ej20y into 2010 Legacy GT, questions follow

It has been hard trying to search for 5th gen jdm swaps. Bought a 2010 LGT which had a loss of compression on cylinders 1 and 3. Looked for jdm swaps write ups to get a road map for what would be required to do a jdm swap and ran into a month of reading. Since all of it amounted to AVCS being functional or not after the swap, at least for 4th gen LGTs, I settled on a jdm 2006 legacy gt 2.0 motor because it came from the factory with dual avcs like the 2010 LGT (usdm) car that I bought did. My thinking was that the required bits on the ej20y (hardware) and the required bits on the 2010 ecu (software) would mesh.

 

The engine is out now and the ancillary hardware is being swapped from the compromised 2.5 to the replacement 2.0. While the engine is out, I would like to know if I would need to modify/change the harness, or is my theory correct, and it will plug up and work?

 

Keeping the USDM ecu to manage the ej20y

Will be tuned by a capable and knowledgeable Subaru tuner to work out any bugs that may arise...

But while the engine is out, I want to make sure and do all that needs to be done before putting it back in.

 

Rebuilding the 2.5 is not a route I want to take.

 

All your help is appreciated.

 

P.S.

Has no one played around with the 5th Gen LGTs. The site is full of 4th Gen LGT swaps.

It has been hard trying to search for 5th gen jdm swaps. Bought a 2010 LGT which had a loss of compression on cylinders 1 and 3. Looked for jdm swaps write ups to get a road map for what would be required to do a jdm swap and ran into a month of reading. Since all of it amounted to AVCS being functional or not after the swap, at least for 4th gen LGTs, I settled on a jdm 2006 legacy gt 2.0 motor because it came from the factory with dual avcs like the 2010 LGT (usdm) car that I bought did. My thinking was that the required bits on the ej20y (hardware) and the required bits on the 2010 ecu (software) would mesh.

 

 

 

The engine is out now and the ancillary hardware is being swapped from the compromised 2.5 to the replacement 2.0. While the engine is out, I would like to know if I would need to modify/change the harness, or is my theory correct, and it will plug up and work?

 

 

 

Keeping the USDM ecu to manage the ej20y

 

Will be tuned by a capable and knowledgeable Subaru tuner to work out any bugs that may arise...

 

But while the engine is out, I want to make sure and do all that needs to be done before putting it back in.

 

 

 

Rebuilding the 2.5 is not a route I want to take.

 

 

 

All your help is appreciated.

 

 

 

P.S.

 

Has no one played around with the 5th Gen LGTs. The site is full of 4th Gen LGT swaps.

Noone has, the 2.5 makes more power and this gen has not had the reliability issues of the previous ones. You need to be sure the scavenger oil pump bolts up to the passenger head of the JDM engine, and compare wiring diagrams of the two. You should also make sure the oil pan will clear the turbo and manifold, and the water pump has the provision for the turbo cooling lines.

 

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The 5th Gen has scavenge oil pump for the low mount turbo. The EJ20Y does not have that. You need at least intake cams for the oil pump to function. I don't know if the EJ20 heads have the provision for mounting the scavenge pump or if the Ej255 cams interchange into the EJ20Y.

 

If you were to able to get the scavenge pump to work. You may be able to plug in the Dual AVCS or perhaps rewire them to work using the service manual. You will need to the tune the motor for the change in displacement.

Thank you for the responses. I went with the ej20y b/c a replacement 2.5 is a hard thing to find. Maybe rebuilding, though I'm against it, was the way to go. I'll look into the the things you both mentioned. I have a reputable tuner with many years of Subaru tuning experience to sort out the ecu. Hopefully I can get this to work.

 

If you think of anything else do not hesitate to drop a note.

You need at least intake cams for the oil pump to function. I don't know if the EJ20 heads have the provision for mounting the scavenge pump or if the Ej255 cams interchange into the EJ20Y.

 

 

This I'll need to look into more. Total novice with Subarus, usually tune Saabs... And no, not the 9-2 aeros.

