98 rs engine to a 98 legacy?

[98skuby]

anyone know if a 98 rs stock engine will fit and work in a 98 legacy?

james

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[Matt Monson]

Legarus...

[MeanEditor]

yes it will fit.

[Wiscon_Mark]

It's the same engine as a 98GT.

For future reference, all EJ engines and EJ transmissions will bolt up to all Legacys, Imprezas, Foresters, etc. Actually the EZ engines fall into that too.

[KD7000]

Why go through the trouble of installing an equally old stock engine?

[spdracr00]

well, sorta, any newer 2.5SOHC 2000+ from an impreza will not "just drop in" to a legacy. there are some hardlines that are different. I know because i bought a 2000 2.5rs engine to put into my 99 legacy when i blew a HG and it was not the same.

[subiekid]

There are also differences in MAF vs MAP between the years.

[rougeben83]

Originally Posted by subiekid

There are also differences in MAF vs MAP between the years.

Yes, that also went along with the Phase 2 revision.

[Patrick Olsen]

To get a bit off topic...

Originally Posted by spdracr00

well, sorta, any newer 2.5SOHC 2000+ from an impreza will not "just drop in" to a legacy. there are some hardlines that are different. I know because i bought a 2000 2.5rs engine to put into my 99 legacy when i blew a HG and it was not the same.

What about sensors? Obviously the MAP/MAF thing is the big one that everyone points out, but what about other sensors? I've thought about converting to a SOHC ECU for the possibility of reflashing it, but if I have to rewire things completely that would suck. (And yes, I realize that the SOHC ECUs have different plugs than our DOHC ECUs, I'm looking past that for the moment.)

Pat

[spdracr00]

you just reuse your old manifold with your old sensors is the best way i found. but if you wanna use a stock SOHC motor then yeah, you have to rewire it and thats a pain in the butt. besides if you use the sohc 2.5 with a dohc 2.5 exhaust manifold you get higher compression and more power.. cept you will have to run prem fuel.

[MeanEditor]

we are running a 2.5RS heads on an STI block and our stock 97 LGT harness plugged in with no issues.
You just need to use your same intake manifold as there seem to be differences even between a model years and models.

[Matt Monson]

Originally Posted by spdracr00

you just reuse your old manifold with your old sensors is the best way i found. but if you wanna use a stock SOHC motor then yeah, you have to rewire it and thats a pain in the butt. besides if you use the sohc 2.5 with a dohc 2.5 exhaust manifold you get higher compression and more power.. cept you will have to run prem fuel.

Kindly explain to me how you managed to bolt up the in-line bolt pattern of the DOHC Ej25 manifold to the offset pattern of the SOHC Ej25 heads?

[Wiscon_Mark]

Maybe he swapped heads?

Of course that would mean a lot more work...

[Matt Monson]

Originally Posted by Wiscon_Mark

Maybe he swapped heads?

Of course that would mean a lot more work...

That's totally different than what he is giving advice about. Pat Olsen already has an phase II shortblock mated to his phase I heads in his GT. What he was asking about was installing the COMPLETE SOHC Ej25 engine. And spdracr seems confused about more than just that since the exhaust manifold has nothing to do with one's compression ratio. It's the use of the phase II block with less piston dish that makes the compression go up with mated to the phase I DOHC EJ25 heads...

[Wiscon_Mark]

Oh, I was reading that wrong. I was thinking intake manifold.

duh!

[iluvdrt]

Originally Posted by MeanEditor

we are running a 2.5RS heads on an STI block and our stock 97 LGT harness plugged in with no issues.
You just need to use your same intake manifold as there seem to be differences even between a model years and models.

What did you do for engine management, and injectors? Did you change the fuel pump? I am thinking about doing my swap again.

[Patrick Olsen]

Originally Posted by 98skuby

anyone know if a 98 rs stock engine will fit and work in a 98 legacy?

In doing essentially the same thing this weekend ('98 2.5RS into '97 2.5GT) I found that there are some slight differences in the intake manifolds and the vacuum lines. Here are two pics of the 2.5GT intake manifold, followed by 3 pics of the 2.5RS manifold.




Here you can see no vacuum lines coming off the passenger front to whatever that black canister is. (Fuel vapor recovery I think?)

Here's that little nub that's tapped, but as you can see there's a plug in it, so I don't know why it's that way.

And here you can see the TB only has two vacuum connections to it (although there are ports there for more, but then the bump on top of the plenum is tapped and has a hose nipple, so there are still 3 connections there total.


The intake manifolds are identical, just for whatever reason the 2.5RS one has a couple spots tapped that aren't tapped on the 2.5GT one. Weird. Because I would have to remove the intake to get to the vacuum/fuel vapor vent lines anyway, I'm just swapping the whole intake manifold from my original engine over to the "new" engine.

Pat

[Wiscon_Mark]

No H6 project, eh Pat?

Good Info though

[Dan Cech]

Pat,

The reason for the differences is that the 98+ impreza has the pcv canister at the rear of the car, whereas the 97 legacy has it in the engine bay.

When I put the 98 Impreza motor in my car, I did the same and reused the 97 intake manifold and all the associated vacuum lines, etc. It made for a much simpler swap.

[Patrick Olsen]

Originally Posted by Wiscon_Mark

No H6 project, eh Pat?

Eventually. The EZ30R and an STI 6-speed are both sitting in my garage. (My impenetrable, locked garage.) Probably next summer?

Originally Posted by Dan Cech

Pat,

The reason for the differences is that the 98+ impreza has the pcv canister at the rear of the car, whereas the 97 legacy has it in the engine bay.

When I put the 98 Impreza motor in my car, I did the same and reused the 97 intake manifold and all the associated vacuum lines, etc. It made for a much simpler swap.

Roger that, thanks, Dan.

Pat

[MeanEditor]

Originally Posted by iluvdrt

What did you do for engine management, and injectors? Did you change the fuel pump? I am thinking about doing my swap again.

The PLAN was for a stand-alone, but we were in a jam and a PP6 went in, now we are going to do the stand-alone, PP6 just can't deal with big injectors. We have a walbro 255, we used an old single turbo Supra adaptor kit. Injectors are Stock STI at the moment but we have a set of modded stock 97 LGT injectors that look to be about the same as modded STI side-feeds. But we will flow test and see.

[iluvdrt]

Originally Posted by MeanEditor

The PLAN was for a stand-alone, but we were in a jam and a PP6 went in, now we are going to do the stand-alone, PP6 just can't deal with big injectors. We have a walbro 255, we used an old single turbo Supra adaptor kit. Injectors are Stock STI at the moment but we have a set of modded stock 97 LGT injectors that look to be about the same as modded STI side-feeds. But we will flow test and see.

What is the supra adpater kit?
What are you useing for the standalone, an APEXI AFC?