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I'm looking for information on my '94 Legacy SS turbo system. I understand the stock turbo that should be in there right now is the IHI VF11, is this correct? If this is the case, will any IHI turbo bolt right up?

The important question is this - which commercially-available turbos have been discovered as direct replacements for the stock unit, while providing higher output / possibility of more boost efficiently? If I have to remove and replace my turbo at some point soon (the car's got 210,000+ km on it) I'd like to replace it with a better turbo. Anyone know what the options are?

And for the turbos that would almost bolt right up but require slight modification, please elaborate -- I am a little lost when it comes to turbo models and spooling and output efficiency...

Looking for recommendations from the pros.

Thanks

http://bbs.legacycentral.org/viewtopic.php?t=15892

http://www.deadboltspeed.com/subaruindex.html

There are two coolant lines and two oil lines that bolt to the turbo. Sometimes these need to be slightly modified to attach to the turbo. Also the compressor outlet points out at a certain angle... sometimes a different turbo will have a different angle, but you can change this if necessary. It is called clocking.

Our turbo has a 90 degree elbow on the compressor inlet. Later IHI turbos do not have this, like the WRX. So if you want to install one of those turbos you have to get the intake to bend that 90 degrees to get to the turbo somehow with the stock intake box.

The TD05-16G is a much better flowing turbo. Larger exhaust housing to flow more power. Deadbolt sells them as direct bolt on units to our engine.

Hmm, I see. Thanks for the info. Unfortuantely thats a bit too expensive for my... well, not tastes. More like... wallet. I was hoping for something a bit cheaper

Do all TD05-16g turbos have the proper coolant lines, oil lines, and that 90 degree bend on the inlet you spoke of? Or is Deadbolt modifying them and selling them to fit our cars? Maybe I could get a TD05-16g somewheres and have them monster-port and ceramic coat both ends, instead of dropping $1g.

Any other options for direct replacements that we know of? Maybe a turbo that almost fits with a known part to make that 90 degree bend for our compressor inlets?

93-96 STi's had this 16-g turbo. the ones on the site are new warrantied items. you can find used 16-g's occasionally. but don't get the one found on mitsubishis... only the one that came on the sti. It is relatively bolt on. You will have to modify the oil and coolant lines a little.

or you can find used ihi units like the vf-23 which would work really well on the engine. You'd have to fabricate something to make the 90 degree turn, though. it's pretty much a custom application whatever you decide to put on since these cars don't have a large following with only a couple thousand units existing on this side of the planet.

I see, thank you. I've looked up these turbos and I see graphs I don't understand - compressor maps? They have three axis and all sorts of curves on them. Would the VF-23 or the 16g be a better choice as far as potential power is concerned for an EJ22t? What is the main thing to look at -- rated CFM at certain PSI? If I'm going to have to slightly modify any turbo that's not a VF-11 anyway I'd rather select one with the most potential.

Of course, any suggestions or anything someone wants to point out would be appreciated too. I'm learning quite a bit here, thank you.

Also... VF-23s come with water jackets too right? I wouldn't want to get a turbo that wasn't water-cooled, since our systems already implement that anyway.

Is the VF-10 or the VF-11 larger? I've read some posts that state certain legacys have VF-10 turbos. Which do the north american '94 sport sedans have? Mine originated in Canada as far as I can tell.

They are identicle except that the VF11 has a slightly larger compressor wheel.

I thought and had posted that 4eat Legacy turbos came with the VF10 and 5mt Legacy turbos got the VF11 but we had at least one guy that has a VF11 on his 4eat, soooo that theory is kinda up in the air right now. It could be that they went to a larger (or smaller) compressor wheel in between model years but that's just a thought and not proven. Or it could be that wagons got the VF10 and sedans got the VF11, I'm not sure. The only way to know for sure what you've got is to check the #'s on the turbo.

I was afraid you'd say that. Well, the important thing is that the VF-10 and VF-11 both bolt up to all Legacys, correct? I'm trying to figure out if, no matter which one I have currently, the TD05-16g swap is still possible without too much modification.

Just the coolant and oil lines need to be swapped for that one, as long as its from a 93-96 wrx, correct? That sounds like a plan to me. I gotta find me one o'dems and have it ported and ceramic coated, and that sounds like an upgrade.

Anybody recommend any other turbo than the TD05-16g from 93-96 wrx's? Or is it pretty much the board consensus that it is the best turbo for our cars?

It is the best 90 degree elbow turbo for our cars. The high-output turbo that Subaru chose for our displacement engines (on the 22B) is the IHI VF-23.

You occasionally find these used on e-bay also.

hmm... what if I can find a TD05-16g in a junkyard somewheres and its crap - except for the elbow. Are those 90* elbows easy to remove and put onto a VF-23, assuming thats actually the better turbo for the job of boosting our engines the most efficiently?

Your not gonna find a Subaru TD05 in a junkyard in north america. Your gonna have to look overseas at yards. Maybe somebody on the Liberty RS http://www.rslibertyclub.org forum might have one. I waited over 2 years to get mine, it finally poped up on Ebay in the UK and I snatched it. From what I hear the TD05 is super reliable, and the power comes stunningly hard at ~4000 rpm. Its a laggy turbo but more then makes up for it in top end.

Mark,

Well, I'm not sure I'd like having such a laggy turbo - 4000RPMs is a bit high to wait for full boost. Are the VF-23's a bit more reasonable with the lag? How do they compare to a 16g for top end and potential?

