Welcome to the North American Subaru Impreza Owners Club Friday March 29, 2024
Home Forums Images WikiNASIOC Products Store Modifications Upgrade Garage
NASIOC
Go Back   NASIOC > NASIOC General > Newbies & FAQs

Welcome to NASIOC - The world's largest online community for Subaru enthusiasts!
Welcome to the NASIOC.com Subaru forum.

You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, free of charge, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, so please join our community today!

If you have any problems with the registration process or your account login, please contact us.







* As an Amazon Associate I earn from qualifying purchases. 
* Registered users of the site do not see these ads. 
Reply
 
Thread Tools Display Modes
Old 01-01-2021, 11:40 PM   #876
oem_turbo
Scooby Newbie
 
Member#: 199558
Join Date: Jan 2009
Cool VF48 High Flow with Twin-Scroll P25 Turbine Housing

Okay group.... been thinking about a few things with respect to the OEM++ theme of things Nick was talking about. This will be a long write up but it will be worth it.

Theory:
————-
I love the idea of OEM++. The USDM versions of the EJ motor can really be lethargic. They need a lot more response. I love the 2.5L displacement and the outright torque you get but the free spinning EJ207 engines with their shorter stroke and efficient header design screams joy.

Have you guys ever driven the FA20? The spool up is amazingly quick and really comes alive with a basic reflash to get rid of the rev hang and etc. To make the EJ25 spool closer like the FA20 (hard to do with the Direct Injection) but put out the 350-400whp range from a relatively standard IHI turbo is the way Subaru should have done it from the get go. Nick commented about this earlier in the thread when comparing the FA20 Turbo against the VF48,VF51,VF56,VF58. The FA20 engine kills it on torque.

My Engine Needs:
————————----
I have a 2006 Subaru STi with the EJ257 motor here in the USA. Love the car. 68k original miles and the maintenance is tip top. I plan to race it in the Midwest Gridlife Street Series. We are only allowed factory turbochargers and can only boost 20% above stock. Has to have climate control and interior pieces. It’s a street car with bolt on’s for argument sake.

Ideally, the best turbo for me would be cheap, fast, reliable and a Subaru OEM part number. It should be twin-scroll, bolt-on, make 400+ hp and be ball bearing.

The fastest guy in the pack has a 2011 WRX with the S209 RA “HKS” turbo and absolutely dominates the field. The Evo’s are genuinely fast as well with their turbos that are far larger and inherently boost more from factory but this guy takes the cake. I want to compete in this category and be competitive as well but don't want to spend $3,000+ on a turbo to do it, so i want to get creative and started doing my IHI Turbo Research.

Turbo Options:
————————
1. S209 RA “HKS” turbo
- I can get this turbo and call it at day but at over $3,000 for this turbo ($4000+ MSRP) and hard as hell to come by from Subaru. For me, it’s a tough sell. I enjoy the twin scroll operation from the EJ207’s because it does that much better with half a liter down of displacement. Sure, it makes 400whp on e85 @ 18.5psi but I'm not getting twin-scroll operation and it's mighty expensive.

2. VF58 or VF56 or VF53
- VF58. hahaha.... it's more rare than diamonds and ungodly expensive. I am proud to see Nick (post above) got one. It's beautiful with it's ball-bearing CHRA and Ti-AL Turbine but Lord knows I can't find one without paying a massively for it. The VF56 is way hard to find as well and nearly on the VF58 level for rarity. I can get the VF53 from Subaru Japan and it’s twin scroll but it’s still up around $2900. That’s another tough sell. I would still be down on horsepower out of all of these turbo's. They all max around 360whp on e85 and it puts me above the 20% extra boost rule.

3. VF42
- Would love this but very hard to come by and when I did find it on Japan Yahoo Auctions it was $2200 + shipping. I still would like more power. I don’t see guys doing more than 340whp without a lot of boost and higher octane ratings.

4. IHI VF48 Hi Flow (New 2020)
- I can do this with a nice EL Header (KillerB) and make the 400whp at 18.5psi that I need to be competitive. But again, it's a single scroll turbo. At least it's cost effective and very much available. Sigh.....okay. NEXT.

5. IHI VF49 High Flow (New 2020)
- I previously mentioned this one above with my previous post. It’s available for sale early 2021. I can place the order for it and should have it in time for race season this summer! But $2990 Shipped. Ouch! It’s rated for 400hp and looks like the twin scroll version of the high flow VF48 stated above with a slightly larger compressor wheel, probably due to the inherent efficient nature of the twin-scroll design. BUT.... Why so much money!?

6. Custom option....... read next...!

Custom Factory Turbo
——————————-
I want Twin-Scroll, 400hp, a lower cost and factory IHI components (due to rules and regs for street class racing rules).

The high flow VF48 from IHI is a journal bearing unit. If I forgo the ball bearing aspect of it and the twin scroll, it’s the most ideal for my situation.

