m5 dyno results from accross the pond. Highlighting the difference between a hot and cooler engine... - The Unofficial BMW M5 Messageboard (m5board.com)

EPDM · 7th August 2009, 21:24

Hi,

I recently aquired a 99 model m5 with only about 55k miles. Changed the usual MAF's which helped to wake her up a bit aswell as both post lambda sensors as one showed a fault when cold.

Anyway as I own a inertia ( non braked) dynomometer as part of our tuning company I obviously, now that I had some time to spare, wanted to dyno the beast see if we can improve a bit on the power output.

Edit: yes its certainly helps if the correct fuses are pulled...:-)

MrCrashRR · 7th August 2009, 21:59

What fuses did you pull, the m5 requires that you pull fuses to dyno it. IIRC 17, and 35, but please search for the correct ones.

EPDM · 7th August 2009, 22:20

Quote:

Originally Posted by MrCrashRR

What fuses did you pull, the m5 requires that you pull fuses to dyno it. IIRC 17, and 35, but please search for the correct ones.

Ah, I think I may have pulled the wrong fuses then...will check tomorrow, Thanks.

jrhaile · 7th August 2009, 22:22

It's fused 17 and 30 just an fyi...

EPDM · 8th August 2009, 14:12

Ok, so here is the result from the dyno once I pulled the right fuses ( 17,30).

Its an exceptionally hot day ( 27c = 80F) here at least for finnish circumstances so I guess the output not being too great and after having read dynan's take on the matter, are still within the realms of normality. Our dyno tends to show quite conservative figure anyway as far as hp is concerned, torque is usually similar to those of other dynos I have compared.

Note that we use engine output and the DIN format to display the results. As its easy to convert this on this dyno computer I also included the output in terms of wheel power and your SAE format. (BANK#2 and #4) Another good thing with this dyno is that one can adjust the scale of the graph so as to accurately scale it to the revlimiter. Hence I I have included both 4th and 5th gear pulls.

the power losses are therefore only applicable to the engine output data. We measure torque in NM here but if you convert it to for your wheel output and sae it would be 318,9ft/lb for the 5th gear pull ( hope thats correct?)

Here are some more pics of the car on the dyno. Its a basic inertia wheel barrel type version. Note the fan housing is strictly patended and may under no circumstances be copied...

Index of /niko/mycorradoweb/m5e39silver/dyno

There is a dyno day at my premises next saturday with among others a couple of m5, so it will be good to be able to compare the output to them. Also I might have a different programme installed by then.

EPDM · 8th August 2009, 15:50

Perhaps the most interesting finding of this test is the result I got when I left the car on the dyno for about two hours with the fan on. This I presume cooled down the radiator more than the engine oil so I dynoed the car as soon as the last light on the rev meter went out.

Amazingly...well at least to me is that the difference between a hot engine and a cooler ( certainly not cold) can be so big!

This is quite frustrating actually. As it would indicate that for ACCURATE before and after tests one would indeed have to test the cars with as identical as possible coolant temperatures and oil temperature, nevermind the outside tempertaure, which this dyno computer supposedly can somehow calculate...

Italowestern · 13th August 2009, 23:12

I think that the biggest difference comes when the intake air has been cooled down. That will increase the output as increased amount of oxygen/gas mixture at same revs simply gives more power and torque. The exact engine temperature does not make that big difference.

Thus, cool down the space around and try to get the best results in power. You could also lead the cooler air by tubes directly to intake filter boxes from outside of the hall or where ever coolest air is available. Through fridge room is good.. Then measure the air temperature to get the comparable figures.

Naturally the engine heat also warms up the filter housings and surroundings and therefore the breathed air is good to lead by isolated pipes to the boxes. 10 degrees difference in breathed air temperature will change the power out remarkably. If it even is a bit moist, it will cool down itself more in the pipes due to evaporation and gives further more power output.

In normal conditions that will happen on the road too if the intake pipes are correctly set to get fresh air in and even further if the channels can use wind pressure charging like applied to fast motorcycles and drag race cars.