2.5i turbo build plans

I know a lot of these posts come around, but never follow through. But I will follow through with this for sure. I've got my parts list complete, and have begun ordering bits & pieces.

Background: I've had the car for several years and have had the itch for a new car lately. I can't justify it, mine has been paid off and there's nothing wrong with it. So instead of spending 20k+ on a new(er) car, I'm going to spend less than $2500 and make this one a lot more fun and "new" to me again.

Car: 2008 Subaru Legacy 2.5i 4EAT 86k miles

Mods:

-H&R springs w/ Koni struts

-Damn near every suspension bushing is Whiteline/Energy

-Whiteline rear sway bar

-LGT brakes w/ DBA rotors

-Delta 1000 cams

-Grimmspeed LW crank pulley

-Grimmspeed phenolic intake spacers

-AEM dry-flow filter

-hybrid intake system

-WRX injectors

-e85 fuel

-Infernofab 4-2-1 header

-Infernofab high-flow cat

-stock GT midpipe

-HKS Silent Hi-Power axleback

Turbo build list in next post --->

I'd like to say I'm doing this the "right" way. But I suppose there isn't a perfect way to do it, aside from either swapping a factory turbo motor in or selling the car and buying a factory turbo car. (I'm sure I'll hear that a million times during this)

I'm not buying the AVO kit, I'm not cutting my crossmember or making a funky up pipe. I'm going to use as many stock turbo parts I can to make this appear like it came from the factory. I feel that is the right way to do it.

I won't type out the entire parts list, there's too many small things that most of you won't care about. But here's the main pieces:

-Kinugawa TD04HL-20T

-OEM turbo header/UP

-CNT catless downpipe

-LGT airbox lid/MAF

-OEM turbo inlet

-OEM BPV

-Water to air intercooler

-LGT front crossmember

-OEM turbo swaybar

I will have more parts and much more detail in future posts as I begin work.

My friend has talked me into creating a youtube channel to document the progress of this build. This is my daily driver, so I will be doing a little at a time on weekends.

Channel: https://www.youtube.com/channel/UCBSXLycHuFhgv3DY4TtHGzw

First Video!

'08 Legacy 2.5i Intro & Drive

I can't wait to see this done. I come from the 2.5i, STI, WRX and more worlds I know a guy that will tune it for you also. XRT tuning, He tuned my 2.5i. It's still on the road today and has 180k miles. I talked to the guy who has it last week..

Nice! I’ve heard good things about XRT.. I’ll most likely contact him when I get to that point.

Side note.. all parts have been ordered!

Before you do anything. I would talk with a tuner to see if they are able to open source tune the car. I had a 2.5i also slapped on a turbo but when I went to get it tuned. The place couldn’t find my ecu definitions. Asked on here for help. Was told to message someone “sorry forgot his username” about them. He sent we a website with tons of Subaru ecu parameters. Sent the link to my tuner. None of the Legacy 2.5i 4eat Roms had the parameters he needed to tune it. It all ended up working out tho. I bought a legacy gt and swapped most of the stuff I bought for it to this car.

Im not one of those people that will tell you to not do it and buy a turbo car instead. But I will tell you it didn’t work out for me and before you spend money on parts take it somewhere that tunes subies and let them plug the car in to see if they are able to do it. Even if they charge you a fee to check it would be better spent then getting your hopes up like I did.

If they end up saying yes then great I’ll be sure to watch the progress myself I love n/a turbo builds.

I can't wait to see this done. I come from the 2.5i, STI, WRX and more worlds I know a guy that will tune it for you also. XRT tuning, He tuned my 2.5i. It's still on the road today and has 180k miles. I talked to the guy who has it last week..

Just say this post after my big rambling lol but was your 2.5i 4eat or manual?

Before you do anything. I would talk with a tuner to see if they are able to open source tune the car. I had a 2.5i also slapped on a turbo but when I went to get it tuned. The place couldn’t find my ecu definitions. Asked on here for help. Was told to message someone “sorry forgot his username” about them. He sent we a website with tons of Subaru ecu parameters. Sent the link to my tuner. None of the Legacy 2.5i 4eat Roms had the parameters he needed to tune it. It all ended up working out tho. I bought a legacy gt and swapped most of the stuff I bought for it to this car.

