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      03-17-2009, 04:14 PM   #1
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Dyno Pull, or why I'm dumb as a bag of hammers

They say confession is good for your soul...

So for the hell of it (and because I was curious) I scheduled a dyno run at a local shop in San Jose CA. I won't name which one because I don't want to tarnish them with my own stupidity, and they were pretty nice... Sorta. I mean, I've never done this before - I never had a car where I wanted to before - so I wasn't sure what to expect.

I give them all my info and my key at the service desk and they say the dyno guy will be there shortly, I should have a seat. I look outside like 10 minutes later and my car's no longer in the lot, so I assume they'd taken it back to get it set up. I went out and checked, yep, they had, so went back in and asked the guy if it was ok to go watch (especially since I'd also assumed they'd tell me when they were going to start hooking it up). He said sure, so long as I didn't wander around the bay, of course.

I watch them hook it up, it's a Dynapack (bolts to the hubs, no drums) so they're pulling the wheels off, bolting on the adapters for the BMW hubs, etc. Guy doing this part seems nice enough. They get it hooked up and dyno guy shows up, also nice but doesn't say much to me, just heads in. Asks me two questions total: How high do I want it revved (rev limiter's fine, says I) and how to turn DSC off.

So at this point I'm thinking, maybe I should tell them to press the Power button before they start the test? But I'm shy, I didn't really want to speak up, and I figure if they found the DSC button it's pretty hard to miss the "POWER" button right next to it. This was 100% my stupid mistake not to say anything at this point, I told myself I didn't need to but mostly I didn't want them to think I was telling them how to do their jobs.

He finishes all three pulls, they've unbolted the adapters and he hands me the printouts... And the numbers are way too low. I don't have them in front of me but they're not what I expected. So I say, uh, you did push the Power button, right?

"Power button?"



Great. I'm so angry at myself at this point, and I had to get to work, that I said fine, just go ahead and just finish putting it back together. I want to blame them but I can't, I should have said something when they didn't ask, and I'm sure if I'd said it was a fuckup and I wanted them to redo it they would have. But argh, what a way to ruin my own morning.

So hey, if anyone wants to know torque/hp ratings of a neutered M3 with an AA underdrive pulled and Remus sport exhausts, I'm the dude to ask.
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      03-17-2009, 04:17 PM   #2
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I will have the AA exhaust and the pulley. Where did you get them installed at? DO you like both of them?
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      03-17-2009, 04:25 PM   #3
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The power button has nothing to do with power delivered only the response of the throttle pedal.
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      03-17-2009, 04:27 PM   #4
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The numbers you get from a dyno at the wheels won't be anywhere near what the published numbers at the crank are. They will be much lower. I don't know if you know this or not. Forgive me if this is already obvious to you.

I really don't think the POWER button should have anything to do with power and torque measurements. All it does is raise the response from the throttle pedal. Please post your numbers.
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      03-17-2009, 04:30 PM   #5
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The power button governs throttle response, why are you angry?
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      03-17-2009, 04:34 PM   #6
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So my initial hope was that the power button only changes throttle response, but Googling around suggests you have a lower rev limit (which shouldn't make much difference) and -20bhp without it. I do not pretend to be an expert though, and nothing I found was definitive one way or the other.

Example: http://www.honestjohn.co.uk/road_tests/index.htm?id=290

"But you don’t actually get those last 800rpm and 20bhp unless you press the ‘Power’ button, or pre-programme that into your ‘Mdrive’ preferences."

I'm happy to be wrong; I know it doesn't just modify the sensitivity - you can have the throttle rock-steady in a certain position, hit 'power' and it lurches forward. Now I understand that may be (and it sounds like is? Please be true) that it's just because it shifts the throttle mapping.