This is where it gets interesting. All the Journal Bearing turbine housings are compatible with each other. So.....If I were to get a VF37 turbine housing (twin-scroll), I can use it on any journal bearing VF-series turbo. Thus converting any single-scroll VF39,43,48, 52 turbo to TWIN-SCROLL operation without any modification to the CHRA.

Which means, I can buy the VF48 High Flow Turbo and swap a P25 VF37 Journal Bearing Turbine Housing and thus converting the new VF48HF to a twin-scroll using factory parts. I can look forward to seeing a potential 500-700rpms reduction in spool time switching to twin-scroll operation.

Parts Needed:
-----------------
1.Kinugawa makes the P25 Journal Bearing Turbine Housing (i will be using a factory IHI unit: https://www.ebay.com/itm/193804066067

2. The VF48HF Turbo is easily and readily attainable here: https://www.full-race.com/store/suba...and-04-07-wrx/

3. Upgraded Actuator is advised for 14.7psi (1 bar) to keep the IWG shut a little longer for better spool up instead of creeping open at 7psi on its way up to your full boost 18-20psi. Available from several sources but this one is my cost effective choice: https://www.ebay.com/itm/273820715136

Total Build Cost: $1470 (rounding up & w/ shipping)

In Conclusion.....

This would leave me with an IHI VF48 High-Flow Turbo that has been verified to make 400whp/400wtq @ 18.5psi and it makes 300wtq @ 2700rpms and 400wtq @ 3700rpms. All with E85 with and in Single Scroll Operation.

....... but instead, it SHOULD make a theoretical 300wtq @2200rpms and 400wtq @ 3200rpms due to the P25 VF37 twin-scroll nature of the turbine I would be swapping in. This should give any VF56 or VF58 or S209RA "HKS Turbo" a huge run for their money, at literally LESS than HALF THE COST. All factory IHI/Subaru Parts.

Notes that matter! I don't get the transient response of the VF58 that has a ball-bearing CHRA and a Ti-AL Turbine Wheel and no dyno can truly quantify what transient response really feels like. This is where the VF58 truly wins out but I can't have everything at this price point.

For comparison sake, the lead contender in the Gridlife Street Series Class uses the S209 RA "HKS Turbo" that makes 300wtq @ 3900rpms (93 octane), to be fair, E85 would shrink that another 400-500rpms cause you can throw more timing at it but lets say its 500rpms of spool cause of e85, you're 300wtq @3400rpms STILL! This turbo makes the horsepower but always around 1000rpms later compared to it's twin-scroll counterpart. Even a S208 with a VF56 demolishes the USDM S209-RA in responsiveness with 1/2 Liter Less engine displacement a touch lower static compression. Twin-Scroll Efficiency for the win.

I wouldn't be surprised if I don't make the same peak HP as the S209 RA "HKS Turbo" which is around 420hp but i'll demolish on torque made earlier in the power band and TORQUE is what accelerates a car faster, not Horsepower.

Even if you're not in the "Street Series" of Gridlife. This combo would be KILLER on the street and could make it boost a bit more around 21psi. I plan to have a couple maps made on my CobbAP to load so I can have fun on the street and on the track in different ways. I also want to push the limit off the track and see how much I can get out of this turbo.

I welcome any thoughts or feedback everyone has on this. I'm getting ready to move in this direction in a couple more paychecks.

Best,
Jonathan
* Registered users of the site do not see these ads.

Last edited by oem_turbo; 01-02-2021 at 12:03 AM.
oem_turbo is offline   Reply With Quote
Sponsored Links
* Registered users of the site do not see these ads.
Old 01-02-2021, 02:41 PM   #877
VWci
Scooby Newbie
 
Member#: 260436
Join Date: Oct 2010
Chapter/Region: International
Location: Ankara/Turkiye
Vehicle:
2003 EDM WRX
JBP

Default

Why dont you take Tomei T380b Ej/Ts into consideration? Little bit expensive though
VWci is offline   Reply With Quote
Old 01-02-2021, 08:29 PM   #878
oem_turbo
Scooby Newbie
 
Member#: 199558
Join Date: Jan 2009
Default

Quote:
Originally Posted by VWci View Post
Why dont you take Tomei T380b Ej/Ts into consideration? Little bit expensive though
You didn’t read what I wrote entirely. I have to run a stock turbo for the racing series I would like to participate in. Besides, why pay $2800+Shipping for that when I can get a VF53, high flow VF49 for the same money and it’s IHI direct. Besides, for those of you that want aftermarket and not only IHI. I would rather run a Kinugawa TD05-20G ball bearing turbo and spend $1200 shipped and get more bang for the buck.
oem_turbo is offline   Reply With Quote
Old 01-03-2021, 01:46 PM   #879
VWci
Scooby Newbie
 
Member#: 260436
Join Date: Oct 2010
Chapter/Region: International
Location: Ankara/Turkiye
Vehicle:
2003 EDM WRX
JBP

Default

Do they check turbos before race dimensional wise?

