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03-17-2009, 07:29 PM | #23 | |
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03-17-2009, 07:36 PM | #24 | |
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03-18-2009, 03:39 PM | #27 |
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Drives: 2008 E92 M3 Jerez Black
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I have had 4 sessions on a dynapack (hub based dyno) and there are way too many smarts in the car to just test out of the box as the car knows its not moving and will refuse to allow manual changing beyond 2nd gear to get to your desired gear.
This is what we did.. 1. Turn of DSC fully at the button as well as change your Msetting in the idrive to DSC off just in case 2. Trick the car to trip ABS, we did this by pulling a few runs in D5/6/7 and it just went off (alternatively pull one of the ABS sensors of the wheel) 3. At this point we were able to pull 3 runs and then the car convinces itself that you have been using launch control and will retard the engine. We saw 70hp losses on subsequent runs. 4. To avoid above just run the car on the dyno for 5 miles and it resets itself. Here was my last run following AA software and dinan throttle bodies, not as good as we expected but transpires BMW didnt calibrate the TB's correctly and we had AFR problems. Final thing is that the DCT seems to have a torque controller which we are seeing as a roller coaster curve, rather than the flatter curves that the 6mt guys seems to be getting. will be dynoing again in 2 weeks now that the software and TBs have been recalibrated, Attachment 249667
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2008 M3 DCT, Jerez Black
Eisenmann Race, custom pipes high flow 300 cell primary 2nd cat delete AA software, Pulley, air filter, Dinan TB's Brembo BBK, BBS CH wheels, Dinan camber plates KW V3 suspension, Dinan 3.62 Diff, Recaro Profi seats, custom harness bar |
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03-18-2009, 03:49 PM | #28 |
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please let us know the result. I have very close set up as you.
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03-18-2009, 03:51 PM | #29 | |||
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There's some good stuff in there pencilgeek, thanks. However I have to wonder about a couple items: Quote:
At the end of the day, if you want to compare runs, the important thing is you must stay on the same dyno and run in the same gear every run. Quote:
BTW sprockets are for chains (like on your bicycle) and I don't think the transmission is a box o' chains. It has gears. |
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03-18-2009, 04:14 PM | #30 |
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Thanks for the info, it looks a bit more complicated than I had hoped...I have the impression that my car is a bit more powerfull than the norm and wanted to test it to find out but maybe I'll just settle for living with the illusion!
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03-18-2009, 04:18 PM | #31 |
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It sounds complicated but its not....and getting a baseline is really good for future mod assessment. Also hearing your car redline in a closed environment is intoxicating
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2008 M3 DCT, Jerez Black
Eisenmann Race, custom pipes high flow 300 cell primary 2nd cat delete AA software, Pulley, air filter, Dinan TB's Brembo BBK, BBS CH wheels, Dinan camber plates KW V3 suspension, Dinan 3.62 Diff, Recaro Profi seats, custom harness bar |
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03-18-2009, 05:49 PM | #32 | |||
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Damn pencilgeek after I saw the sprocket thing I have to admit I assumed you were rather out to lunch and was therefore extremely skeptical of the rest of the post. Looking up your other posts I see you know your shit, which I appreciate... teaches me to jump to conclusions.