 

I thought by Going with a motor that had Dual AVCS I wouldn't need to change the cams. The mechanic doing most of the heavy lifting thinks that it will work. I'll keep you guys posted. Also, if any of you has a reliable source for a 2.5 turbo motor please let me know.

http://www.car-part.com is a good resource for used parts most offer warranties too, an engine for our car will not be cheap though. I would have bought a new short block for the time and money put into a conversion/rebuild.

http://www.car-part.com is a good resource for used parts most offer warranties too, an engine for our car will not be cheap though. I would have bought a new short block for the time and money put into a conversion/rebuild.

 

I went the same way with mine, the used stock engines were way too expensive for what you get (~5k for something that had 100k on it) and the JDM's were cheaper, but still a used engine with unknown history/miles. I was planning on pushing the car a bit more and a used block most likely had the same curse as the stock one.

do you know why you have low compression? seeing how 1 and 3 are same bank it might be as simple as jumped time

http://www.car-part.com is a good resource for used parts most offer warranties too, an engine for our car will not be cheap though. I would have bought a new short block for the time and money put into a conversion/rebuild.

 

Looking at the site now. Nice resource. Thank you.

do you know why you have low compression? seeing how 1 and 3 are same bank it might be as simple as jumped time

 

How would I begin to investigate this?

take off the timing cover and rotate the engine to top dead. if the marks don't line up rotate the engine once again to top dead. since the crank turns twice to one camshaft revolution it might not be lined up on the first time you turn the crank top dead. if its all lined up the next step would be to do a cylinder leakage test. most people tell you to remove valve covers and make sure the lobes are off the lifter and blah blah. I cheat though and set the pressure on the leakage tester low then just turn the engine till it seals the best. then just turn the pressure up some and listen for air in the throttle body(bad intake valves), tail pipe(bad exhaust valve), or through the oil cap. some there will probably normal, all engines have blow by. More then likely you have bad exhaust valves, it'll be considerably cheaper to fix the heads than to replace the engine and you'll be much happier with the end result

take off the timing cover and rotate the engine to top dead. if the marks don't line up rotate the engine once again to top dead. since the crank turns twice to one camshaft revolution it might not be lined up on the first time you turn the crank top dead. if its all lined up the next step would be to do a cylinder leakage test. most people tell you to remove valve covers and make sure the lobes are off the lifter and blah blah. I cheat though and set the pressure on the leakage tester low then just turn the engine till it seals the best. then just turn the pressure up some and listen for air in the throttle body(bad intake valves), tail pipe(bad exhaust valve), or through the oil cap. some there will probably normal, all engines have blow by. More then likely you have bad exhaust valves, it'll be considerably cheaper to fix the heads than to replace the engine and you'll be much happier with the end result

 

I'll try this over the weekend. A compression test was done before the engine was pulled but I'll look for the alignment of the cams and the other things you've mentioned. If this resolves it, there are a few donor 5th gen cars out there for sale with dead engines. They would find a new home in my garage.

Quick update, buying a built 2.5 block for the 2010 LGT. Manley internals and such, forgive the spelling if I'm wrong. Taking the ej20y and dropping it into an 06 LGT, mainly because it has been done and there is tons of support for it. Will probably sell the 06 LGT to recoup some of the money spent. Shame is, I've already swapped over most of the parts and was ready to drop it in. Then came across a place that built 2.5 engines at a really reasonable price.

 

I'll let you know how it all goes.

who's building the block? asking for a friend...

Taking the ej20y and dropping it into an 06 LGT, mainly because it has been done and there is tons of support for it. Will probably sell the 06 LGT to recoup some of the money spent.

 

You may want to read up on the EJ20X/Y threads in the 4th Gen section.

DDA Tuned in Newburgh. I'll be buying the built short block from them. This is my first experience with them, so I can't say much more. The initial conversations seemed promising however.

 

Does anyone have any experience dealing with DDA?