Also... do I have to watch what car the VF-23 came from, like the 16g (Subaru not Mitsu), or will pretty much any VF-23 bolt right up except for the inlet bend?

The VF-23 is only for a subaru. They don't fit right in, with the inlet pipe being set up for the newer straight not 90 elbow like ours. The big thing is the bolt patern on the up-pipe and down-pipe is the same as stock. What do you want from a turbo? You will have to do a lot of work (fuel, ecu) to make any differences between those turbos come out. The only thing I can say is I don't care for mitsu turbos much, they seem laggy. I have not driven a subaru with a 16g or a VF-23. I have driven a lot of different cars with IHI's and mitsu turbos.
I'd say push the stock turbo before you buy a new one.

good advice at its best... pushing!

(I think im about at its efficiency limits now though...)

Try a DP without a cat I bet it's a whole different animal than stock, looking at your mods. It might give you an idea of what you want your car to be like when you are all done. I'll let you know when I figure it out for my car.

Hmm, havent looked at the exhaust system at all yet, you're right that would probably change the characteristics of the stock turbo a bit. Wait, are you suggesting I run open-downpipe? ... but I might drown out the sound of my BOV

I'm gonna have to get under there and see what can be done without actually going to an exhaust shop for a turbo-back, because that's some cash...

Also going to go find compressor maps for the VF-11, VF-23, and the 16g since we know they at least bolt up with some minor mods... I know I saw them somewhere in one of the searches I did. Then, I have to learn how to read compressor maps

The last page in the 1992 FSM scan .PDF file seems to be a compressor map for the EJ22 turbo - it does not say VF-11 anywhere on it, however. Is this the right map?

Straight DP is kind of loud for a street car. The stock DP with cat is pretty bad, after that the next thing is the muffler. I made a 2.5in bellmouth DP and I still need to replace the muffler with a straight through type. That's all I'm going to do with the exhaust untill I get crazy. I guess I could have gone full 2.5in but it wouldn't have made much difference without more boost. Have you seen my post on a making a hybrid IHI? I think it's a great turbo for the street. Full boost real low, doesn't run out on the top end like the stocker. Makes my old beat up Legacy way more fun to drive than my new WRX!

Kelley is running a vf-23 in his legacy with a front mount intercooler, and a turbo back exhaust along with headers, and a different ecu and was pushing close to 400 hp out of his car.

Plus he said he was seeing full boost around 2800 iirc.

Look up posts by Kelley. You should find some nice write ups.

K you got the right idea, keep the factory turbo and make a huge down pipe no cats and pick a muffler. this will give you no lagga and lots of turbo power at the top end. this set up will make you scared.

you can also put a ford thunder bird turbo on ihi warner ish, only the front housing and fan its tricky but it fits then you got to get a 90deg elbow agian. if you look in some scrap yards you can get a crazy elbow off of a pontiac turbo that one will work.

i got a ihi tdo4l wihch is on wrx turbos, it is just as fast as the factory turbo but you got to get a sparco 90deg elbow.

i dont think it will blow i got factory turbo on 750000ks still stong like bull.

wait.. I thought the t3 from the t-bird was an exhaust-side donor, not a compressor-side donor for a hybrid with our vf-11s.... right? Which would mean we retain the whole intake side of the vf-11, so no need to find a new elbow. Or am I way off? (again?)

I checked out that DIY hybrid post and am very interested to try it out. What kind of boost level efficiency are we looking at then? Can it hold to say 20psi then without pumping out the superheated plasma? I know with a turbo in its efficiency range at that boost level I will definately need larger injectors and more fuel flow, probably aftermarket injector control too, just planning for the future.

The "T-Bird upgrade" is usually the compressor (intake side) from an IHI RHB5 from a Thunderbird. The RHB5 / RHB52 series of turbos came with a few different compressor and exhaust wheels, and apparently the one on the Thunderbird had the largest compressor.

Ok, starting to make sense now. So I will need to search for that pontiac turbo for the inlet elbow as well while I'm hunting? Or can we remove and reuse the stock elbow somehow?

Do we have an exact model name for the specific turbo that came in the thunderbirds, other than RHB5/RHB52?

And... since we're using the compressor side of this turbo, anyone have a compressor map for it?

The stock elbow is held onto the stock compressor housing with two bolts, so it's plausible that you could make it fit onto the T-bird's compressor housing. Maybe you could shave the compressor inlet so it doesn't jut out, and then weld or epoxy on a pair of studs to go through the holes of the elbow.

I don't know if there are any more specific model numbers or anything. And I've never seen a compressor map from IHI except for the alleged EJ22T turbo compressor map at the end of the factory service manual scans PDF that Josh has.

I see. So the two-bolt pattern we've got to hold on our inlet elbows differs from that on the RHB5 inlet. Is this perhaps something that can be replaced with a 90 degree hose bend? Amazon Hose here in town has all sizes of rubber or silicon hosing, since they cater to large diesel truck needs. The RHB5, I'm assuming, has a straight inlet opening, over which a coupler may be clamped - correct? Perhaps I can fashion something to mate up to the stock pieces without having to resort to welding or epoxy, as I'd hate to have either of those fail on me.

Do we know what size the inlet is to the RHB5 turbo, and what size it has to connect to? (is this Boot B?)