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Discussion Starter #1
I did do some searching and found that most people don't go with these turbo's and actually put them down. From the research I have done this seems like a good bang for the buck upgrade. Z-1 performance offers it as a staged kit for the price that I see for just the turbo of another brand. To me it seems logical, I would think I could see a good gain in power especially in the top end while retaining the early spool up for daily driving. While I know I could make bigger #'s with a different turbo it seems that this makes sense for the street because there is minimal lag. What are your opinions? With this install and a protune I would think I could see some good #'s.

here is the link to that staged upgrade

http://www.z1auto.com/prodmore.asp?model=wrx&cat=turbo&prodid=1025
 

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styx said:
Those are for a WRX - do not monkey with those kits.
There are 100's of turbo threads; try the search button too.
exactly.
that's an upgrade for a wrx.
a vf34 might give you 5 - 10 hp over a vf39. that's it. not a worthwhile "upgrade" for an sti.


J.
 

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What about the VF22....it's the largest IHI right? How does it compare in size to say the 20g or Green? They state on their site that it was used on their STi engine swap project car.
 

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mtskibum16 said:
What about the VF22....it's the largest IHI right? How does it compare in size to say the 20g or Green? They state on their site that it was used on their STi engine swap project car.
VF22 ; flows around 440 CFM at 14.7 PSI
VF34 ; flows around 430 CFM at 14.7 PSI

VF22 has a 35 lbs/min compressor, and a p20 turbine housing
VF34 has a 35 lb/min compressor, and a smaller p18 turbine housing

the VF39 is almost the same as the VF34, but has a different variation of the p18 exhaust housing IIRC. resulting in faster spool, but less top-end.

please correct me if i'm wrong :)


for comparison; the popular 20G compressor wheel is 44 lbs/min and will flow about 650 CFM at 14.7 PSI

the FPgreen has a 49 lbs/min compressor. can't recall (or quickly find) any cfm ratings, but it's most likely more than the 20G :)


J.
 

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Get ahold of your regional chapter, either here or on NASIOC, and ride in some various turbo equipped cars. Don't waist your time with an ihi turbo...at all.

You have no idea what a 6speed and a 2.5 can to for ACTUAL spool/lag/boost threshold...it does wonders.

jtrafidlo said:
I did do some searching and found that most people don't go with these turbo's and actually put them down. From the research I have done this seems like a good bang for the buck upgrade. Z-1 performance offers it as a staged kit for the price that I see for just the turbo of another brand. To me it seems logical, I would think I could see a good gain in power especially in the top end while retaining the early spool up for daily driving. While I know I could make bigger #'s with a different turbo it seems that this makes sense for the street because there is minimal lag. What are your opinions? With this install and a protune I would think I could see some good #'s.

here is the link to that staged upgrade

http://www.z1auto.com/prodmore.asp?model=wrx&cat=turbo&prodid=1025
 

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HA, dont get an IHI turbo unless you are just replacing it and dont have money to upgrade. If you want a very reliable daily driver that you wotn have problems with go for a 20G setup. If you want a very fast daily driver that see's the track often go for a 30R setup. If all you do is drag race and go to the track and this is mostly a fun car then get a GT35R but make sure you have money on the side for a built motor.
 

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jph said:
VF22 ; flows around 440 CFM at 14.7 PSI
VF34 ; flows around 430 CFM at 14.7 PSI

VF22 has a 35 lbs/min compressor, and a p20 turbine housing
VF34 has a 35 lb/min compressor, and a smaller p18 turbine housing

the VF39 is almost the same as the VF34, but has a different variation of the p18 exhaust housing IIRC. resulting in faster spool, but less top-end.

please correct me if i'm wrong :)


for comparison; the popular 20G compressor wheel is 44 lbs/min and will flow about 650 CFM at 14.7 PSI

the FPgreen has a 49 lbs/min compressor. can't recall (or quickly find) any cfm ratings, but it's most likely more than the 20G :)


J.
Thank you for the info...the 20g is the smallest I would ever go. I am thinking 20g, Green, or GT52 right now.
 

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excellent post, looks like i'm headed the 20G route :D

jph said:
VF22 ; flows around 440 CFM at 14.7 PSI
VF34 ; flows around 430 CFM at 14.7 PSI

VF22 has a 35 lbs/min compressor, and a p20 turbine housing
VF34 has a 35 lb/min compressor, and a smaller p18 turbine housing

the VF39 is almost the same as the VF34, but has a different variation of the p18 exhaust housing IIRC. resulting in faster spool, but less top-end.

please correct me if i'm wrong :)


for comparison; the popular 20G compressor wheel is 44 lbs/min and will flow about 650 CFM at 14.7 PSI

the FPgreen has a 49 lbs/min compressor. can't recall (or quickly find) any cfm ratings, but it's most likely more than the 20G :)


J.
 