You may want to read up on the EJ20X/Y threads in the 4th Gen section.

 

I did. That's why the change. I still like the ej20y, and would like to build one, so I'm looking for a Gen 4 lgt to drop it into.

 

But the easy of dropping another 2.5 back into the Gen 5 lgt, and an already built one at that, can't pass it up.

 

My only concerns with the 2.0 is how noticeable the drop off in low end torque would be. Can someone answer that from a real world daily driving application?

Edited November 4, 2019 by subie2nr

I did. That why the change. I still like the ej20y, and would like to build one, so I'm looking for a Gen 4 lgt to drop it into.

 

But the easy of dropping another 2.5 back into the Gen 5 lgt, and an already built one at that, can't pass it up.

 

My only concerns with the 2.0 is how noticeable the drop off in low end torque would be. Can someone answer that from a real world daily driving application?

 

That would depend on the size and ability of your turbo. In a low mount EL configuration like the 5th gen has it probably wouldn't matter with a twin scroll just right size turbo. It would spool early enough and hold on long enough for some really good numbers. The side mount turbo of older models though would be a different story. The runners are longer and there is noticeably more lag even with a twin scroll. But there are lots options there too.

That would depend on the size and ability of your turbo. In a low mount EL configuration like the 5th gen has it probably wouldn't matter with a twin scroll just right size turbo. It would spool early enough and hold on long enough for some really good numbers. The side mount turbo of older models though would be a different story. The runners are longer and there is noticeably more lag even with a twin scroll. But there are lots options there too.

 

That's encouraging. I'll start doing a search for turbos that fit on the ej20y. I had planned to use the stock LGT 2.5 turbo to complete the swap. This may still happen to get the car up and broken in with the new engine. But now I'll have my eyes open for a replacement turbo. Any recommendations? In the saab world td04s aren't too shabby, but I don't think they're twin scroll. They may not fit. I'll have to find out which cars came here with the twin scroll turbo and start sourcing a replacement.

The Dual AVCS also help low end torque, assuming you use a JDM ECM and wiring up the DAVCS in your swap.

Read up on engine and turbo failures in the 4th gen section. Any oiled parts (oil cooler, turbo, oil lines, heads, etc) that are reused need to be thoroughly cleaned to ensure residual contaminants from the old engine don’t take out the new one. Depending on the failure there is also a chance the turbo was starved of oil when the engine was on its way out.

The Dual AVCS also help low end torque, assuming you use a JDM ECM and wiring up the DAVCS in your swap.

 

Missed out on the 4th den body. The 2.0 is ready to go in, so I may just drop it into the fifth den and find another fifth Gen donor body when I get the built engine.

 

The fifth Gen came with davcs, hoping I won't need the jdm, and a custom tune will make all the components work.

Did my reading. And that is the one thing that remains consistent. Cleaning all the parts that oil ran through.

Missed out on the 4th den body. The 2.0 is ready to go in, so I may just drop it into the fifth den and find another fifth Gen donor body when I get the built engine.

 

The fifth Gen came with davcs, hoping I won't need the jdm, and a custom tune will make all the components work.

 

Did you forget about the intake cam running the scavenge pump? Fifth Gen are rarer than 4th Gen and don't have as many engine failures.

 

Personally I would sell the EJ20Y and cut your loses. If you look at the timeline of the threads who done successful swaps, most a take a year to sort out. There are a lot of poorly done EJ20X/Y swap that were done for just cost savings don't run right. The Ej20 swap also tanks the value. Just look at the 2009 OBXT EJ20 swap that was sorted out that sold for under $4k.

I'm actually waiting for a quote to come back on a built 2.5 engine. But I think I will source a body with the options I want and then do that swap. The price dropping is a bit of a concern.

 

I'll keep you all posted. I like the 5 Gen 2.5, but it's hard to get folks to respond to inquiries. If you guys have any resources or reliable engine rebuilders I'm all ears. I've tried the one mentioned above, but still no bites.