2.5L turbo to 2.0L turbo success 2.0L is way Better

Whats going on guys so today i got my 05 legacy back from the shop that did my JDM engine swap and wow !!!!! the 2.0L feels alot better and my butt dyno says im getting around the same power as my 2.5L. i have no codes my cob access port works using the usdm ecu and im super impressed at how strong those 2.0L motors are . In order for the 2.0L to work in my car we had to get my stock exhaust, turbo, down pipe, intake, injectors, coils, wiring harness from the old engine and put that into the new engine for it to work properly. i would say the only thing thats sort of worrying me is that from 3rd gear to 5th gear when i floor it the boost is at 14.5psi the entire time until i stop stepping on it when i had the 2.5L that came with my legacy 05 the psi would start to decrease but with the 2.0L the psi just stays at 14.5 only while im flooring it, the owner of the shop told me that the engine he put in my car is a spec B or something along those lines and in japan people he knows have built cars on the 2.0L with out a problem apparently they are rated to handle 400 horses according to that shop owner . im super pleased with the 2.0L turbo jdm !!

Glad to hear things went well. keep us updated.

I would be treading lightly. If you haven't done some datalogging I would strongly suggest it to confirm that there is no knocking.

 

Why didn't the shop finish the job and use the JDM ECU?

Whats going on guys so today i got my 05 legacy back from the shop that did my JDM engine swap and wow !!!!! the 2.0L feels alot better and my butt dyno says im getting around the same power as my 2.5L. i have no codes my cob access port works using the usdm ecu and im super impressed at how strong those 2.0L motors are . In order for the 2.0L to work in my car we had to get my stock exhaust, turbo, down pipe, intake, injectors, coils, wiring harness from the old engine and put that into the new engine for it to work properly. i would say the only thing thats sort of worrying me is that from 3rd gear to 5th gear when i floor it the boost is at 14.5psi the entire time until i stop stepping on it when i had the 2.5L that came with my legacy 05 the psi would start to decrease but with the 2.0L the psi just stays at 14.5 only while im flooring it, the owner of the shop told me that the engine he put in my car is a spec B or something along those lines and in japan people he knows have built cars on the 2.0L with out a problem apparently they are rated to handle 400 horses according to that shop owner . im super pleased with the 2.0L turbo jdm !!

 

I'm just gonna guess and say AQ Motorsports did the work?

I would be treading lightly. If you haven't done some datalogging I would strongly suggest it to confirm that there is no knocking.

 

Why didn't the shop finish the job and use the JDM ECU?

 

so far the car runs smooth, as for the not getting the JDM ECU i want to still be able to pass smog with that jdm ecu i cant do that and my cobb access port wont work either. im eventually going to try and get the car tuned but for now ill just baby it . the only time i sort of step on it is on the free way and thats when im going 60-70mph ill do a pull to like 100 - 115mph and its butter smooth but im not planning on launching the car or anything of that sort the engine i got only has 45k miles on it feels way better than my 2.5 that had 155k lol

I'm just gonna guess and say AQ Motorsports did the work?

 

 

 

it was done at jdm imports out of garden grove california .

the only sort of strange thing is the psi stays at 14.5 solid !!! when the pedal is pushed all the way down which is a little bit strange , i thought that psi would tapper off but no.... with the 2.5l at some point while flooring it the psi would drop little by little. i got told on a facebook group im part of for legacies that the 2.0L jdm engine i got comes with forged internals and that the 14.5psi is not going to break anything but like i said i rarely floor it usually drive the car normal 90% of the time

If it's from a Legacy, no, it does not have forged internals. And Spec B is just a trim, nothing to do with engine internals. Somebody is feeding you some BS.

If it's from a Legacy, no, it does not have forged internals. And Spec B is just a trim, nothing to do with engine internals. Somebody is feeding you some BS.

 

did i get duped lol ?

 

also do you know if there is a cobb access port map for the legacy 2.0L engines ? or would i have to find a tuner to do that ?

If it's from a Legacy, no, it does not have forged internals. And Spec B is just a trim, nothing to do with engine internals. Somebody is feeding you some BS.

 

from another legacy forum

 

" Well one thing I can tell you, the JDM's are better.

The only thing I have seen that has given a bad score to the JDM's, is that study has shown that it is unable to take an ethanol blend fuel.

But outside of that, the blocks are pretty much solid and superior to the USDM a lot of them come with stronger internals than the american/ USDM ones "

If it's from a Legacy, no, it does not have forged internals. And Spec B is just a trim, nothing to do with engine internals. Somebody is feeding you some BS.