I am asking because I think you can remove easily tomei plate on the turbo. At the end it is oem subaru/ihi turbo and has subaru part number. And ihi vf48 hf also has plate which covers oem stamps.

What about ihi vf22 ts or vf34 ts? Both bb and vf22s compressor wheel is closer to or same with ihivf48hf if i remember correctly.
VWci is offline   Reply With Quote
Old 01-03-2021, 09:35 PM   #880
oem_turbo
Scooby Newbie
 
Member#: 199558
Join Date: Jan 2009
Default

Quote:
Originally Posted by VWci View Post
Do they check turbos before race dimensional wise?

I am asking because I think you can remove easily tomei plate on the turbo. At the end it is oem subaru/ihi turbo and has subaru part number. And ihi vf48 hf also has plate which covers oem stamps.

What about ihi vf22 ts or vf34 ts? Both bb and vf22s compressor wheel is closer to or same with ihivf48hf if i remember correctly.
It's an honor system until you're placing a podium finish, which I plan to do. You're also suggesting I cheat the race by switching out "tags" on the compressor housing. Uh no. Not only is that un-ethical, I also feel it takes away from my very well thought out post earlier about a twin-scroll VF48HF. Please stop suggesting your notions and ideas. You're not being constructive.
oem_turbo is offline   Reply With Quote
Old 01-04-2021, 08:55 AM   #881
N-Bomb
Scooby Newbie
 
Member#: 309465
Join Date: Feb 2012
Chapter/Region: E. Canada
Location: Toronto
Vehicle:
1999 GC + ver 9 swap
Feather White

Default

Guys, is there a way to buy IHI turbos new? I'm looking for a bolt-in upgrade from my VF-37, and it's not easy to find a VF-36 around, nor do I know what to look for in terms of a used turbo's condition.
N-Bomb is offline   Reply With Quote
Old 01-05-2021, 01:32 AM   #882
oem_turbo
Scooby Newbie
 
Member#: 199558
Join Date: Jan 2009
Default

Quote:
Originally Posted by N-Bomb View Post
Guys, is there a way to buy IHI turbos new? I'm looking for a bolt-in upgrade from my VF-37, and it's not easy to find a VF-36 around, nor do I know what to look for in terms of a used turbo's condition.
Some are available through Subaru direct.
But that's exactly what I just posted.
An upgrade for your VF37 would be the VF48. Remove the turbine housing from your VF37 and bolt it onto the new high flow VF48. You'll make 400whp/400wtq with all the twin-scroll benefits. That's exactly what I want to do in the coming weeks.
oem_turbo is offline   Reply With Quote
Old 01-05-2021, 08:40 AM   #883
N-Bomb
Scooby Newbie
 
Member#: 309465
Join Date: Feb 2012
Chapter/Region: E. Canada
Location: Toronto
Vehicle:
1999 GC + ver 9 swap
Feather White

Default

Hey, thanks. I've never really been able to quite wrap my head around the black magic of turbos, except for some really basic things.

Would this combo be more responsive than a stock VF-37?




Quote:
Originally Posted by oem_turbo View Post
Some are available through Subaru direct.
But that's exactly what I just posted.
An upgrade for your VF37 would be the VF48. Remove the turbine housing from your VF37 and bolt it onto the new high flow VF48. You'll make 400whp/400wtq with all the twin-scroll benefits. That's exactly what I want to do in the coming weeks.
N-Bomb is offline   Reply With Quote
Old 01-05-2021, 01:52 PM   #884
oem_turbo
Scooby Newbie
 
Member#: 199558
Join Date: Jan 2009
Default

Quote:
Originally Posted by N-Bomb View Post
Hey, thanks. I've never really been able to quite wrap my head around the black magic of turbos, except for some really basic things.

Would this combo be more responsive than a stock VF-37?
It's okay. I know it takes a lot. I've had to do so much research to figure this stuff out too, especially when in keeping with factory IHI stuff.

About the responsiveness being great, i would say, YES. Here's my logic. The VF48HF (HF = high flow), that I posted about earlier has been doing better spool up than the old VF48 with pump gas 93 octane, apples to apples comparison. I think this lends itself to the aluminum compressor wheel that is lighter than the stock casted one and it also has better aerodynamics. I feel you will get all the VF37 spool with all the 400hp capabilities of the VF48HF.

Right now, I just picked up a VF37 for cheap with questionable life left in the CHRA. That's fine by me. All I need is the turbine housing like you. I already have a tired VF48 in my 06' STI. It's the off-season at the moment and my daily driver for a little while longer. I'm going to refresh the VF48 and bolt it against the VF37 turbine housing. Put on a 14.7psi wastegate actuator (so it doesn't creep open around 7psi so easily like the stock one does) and give it a mild retune to compensate for the better low end torque i expect to receive. I should make the same 300whp/300wtq like before but with completely different behaviour due to the twin-scroll turbine and twin-scroll factory exhaust manifold hardware. I should even pick up MPG around town with the extra torque and efficiency.

