E90Post
 


Bimmer Retrofit
 
BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Powertrain and Drivetrain Discussions > NA Engine (non-turbo) / Drivetrain / Exhaust Modifications > Correct Gear Ratio for Dyno



Reply
 
Thread Tools Search this Thread
      02-27-2006, 11:53 AM   #1
MORRWheels
MORRWheels's Avatar
United_States
109
Rep
1,770
Posts

 
Drives: BMWs
Join Date: Sep 2005
Location: USA

iTrader: (1)

Send a message via AIM to MORRWheels
Correct Gear Ratio for Dyno

Supposely the appropiate gear ratio to dyno is the closest to 1:1.

Manual gear ratios - I/II 4.32/2.46 :1
Manual gear ratios - III/IV 1.66/1.23 :1
Manual gear ratios - V/VI/R 1.00/0.85/3.94 :1
Manual gear ratios - Final drive ratio 3.23 :1

In the E90, that would make fifth gear the appropiate gear ratio. And so many people getting crazy numbers dynoing in 3rd and 4th... shame...shame..
Appreciate 0
      03-05-2006, 01:03 AM   #2
kt157
Captain
kt157's Avatar
United_States
11
Rep
926
Posts

 
Drives: jet black 330i
Join Date: Sep 2005
Location: BayArea, CA

iTrader: (1)

Send a message via AIM to kt157
damn, then the wheels will be spinning about 130+mph
that would suck for the people without zsp
Appreciate 0
      03-05-2006, 01:08 AM   #3
sdorn
Lieutenant
sdorn's Avatar
6
Rep
491
Posts

 
Drives: 2006 Jet Black 325i
Join Date: Feb 2006
Location: Atlanta

iTrader: (0)

1. What is zsp?

2. You are supposed to dyno in the gear closest to 1:1, but it won't give way out of line numbers if you dyno in another gear. The final drive ratio also goes into the equation, and not all cars have the same final drive ratio. The dyno measures torque, and torque isn't affected by the transmission or the final drive ratio.
__________________
2008 Sparkling Graphite 535i
2009 Land Rover LR2
2003 Porsche 911 Turbo (SOLD)
2006 Jet Black 325i (SOLD)
2001 Bullitt Mustang (450rwhp - SOLD)
Appreciate 0
      03-08-2006, 11:32 AM   #4
MORRWheels
MORRWheels's Avatar
United_States
109
Rep
1,770
Posts

 
Drives: BMWs
Join Date: Sep 2005
Location: USA

iTrader: (1)

Send a message via AIM to MORRWheels
Quote:
Originally Posted by sdorn
1. What is zsp?

2. You are supposed to dyno in the gear closest to 1:1, but it won't give way out of line numbers if you dyno in another gear. The final drive ratio also goes into the equation, and not all cars have the same final drive ratio. The dyno measures torque, and torque isn't affected by the transmission or the final drive ratio.
My friends, closest to 1:1 is the most appropiate for accurate numbers.
Appreciate 0
      03-08-2006, 12:03 PM   #5
ksfrogman
Major General
ksfrogman's Avatar
United_States
154
Rep
6,751
Posts

 
Drives: E90 330i 6MT
Join Date: Nov 2005
Location: Torrance, CA

iTrader: (12)

Garage List
2006 330i  [0.00]
2006 330i  [0.00]
Send a message via AIM to ksfrogman
Quote:
Originally Posted by sdorn
1. What is zsp?

2. You are supposed to dyno in the gear closest to 1:1, but it won't give way out of line numbers if you dyno in another gear. The final drive ratio also goes into the equation, and not all cars have the same final drive ratio. The dyno measures torque, and torque isn't affected by the transmission or the final drive ratio.
ZSP = Sport Package.

ABBREVIATIONS THREAD:

http://www.e90post.com/forums/showthread.php?t=11465
__________________
Appreciate 0
      03-08-2006, 12:19 PM   #6
HRC
MAUI BUILT
HRC's Avatar
United_States
140
Rep
7,779
Posts

 
Drives: 2006 330i MT
Join Date: Jun 2005
Location: NORCAL

iTrader: (10)

Garage List
2006 330i  [0.00]
Send a message via AIM to HRC
Quote:
Originally Posted by carlitosz
My friends, closest to 1:1 is the most appropiate for accurate numbers.

Painfully obvious!!!

Danny
__________________
Arctic/Blk Leather/Alum.Trim/MT/ZSP/Sunshades/Blk Lines/M3 Illuminated Knob/Alcantara Performance Wheel/M-E-Brake Handle/Euro Fog Switch/Koni Yellows/H&R Sport Springs/19" VMR V718's w/PS2 Tires/M-Tech Body Kit/Carbon Fiber Spoiler/Bimmian Interior Bulbs/OEM Eye Glass Tray/SSK/Alcantara Boot/Split Armrest/OEM Dual Rear Power Outlets/Rear Ashtray Delete/OEM Alum. Pedals/Osram 6000K/Brex Rings/LED Side Markers/BMS Power Box
Appreciate 0
      03-08-2006, 10:38 PM   #7
Itchy Foot
Registered
0
Rep
2
Posts

 
Drives: AWD
Join Date: Feb 2006
Location: Toronto

iTrader: (0)

Quote:
Originally Posted by sdorn
1. What is zsp?

