vf36

Subtle · Post by **Subtle** » Fri Mar 17, 2006 3:53 pm

Which new production models use the vf36 with the equal-length headers

free5ty1e · Post by **free5ty1e** » Fri Mar 17, 2006 5:41 pm

I don't know about the equal-length headers, but I do know the VF36 comes stock on a JDM STi "Spec C" - not entirely sure which 200x year model that was available on.

Subtle · Post by **Subtle** » Fri Mar 17, 2006 10:50 pm

Talked to the guys at Rocket Rally --they are using the headers off the sti 8 version or whatever. Rough estimate 1500 + the same for the vf36 in US.$.

The vf34 will be good and the new stuff is v. good.--at more than 3 times
the cost of dropping in the 34.

free5ty1e · Post by **free5ty1e** » Sat Mar 18, 2006 2:56 pm

Might have found another VF36 kit for sale on NASIOC:

http://forums.nasioc.com/forums/showthread.php?t=697442

edit: Now I'm confused. I also found someone selling a "twin-scroll" vf38 turbo, but it certainly does not look to be twin-scroll from the photos. Do the new JDM Legacy GTs come with a new style of IHI twinscroll turbo, or is this guy full of it?

http://forums.nasioc.com/forums/showthr ... light=vf38

mikec · Post by **mikec** » Sat Mar 18, 2006 3:05 pm

Yeah, I thought twin scroll stuff had dual inlets on the exhaust side, at the very least. That looks like any old turbo to me, aside from the compressor outlet.

Subtle · Post by **Subtle** » Sat Mar 18, 2006 4:59 pm

Chris--- I talked to the guy at his shop in Austin.

That kit was fluke and he has no idea when another would appear.

APS has the right kind of header.

I'm tempted, the budget can handle it, but my thrifty side is stalling me out.

free5ty1e · Post by **free5ty1e** » Sat Mar 18, 2006 6:05 pm

Word. It might be less painful to just get a VF37 setup, since Deadbolt can apparently machine these to accept the PE1820 compressor wheel; then you've got a nice Power Enterprises twinscroll.

I could do this to the VF36 but the replacement compressor wheel is not titanium, so it would be tough to give that up.

Once the VF36 setup is running, I'm going to seriously begin considering a VNT (variable nozzle turbo) setup for the other SS. I know that's a massive undertaking but I want to experiment with the technology... in theory it should result in the ultimate turbocharged vehicle with instant spool AND high top end.

Subtle · Post by **Subtle** » Sat Mar 18, 2006 6:27 pm

I'm not looking for huge HP. but a necessary improvement over the vf11.

This has taken me from thinking about a vf34 to the possibility of the twin scroll, which would provide a hell of a step to improved performance for street as well as a few track days.

My thinking remains simple--If the ball-bearinged 36 spools faster than a 37 that' good enough for me,
. Getting into modding the turbo itself seems of little interest for my objectives.

free5ty1e · Post by **free5ty1e** » Sat Mar 18, 2006 11:56 pm

I'm with you on that one.

Keep checking NASIOC, I've seen many references to sold VF36 turbos...

free5ty1e · Post by **free5ty1e** » Fri Mar 31, 2006 2:46 pm

After an exhaustive session repacking the truck, I managed to locate the VF36 and piping and set it aside. So far I've taken photos of the downpipe. I'll get photos of the rest this weekend and post 'em up here.

free5ty1e · Post by **free5ty1e** » Sat Apr 01, 2006 12:07 am

OK - got some photos together of the VF36 setup. The designation stamp on the turbo itself reads:

VF36 0210
RHF5HB24661E
14411 AA492

Obviously, the last line is the Subaru part number. If anyone finds out what this turbo costs from a dealer and even if it can be purchased, I'd be interested to see....

No visible part numbers on the pipes. The downpipe has an O2 sensor bung (and an O2 sensor, to boot!) on each end.

The oil pan, pickup, and matching Subaru gasket goop were just recently purchased from Michael at Star Subaru - thanks man!

There is NO shaft play whatsoever. This is the smoothest turbocharger I've ever turned with my fingers. I can imagine how effortless this thing would be to spool up.

Subtle · Post by **Subtle** » Sat Apr 01, 2006 12:15 am

Green with envy

entirelyturbo · Post by **entirelyturbo** » Sun Apr 02, 2006 4:39 pm

Good stuff man! I seriously can't wait to see this setup on your car!

I'll give the turbo part # a try tomorrow... I don't think it will work, but ya never know...

THAWA · Post by **THAWA** » Sun Apr 02, 2006 4:49 pm

Chris, can you take some measurements? Like inlet, outlet, I doubt you're taking it apart but if you do inducer/exducer, turbing blades, etc.

It's interesting that the VF36 recieves a bellmouth, I don't believe any other OEM downpipe has a bellmouth.