I want to see what kind of results I get for drive-ability and etc. Then, i'll swap to the VF48HF and make all the jam. I plan to do it with the plastic 08+ wrx intake manifold to keep my IAT down and it's a better more equally flowing manifold. That's for another discussion though. I may look into porting out the IWG holes a touch more so I can lower the backpressure as well. I do want to see how it handles it stock though.

I'll keep this group updated with my results as I progress.
oem_turbo is offline   Reply With Quote
Old 03-25-2021, 11:37 PM   #885
oem_turbo
Scooby Newbie
 
Member#: 199558
Join Date: Jan 2009
Default

Going back to what i said. I have finally got my turbo back from the builder. I went a slightly different but similar route.

What you see below is:

- VF48 Compressor Housing
- VF37 Twin-Scroll Turbine Housing
- Garrett G25-550 Billet Compressor
- Garrett G25-550 Turbine Wheel
- Upgrade Thrust Bearing Washer
- Arashi Dual-Port IWG Actuator with a 16psi Spring
- Silver Ceramic Coating

This setup has been proven on the VF39, VF48, VF52 turbos making 400whp+ with FASTER than stock IHI Turbo Response. This is the first of it's kind with a twin scroll turbine.

I am running 850cc drop-in side feed injectors, so I am limited to using 93 octane but I should be able to do a solid 350whp at about ~19psi. Still on the stock EJ257 motor, so don't want to push it too hard. Besides, I like to do things in stages. Over next winter, I will go with a complete fuel system that can e85 flex fuel and see if I can make all the 400whp jam i want.

The key to this turbo is, the G25 Turbine Wheel itself. The wheel is not only going to make it spool up faster due to the latest aero possible from the G-Series Garrett Turbo lineup but more importantly, it will lower the back pressure values. Allowing the motor to breathe better and being able to control boost much better. If you have a lower back pressure value, that means less mechanical pressure is being placed on the IWG flapper, making the actuator and boost control solenoid working a lot less harder.

- VF48 Turbo does full boost by 3000rpms on 93 octane
- Cobb TD05 20g does full boost by 3500rpms on 93 octane
- With twin scroll making things more efficient and the advanced G25-550 turbine aero and the fact that we have already seen faster than stock boost response with this turbine, i expect to do full boost by 2800rpms conservatively.


I initially wanted to do something that was going to keep me within competition guidelines for the GridLife Series but I have decided to put off those wants/needs for next year and i'll do it with a Honda Civic rather than the STi. I'll keep it as the weekend warrior that puts a smile on my face.

I'll keep this group informed with my progress. I did a dyno run prior to this and did 240whp/240wtq. To move up to 340whp and 340wtq with faster than VF48 Response is going to be a night and day difference.

......This should serve as PROOF that you can take a standard VF39 or VF48 turbo of any type you'd like and adapt an IHI Twin Scroll VF37 turbine housing with ZERO modification. VF58 is the king but in my humble opinion, I have it beat. This turbo is 400whp proven capable, faster boost response, lower backpressure ratios and for way less money. Under $1000 USD. VF58 does have the lighter turbine wheel and ball bearing. I say the G25 Turbine new age clean sheet turbine aero makes up for it.

Keep you guys posted! :-)

https://ibb.co/SwYfKhK
https://ibb.co/TbsgMDy
https://ibb.co/Dbn3DZN
https://ibb.co/7jYcHC9
https://ibb.co/YcJZZZy



Quote:
Originally Posted by oem_turbo View Post
Okay group.... been thinking about a few things with respect to the OEM++ theme of things Nick was talking about. This will be a long write up but it will be worth it.



Theory:
-----
I love the idea of OEM++. The USDM versions of the EJ motor can really be lethargic. They need a lot more response. I love the 2.5L displacement and the outright torque you get but the free spinning EJ207 engines with their shorter stroke and efficient header design screams joy.

Have you guys ever driven the FA20? The spool up is amazingly quick and really comes alive with a basic reflash to get rid of the rev hang and etc. To make the EJ25 spool closer like the FA20 (hard to do with the Direct Injection) but put out the 350-400whp range from a relatively standard IHI turbo is the way Subaru should have done it from the get go. Nick commented about this earlier in the thread when comparing the FA20 Turbo against the VF48,VF51,VF56,VF58. The FA20 engine kills it on torque.

My Engine Needs:
------** *8212;-----
I have a 2006 Subaru STi with the EJ257 motor here in the USA. Love the car. 68k original miles and the maintenance is tip top. I plan to race it in the Midwest Gridlife Street Series. We are only allowed factory turbochargers and can only boost 20% above stock. Has to have climate control and interior pieces. It's a street car with bolt on's for argument sake.

Ideally, the best turbo for me would be cheap, fast, reliable and a Subaru OEM part number. It should be twin-scroll, bolt-on, make 400+ hp and be ball bearing.