 

from a mod at the other forums

 

 

here's the long and the short of it .....JDM EJ20 > USDM EJ20 because of:

 

stronger block many times forged internals with stronger bottom end from factory.

better flowing heads

stronger pistons, rods

bigger turbo / intercooler

better ecu tuning from stock

 

We lost out on the above because of the US government and emissions laws

the JDM engines are built a lot different from the USDM engines stock to stock the jdm ej20s can take about 100-150 more horsepower than its American Counterpart .

so far the car runs smooth, as for the not getting the JDM ECU i want to still be able to pass smog with that jdm ecu i cant do that and my cobb access port wont work either. im eventually going to try and get the car tuned but for now ill just baby it . the only time i sort of step on it is on the free way and thats when im going 60-70mph ill do a pull to like 100 - 115mph and its butter smooth but im not planning on launching the car or anything of that sort the engine i got only has 45k miles on it feels way better than my 2.5 that had 155k lol

 

I don't care if it runs smooth or not. The EJ20X and Y engines have 9.5:1 compression pistons in them, it WILL knock. I had to pull a lot of timing out of both the US timing tables and the JDM tables when I was running each ECU. If you run that way for too long you'll get the opportunity to do another motor swap.

 

Why can't you get the car running right then swap to the US ecu for an emissions check if it wouldn't pass with the JDM one installed?

 

There is plenty of support for the JDM ecu and tuning via the open source channels. No need for an access port.

 

Someone is feeding you a bunch of BS. The JDM legacy motors do not have forged internals. From what I've seen of them they were simply designed for moderate power with an emphasis on efficiency. Hence the high compression pistons.

Some of the JDM EJ20 engines did come with better internal components. Not all of them. (see EJ208, EJ207 engines). Most are open deck blocks as well, not semi-open like most turbo 2.5L.

 

You need to check exactly what car and trim yours came out of before assuming your got all of these improvements; that means doing more research than what the shop who sold it to you is telling you at face value.

 

Also, your boost "improvement" was likely due to either 1) a previous boost leak or 2)previous tuning issue. Both of which would have been fixed incidentally by swapping the engine.

I think a 2.0L is better sized for the VF40 turbos. It's possible that the 2.5L was just overspinning the turbo.

 

Did the car get tuned at all? Wastegate tables might have been modified to keep more boost to redline too.

 

What did you do with the Exhaust AVCS? Did you swap in a non AVCS cam?

I think a 2.0L is better sized for the VF40 turbos. It's possible that the 2.5L was just overspinning the turbo.

 

Did the car get tuned at all? Wastegate tables might have been modified to keep more boost to redline too.

 

What did you do with the Exhaust AVCS? Did you swap in a non AVCS cam?

 

Everytime I read one of your posts I learn something.

 

nohomo

Boost tapper is due to the ECM tune intentionally limiting it or more likely the turbo can not supply enough air flow to maintain the boost level.

so far the car runs smooth, as for the not getting the JDM ECU i want to still be able to pass smog with that jdm ecu i cant do that and my cobb access port wont work either. im eventually going to try and get the car tuned but for now ill just baby it . the only time i sort of step on it is on the free way and thats when im going 60-70mph ill do a pull to like 100 - 115mph and its butter smooth but im not planning on launching the car or anything of that sort the engine i got only has 45k miles on it feels way better than my 2.5 that had 155k lol

 

Highway WOT runs are far worse on the engine than launching it.

Boost tapper is due to the ECM tune intentionally limiting it or more likely the turbo can not supply enough air flow to maintain the boost level.

 

It happens even without ECU's involvement and without boost controllers too. My wastegate is boost controllerless, it gets 13psi at peak torque, but then tapers down to 12 by redline.

 

You are onto something with the second part . As the CFM increases, inefficiencies of the piping and intercooler start restricting the airflow (think of exhaust back pressure), this is called pressure drop. This could lead to to turbo not being able to supply enough air (going outside of the efficiency islands).

 

Here's an example...

Say you have a 13psi wastegate and it's reference is fed from the turbo outlet (like it is on our cars). At redline a turbo is creating 13psi at the outlet, but the intercooler and piping have a 2psi pressure drop, which results in only 11psi reaching the manifold. At 13psi you're turbo still has plenty of breath, so you seeing 11psi is not indicative of turbo being unable to supply more air, it's just the wastegate sees 13psi and opens, which prevents the turbo from building any more boost.

 

One easy way to prevent this boost pressure loss is to simply change the wastegate reference point (SR20DET Nissans did it like this in the 90's). If you change it to be post intercooler, as close to throttle body, wastegate will now see 11psi too, thus it will stay closed longer. End result is you now see 13psi at the manifold, but nothing is free, your turbo is now runnign at 15psi.

 

Our cars do the same thing, just with an electronic boost controller. They fool the wastegate into seeing less pressure, thus staying closed longer. At which point the wastegate reference point doesn't really matter (hence it's on the turbos for our cars).

We lost out on the above because of the US government and emissions laws

the JDM engines are built a lot different from the USDM engines stock to stock the jdm ej20s can take about 100-150 more horsepower than its American Counterpart .

 

Keep in mind that Japan also uses higher octane fuel than we do. 100 octane is available there (RON) which translates to a 94 or 95 octane in the US (AKI).

 

I'd suggest getting the car tuned as soon as you can.