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Old 08-16-2012, 11:51 AM   #189
prochucker
Scooby Specialist
 
Member#: 21038
Join Date: Jul 2002
Chapter/Region: South East
Location: Jacksonville, FL JMS #12
Vehicle:
05 STi CGM
08 WRX 5D SSM

Subaru Stars

Quote:
Originally Posted by DreamEvil View Post
This is a some what off topic question but I am about to be swapping a sti transmission into my car and I was wondering if these statements are true...

1. Gas mileage will go down? From what I have read the 06 sti trans has a shorter 6th then the wrx does 5th, If this is so how significant of a MPG decrease will I be seeing?

The gearing in the WRX 5TH & the STI 6TH is very close. About 75 MPH @ 3K RPM. I've driven regularly an '02 & '03 WRX, '05 STi, & an '08 WRX. If there's a difference it's not very noticeable

2. Second question is, and I know and agree that any loss is worth the room to grow by doing this swap, How negatively will this swap effect my cars performance? I have heard the sti trans eats up more power so I would actually be losing whp by doing this swap. Additionally in the wrx 5spd I know you can hit 60+mph in second gear where as in the sti's I have heard you need to shift to third I imagine this would effect my 0-60 times as well as 1/4 times? If so how much power would I be losing on estimation and how badly would this effect my 0-60 and 1/4 times? if at all?

Yes, you will have to shift before 60MPH, but that said, most people still get better 0-60 times in an STi. Lower gear ratio = faster acceleration. I am unsure about the power loss in the 2 drive trains, but again, I wouldn't imagine it would be a great amount. With the better gear ratios, most people will have a better 1/4 mile time, you are still going to wind up at the end in 4th gear.

I am full aware any light you guys can shed on this would be pure speculation but I would like to see what kind of draw backs I would be facing after doing this swap.

I am not huge on the track but I ran the car once and it ran a 12.6 with the wrx 5 speed to give you a idea of where I am at now. The car also put down 330whp/310wtq, and I currently average a bout 20mpg city, 27mpg high way.

I don't want my questions to make me come off as being immature and only looking at short term things, but this swap is going to be a hard hit on my wallet and I know there wont be any power adder mods going on for a while after doing this. So I would like to see where my car may be at for a few months.

Thanks for any help you guys can provide on these questions!
Below is are the stock gear ratios, I scavenged from somewhere else on NASIOC. Somewhere there is a chart that actually gave you the speeds each 1K RPM in each gear, but I couldn't find it. If people are loosing gas mileage with the swap, I would say it is more likely that their driving & acceleration methods changed when they swapped. The very similar top gear ratios, make it unlikely that there is where they are loosing the MPG.

Factory Gear Ratios for Reference
All-Wheel-Drive 5-speed Transmissions
USDM
3.454 / 1.947 / 1.366 / 0.972 / 0.738 / 3.900FD - '02-'05 USDM WRX
3.454 / 1.947 / 1.366 / 0.972 / 0.738 / 3.700FD - '06-'07 USDM WRX
3.166 / 1.882 / 1.296 / 0.972 / 0.738 / 3.900FD - '08-current USDM WRX
3.454 / 1.947 / 1.366 / 0.972 / 0.738 / 4.444FD - '04-'08 Forester 2.5XT
3.454 / 2.062 / 1.448 / 1.088 / 0.780 / 4.111FD - '04-current Forester non-turbo
3.166 / 1.882 / 1.296 / 0.972 / 0.738 / 4.111FD - '05-'06 USDM Legacy 2.5GT
3.166 / 1.882 / 1.296 / 0.972 / 0.738 / 3.900FD - '07-'09 USDM Legacy 2.5GT
3.166 / 1.882 / 1.296 / 0.972 / 0.738 / 4.444FD - '05-'09 USDM Outback 2.5XT
3.545 / 2.111 / 1.448 / 1.088 / 0.780 / 4.111FD - '98-'01 USDM Impreza 2.5RS
3.545 / 2.111 / 1.448 / 1.088 / 0.780 / 3.900FD - '96-'01 USDM Impreza L/OBS
3.545 / 2.111 / 1.448 / 1.088 / 0.780 / 4.111FD - '96-'99 USDM Legacy 2.5GT
3.545 / 2.111 / 1.448 / 1.088 / 0.871 / 4.111FD - '96-'99 USDM Legacy Outback
3.454 / 2.062 / 1.448 / 1.088 / 0.871 / 4.111FD - '00-'07 USDM Outback
3.454 / 2.062 / 1.448 / 1.088 / 0.825 / 4.111FD - '08-current USDM Outback
3.454 / 2.062 / 1.448 / 1.088 / 0.780 / 4.111FD - '02-'04 USDM Impreza 2.5RS/'05 Impreza 2.5RS Sport
3.545 / 1.947 / 1.366 / 0.972 / 0.780 / 4.111FD - '93-'94 USDM Impreza 1.8L
3.545 / 2.111 / 1.448 / 1.088 / 0.825 / 3.900FD - '95 USDM Impreza 1.8L

JDM
3.454 / 2.062 / 1.448 / 1.088 / 0.825 / 4.111FD - '93-'96 JDM Impreza WRX/STi
3.454 / 2.333 / 1.750 / 1.354 / 0.972 / 3.900FD - '93 JDM Impreza WRX RA
3.454 / 2.333 / 1.750 / 1.354 / 0.972 / 4.111FD - '94-'95 JDM Impreza WRX RA/STi RA
3.454 / 2.062 / 1.448 / 1.088 / 0.825 / 4.111FD - '93-'00 JDM Impreza WRX Wagon
3.083 / 2.062 / 1.545 / 1.151 / 0.825 / 4.444FD - '97-'00 JDM Impreza WRX RA/Type R/STi RA/22B STi
3.166 / 1.882 / 1.296 / 0.972 / 0.738 / 4.444FD - '97-'00 JDM Impreza WRX/STi


All-Wheel-Drive 6-speed Transmissions
3.636 / 2.375 / 1.761 / 1.346 / 1.062 / 0.842 / 3.900FD
- JDM Impreza WRX Spec C/STi/STi Spec C RA/V-Limted/S202/S203/S204/Spec C RA-R
- AUS Impreza WRX STi

3.636 / 2.235 / 1.521 / 1.137 / 0.971 / 0.756 / 3.900FD
- USDM 2007-current Impreza WRX STi

3.636 / 2.375 / 1.761 / 1.346 / 0.971 / 0.756 / 3.900FD
- USDM 2004-2006 Impreza WRX STi
- UK/Europe/NZ Impreza WRX STi
- JDM Legacy 3.0R Spec B

3.636 / 2.235 / 1.521 / 1.137 / 0.891 / 0.707 / 3.900FD
- USDM 2007-2009 Legacy 2.5GT Spec B
- JDM Forester STi



Calculators for Speed and RPM
http://www.car-videos.net/tools/speedrpm.asp
http://www.teammfactory.com/gearcalculator.php


[i]
http://spda-online.ca/modules/tinyco...ite/tc_28.html
http://www.ausubaru.com/wiki/index.p...e=TRANSMISSION
http://www.rexnet.com.au/forum/index...howtopic=29168
http://www.cars101.com/[/i
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