The fastest guy in the pack has a 2011 WRX with the S209 RA "HKS" turbo and absolutely dominates the field. The Evo's are genuinely fast as well with their turbos that are far larger and inherently boost more from factory but this guy takes the cake. I want to compete in this category and be competitive as well but don't want to spend $3,000+ on a turbo to do it, so i want to get creative and started doing my IHI Turbo Research.

Turbo Options:
------** *8212;-
1. S209 RA "HKS" turbo
- I can get this turbo and call it at day but at over $3,000 for this turbo ($4000+ MSRP) and hard as hell to come by from Subaru. For me, it's a tough sell. I enjoy the twin scroll operation from the EJ207's because it does that much better with half a liter down of displacement. Sure, it makes 400whp on e85 @ 18.5psi but I'm not getting twin-scroll operation and it's mighty expensive.

2. VF58 or VF56 or VF53
- VF58. hahaha.... it's more rare than diamonds and ungodly expensive. I am proud to see Nick (post above) got one. It's beautiful with it's ball-bearing CHRA and Ti-AL Turbine but Lord knows I can't find one without paying a massively for it. The VF56 is way hard to find as well and nearly on the VF58 level for rarity. I can get the VF53 from Subaru Japan and it's twin scroll but it's still up around $2900. That's another tough sell. I would still be down on horsepower out of all of these turbo's. They all max around 360whp on e85 and it puts me above the 20% extra boost rule.

3. VF42
- Would love this but very hard to come by and when I did find it on Japan Yahoo Auctions it was $2200 + shipping. I still would like more power. I don't see guys doing more than 340whp without a lot of boost and higher octane ratings.

4. IHI VF48 Hi Flow (New 2020)
- I can do this with a nice EL Header (KillerB) and make the 400whp at 18.5psi that I need to be competitive. But again, it's a single scroll turbo. At least it's cost effective and very much available. Sigh.....okay. NEXT.

5. IHI VF49 High Flow (New 2020)
- I previously mentioned this one above with my previous post. It's available for sale early 2021. I can place the order for it and should have it in time for race season this summer! But $2990 Shipped. Ouch! It's rated for 400hp and looks like the twin scroll version of the high flow VF48 stated above with a slightly larger compressor wheel, probably due to the inherent efficient nature of the twin-scroll design. BUT.... Why so much money!?

6. Custom option....... read next...!

Custom Factory Turbo
------** *8212;----
I want Twin-Scroll, 400hp, a lower cost and factory IHI components (due to rules and regs for street class racing rules).

The high flow VF48 from IHI is a journal bearing unit. If I forgo the ball bearing aspect of it and the twin scroll, it's the most ideal for my situation.

This is where it gets interesting. All the Journal Bearing turbine housings are compatible with each other. So.....If I were to get a VF37 turbine housing (twin-scroll), I can use it on any journal bearing VF-series turbo. Thus converting any single-scroll VF39,43,48, 52 turbo to TWIN-SCROLL operation without any modification to the CHRA.

Which means, I can buy the VF48 High Flow Turbo and swap a P25 VF37 Journal Bearing Turbine Housing and thus converting the new VF48HF to a twin-scroll using factory parts. I can look forward to seeing a potential 500-700rpms reduction in spool time switching to twin-scroll operation.

Parts Needed:
-----------------
1.Kinugawa makes the P25 Journal Bearing Turbine Housing (i will be using a factory IHI unit: https://www.ebay.com/itm/193804066067

2. The VF48HF Turbo is easily and readily attainable here: https://www.full-race.com/store/suba...and-04-07-wrx/

3. Upgraded Actuator is advised for 14.7psi (1 bar) to keep the IWG shut a little longer for better spool up instead of creeping open at 7psi on its way up to your full boost 18-20psi. Available from several sources but this one is my cost effective choice: https://www.ebay.com/itm/273820715136

Total Build Cost: $1470 (rounding up & w/ shipping)

In Conclusion.....

This would leave me with an IHI VF48 High-Flow Turbo that has been verified to make 400whp/400wtq @ 18.5psi and it makes 300wtq @ 2700rpms and 400wtq @ 3700rpms. All with E85 with and in Single Scroll Operation.

....... but instead, it SHOULD make a theoretical 300wtq @2200rpms and 400wtq @ 3200rpms due to the P25 VF37 twin-scroll nature of the turbine I would be swapping in. This should give any VF56 or VF58 or S209RA "HKS Turbo" a huge run for their money, at literally LESS than HALF THE COST. All factory IHI/Subaru Parts.

Notes that matter! I don't get the transient response of the VF58 that has a ball-bearing CHRA and a Ti-AL Turbine Wheel and no dyno can truly quantify what transient response really feels like. This is where the VF58 truly wins out but I can't have everything at this price point.

For comparison sake, the lead contender in the Gridlife Street Series Class uses the S209 RA "HKS Turbo" that makes 300wtq @ 3900rpms (93 octane), to be fair, E85 would shrink that another 400-500rpms cause you can throw more timing at it but lets say its 500rpms of spool cause of e85, you're 300wtq @3400rpms STILL! This turbo makes the horsepower but always around 1000rpms later compared to it's twin-scroll counterpart. Even a S208 with a VF56 demolishes the USDM S209-RA in responsiveness with 1/2 Liter Less engine displacement a touch lower static compression. Twin-Scroll Efficiency for the win.