To answer the other question, I installed the pulley and exhaust myself. I'm happy with 'em.
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      03-17-2009, 04:41 PM   #7
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Quote:
Originally Posted by wolftrouble View Post

Example: http://www.honestjohn.co.uk/road_tests/index.htm?id=290

"But you don’t actually get those last 800rpm and 20bhp unless you press the ‘Power’ button, or pre-programme that into your ‘Mdrive’ preferences."
That's the very first time that I read something like that... if that is true, and normal is 400bhp and Power is 420 bhp, then what is Power Plus in the M Drive???
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      03-17-2009, 04:45 PM   #8
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Honestly I believe you guys more than I trust random web pages, even if they are by some guy named "Honest John". But I just don't want anyone to think I just assumed sans-Power would be anything but changes to the throttle behavior, I really did try to check first!

I'll post the results once I scan in the graphs tonight.
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      03-17-2009, 04:50 PM   #9
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Anyone successfully run a DCT m3 on a Dyno?
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      03-17-2009, 04:50 PM   #10
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Quote:
Originally Posted by wolftrouble View Post
Honestly I believe you guys more than I trust random web pages, even if they are by some guy named "Honest John". But I just don't want anyone to think I just assumed sans-Power would be anything but changes to the throttle behavior, I really did try to check first!

I'll post the results once I scan in the graphs tonight.
My wifes cousin's half-brother also told me about this and he heard this also from somebody who knows somebody at a BMW dealership in Munich
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      03-17-2009, 04:55 PM   #11
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      03-17-2009, 04:57 PM   #12
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There is so much misinformation I get to the point I tell myself to move on, quit reading this crap, go find something useful to do, but here I am, again...
The power button should not be labeled "power", it should be labeled "throttle sensitivity". That's all it does; changes the relationship between what the engine sees for a given pedal position in the lower and middle throttle positions. Wide open throttle is still wide open throttle. It does absolutely nothing to the power output of the engine. It does absolutely nothing to the redline, electronic tuning, horsepower or torque or anything else that has anything to do with the performance of the engine. The power button will have absolutely no affect in any way on the readings from a dyno.
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      03-17-2009, 04:58 PM   #13
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"Power" does not change horsepower output. Not Sport, nor Sport Plus. I've heard people ask engineers and testpilots from BMW multiple times, same answer every time. The only thing would be that you would spend a longer time "getting to the bottom of the pedal" to put in layman's terms.
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      03-17-2009, 05:00 PM   #14
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Quote:
Originally Posted by wolftrouble View Post
Example: http://www.honestjohn.co.uk/road_tests/index.htm?id=290

"But you don’t actually get those last 800rpm and 20bhp unless you press the ‘Power’ button, or pre-programme that into your ‘Mdrive’ preferences."

I'm happy to be wrong; I know it doesn't just modify the sensitivity - you can have the throttle rock-steady in a certain position, hit 'power' and it lurches forward. Now I understand that may be (and it sounds like is? Please be true) that it's just because it shifts the throttle mapping.

To answer the other question, I installed the pulley and exhaust myself. I'm happy with 'em.
I believe Honest John is getting his power buttons mixed up with the M5/M6. I've never heard of this for the M3 and I've read a lot of stuff on it. I'm sure all of BMW's literature about the car (that's all over the Internet) would have mentioned it.

The E46 M3 was just like this; keep foot at same throttle position, hit sport, lurch forward. Imagine a graph of throttle position vs. actual throttle opening. With the sport off the graph has a certain slope. With power on this slope is greater. For a given throttle position, the throttle opens more with sport on vs. sport off. But the top of the curve -- the wide open throttle part -- is the same. WOT is WOT; sport or no sport. Greater throttle response just makes you feel that the engine is stronger.
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      03-17-2009, 05:01 PM   #15
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Quote:
Originally Posted by MysticBlue View Post
The power button should not be labeled "power", it should be labeled "throttle sensitivity".
No, then the button would be too big.
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      03-17-2009, 05:09 PM   #16
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Quote:
Originally Posted by ersin View Post
No, then the button would be too big.
That is some funny shit right there. Maybe label it "DOES NOT ADD HORSEPOWER BUT YOU SHOULD PUSH ME ANYWAY COME ON JUST PUSH ME".
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      03-17-2009, 05:59 PM   #17
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Ok! Armed with helpful information given here and suggested by others I went over the graphs and I think I see some of the confusion. See graph, and sorry for the shitty iPhone picture.

