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Discussion Starter #21
I haven't had any luck sourcing a VF56, but I was able to find a VF58 (ST14411ZR010) for the low price of $3,380 plus shipping.. I believe that this was the turbo used on the S206 & S206 NBR.

ST14411ZR010 / TURBO CHARGER ASSEMBLY / IMPREZA / subaru | part detail|JP-CarParts.com

I like the OEM/JDM rareness factor, but for that price I'd just go with something like the Blouch Dom 1.5XT-R twin scroll turbo with the JDM manifold and downpipe. It's a little bit larger of a turbo, but is half the price.

dlheman - very nice setup! Thanks for sharing all of the details. Any recommendations on where to source rare JDM turbos like yours? I'd love to do something like this to my '19 STI once it's paid off and out of warranty... but if I'm being honest, I probably wont wait that long :lol:
Hello,

I found the VF56 out of sheer luck - in Lithuania~! :D

It is a fantastic turbo for those who wants to have an immediate throttle response and linear power delivery. It felt a lot like supercharging than turbo charging if that helps.

Depending on your goal, the Blouch 1.5XTR twinscroll looks like a good choice. Maybe pair it with Tomei twinscroll manifold too.

While is nice to have a rare item, I simply did it for drivability. And it does spools pretty damn quick (understand this turbo is made for 2.0L) and we have to tame down the boost using 3 port ebcs. When my tuner was dialing the boost with oem 2 port ebcs, at the same wgdc he normally would set for 18-19psi for VF48 the VF56 shoot to 23psi. While the datalog showed no knock correction we think is best to lower the boost for longevity. My tuner had to reduced wgdc down and it still wants to stay at 20psi.

Even at that tune the Sport mode was unusable for daily driving because releasing the throttle between 3k to 4k rpm jerks the engine so hard as the turbo just wants to go. So either I be gentle with throttle by using intelligent mode or committed by using sport sharp which easily pass 4000rpm in a hurry. Thankfully the 3 port EBCS is able to tame down and smooth out the boost curve, settling at around 19.8 psi max boost and taper to around 15psi.

To this day I still hardly use Sport mode as intelligent mode is way more than enough for daily driving. I only use Sport mode on highway but in reality I don’t even need to. And this is at ambient tempt averaging around 32 to 34 Deg C all year long. It is that responsive and there is probably more left in it if I have FMIC and bigger injector. My HKS downpipe has two catalytic converter, and I am still on oem airbox and oem air filter too. Yet since the tune is very stable I probably don’t want to mess around with it anymore. Less wrenching and more driving is always better I guess.

So if your goal is drivability and ability to make use of the engine power for most of the time, this is a great way to do it.
 

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I like the OEM/JDM rareness factor, but for that price I'd just go with something like the Blouch Dom 1.5XT-R twin scroll turbo with the JDM manifold and downpipe. It's a little bit larger of a turbo, but is half the price.
Thanks for that suggestion, I had forgotten that you could get a twin scroll version of the Dom 1.5XT-R. My tuner has previously recommended the single scroll version to me. I'm wondering how the twin scroll Dominator would spool relative to the stock VF48. I'll have a hunt around for some info.

Looking around locally, I can't see anyone selling the JDM headers or downpipe, but the Tomei headers are available, and I found a downpipe made by AVO. I currently have a 3" downpipe and the Killer B Holy Headers with an EBCS and the stock turbo, so it does spool much better than it did stock. But the twin scroll sounds like it'd be great improvement for daily driving. I'll have a chat to the tuner about it.

After reading your thread dlheman I was inspired to try Intelligent mode again, and don't mind it, it's quite smooth, just need to plant the foot if power is desired. For a recent long highway drive, it got me very good fuel usage.
 

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Thanks for that suggestion, I had forgotten that you could get a twin scroll version of the Dom 1.5XT-R. My tuner has previously recommended the single scroll version to me. I'm wondering how the twin scroll Dominator would spool relative to the stock VF48. I'll have a hunt around for some info.

Looking around locally, I can't see anyone selling the JDM headers or downpipe, but the Tomei headers are available, and I found a downpipe made by AVO. I currently have a 3" downpipe and the Killer B Holy Headers with an EBCS and the stock turbo, so it does spool much better than it did stock. But the twin scroll sounds like it'd be great improvement for daily driving. I'll have a chat to the tuner about it.

After reading your thread dlheman I was inspired to try Intelligent mode again, and don't mind it, it's quite smooth, just need to plant the foot if power is desired. For a recent long highway drive, it got me very good fuel usage.
The AVO is probably cheaper, but JapanParts carries the HKS twin scroll downpipe w/ dual cats:
HKS METAL CATALYZER(33005-AF014) | JDM Japanparts.com | VAB/ GRB/ GVB
 

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Discussion Starter #24
The AVO downpipe is the one with cast bellmouth and can be separated from the rest of the downpipe piping right? If so, yeah they look cool. Speaking about downpipe, if you do this conversion and decide to place the OEM front 02 sensor on the downpipe - it won’t read as wideband (just in case you guys didn’t know).

