2.5RS to new 2004 STI

mofong · 08-20-2003, 07:48 PM

is there anyway to do an sti conversion from a 2003 RS to an STI since they both have 2.5l engines. the only big difference i know of is the sohc of the rs and dohc or the sti. are there anyother major differences? what would i do replace the cylinder heads get a some guy who is seriously redoing his sti and take his piping and turbo and stuff and put that all in my car? any ideas or suggestions?

thanks

* Registered users of the site do not see these ads.

AKGC8 · 08-20-2003, 11:03 PM

SOHC/DOHC? No, there's a lot more than that.

You're better off just selling your 2003 RS and getting an STI.

GreenMarine · 08-21-2003, 06:14 AM

I agree.... But good on ya though for wanting to be adventrous!!!

:COOL:

FuJi K · 08-21-2003, 06:51 PM

Since no one answered well enough...

...looks around...

Let me answer some questions.

The STi has completly different interenals in the engine. It runs stronger internals with a compression ratio of 8.2:1, which is why it can run well with the turbocharger. It also has Subaru's AVCS with is another type of variable valve timing which changes the degree of the camshaft via engine RPM. The other biggy is the transmission driveline. The STi, as you may know sports a 6-speed with DCCD.

Depends HOW MUCH of a STi do you want to impersenate. I'm guessing the power output. You can do that with your engine but you'll have to open it up and put stronger parts in so it can HANDLE the boost, that's if you're going to boost it.

I'm sure you can replace your pistons, and rods with the STi ones. Then you'll have warrenty on the parts too!

Then you can turbo it.

You just have to worry about the block. If you don't run high boost say 1.5bar or more then you'll be safe. STi's block is semi closed, yours is open.

AKGC8 · 08-21-2003, 10:15 PM

Subaru isn't going to warranty STI pistons and rods in a 2.5rs block. May be the same dimensions, but it wasn't OEM for that engine.

Like I said, he's better off just getting an STI. With the money you'd spend converting an 03 RS into an STI you could have just sold the RS and bought a new STI(assuming mofong would be paying someone to do the work). Even if you did the work yourself it'll still be expensive because the parts are in high demand now. Plus the resale on an 03 rs converted to an STI would be horrible compared to an actual STI.

So like I said, just get an STI.

08-20-2003, 07:48 PM	#1
mofong Scooby Newbie Member#: 37417 Join Date: May 2003 Chapter/Region: MAIC Location: Baltimore, MD Vehicle: 2003 Impreza RS 2.5 Blue Ridge Pearl	2.5RS to new 2004 STI is there anyway to do an sti conversion from a 2003 RS to an STI since they both have 2.5l engines. the only big difference i know of is the sohc of the rs and dohc or the sti. are there anyother major differences? what would i do replace the cylinder heads get a some guy who is seriously redoing his sti and take his piping and turbo and stuff and put that all in my car? any ideas or suggestions? thanks * Registered users of the site do not see these ads.

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Differences between the 2000 SOHC 2.5rs and the 2004 SOHC 2.5rs	rst4me	Normally Aspirated Powertrain	9	01-25-2007 08:19 AM
1999-2001 2.5RS to 04-06 STi swap	5lipstream	Subaru Conversions	13	09-15-2006 02:45 PM
2004 impreza 2.5rs to a 2000 leg outback	rickinne	Subaru Conversions	6	06-08-2006 09:43 PM
R.I.P 2001 2.5RS - Hello new 2004 WRX	eclip5e	New England Impreza Club Forum -- NESIC	13	10-12-2003 08:27 PM
00' 2.5rs to 97 jdm sti conversion	StrongBow	Subaru Conversions	2	06-30-2003 04:15 PM

08-20-2003, 11:03 PM	#2
AKGC8 Scooby Specialist Member#: 1305 Join Date: Apr 2000 Chapter/Region: AKIC Vehicle: 2000 Impreza	SOHC/DOHC? No, there's a lot more than that. You're better off just selling your 2003 RS and getting an STI.

08-21-2003, 06:14 AM	#3
GreenMarine Scooby Guru Member#: 36080 Join Date: Apr 2003 Chapter/Region: South East Location: Morrisville, NC Vehicle: 1998 Legacy GT Wagon 2006 Impreza STi	I agree.... But good on ya though for wanting to be adventrous!!! :COOL:

08-21-2003, 06:51 PM	#4
FuJi K Scooby Guru Member#: 3687 Join Date: Jan 2001 Chapter/Region: MWSOC Location: St. Paul, MN Vehicle: MY99 GF4 JDM 6spd NF Performance	Since no one answered well enough... ...looks around... Let me answer some questions. The STi has completly different interenals in the engine. It runs stronger internals with a compression ratio of 8.2:1, which is why it can run well with the turbocharger. It also has Subaru's AVCS with is another type of variable valve timing which changes the degree of the camshaft via engine RPM. The other biggy is the transmission driveline. The STi, as you may know sports a 6-speed with DCCD. Depends HOW MUCH of a STi do you want to impersenate. I'm guessing the power output. You can do that with your engine but you'll have to open it up and put stronger parts in so it can HANDLE the boost, that's if you're going to boost it. I'm sure you can replace your pistons, and rods with the STi ones. Then you'll have warrenty on the parts too! Then you can turbo it. You just have to worry about the block. If you don't run high boost say 1.5bar or more then you'll be safe. STi's block is semi closed, yours is open.

08-21-2003, 10:15 PM	#5
AKGC8 Scooby Specialist Member#: 1305 Join Date: Apr 2000 Chapter/Region: AKIC Vehicle: 2000 Impreza	Subaru isn't going to warranty STI pistons and rods in a 2.5rs block. May be the same dimensions, but it wasn't OEM for that engine. Like I said, he's better off just getting an STI. With the money you'd spend converting an 03 RS into an STI you could have just sold the RS and bought a new STI(assuming mofong would be paying someone to do the work). Even if you did the work yourself it'll still be expensive because the parts are in high demand now. Plus the resale on an 03 rs converted to an STI would be horrible compared to an actual STI. So like I said, just get an STI.