Dyno claims max torque 250.7lbft @ 3866 RPM and max hp of 319.9hp @ 8000rpm. However, he asked me beforehand final drive ratio and I didn't know; looks like he just picked randomly 4.5. Actual final drive is 3.846. It also shows a max speed of 122mph, which means no way did he do it in 5th gear which is the 1:1 gear (max speed in 5th ain't 122). Finally, max RPMs he listed @ 8k, not 8350, so I'm guessing he lifted before he hit the rev limiter? Or is that just estimated anyway? I don't understand why the max torque RPM is such a precise number but the HP number seems like he just typed it in, unless it really does generate max hp at exactly 8k.

Once again, sorry for my ignorance, I hope I'm not just spreading MORE bad information with my commentary here.

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      03-17-2009, 06:11 PM   #18
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Quote:
Originally Posted by wolftrouble View Post
"But you don’t actually get those last 800rpm and 20bhp unless you press the ‘Power’ button, or pre-programme that into your ‘Mdrive’ preferences."
Maybe the US Dollar / British Pound exchange rate was higher then?
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      03-17-2009, 06:40 PM   #19
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Quote:
Originally Posted by PencilGeek View Post
First of all, I'm 90% sure I know where you went, and I can tell you what went wrong. I've written about this on many occasions already. But hopefully a new crop of people will learn from these experiences.

First mistake: you let the dyno "guess" your gear ratio. In the absense of actual gear ratio data, the Dynapack can "guess" your gear ratio by holding the motor at a specified RPM and using the hub speed to calculate the gear ratio. This appears to be a 6MT, and 4th gear was used (not 5th). You would have hit the speed limiter in 5th gear. The dyno guessed 4.5:1, when the actual ratio is 4.586:1. This place only has one dyno operator, and he was lazy. If he wanted to, he could have looked up my dyno chart, and used the proper gear ratio. I dyno'd in 3rd, 4th, and 5th gear at this shop.

Second mistake: This particular shop does not have enough air flow for your M3 motor. The M3 motor reads air temperature and air flow and knows when it's sitting still. When there isn't enough air flow, the ECU will richen the fuel mixture, and you'll get a much lower horsepower output. The same thing happened to me at this shop. After I switched shops, also using a Dynapack, I picked up quite a bit of power -- all because of air flow.

Third mistake: You used 4th gear; you should have used 3rd gear. Using a 1:1 gear is a total myth. Every gear ratio (even 1:1) has a primary and secondary sprocket, an output shaft which drives a primary and secondary on the final drive. You're ALWAYS going through four gears sprockets before you measure the output -- even when the gear ratio is 1:1. Different gears have greater and lower mechanical efficiency -- and they go in an inverse ascending order. 6th gear is the least efficient, followed by 5th, 4th, etc. You should dyno in the gear that has the greatest mechanical efficiency -- and won't overload the torque rating of the dyno. On the M3 and Dynapack, that's 3rd gear. (6.084:1)

Using your power or "M" button will have no effect. I dynoed this exact test three separate times, and proved it has no effect. As you figured, turn off DSC. Also turn off all electronics (fans, lights, AC, etc.).

HP = (TQ * RPM) / 5252. It's not just typed in...it's a formula.

Lastly, call Aggressive Performance in San Jose; ask for Su. He'll do it right. He's dyno'd mine 6 or 8 times already. http://www.agpmotorsport.com/home.html

damn.
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      03-17-2009, 06:58 PM   #20
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Quote:
Originally Posted by PencilGeek View Post
First of all, I'm 90% sure I know where you went, and I can tell you what went wrong. I've written about this on many occasions already. But hopefully a new crop of people will learn from these experiences.

First mistake: you let the dyno "guess" your gear ratio. In the absense of actual gear ratio data, the Dynapack can "guess" your gear ratio by holding the motor at a specified RPM and using the hub speed to calculate the gear ratio. This appears to be a 6MT, and 4th gear was used (not 5th). You would have hit the speed limiter in 5th gear. The dyno guessed 4.5:1, when the actual ratio is 4.586:1. This place only has one dyno operator, and he was lazy. If he wanted to, he could have looked up my dyno chart, and used the proper gear ratio. I dyno'd in 3rd, 4th, and 5th gear at this shop.

