Useful Info for Scooby Owners
Discussion
Hi guys we are just posting some info on our website we think people may find useful. While doing that i thought we might aswell copy it over to your guys just in case any of you guys may need this info. Hope it can help:
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 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.
And also:
Boost Targets & Fuel-Cut Limits
WRX/STi Saloon ECU's 2C, U8, W6, W9 - As above, 11.47psi held to redline. Fuel-cut 14.57psi
WRX (1995/96) ECU Z4 - 12.71psi, dropping to 11.78psi @ 6600rpm. Fuel-cut 15.65psi.
UK/Aus/Euro ECU's V7, 7D and 6D - 11.47psi, dropping to 9.47psi at 6600rpm. With Fuel-cut @ 14.87psi
UK Prodive ECU - 13.33psi (peaks to 13.64 @ 5600rpm, drops to 12.71psi @ 6600rpm). Fuel-Cut 15.65psi.
STi RA (1996) ECU 7K - 13.17psi (peaks to 13.64psi @ 5800rpm). Fuel-Cut 15.96psi.
WRX Wagon ECU V9 - 10.55psi dropping to 6.84psi (starts to drop @ 5000rpm). Fuel-Cut 13.79psi
Z4 and UK Prodrive map are near identicle, with the Prodrive Map running slightly more boost.
Boost cut will feel just like switching off the ignition for a few seconds when you are at WOT.
It is not a good thing for the longveity of your engine and is best avoided.
When the engine boost exceeds a predetermined level it occurs to protect from overboost.
The boost on an engine can/will increase with certain mods. eg. ported headers, different exhaust system removing cats etc.You should have a boost guage and AFR meter before raising boost IMHO. A knock link is also advisable. The engine needs more fuel with raised boost and if it is run weak there is a distinct possibility of wrecking the engine.
Do not confuse boost cut with fuel cut which can be experienced when there is little fuel in the tank.(esentially they are the same effect) Fuel cut can be experienced on hard acceleration or long hard right hand corners where there is insufficient fuel to cover the pump pick up. Again this is a BAD thing.
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 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.
And also:
Boost Targets & Fuel-Cut Limits
WRX/STi Saloon ECU's 2C, U8, W6, W9 - As above, 11.47psi held to redline. Fuel-cut 14.57psi
WRX (1995/96) ECU Z4 - 12.71psi, dropping to 11.78psi @ 6600rpm. Fuel-cut 15.65psi.
UK/Aus/Euro ECU's V7, 7D and 6D - 11.47psi, dropping to 9.47psi at 6600rpm. With Fuel-cut @ 14.87psi
UK Prodive ECU - 13.33psi (peaks to 13.64 @ 5600rpm, drops to 12.71psi @ 6600rpm). Fuel-Cut 15.65psi.
STi RA (1996) ECU 7K - 13.17psi (peaks to 13.64psi @ 5800rpm). Fuel-Cut 15.96psi.
WRX Wagon ECU V9 - 10.55psi dropping to 6.84psi (starts to drop @ 5000rpm). Fuel-Cut 13.79psi
Z4 and UK Prodrive map are near identicle, with the Prodrive Map running slightly more boost.
Boost cut will feel just like switching off the ignition for a few seconds when you are at WOT.
It is not a good thing for the longveity of your engine and is best avoided.
When the engine boost exceeds a predetermined level it occurs to protect from overboost.
The boost on an engine can/will increase with certain mods. eg. ported headers, different exhaust system removing cats etc.You should have a boost guage and AFR meter before raising boost IMHO. A knock link is also advisable. The engine needs more fuel with raised boost and if it is run weak there is a distinct possibility of wrecking the engine.
Do not confuse boost cut with fuel cut which can be experienced when there is little fuel in the tank.(esentially they are the same effect) Fuel cut can be experienced on hard acceleration or long hard right hand corners where there is insufficient fuel to cover the pump pick up. Again this is a BAD thing.
Hi there. Very interesting stuff. 
According to the iwoc site (www.iwoc.co.uk/impspec2.html) my 1998 WRX has a VF22 Turbo, however I must say I have found the spool up time pretty good..(some boost from about 2000rpm) perhaps I am just used to it as it is my first Scooby.
Cheers,
Matt
According to the iwoc site (www.iwoc.co.uk/impspec2.html) my 1998 WRX has a VF22 Turbo, however I must say I have found the spool up time pretty good..(some boost from about 2000rpm) perhaps I am just used to it as it is my first Scooby.
Cheers,
Matt
Doc, you forgot to mention the notoriety of the VF22 for eating its compressor blades.
The VF22 is a shyte turbo IME and is only to be recommended if you send it off to TurboTechnics for their hybridisation surgery. Faster spooling and greatly superior reliability.
The VF22 is a shyte turbo IME and is only to be recommended if you send it off to TurboTechnics for their hybridisation surgery. Faster spooling and greatly superior reliability.
Edited by DocJock on Sunday 16th July 09:15
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