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When I bought my 04 STI it was one of the first ones in my area. Not much was known about the VF39 at that time. I picked up a VF22 at XX Tuning for next to nada just to see if it would wake up the 2.5L.

At the time everyone thought the VF22 was an upgrade to the VF39, well it is more of a side grade than an upgrade. All the VF22 does is more the powerband around a little, the peak numbers are almost the same. Also the VF22 has some lag when equipt to a 2.0L WRX but almost none when fitted to the 2.5L STI. Eveyone expected the VF22 to have more topend on the STI than the VF39 but it was the other way around. The VF22 spooled up insanely fast and made big torque numbers with only average power numbers.

I owned an 02 bugeye before the STI so I had the stage 3 Turbo XS kit for the 02 laying around the house. I decided to install the TXS TBE with high flow cat and 2.5" step down at the magnaflow muffle and TXS Type-H BOV on the STI. I sold everything else because the WRX UTEC wouldn't work with the STI's ECU and I thought the TMIC would be different also, I was wrong and kinda bent that I let the Hyperflow go.

So with the idea of going much bigger later I bought a set of PE850cc injectors and an STI UTEC and headed to XX for the install and tune.

The complete list of mods were:
VF22
PE850cc
Walbro 255LPH fuel pump
UTEC with map selector
XX Tuning header kit
TXS TBE w/ HF cat and 2.5" step down
Perrin short ram intake
TXS Type-H BOV

Here is the base line of the STI with the VF22, TXS TBE, XX Tuning header, Perrin SRI and TXS Type-H BOV with the factory ECU and stock fuel system.

This dyno plot is auto-scaled so it looks kinda funny. The WHP and WTQ don't cross at 5250 like a normal print out would.

After installing the Walbro, PE850cc and the UTEC Tony tuned the car for 20 PSI.

Again this is an auto-scaled plot but you can see how the car made torque very quickly with the VF22. The VF22 just didn't move enough air to carry the power higher into the rev band. I know that the tuning for our cars has come along way and the UTEC was the only EM that was avalible at the time I did this setup. I am sure that Cobb AP could have gotten more out of this setup that the UTEC and the step dowm and cat in the exhaust hurt my power also.

I can say that the car would just spin the tires in 1st gear and leave posi patchs when you shift into 2cnd under full throttle. For street use this setup was really responsive. Power was right there in any gear. The short coming was the lack of topend power.

Too many times I would go racing with friend to kill then to the 1/8th mile and just watch them tool on by at the end of the race, VERY frustrating. Cutting a .021 light and a 1.767 60' on a coldtrack in October, getting to the 1/8th in [email protected] and only running a [email protected] is preaty sad. Only gaining 19.76 MPH over the last half of the 1/4 mile sucked. I was always told that all cars are fast at the end of the 1/4 mile, being fast for the first 1/8th is the hard part. Again it seemed that my STI was the oposite of what was expected.

I would have to agree with most of the others in the fact that the 20G would be the smallest turbo that I would recommend for a 2.5L Subaru. Everything that I have seen show the 20G to be very well suited to our cars. It should be an all around great turbo for the 2.5L.

I personaly went with an SR55 for my next setup and I loved it. The power was silly and got me into more trouble that I was expecting. The 2.5L engine just seems to love turbos that can really shovel in the air.
 

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Discussion Starter #16
Thanks, It looks like I'll end up going with a 20G setup when I save some $.
 

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awd4life said:
limited in what way?? top end power, torque, spool characteristics, etc.....???? i'm curious as i'm considering this mod and some meth inj.

sorry for the thread jack, but it's still somewhat on topic. :p
The VF39's turbine just creates too much of a bottle neck for the exhaust side to truely breathe free. The VF22 has a P20 turbine and I think I read that the Vf39 has the P18, some people have said it comes with a P16 but I think the P18 is correct. I ran into back pressure issues while running the VF22 so the VF39 will have the same limitation.

Don't cut corners in respect to the turbo, in the end you will have just wasted time and money. Get the real deal first time around and you will be much better off.
 
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