Do the other twin scroll downpipes have a bellmouth?

free5ty1e · Post by **free5ty1e** » Sun Apr 02, 2006 7:46 pm

I also thought it was cool that the OEM downpipe had a bellmouth. No idea if the VF37 also has one, but from what I understand the setups are supposed to be the same with the turbo as the only difference. So quite possibly.

Here's some measurements taken as best I could with a tape measure (not taking the turbo apart any time soon, of course):

Compressor inlet OD: 2 7/32" (57mm)
Compressor inlet ID: 2" (51mm) (also size of comp. inducer)

Compressor outlet OD: 2" (51mm)
Compressor outlet ID: 1 5/8" (43mm)

Turbine inlets OD: 1 7/8" (49mm) each
Turbine inlets ID: 1 11/16" (42mm) each

Turbine outlet OD: 2 3/4" (70mm)
Turbine outlet ID: 2 5/16" (60mm) (approx. size of turbine exducer)

BAC5.2 · Post by **BAC5.2** » Sun Apr 02, 2006 10:42 pm

free5ty1e wrote:I don't know about the equal-length headers, but I do know the VF36 comes stock on a JDM STi "Spec C" - not entirely sure which 200x year model that was available on.

Version 7. 2001-2003.

No production Turbo Subaru has used equal length headers.

THAWA · Post by **THAWA** » Mon Apr 03, 2006 12:55 am

All twin scroll turbo subarus use equal length headers, as do all the new (06)EJ253.

I don't believe version 7's were twin scroll either. I think twin started in version 8 for Imprezas.

Sweet measurements!

BAC5.2 · Post by **BAC5.2** » Mon Apr 03, 2006 4:42 am

I was thinking equal length, like aftermarket equal length. My bad.

I thought the V7 Spec-C's used a twin scroll VF36?

free5ty1e · Post by **free5ty1e** » Mon Apr 03, 2006 2:03 pm

Damn JDM labels... version this and spec that. That's about as confusing as the stage X scheme. How's a white guy in the USDM supposed to keep track of what's available out there?

BAC5.2 · Post by **BAC5.2** » Mon Apr 03, 2006 4:04 pm

Haha, who knows?

I don't know what benefit I see to a twin-scroll on a subaru would actually be. I mean, a twin scroll on an EVO, with the turbo sitting on top of the exhaust manifold, I can see the benefit. But how much of an advantage would a twin scroll yield? Maybe 100rpm sooner spool?

entirelyturbo · Post by **entirelyturbo** » Mon Apr 03, 2006 8:02 pm

Part number doesn't come up in my system. But if my manager gets a break sometime, I'll ask him about it and see what we can do.

Hardy, I know the 06 EJ253's have the front-side exhaust manifolds (the driver's side goes in front of the oil pan instead of behind it, like the turbos), but they didn't look equal-length to me.

NuwanD · Post by **NuwanD** » Mon Apr 03, 2006 8:19 pm

BAC5.2 wrote:Haha, who knows?

I don't know what benefit I see to a twin-scroll on a subaru would actually be. I mean, a twin scroll on an EVO, with the turbo sitting on top of the exhaust manifold, I can see the benefit. But how much of an advantage would a twin scroll yield? Maybe 100rpm sooner spool?

I've been fortunate enough to be in a car with a the jdm ver 7 spec-c swap (vf36) and the boost comes on quick and very hard with the twin scroll setup. 4 ppl in the car, dry clean pavement , very good summer performance tires... no launch and it spun the tires from a roll in 1st (not to mention 2nd and 3rd as well)

It definately makes a difference, and i'm hoping I can get the same setup at some point.

THAWA · Post by **THAWA** » Mon Apr 03, 2006 8:23 pm

Take the heatshields off, and you'll see.

Subtle · Post by **Subtle** » Tue Apr 04, 2006 1:20 am

On twin-scrolls it is not necessary to have equal length headers.

The key is to have it set up such that the firing order has the exhaust pulses hitting the turbo on alternative sides of the scroll. In this case discrete pulses are better than chaotic ones.

This spins things up faster than just an equivalent build up of pressure would do on a single-scroll.

Physics provides a description of "impulse" as having something to do with force applied over time. An analogy would be the difference between hitting a ball with a bat or merely pushing the ball with the bat.

Pedantically,

BAC5.2 · Post by **BAC5.2** » Wed Apr 05, 2006 3:44 pm

I understand the idea behind twin scroll turbos, and I understand the benefit of them in cars with super-short exhaust manifolds. But is it worth it?

I don't really know.

Externally gating a twin-scroll setup would be tricky... You'd need 2 wastegates, or you'd need an external gate mounted to the turbine housing. The first isn't reasonable, and the second is harder than it sounds.

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