3rd or 4th Gear for Dyno

AMPowerJ · 09-13-2009, 09:32 PM

Hi Guys -

Going to be getting a baseline dyno done soon ... based on my search it looks like some have used 3rd gear and other 4th gear. Does it matter and if so can anyone tell me why? I would assume you enter the gear ratio so any gear would work but I might be wrong.

Thanks!

dcstep · 09-13-2009, 10:05 PM

It DOES matter. It's actually most efficient in fifth, but if the speed governor is still on your ECU you can't use that. I got my next-best results with 4th. We're only talkiing a hp or two, so it's not a really big deal, just use the same gear for all subsequent runs.

Dave

Eugene-TAIWAN · 09-13-2009, 10:38 PM

I have asked the same question and PG has told me the most productive gear is the 3rd. but I know GIAC always dynos on the 4th. I don't know why. But I was using a Dyno pack maybe it has something to do with it.

dcstep · 09-13-2009, 10:50 PM

Yeah, I remember that discussion PG, BUT my car gives the highest reading for hp and torque in 5th on a Dynojet.

Some think that the higher speed of the drum might have some impact on inertia's interaction with the reading mechanism of the drum. The Dynojet operator reports that hp and torque decreases on every car he's tested where the final drive is raised numerically. To me it says that there's likely some error in Dynojet's conversion calculations.

Dave

AMPowerJ · 09-14-2009, 08:04 AM

Thanks guys looks like I will be using 4th gear since I will probably be dynoing on a Dynojet but it is the model that has load cell capability. Not sure if that matters to this discussion but my understanding is it can be toggle between load cell and inertia modes. Should I ask for one in particular? Also does the operator have to enter the gear ratios?

dcstep · 09-14-2009, 10:00 AM

The dyno calculates the gear ratio by comparing engine speed to drum speed, so no worries there. I don't know the answer to the other part of your question. I didn't realize that Dynojets had some optional measuring methods.

Dave

marcielago · 09-14-2009, 08:06 PM

I have another question please if the OP does not mind...

Is there anything else we need to do other than disabling traction control when we dyno the car??

Where I want to go with this question is that I went to a shop which has a Mustang dyno. He always starts the run of the car he's dynoing from an rpm of 4000. When I asked him why, he said that when he has the car at a lower rpm and then goes WOT the gear automatically shifts one or two gears lower. Of course the cars on test I watched were automatics. However I noticed that almost all the runs I see in this forum starts from around 2500 rpm. Does this have to do with the setup of the car before dynoing?

dcstep · 09-14-2009, 08:18 PM

Good Lord, starting at 4000 rpm leaves off tons of data that is helpful at understanding how the car will perform.

You need to insist that he start between 1000 and 2000. Of course a 6MT will stay in whatever gear you chose. For the DCT set it in manual mode.

Dave

marcielago · 09-15-2009, 07:50 PM

Quote:

Originally Posted by dcstep

Good Lord, starting at 4000 rpm leaves off tons of data that is helpful at understanding how the car will perform.

I know, the problem is there is not many dyno shops where I live and the one I go to is almost 100 miles away.

Quote:

Originally Posted by dcstep

You need to insist that he start between 1000 and 2000. Of course a 6MT will stay in whatever gear you chose. For the DCT set it in manual mode.

Even when in manual mode, the gear shifts down when activating WOT.