I wouldn't be surprised if I don't make the same peak HP as the S209 RA "HKS Turbo" which is around 420hp but i'll demolish on torque made earlier in the power band and TORQUE is what accelerates a car faster, not Horsepower.

Even if you're not in the "Street Series" of Gridlife. This combo would be KILLER on the street and could make it boost a bit more around 21psi. I plan to have a couple maps made on my CobbAP to load so I can have fun on the street and on the track in different ways. I also want to push the limit off the track and see how much I can get out of this turbo.

I welcome any thoughts or feedback everyone has on this. I'm getting ready to move in this direction in a couple more paychecks.

Best,
Jonathan

Last edited by oem_turbo; 03-25-2021 at 11:46 PM.
oem_turbo is offline   Reply With Quote
Old 03-30-2021, 10:06 PM   #886
JOutterbridge
Scooby Newbie
 
Member#: 523371
Join Date: Mar 2021
Default

[quote=oem_turbo;46539478]Going back to what i said. I have finally got my turbo back from the builder. I went a slightly different but similar route.

What you see below is:

- VF48 Compressor Housing
- VF37 Twin-Scroll Turbine Housing
- Garrett G25-550 Billet Compressor
- Garrett G25-550 Turbine Wheel
- Upgrade Thrust Bearing Washer
- Arashi Dual-Port IWG Actuator with a 16psi Spring
- Silver Ceramic Coating

Any idea what the VF37 turbine A/R is? I know all the specs of the G25 550. I'd love to have that turbo too but I didn't know you could use the Garrett CHRA inside the stock housing itself. I was gonna get a separate manifold, I didn't even consider twin scroll....
JOutterbridge is offline   Reply With Quote
Old 03-31-2021, 10:49 AM   #887
oem_turbo
Scooby Newbie
 
Member#: 199558
Join Date: Jan 2009
Default

[quote=JOutterbridge;46542269]
Quote:
Originally Posted by oem_turbo View Post
Going back to what i said. I have finally got my turbo back from the builder. I went a slightly different but similar route.

What you see below is:

- VF48 Compressor Housing
- VF37 Twin-Scroll Turbine Housing
- Garrett G25-550 Billet Compressor
- Garrett G25-550 Turbine Wheel
- Upgrade Thrust Bearing Washer
- Arashi Dual-Port IWG Actuator with a 16psi Spring
- Silver Ceramic Coating

Any idea what the VF37 turbine A/R is? I know all the specs of the G25 550. I'd love to have that turbo too but I didn't know you could use the Garrett CHRA inside the stock housing itself. I was gonna get a separate manifold, I didn't even consider twin scroll....
STiNick posted some of his comments about A/R size:

https://www.iwsti.com/threads/stinic....319524/page-3

"For reference, the single scroll VF48's P18 turbine inlet has a non-ported cross-sectional area of ~1570 mm^2. That's ~40% less compared to ~2560 mm^2 for the non-ported P25 twin scroll housing. Also, the wastegate design is significantly better on the twin scroll P25 housing with its dual flappers (one per scroll)."

Don't know the exact size. The P25 is one of the largest, if not, the largest turbine offered for the VF series turbo's. Which makes sense considering the twin scroll nature of the turbo. No different than looking at the Borg Warner SXE series lineup of turbos. Take for instance a S300 sized turbo like the 8376. You can get it with a .88 A/R single scroll or a .91 Twin Scroll. You have to make that turbine slightly larger to accommodate the A/R demands for the split pulse. So it's not a .91 A/R really, it's more like .45 A/R per scroll. There are other factors as well, for instance, the IHI turbo will actually allow for the exhaust gases to hit the turbine wheel at different spots. One scroll will hit it at the tip of the wheel and the other scroll will hit in on the inside of the wheel. This allows for different torque on the wheel for different turbine speeds. You can see this also happen on more modern turbo's like the EFR lineup from Borg Warner.


Moving into the CHRA topic. The CHRA of a Garrett G25-550 is not a drop in, nor could you even do it. That's not how this modification works. You take the turbine wheel and compressor wheel, using the VF37 CHRA and adapt the wheels to that cartridge. The G25-550 compressor wheel is nearly a drop in with some minor machining. THe G25-550 turbine is a knockoff made from inconel for the OD of the turbine housing. The reason for this is, you can get all the advanced aero of the G25 turbine in a smaller package. It allows for a slightly fast spool up, less backpressure (meaning you get better WG control) and overall better flow characteristics across the rpm range.