2. You are supposed to dyno in the gear closest to 1:1, but it won't give way out of line numbers if you dyno in another gear. The final drive ratio also goes into the equation, and not all cars have the same final drive ratio. The dyno measures torque, and torque isn't affected by the transmission or the final drive ratio.
I agree. You are SUPPOSE to, BUT the peak powers won't vary too much.
Appreciate 0
      03-08-2006, 11:25 PM   #8
lux.sh
missing two turbos.
lux.sh's Avatar
United_States
140
Rep
4,860
Posts

 
Drives: fast around corners.
Join Date: Sep 2005
Location: Curves

iTrader: (12)

Garage List
Quote:
Originally Posted by carlitosz
My friends, closest to 1:1 is the most appropiate for accurate numbers.
CAPTAIN OBVIOUS!!!!! THANKS FOR LETTING US KNOW, SIR!

Quote:
Originally Posted by carlitosz
In the E90, that would make fifth gear the appropiate gear ratio. And so many people getting crazy numbers dynoing in 3rd and 4th... shame...shame..
what crazy numbers?
__________________
06 AW E90 330i ZPP/ZSP/Step/Expired Warranty

: Prior Design Front : ACS Rear : ACS Roof : BlackLines : Simota Intake : Carbon Fiber Interior Trim :
: MTEC V3 : 24% Charcoal : V1 Hardwired : Solaris Invisibulbs/LED interior :
Appreciate 0
      03-09-2006, 12:42 AM   #9
MORRWheels
MORRWheels's Avatar
United_States
109
Rep
1,770
Posts

 
Drives: BMWs
Join Date: Sep 2005
Location: USA

iTrader: (1)

Send a message via AIM to MORRWheels
Quote:
Originally Posted by lux.sh
CAPTAIN OBVIOUS!!!!! THANKS FOR LETTING US KNOW, SIR!



what crazy numbers?
200whp - 205whp.
Appreciate 0
      03-09-2006, 04:30 AM   #10
lux.sh
missing two turbos.
lux.sh's Avatar
United_States
140
Rep
4,860
Posts

 
Drives: fast around corners.
Join Date: Sep 2005
Location: Curves

iTrader: (12)

Garage List
Quote:
Originally Posted by carlitosz
200whp - 205whp.
ohhh. for the 325i?

why? whats wrong? you own a 325, you should be happy about it. no?

And I don't get it. Normally, 1:1 direct gear will show best reading because you aren't expericing any loss through the gear teeth. So it should read better numbers if the dyno was done in 5th gear.
__________________
06 AW E90 330i ZPP/ZSP/Step/Expired Warranty

: Prior Design Front : ACS Rear : ACS Roof : BlackLines : Simota Intake : Carbon Fiber Interior Trim :
: MTEC V3 : 24% Charcoal : V1 Hardwired : Solaris Invisibulbs/LED interior :
Appreciate 0
      03-09-2006, 09:22 AM   #11
sdorn
Lieutenant
sdorn's Avatar
6
Rep
491
Posts

 
Drives: 2006 Jet Black 325i
Join Date: Feb 2006
Location: Atlanta

iTrader: (0)

Quote:
Originally Posted by carlitosz
200whp - 205whp.
I don't think those are crazy numbers. These cars are supposed to be much more efficient than other cars, so I could see using a 10% or 12% estimate for drivetrain loss. Generally (at least from what I have read) you use between 15% - 20% for drivetrain loss depending on the car and the transmission. I would also assume that BMW slightly underrates the horsepower on their cars as many other manufacturers do.

If the 325i was actually putting out closer to 225 hp at the crank, then at a 12% loss you would be pretty close to 200rwhp. Using the same logic, I wouldn't be surprised to see 330i's putting down around 235 - 240rwhp.

It is also common for a car manufacturer to exaggerate the difference between two different models to make it seem like they are further apart than they are. For example, back in 2000 and 2001 when Chevrolet was selling the Camaro and Firebird, they would often dyno at over 300rwhp completely stock. They were only rated at between 300 and 320hp at the crank by Chevy. The reason was that Chevy didn't want it to be so obvious that the Corvette and Camaro had virtually the exact same horsepower.
__________________
2008 Sparkling Graphite 535i
2009 Land Rover LR2
2003 Porsche 911 Turbo (SOLD)
2006 Jet Black 325i (SOLD)
2001 Bullitt Mustang (450rwhp - SOLD)
Appreciate 0
Reply

Bookmarks

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -5. The time now is 08:54 AM.




e90post
Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
1Addicts.com, BIMMERPOST.com, E90Post.com, F30Post.com, M3Post.com, ZPost.com, 5Post.com, 6Post.com, 7Post.com, XBimmers.com logo and trademark are properties of BIMMERPOST