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Old 04-18-2002, 05:28 PM   #1
Scooby Newbie
Member#: 17584
Join Date: Apr 2002
Lightbulb best turbo for low boost RS-T?

I followed a link from the "Things to figure out before picking parts for your turbo project" thread and found this great calculator.


It is great quick tool that helps you find where your turbo will be operating in terms of efficiency etc.

Until I used the tool I had planed on using a T3 from a salvage yard, but the match to my application seems to be less than optimal.

plug in 5600 rpm
85 - 90% VE [I used 88%]
3.917" bore
3.110" stroke
boost pressure [ I used 5 - 7 psi ]

And you will get a pretty good idea of how different turbos will perform. It seems that the T3 is too big for the boost I want.

The problem is that the "tool" doesnt have maps for IHI compressors.

RHB52 is the most common subiecharger and I cant find maps for it anywhere. Does anyone have maps for the RHB52 or know where to get them? Yes I did a search

Another thought was the T25 but I cant find maps for it either.
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Old 04-18-2002, 05:41 PM   #2
Frank Army
Member#: 1457
Join Date: May 2000
Chapter/Region: SWIC
Location: Phoenix, AZ
1999 Outback Sport
Steel Blue Mica


And to think, most people feel that the T3 is too small for 5 - 7 psi... I ran a straight Garrett T3 on my RS-T prior to the protoype work that FAT did on my car (RS-TT) and thought it was about the right size...

Then I upgraded to the FAT Stage II kit, with the Stage III/T04E turbo... Now that is just about right... Lots of power from that baby with plenty more availible... I plan on running 10 psi starting early next week when Robert puts in the new spring... Even then I should be able to run 13psi on race gas... Lots of power out of that turbo....

But, if you don't want power, the IHI turbo's are great from what I've heard and read in here. Lots of guys are running the Legacy turbo's on their car... Nice little kit.
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Old 04-18-2002, 07:41 PM   #3
Scooby Specialist
Member#: 11931
Join Date: Nov 2001
Location: Winter Park, FL/ SMU @ Dallas,
2001 2.5 RS Turbo


The RHB5 is definetly a great little turbo, though many say that it is TOO small for the 2.5L engine. I'm running one on my car right now and it works awesome. Of course, at only 4-5 psi, its power output is limited. Once I can find a way to effectively raise the boost (external wastegate) then I will do so.

But, kastle is right, its not a bad solution if your looking to go turbo.

As for the maps, I don't have any/never seen any compressor maps for the RHB5, but I can provide them for the VF-22/23?

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Old 04-18-2002, 07:51 PM   #4
Scooby Specialist
Member#: 5778
Join Date: Apr 2001
Chapter/Region: South East
09 135i
Jet Black


I think the GT25 was one of the more sucessful turbos for that car. It looked small but it carried a big punch. I've been in a few cars with GT25's including DSM and Si's and they were very very nice compared to Kits running t3 or t3/4 hybrids.

A stock WRX or Legacy turbo generally works fine for beginning stage kits.

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Old 04-19-2002, 08:14 AM   #5
Scooby Specialist
Member#: 524
Join Date: Nov 1999
Location: WA
04 STi


I'd use one off of a US legacy turbo as they are dirt cheap out of the yards, and can be later upgraded with any turbo that bolts on a WRX.
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Old 04-19-2002, 10:06 AM   #6

Member#: 922
Join Date: Feb 2000
Chapter/Region: MWSOC
Location: Schaumburg, IL
16 WRX (white)
04 FXT (red)


Originally posted by XT6Wagon
I'd use one off of a US legacy turbo as they are dirt cheap out of the yards, and can be later upgraded with any turbo that bolts on a WRX.
The Legacy turbo (the early 90's ones) are actually smaller then the stock WRX turbo. I have a friend looking to upgrade his wagon to a turbo from a WRX... the intake side is slightly different in design, but with some creativity, it'll work (on that Legacy, that is).
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