 

Im not one of those people that will tell you to not do it and buy a turbo car instead. But I will tell you it didn’t work out for me and before you spend money on parts take it somewhere that tunes subies and let them plug the car in to see if they are able to do it. Even if they charge you a fee to check it would be better spent then getting your hopes up like I did.

 

If they end up saying yes then great I’ll be sure to watch the progress myself I love n/a turbo builds.

Hey thanks for the heads up! Luckily I had my ECU defined on the romraider forums several years ago, I’ve been messing around with the tuning this whole time, learning and experimenting. Shouldn’t be a problem with this build

 

I won't type out the entire parts list, there's too many small things that most of you won't care about. But here's the main pieces:

 

-Kinugawa TD04HL-20T

-OEM turbo header/UP

-CNT catless downpipe

-LGT airbox lid/MAF

-OEM turbo inlet

-OEM BPV

-Water to air intercooler

-LGT front crossmember

-OEM turbo swaybar

 

I will have more parts and much more detail in future posts as I begin work.

-I would skip all the OEM turbo bits and go with a custom UP to go around the cross member. That way you can go with a wider range of turbo housing and be rotated (also eliminates the need for the OEM inlet/aibox/BPV etc). Since the N/A IM isnt designed for turbo snaking a OEM inlet would be a hassle to attempt.

-Skip the LGT sway get a Tribeca one (25mm hollow)

-I would mod the stock mid-pipe to mate to a custom catless DP or I guess mod the CNT catless DP (its cheap enough) to mate to the stock mid pipe

-Air to water is fine but youll be running higher OCT fuel so maybe consider simplifying the setup and go FMIC ?? You'll heatsoak in traffic wither either just one isn't plumbed into the cooling system

-If you go rotated you could look at a GT2860 its small but youll only need/want 6-9lbs boost.

-The Delta 1000s are nice not sure how they will play with F/I

-Can't hurt to grab a spare oil pan

-Pump and injectors should be fine

Good luck

Good luck

Thanks

I’ve ordered everything already, but thanks for the suggestions.

I have the Grimmspeed phenolic spacers, so I think I’ll just have to slightly bend the fuel line and get creative with a coil pack mount. I really like the idea of the stock ish look.

The AWIC isn’t plumbed into the engine’s coolant system, it has its own pump and water supply. It’s super easy to set up, and cheaper than getting FMIC pipes bent and welded.

I’m not sure about the Delta cams + boost either, but we’ll see!

Going to be a fun project! I’d just go with a custom up pipe as well, you’ll end up having to swap tons of stuff otherwise and you’ll have more turbo options if you go custom.

If your going to that hassle may as well buy a wrecked 2.5GT and go to town, NA-T is better left to be cost effective can’t wait to see updates

Sent from my iPhone using Tapatalk

So can't wait to see this thing done

Thanks for the support! All of the parts have been coming in this week. I am excited.

Going to be a fun project! I’d just go with a custom up pipe as well, you’ll end up having to swap tons of stuff otherwise and you’ll have more turbo options if you go custom.

 

If your going to that hassle may as well buy a wrecked 2.5GT and go to town, NA-T is better left to be cost effective can’t wait to see updates

 

 

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We shall see. I know there will be some hurdles, mainly the turbo inlet tube going under the manifold. I think I can make it work fairly easy though.

Thanks!

Its raining and I'm still waiting on some parts, so here's some crappy drawings of the intercooler setup and a dual catch can setup.

The valve cover vent should be filtered air going into the engine from the vacuum created from the PCV valve connection. You really shouldn't need catch can in that location unless the engine has blow by (and then you have bigger issue). The valve cover vent should be from the air box so it has less vacuum than the PCV valve connection or you can put in valve cover breather.

