno measure wheel horsepower) which would give some faith in the dyno.

R.E92 · Post by **R.E92** » Sun Apr 02, 2017 1:17 pm

Very good result though. You will soon get accustomed to the power.
Whenever I go back to the 302bhp stock map the car feels pathetic

jleckenby · Post by **jleckenby** » Sun Apr 02, 2017 1:18 pm

Youre probably right, its going to be factoring in more than just drivetrain. Overall it should be accurate for the headline figure though, thats whats important.

380 at the wheels, lovely

Kingfisher · Post by **Kingfisher** » Mon Apr 03, 2017 5:14 pm

I used to get racing car engines dynoed frequently ... given that all race car engineers seem to hate each other I think they used to tell you what you wanted to hear ... they always slagged off the opposition when it came to producing bhp and as for those charts ... I often used to wonder about them! ...

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