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OEM Subaru turbo for WRX on a 2.0 T4
Posted: Fri Sep 11, 2020 11:21 pm
by CobraJet
I couldn't pass up an offer for a free OEM Subaru turbofrom a WRX. Buddy upgraded his stock turbp to a larger one and just gave it to me!
So what could I expect if I added this to a 2.0 T4 I'm building? It's using 914 heads and a Raby 9600 camshaft, HPMX 40mm carbs. The rotating assembly will be balanced and all the clearances carefully set.
When should the boost start coming on? What would you think that the top boost will be? Any ideas on horspower/torque?
Re: OEM Subaru turbo for WRX on a 2.0 T4
Posted: Sat Sep 12, 2020 5:25 am
by buguy
Depends on which one you got. There were a few different ones depending on the year. I ran one on my 1600 and the boost came on pretty early. I would guess the boost would come in at close to 2000 rpm on a 2L. I pushed mine to over 30 psi, but it's not efficient there. 22 psi or so is about all she wants. I don't remember all the numbers, but i think 275hp is all it will do at that turbos cfm rating. It will definitely work, but maybe on the small side of ideal.
Re: OEM Subaru turbo for WRX on a 2.0 T4
Posted: Sat Sep 12, 2020 5:27 am
by Clonebug
The WRX turbo will support 270 crank hp and can flow 394 cfm.
It’s installed on a 2.0 L boxer engine so you should expect the same characteristics as the oem install.
It’s a great turbo and I’ve been using it for probably 5 plus years.
Boost should come on around 2400 rpm possibly a little earlier....
Re: OEM Subaru turbo for WRX on a 2.0 T4
Posted: Sat Sep 12, 2020 7:43 am
by CobraJet
OK great, much better than I'd thought it would do. Matter of fact better than I had hoped for!

The thing I was most impressed about is the condition it's been kept in. It's very clean, all the oil and air passages have been plugged, it spins super free, and it has almost zero end play. I've been offered turbos before but they've been worn out and filthy.
What do you think, Is this going to need an intercooler?
Re: OEM Subaru turbo for WRX on a 2.0 T4
Posted: Sat Sep 12, 2020 9:02 am
by buguy
I would definitely put an intercooler or water/meth injection on it. Gotta keep those intake temps down.
Re: OEM Subaru turbo for WRX on a 2.0 T4
Posted: Sat Sep 12, 2020 1:15 pm
by CobraJet
Clonebug wrote: ↑Sat Sep 12, 2020 5:27 am
The WRX turbo will support 270 crank hp and can flow 394 cfm.
It’s installed on a 2.0 L boxer engine so you should expect the same characteristics as the oem install.
It’s a great turbo and I’ve been using it for probably 5 plus years.
Boost should come on around 2400 rpm possibly a little earlier....
Great to hear Clonebug! What cam and heads are you running, what RPM range is your engine using?
Re: OEM Subaru turbo for WRX on a 2.0 T4
Posted: Sat Sep 12, 2020 2:39 pm
by rubenski
I have the same on my 1641 built engine, like clone says, boost at 2300 2400 rpm. I'm only at 10psi but i'm at 190hp and 260nm torque.
I have an intercooler installed and a w/m kit on a shelf to use when needed.
I would advise efi, carbs will always mean a compromise at certain levels of tuning.
Enjoy your build!
Verstuurd vanaf mijn SM-A515F met Tapatalk
Re: OEM Subaru turbo for WRX on a 2.0 T4
Posted: Sat Sep 12, 2020 3:35 pm
by buguy
rubenski wrote: ↑Sat Sep 12, 2020 2:39 pm
I have the same on my 1641 built engine, like clone says, boost at 2300 2400 rpm. I'm only at 10psi but i'm at 190hp and 260nm torque.
I have an intercooler installed and a w/m kit on a shelf to use when needed.
I would advise efi, carbs will always mean a compromise at certain levels of tuning.
Enjoy your build!
Verstuurd vanaf mijn SM-A515F met Tapatalk
What kind of rpms to achieve such high hp on low boost and a small turbo?
Gotta be 7000 or so?
Re: OEM Subaru turbo for WRX on a 2.0 T4
Posted: Sat Sep 12, 2020 4:39 pm
by CobraJet
rubenski wrote: ↑Sat Sep 12, 2020 2:39 pm.....
I would advise efi, carbs will always mean a compromise at certain levels of tuning.
Enjoy your build!.....
Hey thanks! I've been collecting parts for a few years now. I already have the carbs and kit new in box so that is what I plan on using. Later on I hope to build an all out monster engine that'll get EFI and a bigger turbo!
Re: OEM Subaru turbo for WRX on a 2.0 T4
Posted: Sat Sep 12, 2020 9:03 pm
by Clonebug
CobraJet wrote: ↑Sat Sep 12, 2020 7:43 am
OK great, much better than I'd thought it would do. Matter of fact better than I had hoped for!