To your last comment, If you're considering a twin-scroll turbo, I would pickup the standard VF37 turbo, manifold setup, do some basic maintenance along with it. Slap it on, and tune it. You'll make the same VF39/48 power but with all torque and the broader power delivery. Then, feel free to bolt on an upgraded/modified VF37 like mine. If you want ALL IN? Sure... you can. I can put you in touch with my turbo rebuilder out here in the midwest and he can have your turbo make all the jam.
oem_turbo is offline   Reply With Quote
Old 04-02-2021, 08:58 AM   #888
JOutterbridge
Scooby Newbie
 
Member#: 523371
Join Date: Mar 2021
Default

Fantastic explanation on the compressor and turbine wheel, thank you. I know that's a modern high tech twin scroll setup but I'm not sure if I'll need all that with the G series. It'll be good to compare though. I'm sure on pump gas it'll definitely be more responsive with the setup you have and be great for auto x.
JOutterbridge is offline   Reply With Quote
Old 05-24-2021, 10:55 AM   #889
Justablueru
Scooby Newbie
 
Member#: 524424
Join Date: May 2021
Default

New to the subaru owners club and took a peek under my hood and found out my car has a forced performance turbo... gonna go back to see which series it is but oh boy.
Justablueru is offline   Reply With Quote
Old 08-06-2021, 05:51 PM   #890
rpurcell
Scooby Newbie
 
Member#: 446521
Join Date: May 2016
Chapter/Region: W. Canada
Location: Vancouver
Vehicle:
2012 STi
Pearl White

Default

Some really good info here, thank you!
rpurcell is offline   Reply With Quote
Old 08-15-2021, 11:24 AM   #891
unisoft
Scooby Newbie
 
Member#: 524599
Join Date: May 2021
Default

Nice Info
unisoft is offline   Reply With Quote
Old 08-15-2021, 11:25 AM   #892
unisoft
Scooby Newbie
 
Member#: 524599
Join Date: May 2021
Default

Very Nice info, good to know !!
unisoft is offline   Reply With Quote
Old 08-16-2021, 02:58 AM   #893
Poke
Scooby Newbie
 
Member#: 526092
Join Date: Aug 2021
Default

Wow thanks for all the info man!
Poke is offline   Reply With Quote
Old 02-05-2022, 12:29 PM   #894
gtasti
Scooby Specialist
 
Member#: 152036
Join Date: Jun 2007
Chapter/Region: E. Canada
Location: Ontario
Vehicle:
2005 Sti
Wrb rhd

Default

Great info here
I'm getting a vf42 to replace my vf37
Wondering if it's worth changing the iwg waste gate or just keep it as is
Also keeping the stock bpv
gtasti is offline   Reply With Quote
Old 07-14-2022, 05:08 PM   #895
NateHornblower
Scooby Newbie
 
Member#: 530390
Join Date: Jun 2022
Chapter/Region: MAIC
Location: Northern Virginia
Default

Tons of excellent info in this thread. I've searched the thread but can't find anything specific to the following question (it could be my search-fu failing me)


Mitsubishi TD04L-13T - (390cfm at 14.7psi, 200-275whp, Bolt-On)

I have a 2002 WRX. Does anyone know what this changes to when the TD04 is rebuilt, ported and polished (hot and cold side)? Does it flow similar to a 19t? Would it make sense (e.g. fall within normal) for a P&P TD04 to hit 21psi @4.6k RPM in third gear at WOT (no CEL, no fuel cut off, just smooth pulling) then taper down to ~16psi at redline and not be considered overboost/boost creep? WGDC was 20, ticked down to zero as it climbed to 21 psi, then worked it's back to 20 as the psi started drop from 21. This would be with supporting injectors, fuel pump, catless up pipe, after market UEL headers, downpipe, CAT back.


Everything I've read makes me think this is within range for both the stock TD04 and especially a p&p TD04. Everything I've read (to include the compressor maps and discussions around them) seems to point to the fact that a p&pTD04 would flow more and produce more power (cerakote finish helping or not is a whole different discussion). Boost target is 18 psi on the tune so I can see why boost creep/overboost is the go to, but I'm not sure. The car did overboost and hit fuel cutoff at WOT in third on the stock turbo with the downpipe and CAT back - but from what I've read THAT is expected as the system is flowing too much/fast for the wastegate to handle so it flows to the turbine and you get runaway boost. But that's what fuel cutoff is for - last ditch insurance plan - because the boost will not taper down.



Anyone have thoughts? I feel like this should be it's own thread but I don't know where to put it.




NateHornblower is offline   Reply With Quote
Old 11-12-2022, 05:23 PM   #896
Robbo770
Scooby Newbie
 
Member#: 528162
Join Date: Jan 2022
Chapter/Region: International
Location: Scotland
Vehicle:
2009 Forester SH
Black

Default Vf57?

