Does anyone have the efficiency map for a stock turbo handy?

[ciper]

A graph would be cool, or if you know off hand what is the optimum range? At what point would the turbo (installed on a legacy 2.2 of course) reach the edge of the range?

I hear many mention running high boost numbers but they forget to tell what turbo is being used. I doubt the stock unit can be pushed that far.

[LegacyT]

For an RHB5 VF 10 like we have (US spec), the optimum is around 14-15 psi. That is with an easier breathing intake and a free-flow exhaust.

Mark,

[ciper]

Really? Stock pressure is far below that, why'd they choose this turbo?

[JasonGrahn]

For an RHB5 VF 10 like we have (US spec), the optimum is around 14-15 psi. That is with an easier breathing intake and a free-flow exhaust.

Mark,

Where did you get these numbers?

[ciper]

I found this

I talked myself into a larger IHI ball bearing turbo upgrade (more on that later). This compressor uses the same up-pipe and down-pipe as the Legacy RHB5 compressor, and is an upgrade compressor, not an OEM. It is not labeled with any model numbers, but it the equivalent to a Garrett T28 turbo which I am told is good for 14 PSI at 7,000 rpm before the thermal efficiency gets worse. I am told he legacy turbo is supposed to be good for 7 PSI at 6,000 before exceeding it's thermal efficiency (hence the 230hp max that Shiv talks about on the legacy turbo).

http://www.imprezars.com/sdsefi.htm

It says that 6k rpm at 7 psi on a 2.5l engine, so Id guess the legacy to be around 9psi?

Another site I found mentioned that 11 is about right on a 1.8 liter engine with this turbo. This was on a mazda 1.8 but it gives an idea.

LegacyT: I think someone may have gave you the info on the wrong turbo

[JasonGrahn]

I found this

http://www.imprezars.com/sdsefi.htm

It says that 6k rpm at 7 psi on a 2.5l engine, so Id guess the legacy to be around 9psi?

That's what you'll spike to stock if you put on a K&N filter and a 3" turbo back w/ no cat.

[LegacyT]

Maybe I got wrong numbers, but I remember seeing a graph of various CFM's for different turbo's (not the recent ones posted here and on nasioc) some 3 years ago, it had the RHB5 VF 10 on there and it showed something like 360 CFM at 14 psi, which isnt bad. I've ran 13 psi with no intercooler on 91 octane and the motor didn't mind it at all, which lead me to think that the turbo is still relatively efficient at around that level. But yeah, maybe the turbos happiest coolest pressure is at 9 psi, I don't know.

Mark,

[ciper]

Not completly related but these two links are great:

http://www.stealth316.com/2-3s-compflowmaps.htm http://www.opeltuners.com/turbo_efficiency/article.html

So what is considered the popular next step up from the stock turbo that is easily available?

[legacy92ej22t]

some usdm legacy's came with the RHB5 VF11 not just the VF10.Does anyone know the optimum for the VF11?


ciper- a nice saab 900 or 93-96 sti or '02+wrx usdm tmic.I haven't actually done mine yet but in doing research everyone told me an intercooler is the best next step for engine performance from the stock setup.the saab and usdm wrx i/c go pretty cheap on ebay but the 93-96 sti usually need to be ordered from new zealand or ausralia and tend to run a bit more.after that a boost gauge then boost controller.

[91scoobiesubie]

how do i know what turbo i have?

[Jaxx]

hmm that is intersting ... i thougth the vf-10 was smaller than that .. mine came from a jdm legacy GT (200 hp ~7 psi stock w/ air to water intercooler)

[legacy92ej22t]

http://www.ihi-turbo.com/turbo_RHE-RHF.htm

Heard the RHF5 is the new version of the RHB5 but is the same.this info doesn't list the different compressor sizes though.

[NICO]

hey i push the stock unit to 20psi it works good 4 me. it all depend s on what type off power or where u whant the power what r u trying to do. drag, track, street, hwy or like me all in one thats the beautie of all wheel drive ahahah. ciao

[ciper]

NICO I WRX U: Even before Im finished I have to say you are running too much boost on that turbo. The efficiency at that boost level will be REALLY bad, you might actually get more HP by dropping the boost!

[NICO]

i tried the drop to 15psi its so slow. i no why it sounds like a lot cuz the intercooler is so big. what i figer is the turbo fills the intercooler but when it gets in the motor its only 15psi so it filling it up at 20psi then drops once its fill up till i use it then if the blow off valve opens it loses agian tihs must sound nuts but i think this how it works so i am only get 15psi in motor and 20psi in the intercooler of build up and if u play wit the blow off it could play a very very very very big roll ciao.

[vrg3]

Nico, don't you have the T-bird compressor swapped in?

[NICO]

i did have it in i change it agian i dont like the spool up it gives me it takes to long. the factory turbo spins so fast it sends my car in worp speed. i got another turbo 4 a crazy swap it came out of a turbo xt the exuste houseing fan is huge i am going to mix all three to see what one i like so far the factory is the best.

[-K-]

The RHF turbos are ball bearing. As for the T-bird compressor, I get 10 psi at 1950. Through the stock exhaust! Good enough for me because the top end is much better than stock.

[EJ20TMAN]

hmm that is intersting ... i thougth the vf-10 was smaller than that .. mine came from a jdm legacy GT (200 hp ~7 psi stock w/ air to water intercooler)

Nah nah bro, they run 9-11 psi on stock JDM cars. They are only good for up to 14 psi nemore then ur just making hot air