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VF35 - VF34 Swap

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Old 10 June 2007, 06:57 PM
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B0DSKI
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Default VF35 - VF34 Swap

Is it a straight swap from a VF35, as fitted as standard to UK MY2003 STi to a VF34 as is fitted to a JDM MY2003 STi ??

If so what sort of power increase could be expected with the appropriate mapping after the swap ???
Old 10 June 2007, 07:53 PM
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Granby
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Yes they are a straight swap but there is very little difference between them, don't think you would get any major power increase by changing as i believe they are both good for about 350bhp, my VF34 is running 333bhp

IHI Turbos


VF22

This turbo has the highest output potential of all of the IHI VF series turbos and is the best choice for those who are looking for loads of top end power. The top end power however, does not come without a cost. The VF22 spools significantly slower than the rest of the IHI models due to the larger P20 exhaust housing and is much less suited for daily driving than some of the other models. Although the largest VF series turbo, the VF22 is not quite optimal for stroked engines or those who wish to run more than 20PSI of boost.

VF23

This turbo is considered a great all-around turbo. Like the VF22 it utilizes the largest P20 exhaust housing. This housing is mated with a smaller compressor housing of the of the VF24. This turbo is considered optimal in applications with range from mild to slightly wild. It does not have the same top end power of the VF22, but spools up significantly quicker.

VF24

This turbo shares its compressor housing with the VF23 however, this housing is mated with a smaller (P18) exhaust side. The smaller characteristics of this turbo allow it to provide ample bottom end power and quick spool. This turbo is very popular for Imprezas with automatic transmissions and Group N rally cars.

VF28

This turbo came standard on the STi Version 5. In terms of overall size, it is smaller than the VF22, VF30 and VF34, and about same size as the VF23.

VF29

This Turbo is nearly identical to the VF24, with the same compressor and exhaust housings. However the compressor wheel in the VF29 is has been changed slightly. The changes made to the compressor wheel in this model are generally viewed as improvements, and as such this unit is typically chosen over the VF24.

VF30

The VF30 is commonly considered the best bang for the buck turbo in the IHI VF series line. A relatively new model the VF30 features the same exhaust housing as the VF24 but a larger compressor side similar to the VF22. The combination of these two parts results in increased output potential without the lag associated with the VF22. Although it doesn't offer the top end supremacy of the VF22, the VF30 is a great compromise between these unit and the quicker spooling models.

VF34

The VF34 is nearly identical to the VF30, with the same exhaust housing and compressor. However the VF34 goes back to the ball bearing design, and in doing so achieves full boost approximately 500RPM sooner than the comparable VF30. The VF34 is the most recent IHI design and as such costs slightly more than its counterpart. Top end performance and maximum output are identical to the 30.

VF35

The VF35 has identical internals as the VF30 and it uses divided thrust bearings. However, the exhaust housing is a P15 which means this turbo will have fantastic spool characteristics. This turbo is standard on the new WRX Type RA. LIMITED SUPPLY.

VF36

Roller bearing version of the twin scroll VF37, also has a titanium turbine and shaft for even quicker spool. Same compressor housing as VF30/34, however twin scroll P25 exhaust housing provides slightly better top end output due to reduced exhaust pulse interference. This turbo is good for 400HP and used on JDM STI Spec C from 2003 onwards.

VF37 (thrust bearing)

Enter the age of twin scroll IHI turbos. Same compressor housing as VF30/34, however has a new twin scroll P25 exhaust housing that provides slightly better top end output due to reduced exhaust pulse interference. Twin scroll also provides better spool up for improved low down response over the VF30/34. This turbo is good for 400HP and used on JDM STI from 2003 onwards.

VF38

Twin scroll turbo with titanium turbine and shaft. Smaller compressor housing than VF36/VF37 provides tremendous spool up capabilities but less top end than VF36/37. The spool capabilities of this turbo are demonstrated on the JDM Legacy GT, which reaches peak torque at 2400RPM.

VF39

Single scroll turbo used on USDM STI and latest 2.5L STIs released internationally. Smaller than VF30/VF34.

VF42

Exclusive turbo to the S203/S204 models, this features a twin scroll design with a slightly larger compressor than the VF36/37 turbos and different turbine design (more blades). The VF42 is a roller-bearing turbo and is likely of similar size to the VF22 turbo, but with twin scroll exhaust housing for faster spool and superior top end performance due to reduced exhaust pulse interference'

Last edited by Granby; 10 June 2007 at 08:00 PM.
Old 10 June 2007, 08:22 PM
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Thanks for that Granby
Old 10 June 2007, 10:00 PM
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Can a VF37 twin scroll be retro fitted to a MY2003 UK STi ???
Old 10 June 2007, 10:04 PM
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Originally Posted by B0DSKI
Can a VF37 twin scroll be retro fitted to a MY2003 UK STi ???
You can but it's quite a bit of work (i've looked into it), you will need turbo - downpipe - up-pipe - headers & sump
Old 11 June 2007, 07:28 AM
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Originally Posted by Granby
You can but it's quite a bit of work (i've looked into it), you will need turbo - downpipe - up-pipe - headers & sump
Bugger that then
Old 11 June 2007, 07:31 AM
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Jap performance parts sell the whole lot as a kit.... or did?
Old 11 June 2007, 06:07 PM
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Originally Posted by B0DSKI
Bugger that then
Exactly what i thought
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