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...hmmmm.... I've never heard of that... are they british, or of some other unworldly origin? |
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03-18-2009, 08:16 PM | #33 |
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PG
I will document and film where appropriate the next Dyno tests with the DCT transmission. Once the ABS is triggered, you can change up and down through the gears. The last run I did we tried 6th gear (given there are 7 with the DCT box) and no issues other than a starting torque number of 273ft/lbs at 2900 RPM. Did you find your AFR numbers constant between 4k and 7k rpm
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2008 M3 DCT, Jerez Black
Eisenmann Race, custom pipes high flow 300 cell primary 2nd cat delete AA software, Pulley, air filter, Dinan TB's Brembo BBK, BBS CH wheels, Dinan camber plates KW V3 suspension, Dinan 3.62 Diff, Recaro Profi seats, custom harness bar |
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03-19-2009, 07:40 AM | #34 | |
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I was at a dyno session the other day where they ran an M5 with a modified exhaust and the sound was spine chilling. |
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03-19-2009, 03:44 PM | #35 |
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More gear efficiency stuff for PG or whoever is interested:
I looked around a bit for gear efficiency stuff and really only found one place that has a calculator for spur or helical gears, here: http://www.roymech.co.uk/Useful_Tabl...fficiency.html I used the spur gear equations in the "spur gears / helical gears" section. I'm sure helical would be different, but I'm really just looking for trends more than absolute numbers, so I think this is ok. PG posted some educated guesses of gear tooth counts for the 6MT, that's what I used for the calcs. (If anyone tears down their gearbox please count some teeth) I estimated the friction coefficient to be 0.05 for all gears. It's just a guess, but again we are just looking for trends so it doesn't matter too much. Below see the "Power loss" for each gear as calculated. The lower the power loss, the higher the efficiency. Gear/Power loss % 1 /0.92 2 /0.52 3 /0.42 4 /0.49 5 /0.64 6 /0.62 I would love to post more info but I couldn't figure out how to get an image of my Excel worksheet in this post so I stripped it down to just the Gear and "Power loss" columns. The data does not show a trend of efficiency vs. gear ratio. The data shows third gear is most efficient, and 1st gear is least efficient. *Insert big caveat* Please note this is frictional power loss in the teeth only. "Windage", or the losses of churning up all the gear oil, are not included. There's a whole bunch of other stuff that goes into gear efficiency like loading, gear speed, etc. which makes me think the only way to ever know the efficiency is through testing. Here's an interesting NASA paper http://gltrs.grc.nasa.gov/reports/20...003-212222.pdf |
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03-23-2009, 02:55 PM | #36 |
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I promised I'd update the thread when I got the new dyno pulls. Thanks to PencilGeek's excellent advice I went to Aggressive Performance in SJ and Su took care of it professionally and quickly. Really nice guy and really great work.
Dyno chart's below, with what I'd consider to be much more accurate numbers. Also, for funsies I brought along a digitial recorder and some hi-end condenser mics and got a great audio recording of the last pull; I'll probably post it somewhere if anyone wants to hear it. Not the kind of sound you usually get to hear with it standing still. Thanks again everyone, especially Pencilgeek for all the help. Su was kind enough to give me a copy of the Dynapack reader file so if anyone's curious about any of the stats besides hp/torque let me know and I can forward it along. |
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03-23-2009, 03:11 PM | #37 |
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post the clips!!
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03-23-2009, 03:31 PM | #38 | |
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Can't wait to hear your sound clips. I may take a condensor mic and DSD recorder to my next dyno session. Dave
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03-23-2009, 03:51 PM | #39 |
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Not stock. That's with the AA underdrive pulley, Remus Sport exhaust, and RPI scoops (which we'll just pretend are red decorations, for the purposes of a dyno pull. )
Assuming 15% drivetrain loss that gives it ~424bhp at the crank, yes? Listen to me pretending I know what I'm talking about. |
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03-23-2009, 03:55 PM | #40 | |
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03-23-2009, 04:09 PM | #41 |
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Oops, sorry, yes - that also includes an MS air filter. I forgot, the mod took me like 10m to install.
My audio recording, FWIW, was done with an Olympus LS-10 and a pair of Core Sound Binaural mics. Kind of screwed up the positioning a little, I put them about 15ft behind the rear of the car, offset to the side about 3 feet but not enough to avoid the wind from the exhaust making a slight whooshing sound (sounds a little like tape hiss) on the recording. |
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03-23-2009, 10:35 PM | #42 |
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Audio is here: http://web.me.com/wolftrouble/M3/M3.html
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03-24-2009, 08:46 AM | #43 | |
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It'll be interesting to contrast my Active Autowerke Signature. At WOT it also sounds very American-8ish from inside, so they may be similar. Under light throttle/high revs it sounds way different inside. Cruising up and down parking structures at 1500 to 3000 rpm in second it sounds like a huge, high reving, exotic motorcycle. I just need a couple of hundred more miles on my 4.10 FD before I go back to the dyno. Dave
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