What Gear to Rolling Road a 135i DCT?

Vtec Abuser · 06-01-2011, 11:08 AM

As title says guys, what gear is best to RR a 135i with the 7 speed DCT. I have had mine on 3 different sets of rollers now and 2 of the operators say 5th gear and the other said 4th?!?!

bogart · 06-01-2011, 01:11 PM

5th gear, that is when you will be pushing the most boost too... So... 80% of 370 is about 295hp... do you have anything done to your car?

Aries932 · 06-01-2011, 01:15 PM

Yea it is 5th because the 7th gear is not an overdrive gear like normal 7 speed transmissions.

Vtec Abuser · 06-01-2011, 01:17 PM

It made 314 @ the crank IIRC, which seems to be about the norm from what I have read..

bogart · 06-01-2011, 02:07 PM

what flash/software do you have? sounds about right.

Vtec Abuser · 06-01-2011, 03:45 PM

Quote:

Originally Posted by bogart

what flash/software do you have? sounds about right.

Stock mate..

bogart · 06-01-2011, 03:50 PM

DMS site says 370 hp, 405 ft-lb... Did you have to send them your ECU?

Vtec Abuser · 06-01-2011, 04:04 PM

Quote:

Originally Posted by bogart

DMS site says 370 hp, 405 ft-lb... Did you have to send them your ECU?

They do them on the bench, but OBD is very close from what they tell me..

GeeRam · 06-01-2011, 05:05 PM

Quote:

Originally Posted by Vtec Abuser

As title says guys, what gear is best to RR a 135i with the 7 speed DCT. I have had mine on 3 different sets of rollers now and 2 of the operators say 5th gear and the other said 4th?!?!

I was told that the general rule of thumb is to run the car in the gear that accelerates from 60 - 120mph the fastest. When my car has been on the rollers, it won't do 120mph in 4th, so 5th was used on 2 occasions and 4th on the other (producing worse results by some 25bhp @ the crank)..
So guys, what are your opinions?

It used to be that the gear to use was the one that gave (or was closest to) a direct 1:1 ratio, therby not causing gear multiplication factors to give misleading figures.
On a DCt car that would actually be 7th as that's direct 1:1....... however, with the very rear axle ratio fitted to compensate for the direct 1:1 7th gear, I wonder if the revs would drop sufficently on a RR to use 7th.
5th is too low a gear IMHO.....

Vtec Abuser · 06-02-2011, 03:07 AM

7th?!?!?

bogart · 06-02-2011, 07:46 AM

definitely not 7th, lol...

GeeRam · 06-02-2011, 04:06 PM

Quote:

Originally Posted by bogart

definitely not 7th, lol...

Any lower gear will be giving false readings though, as you are running through a gear rather than direct, so whatever figures anyone claims using 5th or 6th will be 'fake' as the gearing will cause a multiplication factor of and give an increased 'calculated' flywheel figure.
Unless the RR can be programmed to allow for the gear ratios..?

The only problem with direct 1:1 in 7th will because of the really high CWP ratio in the DCT cars......?

You should be able to see the differences in rwp in the different gears though (ignoring 'calculated' flywheel figures)

Aries932 · 06-02-2011, 04:26 PM

I was actually just going by what Shiv directed was the best gear to dyno a DCT with...which was 5th. I would imagine he would have a pretty good idea about the best gear to test the car with considering the amount of dyno's he has run with his DCT.

http://www.e90post.com/forums/showth...ht=vishnu+dyno

Why Dyno in 5th gear over 4th?

Quote:

Originally Posted by shiv@vishnu

Because 5th gear on the 7dct is geared like 4th gear on the 6at/6mt. Goes up to ~140mph. 4th gear would be a bit too short of a run.

06-01-2011, 11:08 AM	#1
Vtec Abuser First Lieutenant 35 Rep 367 Posts Drives: 2012 135i DCT Join Date: Jan 2009 Location: Every-bloody-where.. iTrader: (0)	What Gear to Rolling Road a 135i DCT? As title says guys, what gear is best to RR a 135i with the 7 speed DCT. I have had mine on 3 different sets of rollers now and 2 of the operators say 5th gear and the other said 4th?!?! Last edited by Vtec Abuser; 06-19-2011 at 05:40 AM..
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06-01-2011, 01:11 PM	#2
bogart Lieutenant Colonel 117 Rep 1,664 Posts Drives: E82 N55 DCT Join Date: Nov 2010 Location: STL, MO iTrader: (4) Garage List 2011 BMW 135i [7.06]	5th gear, that is when you will be pushing the most boost too... So... 80% of 370 is about 295hp... do you have anything done to your car? __________________
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06-01-2011, 01:15 PM	#3
Aries932 Captain 38 Rep 611 Posts Drives: AW 2011 135i DCT Join Date: Feb 2007 Location: Woodland Hills, CA iTrader: (3)	Yea it is 5th because the 7th gear is not an overdrive gear like normal 7 speed transmissions. __________________ 2011 AW 135i - DCT - M Package - BMW Performance Suspension Kit - Berk Street Midpipes - Evolution Racewerks FMIC - JB4 - BMS Intake - BMS Downpipes
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06-01-2011, 01:17 PM	#4
Vtec Abuser First Lieutenant 35 Rep 367 Posts Drives: 2012 135i DCT Join Date: Jan 2009 Location: Every-bloody-where.. iTrader: (0)	It made 314 @ the crank IIRC, which seems to be about the norm from what I have read.. Last edited by Vtec Abuser; 06-19-2011 at 05:41 AM..
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06-01-2011, 02:07 PM	#5
bogart Lieutenant Colonel 117 Rep 1,664 Posts Drives: E82 N55 DCT Join Date: Nov 2010 Location: STL, MO iTrader: (4) Garage List 2011 BMW 135i [7.06]	what flash/software do you have? sounds about right. __________________
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06-01-2011, 03:50 PM	#7
bogart Lieutenant Colonel 117 Rep 1,664 Posts Drives: E82 N55 DCT Join Date: Nov 2010 Location: STL, MO iTrader: (4) Garage List 2011 BMW 135i [7.06]	DMS site says 370 hp, 405 ft-lb... Did you have to send them your ECU? __________________
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06-02-2011, 03:07 AM	#10
Vtec Abuser First Lieutenant 35 Rep 367 Posts Drives: 2012 135i DCT Join Date: Jan 2009 Location: Every-bloody-where.. iTrader: (0)	7th?!?!?
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06-02-2011, 07:46 AM	#11
bogart Lieutenant Colonel 117 Rep 1,664 Posts Drives: E82 N55 DCT Join Date: Nov 2010 Location: STL, MO iTrader: (4) Garage List 2011 BMW 135i [7.06]	definitely not 7th, lol... __________________
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