Turbo ID for Larry Yee + much more Soob Turbo Info

[ssspoon@aol.com]

We got the following from Larry Yee "lgyee4" <lgyee4@yahoo.com>
Subject: turbocharger id

QUESTION
Does anyone know the model number of the turbocharger that comes as OE on a 93 legacy turbo (AT, Calif., etc.)?

ANSWER
Larry I'm not sure there were any Legacy Turbos built for California, nor whether the auto trans units differ from the manual trans turbos, but I don't think so.

I have seen the following designations for the North America unit
IIP 15-40
RHB5 and RHB52
VF11 and VF119011
P/N 14412AA070

QUESTION
Also, what are the options on replacing it with a better unit. I have heard that some legacy owners are replacing the stock unit with an IHI VF 24.

ANSWER
I believe many of the early overseas Legacys used a slightly larger VF10. The STi VF24 is probably a good choice too, or a WRX Mitsu TD04 or TD05 turbo.

Of the VF24, MRT says; "Best turbo for Auto’s and cars that want the best bottom end and least lag."

Just remember, since we got the only non-intercooled turbo Subaru, our turbo compressor outlet points up at a 45 degree angle to the throttle body, and everybody else's points horizontally at the intercooler inlet, or has an elbow to make the transition. Some adaptation will be necessary.

QUESTION
What are symptoms of a bad wastegate control?

ANSWER
If your wastegate doesn't open, your turbo may overspeed/overboost, so your ECU should initiate an ignition or fuel cut


For a very extensive breakdown of various Subaru turbos go to MRT website Performance page

http://www.mrtrally.com.au/performance/

Go to Technical Info and Tips menu
Go down to forth choice Turbo Data
An Adobe Acrobat file will load and you're off and running
I have tried to duplicate most of the info below, but there are color pics and a comparison chart that don't copy/paste very well

FROM MRT WEBSITE

Typical applications

The “VF” series of turbo’s all have straight inlet paths, so when fitting to early Legacy/Liberty and
WRX’s they need major changes to the compressor housing to take the elbow inlet. OR a modified
inlet manifold is required. (THIS IS WHAT I WAS REFERRING TO)
All VF series turbo’s are manufactured by IHI, Japan
Typically all Sti models come with an IHI turbo, and All WRX’s come with a Mitsubishi turbo.
WRX’s Ver 1,2,3 all came with TD05 turbo’s with a 90 degree elbow inlet, whilst the later Ver 4
and 5 came with a TD04 that had a straight inlet path and was slightly smaller for better bottom end
performance and less lag.
All VF turbo’s and older units have built in waste gates.

Exhaust fitting and design

All VF series turbo’s feature the same bolt pattern and exhaust joints, so swapping them is
relatively easy.
The critical part is the design of the splitter for the exhaust collector. As the VF turbo’s have a
different depth to them when compared to the factory TD04 and TD0505. Meaning if you swap
turbo’s you should adjust the length of the splitter. A Splitter made for a VF turbo will be too long
for a TD04/05 (the exhaust simply wont bolt up) and a splitter made for a TD04/5 will be too short
for a VF and hence allow gasses to mix too early causing an increase in lag and less power. (for
more data on this exhaust feature refer MRT Performance)
If you require a turbo larger than a VF22 MRT recommend a Garret 400 – 450 roller bearing unit, if
you are building a serious drag car then a larger turbo with remote waste gate will be required

General

All of these above turbo’s have a 60mm Outside Diameter inlet to suit the OE inlet pipe.
Size of Turbo should be also considered for gas flow. With high output engines and or large
capacities, the physical size of the waste gate (hole) will be a restriction when added to the turbine
(hole) This is like fitting a big engine with a small restrictive exhaust
Hence the need (in some cases) for remote waste gates.
A remote waste gate will flow more, because it is larger, and effectively give better boost control.
The downside is they are awkward to fit and difficult to tune with the OE ECU.

VF22
WRX Japanese domestic market
Best turbo for high output engine. Highest capacity of all IHI “STi” turbo’s. OK for high boost or
stroker engines. Best fitted with cars that at least have a front mount intercooler. Not recommended
for really big boost stroker engines or cars that run over 25 psi boost.
Same Turbine housing and wheel as a VF23 (20) with larger Compressor housing.
Only fit this turbo if you have at least an exhaust, front mount intercooler and air inlet mods. Its
good also if you plan internal engine mods.
This turbo has the most lag of all the VF series.

VF23
Sti Ver 3 June 1996
Good all round turbo with straight inlet path
Same compressor housing and wheel as a VF24 with larger Turbine housing (20)
Great turbo for mildly modified cars and those who are unsure of their plans for the future

VF24
STi ver 4, June 1997
Common for Group N rally cars and has good bottom end. Not recommended for stroker engines or
engines with high boost as turbo is small and can over speed.
Same compressor housing and wheel as a VF23 with smaller Turbine housing (18)
Best turbo for Auto’s and cars that want the best bottom end and least lag.

VF28
STi Ver 5, June 1998.
Basically the same as VF24

VF29
WRX Japanese domestic market
Basically the same as VF24 except has a different location for the pressure hose on the waste gate
actuator
Compressor wheel is slightly different.

I HAVE TO SAY MRT GIVES SOME GOOD STUFF, AND THAT'S NO SHIT

Larry Witherspoon
Torrance (Los Angeles)
day/office phone 562-982-7720
larry.d.witherspoon@boeing.com
ssspoon@aol.com