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Posted by: partwerks Aug 27 2022, 02:28 PM

Which year of Subaru STI is best to use, along with a transaxle?

Posted by: VaccaRabite Aug 29 2022, 07:54 AM

First off, there is no reason to use an STi motor. Most of the improvements to the STi were suspension and bodywork - and even minor mods on a standard WRX would net more power more easily then the STi. (been there, done that). If you are looking for power, both WRX and STi need significant work done.

The previous gen 2.0 twin scroll turbo motors are amazing. I had mine safely tuned with 315 all wheel HP and Torque (which is the limit for not doing internals)
And the older WRX and newer 2.5L STi motors have had decades of experience running every level of tune you can imagine.

For transmissions, you want to follow the lead of whatever kit you are using to convert from AWD to FWD - but usually its the 5MT. I have no idea if the new 6 speed boxes work.

Zach

Posted by: tazz9924 Aug 29 2022, 08:18 PM

Sti motor is stronger because it has forged pistons which take boost better. I think up to 400hp, to the wrx’s 320hp. 5mts are pretty similar outside of final drive ratio. 4.11 seemed a bit short on a turbocharged car.

Posted by: barnfind9141972 Aug 29 2022, 09:33 PM

if you want big boost or go big in power in general go STI motor, WRX motor will be obviously a lot of fun but more of a bolt on situation without pushing the rods too much

Posted by: mgp4591 Aug 30 2022, 01:15 AM

QUOTE(VaccaRabite @ Aug 29 2022, 07:54 AM)

Posted by: partwerks Aug 30 2022, 06:08 AM

QUOTE(mgp4591 @ Aug 29 2022, 11:15 PM)

QUOTE(VaccaRabite @ Aug 29 2022, 07:54 AM)

First off, there is no reason to use an STi motor. Most of the improvements to the STi were suspension and bodywork - and even minor mods on a standard WRX would net more power more easily then the STi. (been there, done that). If you are looking for power, both WRX and STi need significant work done.

The previous gen 2.0 twin scroll turbo motors are amazing. I had mine safely tuned with 315 all wheel HP and Torque (which is the limit for not doing internals)
And the older WRX and newer 2.5L STi motors have had decades of experience running every level of tune you can imagine.

For transmissions, you want to follow the lead of whatever kit you are using to convert from AWD to FWD - but usually its the 5MT. I have no idea if the new 6 speed boxes work.

Zach

Isn't the STI 6spd a little large for the conversion? That's what's been reported here before but I have no first hand idea. My 5spd fits fairly tight as is...

Posted by: Literati914 Aug 30 2022, 11:03 AM

Yea, I think you want the WRX 6 speed or Forrester 6 speed BUT NOT the STi, that's my understanding.


.

Posted by: partwerks Aug 31 2022, 06:35 PM

[quote name='Literati914' date='Aug 30 2022, 09:03 AM' post='3025900']
Yea, I think you want the WRX 6 speed or Forrester 6 speed BUT NOT the STi, that's my understanding.

I read that also, but isn't the road gear a 4.11 in the Forrester?
I wonder how hard, or could a different road gear be put in, like a 3.7 for example?
One favorable thing is already having the linkage on the trans.

Is the shifter backwards orientation, or do they use the MR2 shifter with this setup?

Posted by: zipedadoo Aug 31 2022, 09:02 PM

Yeah, use the MR2 shifter or something similar.