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Go Back   E46Fanatics > Tuning & Tech > Driveline, Engine & DME Tuning

Driveline, Engine & DME Tuning
Talk about driveline improvements, NA tuning and DME tuning your E46 BMW here. This includes diffs, intakes, exhausts, chips, software and OBD tuning.

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Old 02-23-2012, 06:24 AM   #141
moranor
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snikwad you are 100% correct i calculated the torque and im very open to the the fact i may have made a mistake somewhere... if anyone has another formula to work it out please do so we can see if it is accurate...
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Old 02-23-2012, 06:42 AM   #142
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k, im no expert, i only know what i read on the webz and sh1t, BUT in the OP's dyno, i dont see RPM. i see speed.
http://forum.e46fanatics.com/attachm...3&d=1309249386
OP never told us what gear they used, so we cant know for sure what the RPM was he gained this magnificent power at. right?
So without RPM, how can we determine what torque he layed down?

I see N on the right side Y axis, but im used to seeing ft-lbs there, so i
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Old 02-23-2012, 06:57 AM   #143
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i got the rpm from the op by asking what the redline is on his car so making the highest point 7000rpm you can divide the graph up by that... i also confirmed with the op where the dip in torque was which confirmed that i had the RPM right... further more there is quite a large flat spot at 4000 rpm where peak torque is i am 100% sure the rpm is right what i am unsure of is if this formula works 100% i tried another similar one and it gave similar results...

alot of people also simply drop the last 0 to get the Nm number which is not 100% accurate but is supposedly a quick way to get an approximate number...

anyway i have emailed the tuner about this and im hoping to get some clarification from him
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Old 02-23-2012, 07:04 AM   #144
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how can you be sure where the peak torque is with cams. from what little i know cams alters where things peak, and it would seem these big cams would def do that.
I thought we agreed that the dip is where the disa switched over. Thats not necessarily where the torque peaks, id assume it not near there at at all. Around 3500-4000 is where the stock motor torque peaks out, i'd bet these cams combined with a full exhaust would shift all that higher. His diff may bring it back down, but not that much i think.

Im just thinking out loud here, not trying to talk smack to anyone, btw.
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Old 02-23-2012, 07:11 AM   #145
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well the op said his max rpm was at the stock 6800rpm and the dip was at 3000rpm using that and the fact that most dynos start at about 2000rpm i got that one block on the graph =100rpm

I will do a gear ratio calculation now also because i know the 323i has a 3.07 diff and see if the numbers line up again
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Old 02-23-2012, 07:14 AM   #146
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didnt he say he had the upgraded diff in for that dyno run too?
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Old 02-23-2012, 07:31 AM   #147
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nope he still has the stock diff he want to get a shorter ratio
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Old 02-23-2012, 07:43 AM   #148
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oh, ok. hopefully the shop replies. would love to hear the real TQ figures.
I do expect it to be the same or more than a US spec E36 M tho.
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Old 02-23-2012, 07:49 AM   #149
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ok with that ratio its a 4th gear pull because thats where 4th tops out with a 3.07 diff...

so at 140kph the rpm should be about 4500


now redoing the calculation at 4500rpm
Torque [Nm] = 9549 x Power [kW] / Revs [rpm]

Torque [Nm] = (9549 x 127 [kW]) / 4500 [rpm]
Torque [Nm] = 269Nm at the wheels

so then it has 198ftlb at the wheels

which is 310Nm at the crank with 15% loss at the wheels

as stated Nm is normally directly related to displacement
so 2494 should = 249.4Nm +-10% (274.34)

M3 (EUR) 3246cc 365 Nm (12.5% above expected Nm)
M3 CSL 3246cc 370 Nm (14% above expected Nm)
M3 GTR (Race) 3997cc 479 Nm (20% above expected Nm)

so i think its safe to say the car probably has around 300Nm at the crank and my 1st calculation was very wrong?

hopefully the tuner will get back to me so we also have some input from him
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Old 02-23-2012, 07:51 AM   #150
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YAYY, see thats still impressive. more believable too. man that lil think must pull like a horse once it hits the power band.
WE NEED VIDEOS!!!
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Old 02-23-2012, 07:57 AM   #151
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the bad news is now the dip is at 4000rpm so is not much fun to drive in normal rpm range
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Old 02-23-2012, 08:00 AM   #152
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Considering that even with the dip its still more than stock, most likely, it wont be bad. Plus the diff and LTW flywheel should mask it some.
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Old 02-23-2012, 08:12 AM   #153
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i dont know if i can get 150kw-165kw and 275Nm-295Nm like my tuner suggests for $200 it does not seem worth it to pay $2000 for 180kw and 300Nm...

think ill just continue saving for the supercharger...
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Old 02-23-2012, 08:13 AM   #154
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the change in the torque curve will also change the feel of the car completely and im not sure i will like it...
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Old 02-23-2012, 08:53 AM   #155
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the change in the torque curve will also change the feel of the car completely and im not sure i will like it...
Yes feel of car is totally diffrent ur right about not having that much fun a normal rpm but when it gets to the right rpm it's alot of fun and u dnt usually race Somone at low rpm :-)
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Old 02-23-2012, 08:55 AM   #156
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YAYY, see thats still impressive. more believable too. man that lil think must pull like a horse once it hits the power band.
WE NEED VIDEOS!!!
Come to oz we will go for a test drive
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Old 02-23-2012, 09:03 AM   #157
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i wish i could drive your car to decide i like that when i put my foot flat now i get torque at any rpm... from a cost to gain ratio i dont think its going to be worth it for me because i can get a custom dyno tune cheap... if i was paying what you guys pay for custom tunes i would probably fit the cam to get the most out of the money spent on the tune...
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Old 02-23-2012, 10:10 AM   #158
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And I'm pretty sure it is at the wheels because that's where the dyno is taking measurement from
shifty1982,

For now, I'm a believer; I have faith.

But.......just to let you know, a modern dyno can give out almost any HP number the dyno operator asks for. In this case, don't assume that just because your Bimmer was sitting on a chassis dyno, it spit out a WHP number. A modern dyno can be told to calculate back to "Crank HP & Crank TQ".

The very best way to determine if your HP & TQ numbers are somewhat accurate, is to take it to another dyno shop that uses the same dyno.


Good luck.
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Old 02-23-2012, 12:03 PM   #159
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Come to oz we will go for a test drive
hahah, my buddy lives in Oatley, but alas, Aussie isnt on the radar at this time
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Old 03-06-2012, 04:14 AM   #160
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Blew diff today time to get the welder out and turn it into a locker fun time
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