Any info on the ili vf57?
Robbo770 is offline   Reply With Quote
Old 03-23-2023, 03:02 PM   #897
oreganobag
Scooby Newbie
 
Member#: 518019
Join Date: Aug 2020
Default

I am nearly done with the build on my 05 STI. I'm going for OEM+ looks and performance on a stock block, and not looking to blow anything up or build a $10,000 block. I'm looking for advice on what to wrap it up with. Here is the mod list:

Engine:

Grimmspeed Dry Con Filter
Grimmspeed Postmaf Hose
Tomei Turbo Inlet
Stock Turbo
Grimmspeed Uppipe
Grimmspeed Limited Divorced Downpipe
Grimmspeed Headers
Boomba BPV
Tomei Expreme Ti Catback
Grimmspeed 3-port EBCS
Everything else is stock

Drivetrain:
Southbend Stage 2 Clutch
JDM STI Chromoly Flywheel
Fluidamper
InsaneShaft 500hp axles

It's got all the other reliability mods like a Killer B Pan, baffle and pickup, GAD 4th cylinder cooling mod, koyorad radiator, IAG AOS.

I'm not looking to add any more massive power. I like my 3000 RPM low end turbo spool that sits my ass in the seat and want to keep it down low like that.

I'm looking at adding a Hill Country restored VF48 turbo (Or the new redesigned IHI VF48 Hi Flow), ported and polished. Should I keep the stock compressor wheel size or step up to 16g? I'm not exactly sure what size the stock one is, or if I'll loose too much power down low going from stock to 16g or 18g or whatever. Should I go 9 blade or 11 blade wheel?

I'll also be throwing on a Killer B's hard turbo inlet.
With the turbo, my etuner said I might be close to maxing out my injectors, so any recommendations on larger injectors without going crazy? Would I also need a fuel pump and any recommendations there?

Any other recommended mods before I button up the car and start saving for a fresh high quality repaint and throw down some WRC rally vinyl on it like the 15 year old me always wanted? I'm not looking to go massively over 300 WHP (I think I'm at 260 - 280 right now) and I like the powerband the way it is right now (meaning I don't want the turbo to be so massive that I need to keep it above 5000 RPM for the turbo to spin).
oreganobag is offline   Reply With Quote
Old 03-23-2023, 03:03 PM   #898
oreganobag
Scooby Newbie
 
Member#: 518019
Join Date: Aug 2020
Default

I am nearly done with the build on my 05 STI. I'm going for OEM+ looks and performance on a stock block, and not looking to blow anything up or build a $10,000 block. I'm looking for advice on what to wrap it up with. Here is the mod list:

Engine:

Grimmspeed Dry Con Filter
Grimmspeed Postmaf Hose
Tomei Turbo Inlet
Stock Turbo
Grimmspeed Uppipe
Grimmspeed Limited Divorced Downpipe
Grimmspeed Headers
Boomba BPV
Tomei Expreme Ti Catback
Grimmspeed 3-port EBCS
Everything else is stock

Drivetrain:
Southbend Stage 2 Clutch
JDM STI Chromoly Flywheel
Fluidamper
InsaneShaft 500hp axles

It's got all the other reliability mods like a Killer B Pan, baffle and pickup, GAD 4th cylinder cooling mod, koyorad radiator, IAG AOS.

I'm not looking to add any more massive power. I like my 3000 RPM low end turbo spool that sits my ass in the seat and want to keep it down low like that.

I'm looking at adding a Hill Country restored VF48 turbo (Or the new redesigned IHI VF48 Hi Flow), ported and polished. Should I keep the stock compressor wheel size or step up to 16g? I'm not exactly sure what size the stock one is, or if I'll loose too much power down low going from stock to 16g or 18g or whatever. Should I go 9 blade or 11 blade wheel?

I'll also be throwing on a Killer B's hard turbo inlet.
With the turbo, my etuner said I might be close to maxing out my injectors, so any recommendations on larger injectors without going crazy? Would I also need a fuel pump and any recommendations there?

Any other recommended mods before I button up the car and start saving for a fresh high quality repaint and throw down some WRC rally vinyl on it like the 15 year old me always wanted? I'm not looking to go massively over 300 WHP (I think I'm at 260 - 280 right now) and I like the powerband the way it is right now (meaning I don't want the turbo to be so massive that I need to keep it above 5000 RPM for the turbo to spin).
oreganobag is offline   Reply With Quote
Old 04-06-2023, 02:42 AM   #899
weeznur32
Scooby Newbie
 
Member#: 533776
Join Date: Apr 2023
Default Informative

Glad this was stickied. Answered so many questions.
weeznur32 is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Subaru Wagons listed first on 10 Used Cars that Seem to Last Forever pepperjack News & Rumors 74 07-14-2015 07:07 AM
is there a Subaru turbo list? housedj General Community 8 03-18-2009 12:48 PM
subaru forum list 949 General Community 10 11-01-2005 11:32 PM
Subaru wish list carrera News & Rumors 9 06-19-2002 08:45 PM
('93-'01) Subaru Mailing List rubadub Impreza Forum 3 08-18-2001 02:40 PM

All times are GMT -4. The time now is 08:30 AM.


Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Powered by Searchlight © 2024 Axivo Inc.
Copyright ©1999 - 2019, North American Subaru Impreza Owners Club, Inc.

As an Amazon Associate I earn from qualifying purchases.

When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission
Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.