legacycentral bbs

Just updating the title to reflect the path of the rest of this thread. I've finally gotten my VF36 twin-scroll turbo kit out of storage and will be preparing for it soon. Will take photos and post updates here. Moving to post at the end of this thread now.

Original title:
Twin-scroll headers!

Original first post:
Anyone know of a source for Subaru headers made for use with a twin-scroll turbo? I've been looking but I can't find any twin-scroll MHI turbos. I believe IHI or Garrett may make them, not sure yet. I like the idea of splitting the turbine input to allow for quicker spool-up of larger turbos, it really opens up the high-horsepower applications of our 2.2L engines.

Anyway, would I be looking for any existing headers or would this be a completely custom project? Aside from the oil and water fittings, which would more than likely have to be adapted, I suppose I'd just need the turbo's twin-scroll flange to have welded to my headers at an angle that would allow me to mount it.

How is the valve that allows or denies both turbine inlets access to exhaust airflow controlled? Is it electrical or mechanical, anyone worked with these before?

dont forget to get the oilpan too

i don't think there is any flow control valve... the exaust is simply splitted in two

yeah.. a twin scroll on a 2.0 is fully spooled to 18psi at 2500-2600 rpm I've heard of garret making twin scroll turbos, but i know IHI makes twin scroll turbos, the ones on the JDM STi are the VF36 and VF37 (on is ball bearing, one isnt) you can buy existing twin scroll headers from V8 and newer JDM STi's (i would try kingpin or some other importer) the downpipe flange is different on the twin scroll turbos, so you will have to have a downpipe custom made. the 36 and 37 just have a dual wastegate thing, so exhaust is flowing through both exhaust passages of the turbo all the time. and like morgie said, you will need an oil pan from U.S STi or something twin scroll. i think i have pictures of the headers and turbo if you want them. hope that helps.

Garrett twin scroll eh?


Like this one

Broken pics, Kelly

So anyway, twin-scroll turbos need a separate oil pan? Or did you mean to get a replacement oil pan for the engine with a different turbo drain fitting?

Yes, a twin-scroll, ball-bearing turbo would seem to be an optimum selection.

So certain STi's already have the right headers? Custom downpipe is no problem. I'm looking for information on the IHI VF-36 and VF-37 now, anyone have compressor maps or any info/ratings whatsoever? Compared to a 16G? An 18G? A 20G?

Which one's the ball-bearing turbo? That's the one I want.

no, if you use the factory subaru twin scroll headers, you need a oil pan like the one in the picture below. the headers run right through where half of the oil pan should be. somewhere i have a picture of the headers with all the metal coverings taken off of it, they are actually really well built headers.



this is what the exhaust side of the turbo looks like. see the dual wastegate thing going on.


the VF-37 is the ball-bearing version. here's some info on the turbo at subarureview

for flow charts and stuff i would search nasioc.

this link might interest you....... he's here in washington... but is everything you need+ some extra stuff

That looks like a pretty well designed turbo. It has pretty good separation of the turbine side & wastegate side.

Thats a NICE setup. I'm really liking twin-scroll turbine design, what a freakin' ingenious idea.

Which Garrett is that, Kelly?

Here's a request: Subaru OEM part numbers for the VF37 turbo, twin-scroll header, notched oil pan, and gaskets. Anybody have access to JDM part numbers?

Man I wish I could afford that guy's VF37 kit right now... maybe he'll have it for sale for another pay period or two

Found it! He referenced where he got his, and I missed it the first time, but I typed it into Google and here it is:

https://w109.webminders.com/iaperforman ... nNumber=67

He's selling his for $50 less than the place he got it from.

Edit: scroll to the bottom of the linked page, its the last item. Nice short blocks, by the way.

According to the Rallispec.com VF36 VF37 FAQ, the VF36 is the one with the ball-bearing (better) CHRA, whereas the VF37 has a floating metal bearing (worse due to oil drag?). Both are identical in specification otherwise, both twin-scroll.

I've gathered that Power Enterprises may make a dual ball-bearing version of the VF36/37. How much better theoretically should dual ball bearings be over the VF36's apparently-single bearing? How much better would the ball-bearing center in general be than the floating metal bearing?

I'm thinking it couldn't hurt to have every turbocharger efficiency feature possible, so a twin-scroll, dual ball-bearing ought to spool like a turbine half it's size... right?

i dont know if dual ball bearing would make that much of a difference... at least not as much as the ball-bearing / floating metal bearing does. i think the difference in the ball/floating bearings is a couple-hunderedish RPM.... but dont quote me on that.

yeah... i think all that stuff would help the turbo spool up alot earlier than a normal turbo w/o the twinscroll and stuff.

send Erik (the guy with the twinscroll setup) an email or something... he just had surgery today... so it could be a couple days to a week before you hear from him. he was going to put that twinscroll setup on his forester (it was a spare for his rally car) but then his plans "changed" and he's going a different path with the forester. he's a cool guy and if you are genuinely interested in it i think he would hold it for you, unless someone local came along......

Its a Twin Scroll GT32 Schweitzer. IIRC the A/R was around 1.00

The motor is a fresh EJ22T w/WRX heads w/TWE springs and retainers.



The wastegate pipe in this pic wasnt finished yet, but you can see how it goes.

This is a pic of the motor in the bay.


Sorry for the big pics.

mmmm, horsepower.

Damn thats sweet.

So it seems like the VF36/37 is an upgradable turbo as well, according to those on NASIOC. They say Power Enterprises makes a compressor wheel and housing that turns out to be a nice upgrade, keeps top end up with the VF22, which as I understand it is supposed to be the largest single-scroll turbo IHI makes.

Neat.

On the twin-scroll, Morgie says something about the exhaust being split or divided going into the turbo.

It's worth noting that the concept is to have each combustion impulse
hit the turbo at seperate intervals, rather than just one, more or less,
,continuous build up of
pressure. This is best accomplished by having each header arranged
with the firing order such that the impulses hit each scroll
alternatively.

In vocalizing it-- it would be "bang-whoosh, bang-whoosh", rather than
"bangs-whoosh". If you get my drift.

Bob(normally aspirated engines suck)
ps--interesting pics

If I understand your post correctlly, thats how our header is setup.

left, right- left, right.

The beauty of unequal length.

Legacy GT's and Outback XT's have this oil pan aswell. Pretty much any model that gets a twinscroll in another market has the oil pan. So theoretically you could use a VF38 from a 2.0GT, but it'd be more work to make it work, as it uses the same flange setup as the US 2.5GT

BAC5.2 wrote:The beauty of unequal length.

huh?

After some research, IAperformance regularly supplies complete VF37 setups for $1650 + shipping. Every 2-3 years or so, they get a spec C VF36 setup. They were asking $2200 + shipping for one they just so happen to have incoming.

But then I found this, and absolutely could not pass the opportunity up:

http://www.clubwrx.net/forums/showthread.php?t=112782

...yoink!!

congrats

Sweet shit.

When you get it, care to add information to the turbo thread?

i want info on this as well

but, of course. Many photos and measurements will be had by all, and it will be good. Especially on boost.

(I apologize for the delay; info to come once I have a functional shop/garage again and can unpack the turbo/headers/pipes & get photos/measurements)