Subtraction by Addition: CHECK! Sometimes I hate my car - The Unofficial BMW M5 Messageboard (m5board.com)

jrhaile · 4th July 2009, 02:55

So last month (maybe 2 months ago?) I dynoed a low 326whp and 330ftlbs when I had Dinan intakes, Magnaflow Mufflers and Dinan Tune.

Today I dynoed (granted it was over 90 degrees) 321whp and 338ftlbs at the wheel. Since the last dyno I went with Borla straight-thru mufflers, delete my resonator's, TMS Race tune and Magnaflow high-flow race cats.

I'm simply at a loss as to what is wrong with my car (if there is even anything wrong). Maybe I'm reading into the dyno too much but I like to see results after spending over 1k on upgrades.

A buddy on here and I raced our M5s against each other and we were basically even. His mods are Dinan 3.45, AA Intake, TMS Tune, SS Cans/XPipe. Here is the footage from that night. BMW E39 M5s Comparing Their Cars on Vimeo

We will be doing another race tonight from a 1st gear roll as all of these took place from 2nd and 3rd gear rolls.

Diny · 4th July 2009, 02:58

What numbers were you expecting? If you were expecting 400, like factory specs, then that's crank HP, not wheel HP (which is what a dyno reads).

How are your mafs? How's your fuel filter? Did you pull the fuses that control ABS?

Blockdoc · 4th July 2009, 03:05

Quote:

Originally Posted by jrhaile

So last month (maybe 2 months ago?) I dynoed a low 326whp and 330ftlbs when I had Dinan intakes, Magnaflow Mufflers and Dinan Tune.

Today I dynoed (granted it was over 90 degrees) 321whp and 338ftlbs at the wheel. Since the last dyno I went with Borla straight-thru mufflers, delete my resonator's, TMS Race tune and Magnaflow high-flow race cats.

I'm simply at a loss as to what is wrong with my car (if there is even anything wrong). Maybe I'm reading into the dyno too much but I like to see results after spending over 1k on upgrades.

A buddy on here and I raced our M5s against each other and we were basically even. His mods are Dinan 3.45, AA Intake, TMS Tune, SS Cans/XPipe. Here is the footage from that night. BMW E39 M5s Comparing Their Cars on Vimeo

We will be doing another race tonight from a 1st gear roll as all of these took place from 2nd and 3rd gear rolls.

The WHP, while slightly lower than published specs, is still well within the "normal variance" for our beasts. Numbers I have seen around here foe expected variance in the S62 motor are +/- 10%. It could be the dyno...or just the fact that your beast is closer to the lower end of the specturm. None of the mods you describe reliably contribute HP...especially on a dyno. The just improve the driving experience.

Hope this helps (and didn't just make you feel worse)

Brian

jrhaile · 4th July 2009, 03:15

Quote:

Originally Posted by Diny

What numbers were you expecting? If you were expecting 400, like factory specs, then that's crank HP, not wheel HP (which is what a dyno reads).

How are your mafs? How's your fuel filter? Did you pull the fuses that control ABS?

hehe I know about BHP and WHP lol.. I was expecting at least 330 or 340.

MAFs are OEM with about 3k on them from Bimmerzone. Fuel filter gets replaced twice a year and this one has about 5k on it.

Pulled fuse 17 and 30.

jrhaile · 4th July 2009, 03:17

Quote:

Originally Posted by Blockdoc

The WHP, while slightly lower than published specs, is still well within the "normal variance" for our beasts. Numbers I have seen around here foe expected variance in the S62 motor are +/- 10%. It could be the dyno...or just the fact that your beast is closer to the lower end of the specturm. None of the mods you describe reliably contribute HP...especially on a dyno. The just improve the driving experience.

Hope this helps (and didn't just make you feel worse)

Brian

I understand it's within that 10% range but I would have figured adding those mods would have helped, not hurt my WHP on a dyno. The dyno was a dynocomm. Same one I previously did 326 on.

Oh I should note too that my car has nearly 137k on it

Diny · 4th July 2009, 03:18

Quote:

Originally Posted by jrhaile

I understand it's within that 10% range but I would have figured adding those mods would have helped, not hurt my WHP on a dyno. The dyno was a dynocomm. Same one I previously did 326 on.

Oh I should note too that my car has nearly 137k on it

Did you dyno the car before the mods? If not, then you can't really be sure that those items actually hurt your dyno numbers.

jrhaile · 4th July 2009, 03:20

Quote:

Originally Posted by Diny

Did you dyno the car before the mods? If not, then you can't really be sure that those items actually hurt your dyno numbers.

Yes I did... I did 326whp 2 months ago. Not to be an ***, but did you read my first post or was I unclear? Because I'll correct it if needed

Blockdoc · 4th July 2009, 03:21

Quote:

Originally Posted by jrhaile

I understand it's within that 10% range but I would have figured adding those mods would have helped, not hurt my WHP on a dyno. The dyno was a dynocomm. Same one I previously did 326 on.

Oh I should note too that my car has nearly 137k on it

DOn't lose too much sleep over SMALL changes on a dyno. Read Steve Dinan's white paper on dynoing modern cars. He basically shows that an operator can pretty much choose what HP to come in on.

5 whp change on a dyno is VERY insignificant. That's why many laugh when an aftermarket company clains 5 or 10 HP from a mod...it's literally impossible to show a difference.

In this case...it is possible that the exhaust mods actually hurt your performance. The loss COULD be real.

Cheers,
Brian

jrhaile · 4th July 2009, 03:25

Quote:

Originally Posted by Blockdoc

DOn't lose too much sleep over SMALL changes on a dyno. Read Steve Dinan's white paper on dynoing modern cars. He basically shows that an operator can pretty much choose what HP to come in on.

5 whp change on a dyno is VERY insignificant. That's why many laugh when an aftermarket company clains 5 or 10 HP from a mod...it's literally impossible to show a difference.

In this case...it is possible that the exhaust mods actually hurt your performance. The loss COULD be real.

Cheers,
Brian

And that's what I'm afraid of...Looking at the Borla mufflers, they're basically straight-thru so I would have thought torque loss as a possibility not HP like it was. And removing the resanator's and adding the high flow cats to replace my OEM 135k cats I again thought would have helped and certainly not hurt. Maybe a stock car is a healthy car haha.

blackxs · 4th July 2009, 03:26

The temperature difference between 2 months ago, late spring, and now, summer, would probably be enough to give that 5hp difference.

If not, I would blame lack of backpressure in the exhaust system from your new exhaust setup and the tune could be less than ideal.

If you dynoed them back to back, making sure the temperatures were the same, I would blame the mods. But from the sounds of it the temperature variance is to blame.