The thing I was most impressed about is the condition it's been kept in. It's very clean, all the oil and air passages have been plugged, it spins super free, and it has almost zero end play. I've been offered turbos before but they've been worn out and filthy.
What do you think, Is this going to need an intercooler?
That turbo is not a WRX turbo.......A WRX turbo number is 14412AA360. Yours is more than likely from a Legacy or something similar.
Not that it matters......they are almost identical as far as I can tell.
Re: OEM Subaru turbo for WRX on a 2.0 T4
Posted: Sat Sep 12, 2020 9:13 pm
by Clonebug
CobraJet wrote: ↑Sat Sep 12, 2020 1:15 pm
Clonebug wrote: ↑Sat Sep 12, 2020 5:27 am
The WRX turbo will support 270 crank hp and can flow 394 cfm.
It’s installed on a 2.0 L boxer engine so you should expect the same characteristics as the oem install.
It’s a great turbo and I’ve been using it for probably 5 plus years.
Boost should come on around 2400 rpm possibly a little earlier....
Great to hear Clonebug! What cam and heads are you running, what RPM range is your engine using?
W-100 cam and DRD 40 X 37.5mm heads.
I upgraded the rockers to 1.25 which measure out at 1.38 and installed CB 650 outer springs. I'm getting about .526" lift.
I usually shift between 5200-5500 but have gone as high as 5800 rpm.
Turbo starts boost at 2400 and hits 23 lbs. at about 3800-4000 rpm.
Re: OEM Subaru turbo for WRX on a 2.0 T4
Posted: Sat Sep 12, 2020 11:21 pm
by Dan Dryden
rubenski wrote: ↑Sat Sep 12, 2020 2:39 pm
I have the same on my 1641 built engine, like clone says, boost at 2300 2400 rpm. I'm only at 10psi but i'm at 190hp and 260nm torque.
Verstuurd vanaf mijn SM-A515F met Tapatalk
Wow! Can you tell me more about your engine spec? That’s some very big numbers for only 10psi.



Re: OEM Subaru turbo for WRX on a 2.0 T4
Posted: Sat Sep 12, 2020 11:42 pm
by rubenski
Re: OEM Subaru turbo for WRX on a 2.0 T4
Posted: Sat Sep 12, 2020 11:52 pm
by CobraJet
Clonebug wrote: ↑Sat Sep 12, 2020 9:13 pm
CobraJet wrote: ↑Sat Sep 12, 2020 1:15 pm
Clonebug wrote: ↑Sat Sep 12, 2020 5:27 am
The WRX turbo will support 270 crank hp and can flow 394 cfm.
It’s installed on a 2.0 L boxer engine so you should expect the same characteristics as the oem install.
It’s a great turbo and I’ve been using it for probably 5 plus years.
Boost should come on around 2400 rpm possibly a little earlier....
Great to hear Clonebug! What cam and heads are you running, what RPM range is your engine using?
W-100 cam and DRD 40 X 37.5mm heads.
I upgraded the rockers to 1.25 which measure out at 1.38 and installed CB 650 outer springs. I'm getting about .526" lift.
I usually shift between 5200-5500 but have gone as high as 5800 rpm.
Turbo starts boost at 2400 and hits 23 lbs. at about 3800-4000 rpm.
That cam is very close to the Webcan 86 I was planning on running Clonebug. Either that or the Raby 9600 that I also have. My heads are the Porsche 914 2.0 3 stud intake and have almost the same valve sizes as well. I think that mine is going to have a very simular performance curve, thanks for the data! BTW I followed your buggy thread. Went back to try and read up on it again and WOW, 209 pages! Very good writeup all the way though though.
Re: OEM Subaru turbo for WRX on a 2.0 T4
Posted: Sun Sep 13, 2020 5:43 am
by buguy
That's incredible! Your way over on HP for where the norm is on that sort of boost!