Second mistake: This particular shop does not have enough air flow for your M3 motor. The M3 motor reads air temperature and air flow and knows when it's sitting still. When there isn't enough air flow, the ECU will richen the fuel mixture, and you'll get a much lower horsepower output. The same thing happened to me at this shop. After I switched shops, also using a Dynapack, I picked up quite a bit of power -- all because of air flow.

Third mistake: You used 4th gear; you should have used 3rd gear. Using a 1:1 gear is a total myth. Every gear ratio (even 1:1) has a primary and secondary sprocket, an output shaft which drives a primary and secondary on the final drive. You're ALWAYS going through four gears sprockets before you measure the output -- even when the gear ratio is 1:1. Different gears have greater and lower mechanical efficiency -- and they go in an inverse ascending order. 6th gear is the least efficient, followed by 5th, 4th, etc. You should dyno in the gear that has the greatest mechanical efficiency -- and won't overload the torque rating of the dyno. On the M3 and Dynapack, that's 3rd gear. (6.084:1)

Using your power or "M" button will have no effect. I dynoed this exact test three separate times, and proved it has no effect. As you figured, turn off DSC. Also turn off all electronics (fans, lights, AC, etc.).

HP = (TQ * RPM) / 5252. It's not just typed in...it's a formula.

Lastly, call Aggressive Performance in San Jose; ask for Su. He'll do it right. He's dyno'd mine 6 or 8 times already. http://www.agpmotorsport.com/home.html
Thank you, thank you, thank you. Just talked to Su, heading over there this weekend. He says hi.
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      03-17-2009, 07:03 PM   #21
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Quote:
Originally Posted by PencilGeek View Post
First of all, I'm 90% sure I know where you went, and I can tell you what went wrong. I've written about this on many occasions already. But hopefully a new crop of people will learn from these experiences.

First mistake: you let the dyno "guess" your gear ratio. In the absense of actual gear ratio data, the Dynapack can "guess" your gear ratio by holding the motor at a specified RPM and using the hub speed to calculate the gear ratio. This appears to be a 6MT, and 4th gear was used (not 5th). You would have hit the speed limiter in 5th gear. The dyno guessed 4.5:1, when the actual ratio is 4.586:1. This place only has one dyno operator, and he was lazy. If he wanted to, he could have looked up my dyno chart, and used the proper gear ratio. I dyno'd in 3rd, 4th, and 5th gear at this shop.

Second mistake: This particular shop does not have enough air flow for your M3 motor. The M3 motor reads air temperature and air flow and knows when it's sitting still. When there isn't enough air flow, the ECU will richen the fuel mixture, and you'll get a much lower horsepower output. The same thing happened to me at this shop. After I switched shops, also using a Dynapack, I picked up quite a bit of power -- all because of air flow.

Third mistake: You used 4th gear; you should have used 3rd gear. Using a 1:1 gear is a total myth. Every gear ratio (even 1:1) has a primary and secondary sprocket, an output shaft which drives a primary and secondary on the final drive. You're ALWAYS going through four gears sprockets before you measure the output -- even when the gear ratio is 1:1. Different gears have greater and lower mechanical efficiency -- and they go in an inverse ascending order. 6th gear is the least efficient, followed by 5th, 4th, etc. You should dyno in the gear that has the greatest mechanical efficiency -- and won't overload the torque rating of the dyno. On the M3 and Dynapack, that's 3rd gear. (6.084:1)

Using your power or "M" button will have no effect. I dynoed this exact test three separate times, and proved it has no effect. As you figured, turn off DSC. Also turn off all electronics (fans, lights, AC, etc.).

HP = (TQ * RPM) / 5252. It's not just typed in...it's a formula.

Lastly, call Aggressive Performance in San Jose; ask for Su. He'll do it right. He's dyno'd mine 6 or 8 times already. http://www.agpmotorsport.com/home.html
Snap!
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      03-17-2009, 07:16 PM   #22
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damn.
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Originally Posted by MDCTFTW View Post
Snap!
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