The HKS kit is very nice, albeit expensive. That being said it does comes with dual cat which more often than not made things very expensive in Japan and Europe (check out downpipe from Miltek, Supersprint and Wagner Tuning).

There is a cheaper offering from SARD and that version has the option of running single cat. But, unlike HKS it only has a single mounting bracket, which seemed fine as any other aftermarket downpipe from US also come with just a single mounting bracket. You can also buy Miltek twinscroll downpipe but be sure to get the correct year model.

Here are some other twinscroll that are available on the market:

Another turbo that is available is from Tomei called TB380. This turbo is the result of collaboration between IHI and Tomei aiming to improve the top end of the standard turbo. A tuner from Russia claims this is the exact same turbo found in S207 (if the translation is correct). This is an OEM+ turbo and said to be 380bhp max.

Then there is a high hp option from Chevron Mortorsport UK, made by the famous Owen Development. This particular turbo is said to have the same spool of standard VF36 twinscroll but able to deliver 450bhp.

And then there a twinscroll by Steamspeed, which if I am not mistaken is a hybrid of VF36 and GTX28 turbo. Looks like a great option but I haven’t done much research about it.

So yeah, there are plenty of options depending on what your goal is.
 

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Discussion Starter #25
Oh yeah, be careful when buying turbo that fits jdm setup because some of them like HKS GT3RS and Lichtfield LM turbos are actually twin-entry single scroll turbo made to fit jdm manifold/uppipe. Just be sure they are true twinscroll.
 

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Discussion Starter #26 (Edited)
I found this chart:


GVB = EJ257 with VF48. (should be GVF, but it don't matter).
GRB = EJ207 with VF49 twinscroll
GRB Spec C = EJ207 with VF53 twinscroll
S206 = EJ207 with VF58
 

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I found this chart:
Image Link


GVB = EJ257 with VF48. (should be GVF, but it don't matter).
GRB = EJ207 with VF49 twinscroll
GRB Spec C = EJ207 with VF53 twinscroll
S206 = EJ207 with VF58
Thanks for sharing! It's quite sad how late the torque curve comes on and how early it drops off on the EJ257. I know it's a single scroll, journal bearing turbo, but I expected the extra 463cc of displacement to help offset that a bit. I'm sure the UEL header isn't helping the situation either.

Now only if we could overlay your EJ257 with VF56 twin scroll, ball bearing turbo :) I was really hoping that Subaru would at least put a ball bearing turbo on the S209, but it looks like the HKS unit is still a single scroll, journal bearing turbo.
 

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Discussion Starter #28
Yeah the EJ257+VF48 looks poor compared to its siblings.

And as the chart suggested; if your priority is broad responsive power and not so much as the top end then is a wise idea to use the jdm or other similarly sized twinscroll turbo on EJ257.
 

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Discussion Starter #29
Just to add more information:

WRX STI Spec C R205 (VF56 twinscroll)


2019 WRX STI RA-R (May not even be VF58 at this point).

Sorry for the bad pictures. Subaru used to post such graph on their complete car website but not anymore.
 

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Not 100% relevant, but I wanted to share this because I thought some may find it interesting. A comparison of the JDM S4 FA20 & EJ207 powerbands..

WRX S4 FA20

Max Power: 221kW (300PS) / 5600rpm
Max Torque: 400N・m (40.8kgf・m) / 2000-4800rpm
Engine upper limit rotation speed: 6500rpm

STI EJ207

Max Power: 227kW (308PS) / 6400rpm
Max Torque: 422N・m (43.0kgf・m) / 4400rpm (90% of maximum torque @ 2400rpm)
Engine upper limit rotation speed: 8000rpm

They both have a nice "table top" peak torque plateau thanks to the ELH & twin scroll turbo. The EJ207's peak torque band is a bit higher and narrower, but carries power higher into the RPM range developing a bit more peak HP.

It'll be interesting to see what Subaru can do with the next gen FA powered STI without having to worry about stepping on the EJ's toes.
 

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Discussion Starter #31
Not 100% relevant, but I wanted to share this because I thought some may find it interesting. A comparison of the JDM S4 FA20 & EJ207 powerbands..

WRX S4 FA20
Image Link

Max Power: 221kW (300PS) / 5600rpm
Max Torque: 400N・m (40.8kgf・m) / 2000-4800rpm
Engine upper limit rotation speed: 6500rpm

STI EJ207
Image Link

Max Power: 227kW (308PS) / 6400rpm
Max Torque: 422N・m (43.0kgf・m) / 4400rpm (90% of maximum torque @ 2400rpm)
Engine upper limit rotation speed: 8000rpm

They both have a nice "table top" peak torque plateau thanks to the ELH & twin scroll turbo. The EJ207's peak torque band is a bit higher and narrower, but carries power higher into the RPM range developing a bit more peak HP.