09-13-2009, 09:32 PM	#1
AMPowerJ One mod leads to another ... 415 Rep 2,900 Posts Drives: 2014 F10 M5 Join Date: Apr 2008 Location: Blythewood, SC iTrader: (10)	3rd or 4th Gear for Dyno Hi Guys - Going to be getting a baseline dyno done soon ... based on my search it looks like some have used 3rd gear and other 4th gear. Does it matter and if so can anyone tell me why? I would assume you enter the gear ratio so any gear would work but I might be wrong. Thanks! __________________ Current: 2014 F10 M5 Previous: 2015 F80 M3, 2013 E92 M3, 2013 F10 M5, 2009 E90 M3, 1998 E36 M3
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09-13-2009, 10:05 PM	#2
dcstep Major General 1290 Rep 7,389 Posts Drives: '09 Cpe Silverstone FR 6MT Join Date: Nov 2008 Location: Colorado iTrader: (0) Garage List 2009 M3 [8.40]	It DOES matter. It's actually most efficient in fifth, but if the speed governor is still on your ECU you can't use that. I got my next-best results with 4th. We're only talkiing a hp or two, so it's not a really big deal, just use the same gear for all subsequent runs. Dave __________________ Flickr Photos Ucm, Inc.
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09-13-2009, 10:38 PM	#3
Eugene-TAIWAN Brigadier General 249 Rep 3,157 Posts Drives: E92 M3 Coupe Join Date: Jun 2009 Location: Taiwan iTrader: (4)	I have asked the same question and PG has told me the most productive gear is the 3rd. but I know GIAC always dynos on the 4th. I don't know why. But I was using a Dyno pack maybe it has something to do with it. __________________ Past: Gintani stage3 M3, Cayman GTS present: Porsche 993RWB, 964RS America,996 cupcar, 964 turbo 3.6,Macan Turbo,997GT2,930 turbo,i3, MINI JCW
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09-13-2009, 10:50 PM	#4
dcstep Major General 1290 Rep 7,389 Posts Drives: '09 Cpe Silverstone FR 6MT Join Date: Nov 2008 Location: Colorado iTrader: (0) Garage List 2009 M3 [8.40]	Yeah, I remember that discussion PG, BUT my car gives the highest reading for hp and torque in 5th on a Dynojet. Some think that the higher speed of the drum might have some impact on inertia's interaction with the reading mechanism of the drum. The Dynojet operator reports that hp and torque decreases on every car he's tested where the final drive is raised numerically. To me it says that there's likely some error in Dynojet's conversion calculations. Dave __________________ Flickr Photos Ucm, Inc.
	Appreciate 0 Quote

09-14-2009, 08:04 AM	#5
AMPowerJ One mod leads to another ... 415 Rep 2,900 Posts Drives: 2014 F10 M5 Join Date: Apr 2008 Location: Blythewood, SC iTrader: (10)	Thanks guys looks like I will be using 4th gear since I will probably be dynoing on a Dynojet but it is the model that has load cell capability. Not sure if that matters to this discussion but my understanding is it can be toggle between load cell and inertia modes. Should I ask for one in particular? Also does the operator have to enter the gear ratios? __________________ Current: 2014 F10 M5 Previous: 2015 F80 M3, 2013 E92 M3, 2013 F10 M5, 2009 E90 M3, 1998 E36 M3
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09-14-2009, 10:00 AM	#6
dcstep Major General 1290 Rep 7,389 Posts Drives: '09 Cpe Silverstone FR 6MT Join Date: Nov 2008 Location: Colorado iTrader: (0) Garage List 2009 M3 [8.40]	The dyno calculates the gear ratio by comparing engine speed to drum speed, so no worries there. I don't know the answer to the other part of your question. I didn't realize that Dynojets had some optional measuring methods. Dave __________________ Flickr Photos Ucm, Inc.
	Appreciate 0 Quote

09-14-2009, 08:06 PM	#7
marcielago Private First Class 12 Rep 177 Posts Drives: SG F10 550i MSport, CB E39 M5 Join Date: Sep 2008 Location: Abu Dhabi iTrader: (0)	I have another question please if the OP does not mind... Is there anything else we need to do other than disabling traction control when we dyno the car?? Where I want to go with this question is that I went to a shop which has a Mustang dyno. He always starts the run of the car he's dynoing from an rpm of 4000. When I asked him why, he said that when he has the car at a lower rpm and then goes WOT the gear automatically shifts one or two gears lower. Of course the cars on test I watched were automatics. However I noticed that almost all the runs I see in this forum starts from around 2500 rpm. Does this have to do with the setup of the car before dynoing?
	Appreciate 0 Quote

09-14-2009, 08:18 PM	#8
dcstep Major General 1290 Rep 7,389 Posts Drives: '09 Cpe Silverstone FR 6MT Join Date: Nov 2008 Location: Colorado iTrader: (0) Garage List 2009 M3 [8.40]	Good Lord, starting at 4000 rpm leaves off tons of data that is helpful at understanding how the car will perform. You need to insist that he start between 1000 and 2000. Of course a 6MT will stay in whatever gear you chose. For the DCT set it in manual mode. Dave __________________ Flickr Photos Ucm, Inc.
	Appreciate 0 Quote