The AUSubaru.com.au Forums

Has anyone tried this combination ? Also dos the RS's turbo have the same type inlet housing (bolted on elbow) as the EA82's RHB52-VF11 .

Looking into Subaru factory turbos like TD04's , RS VF12 and Forrester TF035 . Any pics of the Lib RS turbo or the TF035 would be good .

Cheers A .

I'm a bit confused by all these RHB5 turbos but so far it looks like this .

VF2/VF4 standard on EA82T .

VF10 and VF11 almost identical except VF10's turbine has 9 blades and VF11 10 . I think they were std on Legacy auto (Vf11) and Man (VF10) .

VF8 , used on JDM upspec Legacy RS Turbo manual ?

VF12 , largest in series and found on ADM Liberty RS Turbo manual .

Its starting to look like a VF10 or 11 is a better upgrade on an EA82T as the VF12 is larger in its wheels and housings and possibly a bit laggy on an EA82T .

Thoughts ? Cheers A .

Not sure if you've seen Matt's awesome thread....has pretty much the exact info you need in regards to the physical fitting differences over the std EA82 turbo - in his case it was a TD04.
showthread.php?t=8233

Or mine, with the TF035 Suparoo's TF035 & WAIC install

I think the TF035 is a great replacement for the VF4 from the EA82T. If you want the boost to build a little slower, go the TD04. Both the TF035 and TD04 are a lot more common and have less ks on them compared to early lib/leg VF turbos

i think there needs to be a sticky with loads of turbo information. i know there's one in the tech manual- i looked at it last week but they are mostly wrx upgrade ones.
i think a listing of all the subaru used turbos- spooling ranges/what vehicles they are on/ retrofitting/boost capacity/avail/cost. i would but dont have enough time atm.

Early TD04's had an upturned compressor inlet i think.

I doubt I'll be able to resist researching these IHI and Mitsubishi turbos !

The thing thats hard to know is how much better will an EA82T run with a higher compression ratio , spider inlet and a header without that brain dead T piece in it .
It would be dissapointing to find that it wanted to boost too low and having to build another turbocharger . Its important to get the spool up in the right part of the engines rev range because if it's too low the engine response can be hard to regulate and fuel consumption will be poor . If its too high low end torque is poor and you have to rev it to make it go - also bad for fuel consumption .
I'd like to choose something that had slightly larger and smaller A/R turbine housings available because that makes it possible to move the onset of boost around in relation to engine speed .
Given a choice of turbines I'd always go to the slightly higher side because its this thing that drives the compressor and to a large degree dictates exhaust restriction - turbine inlet pressure or backpressure if you like .
Steep learning curve on turbine and compressor sizes and trims next week .

The reason why I started looking into RHB52's like VF8/10/11/12 is that they are sort of similar to the VF2/4 and that would make plumbing them in a bit easier . I do realise that the turbine housing inlet/outlet flange patterns are different to the EA82 VF2/4 but thats just one of those things .

Along the way I'd like to do better than the std cat and I'm wondering if Lib or Impreza down/cat pipes are similar enough to get in an L series once a later turbo is fitted .

Lastly I'd always get a 2nd hand turbo rebuilt or fit a new cartridge to the original housings .
Turbos are always fiddly to work with mainly because of fasteners on the hot side and the high temp environment they live in .

More later , cheers A .

high flow your current turbo... mine is and i come on to 6psi at around 2200rpm and 15psi at around 2800-3000rpm and it is good for 19psi... i think that this combination will be good for a high comp motor. will only run 10psi or 12 if the motor will take it with appropriate tuning.

when i was looking at turbos before the vf12 was going to be the better option and comes on to boost a full 1000rpm sooner than the tdo4 and on a rs running at 16psi is still making good power till 6000rpm.


We need to be adding stuff to the tech section, every bit of research your doing is unreal and a great insight... cheers all

discopotato03 wrote:Its important to get the spool up in the right part of the engines rev range because if it's too low the engine response can be hard to regulate and fuel consumption will be poor

I agree

Although my TF035 is fun and very drivable with its early onset of boost, i feel my fuel consumption has suffered.

I put it down to the fact that in normal driving, it goes from -10mmHg of vac on cruise to 3psi of boost with very little input from the throttle. I wanna get a piggyback computer and see if i can modify my fuel map to make it a little better.

The on boost to early and greater fuel usage is easy to explain .

When a turbo engine comes up onto boost the engine management has to dump in a considerable amount of fuel to prevent a sudden lean out .
Turbos need to be sized so that they don't spool up every time the throttle is opened even slightly .
IMO the idea is to get the engine to stand on its own two feet initially (pre boost) and have the extra torque from boost only there initially if you open the throttle by a fair amount .

The trouble with small engines is that they don't produce a lot of torque at low revs unless the turbo is sized on the small side , this is pretty much the story with L EA82T's in their low CR factory state of tune .
If you can make them breathe in and out more easily and boost the compression ratio a bit then the engine can pull harder without positive inlet manifold pressure . The next step is to use a slightly larger turbo , or at least hot side , so that it won't boost from such low revs . That way the exhaust manifold pressure will be less at low revs and light load which is a big help .

Cheers A .