It'll be interesting to see what Subaru can do with the next gen FA powered STI without having to worry about stepping on the EJ's toes.
Is the EJ207 chart from the latest STI? Looks like they improved it from previous model.
 

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Discussion Starter #32
Comparison between FA20DIT (JDM spec) and the Legacy S402 with its 2.5L twinscroll.





Needless to say, I think the FA20DIT is a nice engine (I only tried it a bit on Forester XT).
 

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Discussion Starter #34
Actually, the GVF STI A-Line has an interesting torque curve of 350nm between 2800rpm to 6000rpm.
 

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...and the Legacy S402 with its 2.5L twinscroll.

Actually, the GVF STI A-Line has an interesting torque curve of 350nm between 2800rpm to 6000rpm.
You find all of the good stuff! I had no idea that there was ever a 2.5L twin scroll offered. Its poweband is very similar to the FA20. It'll be interesting to see what Subaru can do with the FA24DIT if the rumors of it powering the STI are true.

The STI A-Line's torque curve was more along the lines of what I was expecting for the S402's twinscroll 2.5L. Surprisingly, everything that I'm reading about the A-Line suggests that it has a single scroll turbo.
 

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Discussion Starter #36 (Edited)
Yes, the STI A-Line uses VF48 single scroll turbo.

Could be due to the use of automatic transmission.

There was also another 2.5L EJ with twin scroll which uses low mount turbo like the FA20. I think it is on a Legacy around mid 2000.

But yeah, Subaru could have just slap a twin scroll as standard on EJ257.
 

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Yes, the STI A-Line uses VF48 single scroll turbo.

Could be due to the use of automatic transmission.
That makes sense. They could have detuned the peak torque for the automatic transmission and made the curve look flatter. The A-Lines 350 nm is only 258 lb-ft. The current STI's EJ257 makes a peak of 290 lb-ft at 4,000 rpm. I'm betting if Subaru released a dyno chart that it makes at least 350 nm between 3,000-5,500 rpm.

Below is a dyno from Cobb for the '19 STI (stock vs stage 1). It holds the torque pretty well from 3,000 to 5,000 rpm. I could definitely see 2,800 to 6,000 rpm being over 258 lb-ft at the crank given the whp numbers.

 

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Discussion Starter #38
That makes sense. They could have detuned the peak torque for the automatic transmission and made the curve look flatter. The A-Lines 350 nm is only 258 lb-ft. The current STI's EJ257 makes a peak of 290 lb-ft at 4,000 rpm. I'm betting if Subaru released a dyno chart that it makes at least 350 nm between 3,000-5,500 rpm.

Below is a dyno from Cobb for the '19 STI (stock vs stage 1). It holds the torque pretty well from 3,000 to 5,000 rpm. I could definitely see 2,800 to 6,000 rpm being over 258 lb-ft at the crank given the whp numbers.

Image Link
That's it.

Twinscroll turbo is nice on EJ engine.

But I wonder how does an EFR single scroll feels like. Maybe just do a simple upgrade like EFR 6258, equal length manifold and turboback then tune it to suit within the limitation of the stock engine and fueling.
 

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Since this seems to have partially become the twin scroll turbo thread :)

Some details I found on the VF58 from Giorgio Provinciali at Advanced Sports Engineering Lab.

  • IHI VF58 twin scroll ball bearing turbocharger - ST14411ZR010
  • Used on the S206, S207 & S208
  • Larger turbo inlet ID (5mm larger = 54.2mm)
  • 6 blade compressor wheel
  • Titanium turbine wheel (9 blade)
  • Modern version of the VF42 & successor to VF56
  • Compressor housing designed for DBW throttle body
  • Good for ~350 whp
Advanced Sports Engineering Lab said:
As many of You may have noticed and many... - Advanced Sports Engineering Lab | Facebook
R205’s dedicated high flow catalyzer and S208’s IHI VF58 can now output a peak of power at about 7200 rpm (rpms are electronically limited to 8250) and an almost-zero lag twinscroll boost which peaks max torque from 2500-2800 to 4800 rpm. This is the ultimate iteration.
Advanced Sports Engineering Lab said:
VF56 (ST14411ZR000) basically was the DBW version of VF42. It was stock on R205.

VF58 (ST14411ZR010) is stock on s206/207/208.

Both have 9 blades TiAl exhaust wheel, ecc…

VF52 has same compressor wheel diameter size as 56/58 and its compressor is 100% interchangeable over their CHRAs (housings are not)

56/58 are very rare
Advanced Sports Engineering Lab said:
New gen IHIs like VF49, VF53, VF56, VF58 have a slightly larger turbo inlet and a slightly different compressor angle to better fit new ICs and throttle bodies.

VF42 turbo inlet ID = 49.2mm
VF58 turbo inlet ID = 54.2mm

VF58:




VF42 vs VF58:








And a repost of the S206 dyno since I found it in a bit higher quality:



VF56:
 
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