I haven't looked at my Legacy GT PCV operation. My other turbo vehicle has two PCV, one going in front of the turbo for boost operation, one going to the intake manifold for vacuum operation.

The valve cover vent should be filtered air going into the engine from the vacuum created from the PCV valve connection. You really shouldn't need catch can in that location unless the engine has blow by (and then you have bigger issue). The valve cover vent should be from the air box so it has less vacuum than the PCV valve connection or you can put in valve cover breather.

 

I haven't looked at my Legacy GT PCV operation. My other turbo vehicle has two PCV, one going in front of the turbo for boost operation, one going to the intake manifold for vacuum operation.

The PCV valve on my car does go to the intake manifold for strong vacuum. The fitting that the PCV valve attaches to has an elbow that bypasses the PCV valve and goes to the inlet before the turbo(or just the intake tube before the throttle body right now). Boost in the intake manifold will close the PCV valve, and the other 3 connections will still be pulled on through the inlet tube.

You are missing the operation of how a PCV system works. In a properly working system, Air comes out of the PCV, Air goes IN the valve cover vent(s). There is no need to put catch can on the valve cover vents since air is going in them. If you want to put a 2d catch can, put it on the intake manifold to PCV connection.

In the diagram above (assume the tube is the same diameter and essential the same pressure) in boost operation, the PCV valve will not be operational since the PCV valve and Vent will be at the same potential and their will be no differential pressure to move the air. The vacuum on the PCV valve will be matched by the vacuum applied to the valve cover vents. I assume the stock 2.5i system is setup with the vent valve going to the intake. The intake vacuum going to the manual is higher than the air intake, so that is why the stock PCV system functions properly.

I don’t quite understand your explanation. I thought I had it all figured out after reading for a while.. I’ll have to do more research. My stock 2.5i has the pcv valve going to the intake manifold post throttle body. The crank case and both valve covers go to the intake pre throttle body.

I was assuming I could set it up similarly when the turbo is installed, but with cans on the 3 connections going to the intake tube.

This is an image I saved a long time ago...in case I ever got around to doing this turbo setup. I think mine is planned similar to the bottom one.

https://i.imgur.com/rOkB94z.jpg

It’s here! It’s also tiny...but beautiful

I don’t quite understand your explanation. I thought I had it all figured out after reading for a while.. I’ll have to do more research. My stock 2.5i has the pcv valve going to the intake manifold post throttle body. The crank case and both valve covers go to the intake pre throttle body.

I was assuming I could set it up similarly when the turbo is installed, but with cans on the 3 connections going to the intake tube.

You have it right. With manifold vacuum, the PCV check valve is open and drawing air from the turbo inlet, through the breathers into the crankcase, and into the intake manifold so the crankcase vapors can be burned.

With manifold boost, the PCV valve closes and all crankcase blowby goes from the valve covers into the turbo inlet to be burned by the engine.

Your dual can setup is correct. Just make sure the can on the PCV side is between the crankcase and the PCV valve.

Here's a good article that may have you rethinking your setup: https://dsportmag.com/the-tech/quick-tech-the-benefits-of-lowering-crankcase-pressure-part-1/

Good luck with your build!

 

Good luck with your build!

Thank you!

Not sure if you're too far in the build to go with the following option, but may help others.

Rather than use an up pipe to mount the turbo in the classic location, should buy a stock 5th gen header and turbo (low mount).

Anyway this means you'd have no up-pipe and rather than a down pipe you would have a J-pipe. So much more simple.

That way you have the efficiency of a low mount location (great spool) and also not have to worry about cutting the cross member .

This would likely involve using the Gen V legaxy GT sump because it is smaller so it clears the headers.

Other benifit would be that the intercooler piping would be quite short if pairing this with a FMIC.

Finally I should mention that I will be testing a 2015+ WRX header and turbo (mgt2259s) on my ej25 gen v . If it bolts up, this would be another option for those wanting to turbocharge an NA ej25 for cheap (my header and WRX low mount turbo cost $400 aud delivered with only 8000km on it). I picked up a complete 2015 + J-pipe and complete stock exhaust for $100.