Replacing 99 SOHC RS engine with 03 RS--please help

shane falco · 05-02-2010, 03:52 AM

So it sounds like I should be posting here for my engine swap question. I recently bought a 99 RS and it turned out that the engine had a spun bearing. I bought an 03 RS engine and am hoping to get some definitive answers. Here's what I'd posted on the newbie forum a bit earlier. Thanks a lot.

Hello, I have begun the process of replacing my 99 SOHC RS engine [COLOR=#F82C70 ! important][COLOR=#F82C70 ! important][/color][/color]with an 03 RS engine[COLOR=#F82C70 ! important][COLOR=#F82C70 ! important][/color][/color]. I have read through countless threads about what is necessary to complete the installation and have found a lot of conflicting information. I would be extremely grateful if somebody could tell me what's necessary to make this as simple as possible (i.e., do I need to swap [COLOR=#F82C70 ! important][COLOR=#F82C70 ! important][COLOR=#F82C70 ! important][/color][/color][/color]intake manifolds? cam gears? deal with MAF/MAP issues?). Or should it be easier than this? If there's a previous thread you're aware of that deals with this issue, please point me to it.

Thanks so much for any info you can give me.

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scarless ronin · 05-02-2010, 10:28 AM

my bad!! *shuts mouth*

2.5guy · 05-02-2010, 02:04 PM

ok simplest way to swap a motor I recently put in an 06 in my 00 swap your cam and crank gears and your intake manifold. NOT your crank pulley they are the same! By crank gear I mean the gear that the timing belt goes on. Check to make sure your knock sensors are the same. That should be it.

Patrick Olsen · 05-02-2010, 07:48 PM

I would suggest posting this in the Normally Aspirated Powertrain forum, as this isn't really a "built motor" kind of question.

With that said, scarless ronin's comments are not correct. There's no reason at all to worry about wiring harnesses and ECUs. The '99 and '03 engines are mechanically identical, or close enough that there's nothing to worry about with the '99 ECU running an '03 engine. You will retain all of the sensors from the '99 (most important the MAF, which the '03 doesn't have) and the '99 ECU and everything will be just fine.

IMO the easiest way to do the swap is to pull the bad '99 engine, remove the intake manifold (which has all the wiring, injectors, sensors, etc attached to it), install all of that on the '03 long block and you're good to do. I don't think that you'll even need to worry about swapping the cam and crank sprockets, but others in the N/A Powertrain forum could confirm that. (2.5guy had a different situation, as the '06+ 2.5i motors are a different variant of the SOHC EJ25 with variable lift cams. Honestly, I'm surprised he was able to use the '00 cam sprockets on the '06 cams!)

Pat Olsen

2.5guy · 05-02-2010, 08:15 PM

Yup bolted right up! VVT didn't work till I hooked up a manual switch, The reason I told him to switch the gears is just encase they where different. You would have to take them off to check to make sure they have the notch's in the same position's and have the same amount

shane falco · 05-04-2010, 10:31 PM

Thanks a lot for the responses, everyone. Patrick, that's what we ended up doing (swapping intake manifolds only) and everything worked out perfectly.

Patrick Olsen · 05-04-2010, 10:54 PM

Good to hear!

05-02-2010, 03:52 AM	#1
shane falco Scooby Newbie Member#: 240005 Join Date: Mar 2010	Replacing 99 SOHC RS engine with 03 RS--please help So it sounds like I should be posting here for my engine swap question. I recently bought a 99 RS and it turned out that the engine had a spun bearing. I bought an 03 RS engine and am hoping to get some definitive answers. Here's what I'd posted on the newbie forum a bit earlier. Thanks a lot. Hello, I have begun the process of replacing my 99 SOHC RS engine [COLOR=#F82C70 ! important][COLOR=#F82C70 ! important][/color][/color]with an 03 RS engine[COLOR=#F82C70 ! important][COLOR=#F82C70 ! important][/color][/color]. I have read through countless threads about what is necessary to complete the installation and have found a lot of conflicting information. I would be extremely grateful if somebody could tell me what's necessary to make this as simple as possible (i.e., do I need to swap [COLOR=#F82C70 ! important][COLOR=#F82C70 ! important][COLOR=#F82C70 ! important][/color][/color][/color]intake manifolds? cam gears? deal with MAF/MAP issues?). Or should it be easier than this? If there's a previous thread you're aware of that deals with this issue, please point me to it. Thanks so much for any info you can give me. * Registered users of the site do not see these ads.

05-02-2010, 10:28 AM	#2
scarless ronin Scooby Newbie Member#: 212434 Join Date: May 2009 Chapter/Region: Tri-State Location: Wilkes Barre, PA Vehicle: 2000 Imreza RS Dark Red	my bad!! shuts mouth Last edited by scarless ronin; 05-03-2010 at 09:33 AM.

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05-02-2010, 02:04 PM	#3
2.5guy Scooby Newbie Member#: 226957 Join Date: Oct 2009 Chapter/Region: NESIC Location: Wallingford CT Vehicle: 00 2.5RS Coupe Aspen White	ok simplest way to swap a motor I recently put in an 06 in my 00 swap your cam and crank gears and your intake manifold. NOT your crank pulley they are the same! By crank gear I mean the gear that the timing belt goes on. Check to make sure your knock sensors are the same. That should be it.

05-02-2010, 07:48 PM	#4
Patrick Olsen NASIOC Supporter Member#: 120 Join Date: Jul 1999 Chapter/Region: AKIC Location: Where the Navy sends me... Vehicle: 1997 Legacy 2.5GT QuickSilver Metallic	I would suggest posting this in the Normally Aspirated Powertrain forum, as this isn't really a "built motor" kind of question. With that said, scarless ronin's comments are not correct. There's no reason at all to worry about wiring harnesses and ECUs. The '99 and '03 engines are mechanically identical, or close enough that there's nothing to worry about with the '99 ECU running an '03 engine. You will retain all of the sensors from the '99 (most important the MAF, which the '03 doesn't have) and the '99 ECU and everything will be just fine. IMO the easiest way to do the swap is to pull the bad '99 engine, remove the intake manifold (which has all the wiring, injectors, sensors, etc attached to it), install all of that on the '03 long block and you're good to do. I don't think that you'll even need to worry about swapping the cam and crank sprockets, but others in the N/A Powertrain forum could confirm that. (2.5guy had a different situation, as the '06+ 2.5i motors are a different variant of the SOHC EJ25 with variable lift cams. Honestly, I'm surprised he was able to use the '00 cam sprockets on the '06 cams!) Pat Olsen

05-02-2010, 08:15 PM	#5
2.5guy Scooby Newbie Member#: 226957 Join Date: Oct 2009 Chapter/Region: NESIC Location: Wallingford CT Vehicle: 00 2.5RS Coupe Aspen White	Yup bolted right up! VVT didn't work till I hooked up a manual switch, The reason I told him to switch the gears is just encase they where different. You would have to take them off to check to make sure they have the notch's in the same position's and have the same amount

05-04-2010, 10:31 PM	#6
shane falco Scooby Newbie Member#: 240005 Join Date: Mar 2010	Thanks a lot for the responses, everyone. Patrick, that's what we ended up doing (swapping intake manifolds only) and everything worked out perfectly.

05-04-2010, 10:54 PM	#7
Patrick Olsen NASIOC Supporter Member#: 120 Join Date: Jul 1999 Chapter/Region: AKIC Location: Where the Navy sends me... Vehicle: 1997 Legacy 2.5GT QuickSilver Metallic	Good to hear!