joe@raceprecision

Your numbers are good. Actual numbers for the N54 have been closer to 325 - 330 crank. BMW underrates the engine.

Dan's BMW

I have had some dyno esperience with my previous car. Dynos give a fair indication of power but are not 100% accuracte. Different dynos will give different figures even if the same car is run back to back. Often each run can give different results. The dyno result is really useful if you are planning mods but you should use the same dyno every time (also attempting to get the same weather, time of day, operator etc to maintain consistency)

Simple things such as ambient temp, tyre pressure, dyno settings can all have a massive effect on figures. Manufactures figures are calculated in a sterile environment on a test bench. Therefore attaining those figure in the real world can be a challenge!!!

The dyno result looks appropriate for your car taking the above into account. You should run with a high tyre pressure, with all electronics turned off (DTC, air con etc etc). My previous car was a 5 speed manual and it was always run in 4th gear. It is a big no no to run without the fan but it is common to run with the bonnet up.

Output for an AWD car will be lower than a 2wd car, this is due to the additional frictional/gear losses of the extra diff and drive train. The dyno only measures torque and calculates BHP from that figure. On an AWD car you can assume 20% losses back to the flywheel but once again this is an assumption and could be variable.

A better solution would be to find a hub mounted dyno. The wheels are removed and dynos attached to each hub. This removes the variables of tyre pressure and wheel spin, however the other variables remain.


Cheers

EuroCarFan

I think you still may be confused by what you're seeing on the dyno. Dynos measure power at the wheel. The 300hp and 300lb-ft you're expecting to see are at the crank. The dyno numbers you are seeing at the wheels will always be less than the crank hp numbers due to drive train losses.

The other debate going on here is if the numbers you're seeing are too high or too low which is actually irrelevant. I mean you can use them as rough guidelines but they won't confirm if you're particular numbers are right or wrong. Like Dan said above, you can't compare your numbers to other numbers from other machines even if they're also a Dyno Dynamics machine. Just use your baseline numbers to compare to future numbers after mods on the same machine and hopefully when all or most other conditions are the same.

jusdoit

Thanks everyone for all the input. I should be getting my parts from EuroRev one of these days... right Vincent???? After I install the body kit, the first drivetrain rev will be the RDSport exhaust. All I'm concerned about is not losing power. Quad tips look cool, but for me it's not worth an unreasonable dump on HP.

ktlocklear

no vids? :thumbsdown:

Phantom Mark

Sorry if someone already said it but, if you press and hold the DTC button it will totally deactivate the system thus no interfering by the car wheel it detects wheel spin etc........

Did you not do a before and after, or was I being blind ?

jusdoit

I didn't know that about pushing and holding the button in... super cool. In response to your question... I've only done the before dyno. Now it's time to change out the exhaust! I'll post the "after" dyno's later.

C's Bimmer

this is good to know. i have a friend interested in a 535xi who recently asked me if he knew of anyone that had their car actually dyno'ed. thanks for posting.

NobleForums

3 Quick questions:

1. I don't see the intake temperature sensor probe there in the pictures (though the pictures don't show the entire front end of the car). Did they use it?
2. Did they put a correction factor in? Ask them. If you go back there, it should be in your dyno file.
3. Why keep the fan off?