Turbo Compatibility

[crazyricochet]

Agree with Manaz's comments, it's all been done many times before.

The VF52 is the best bang for buck upgrade if you can get a cheap 2nd hand one, or if you spend around $1000 get a new Kinugawa 18g, or if you can afford to spend $2200 get a new ball bearing AVO 380/450 etc whatever tickles your fancy.

The more expensive options will be able to take you a bit further in terms of power but on a stock engine I'm slightly more comfortable with the OEM option. P.S Get the wastegate on the VF52 ported BEFORE you install it and find out it boost creeps to 22.5psi

I'm happy with the VF52 for now and leaving it like that until the engine decides to cark it. *touch wood*

Thanks James. I have never heard of the boost creep thing you mentioned if the wastegate was ported. What is that about?

Ok, I'm no expert on the topic some of this info may be not all technically correct but you get the idea. This is from me doing some research from google and talking with my tuner.

Boost creep is a condition of rising boost levels past what the predetermined level has been set at. Boost creep is caused by a fully opened Wastegate not being able to flow enough exhaust to bypass the housing via the Wastegate itself.

Say you meet your target boost - 18psi, the extra exhaust gas that's coming from your engine should be flowing out the wastegate as it opens because you're at desired boost level. But instead it keeps flowing past the exhaust turbine and not out the wastegate even when it's fully open, this generates more boost than required and suddenly you have no control over how much boost you make as the wastegate isn't taking enough gas flow away from the exhaust turbine.

Now on a stock car it's usually fine and not an issue but once you start adding intake and exhaust mods and turning the boost up and flowing more air it is really really common with these VF52s, some will do it worse than others but generally ALL will.

Numerous threads are found about boost creep with VF52s in google
http://legacygt.com/forums/showthread.p ... 00488.html
http://forums.nasioc.com/forums/showthr ... ?t=2021754

You fix it by "porting" the wastegate, this usually means using a grinder to increase the size of the flapper hole slightly and smooth out the internal area of the exhaust housing to allow the exhaust gas to flow towards the wastegate when it opens.

http://www.wrxforums.com/forums/11-suba ... ing-2.html

A stock VF52 has hard edges inside which seem to restrict flow. Porting it is basically the only cheap reliable answer any decent workshop should be able to do it if you can supply them with the turbo, although you can also use an external wastegate but that would cost significantly more.

Had mine fixed from a dude with an STI from facebook for $100. He'd done quite a few and didn't remove much material, mainly just smoothed out the internal areas and before I was boosting to 22.5psi, then after it was ported was dead level at 14psi and with a retune it's happily peaking at 18psi nice and controlled like.

I just wish I knew about it before I put it on, taking the turbo off again sucks balls but I wasn't aware of boost creep at all until I had the tune done.

[shav]

Thanks James, thats a great explanation. Much appreciated. If I go down this path, I'll get this mod done. Seems like a bit of added insurance otherwise I could end up with issues. Appreciate you spending the time to explain.

[Lane]

I wish that was my forum name now; The Boost Creep

[Gtb08]

Can anybody advise what model WRX VF52 turbo will fit an 08 Liberty? The models with VF52's are many. Just wondering if they are all the same and its just a newer unit that would be a better option

[jarrenowen]

Can anybody advise what model WRX VF52 turbo will fit an 08 Liberty? The models with VF52's are many. Just wondering if they are all the same and its just a newer unit that would be a better option

any vf52 will fit the 07-09 liberty gt's.
the VF52's are from 09-13 wrx's, not 08's as they got the td04.

[Gtb08]

Can anybody advise what model WRX VF52 turbo will fit an 08 Liberty? The models with VF52's are many. Just wondering if they are all the same and its just a newer unit that would be a better option

any vf52 will fit the 07-09 liberty gt's.
the VF52's are from 09-13 wrx's, not 08's as they got the td04.

Awesome, thanks mate....appreciated

[Gtb08]

Just been reading about how the VF52 are cheap and an easy bolt on mod get extra 10-15kw etc- how cheap are we talking?
I cant find a wrecker willing to sell one under $1100.

[shav]

Just been reading about how the VF52 are cheap and an easy bolt on mod get extra 10-15kw etc- how cheap are we talking?
I cant find a wrecker willing to sell one under $1100.

Be on the look out. They can vary depending on km's done and current wear. Between $600-1200 is the norm. Some can be had for less if you are a good negotiator.

[Gtb08]

Agree with Manaz's comments, it's all been done many times before.

The VF52 is the best bang for buck upgrade if you can get a cheap 2nd hand one, or if you spend around $1000 get a new Kinugawa 18g, or if you can afford to spend $2200 get a new ball bearing AVO 380/450 etc whatever tickles your fancy.

The more expensive options will be able to take you a bit further in terms of power but on a stock engine I'm slightly more comfortable with the OEM option. P.S Get the wastegate on the VF52 ported BEFORE you install it and find out it boost creeps to 22.5psi

I'm happy with the VF52 for now and leaving it like that until the engine decides to cark it. *touch wood*

Thanks James. I have never heard of the boost creep thing you mentioned if the wastegate was ported. What is that about?

There are a few threads on the boost creep issue. Common among many makes not just suburus.... I just ported my new vf52 just to avoid having to take it off at a later stage to do it. Will fit it up later this month. Main area im told and did was actually smoothing out the area where the up pipe bolts on to the wastegate door.

[dr20t]

Any of you know the wheel specs for a stock 52, inducer and exducers for comp and turbine?

Comp wheel:
Inducer 46.5mm
Exducer 60mm
Trim : 60

Turbine wheel
Inducer 52.8mm
Exducer 47.8mm

[andy_mac]

Mint. Same as what i've come across elsewhere. How would you expect a turbine wheel that size to cope with a twinscroll housing on an EJ25? Similar limits to the single scroll like the VF52

[dr20t]

Vf52 shares same compressor and turbine wheels as the vf37, which is essentially a journal bearing version of the vf36 twin scroll (ball bearing, titanium wheel and shaft) from the jdm ej207 twin scroll.

Compressor housings are different to suit different TMIC setups, but otherwise is a single scroll version of the twin scroll vf37.

If you're thinking of using this with your jdm legacy twin scroll headers - wont work. You need the vf36/37/42/49/53/56 style twin scroll headers. Any aftermarket twin scroll equal length headers will work too

[andy_mac]

Yea fully aware of the lack of compatibility between the leggy uppipe/headers and sti ones. Thinking more about the spare turbo and 257 shortblock i've got sitting here and getting some aftermarket headers.
Turbo's a custom one with the standard vf36 turbine and housing, upgraded vf36 core and vf22 comp cover with a 49.6/65.8 wheel. Trying to gauge a rough estimate I could get out of it on the 257 as there's next to no info out there for even standard vf36/37 turbo's on 257's

[dr20t]

Its the turbine wheel id be more concerned about on a 257. Would have some serious preturbo backpressure above 5500rpm and thus choke flow up top.

This is particularly true if you're using dual avcs heads...

Mick

[andy_mac]

Exactly what i was worried about. Does the 52 work out alright since its got the smaller comp side so it'll run out of flow on the comp side before it ever hits the wall with regards to egbp

Yea gonna be using the leggy heads.