After searching for ages in all sorts of places i thought i would put together a collaboration of everything i have found so far about the vf series 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.

PE 1818 The 1818 supposedly comes on boost extremely fast...which make it great for road racing or aggressive driving (remember to be responsible :^). The 1818 maxes out somewhere between 350-375 hp.

PE 1820 The 1820 is larger than the 1818 and is capable of running more boost, but at the expense of more turbo lag. Expect it not attain full boost until you have passed 4000 rpm. However, it can be tuned to 400+ hp.



IHI & Garret Turbo Specs
Model Type Compressor Inlet Diameter Compressor Housing Nominal Turbine Housing Turbine Approx A/R Compressor Wheel Blades Turbine Wheel Blades Waste Gate Actuator Turbine Casting ID & Batch
VF22 Roller Bearing 48.5 A 9.4 PZ20-H 94001 0.71 5 11 C395 H, H4
VF 23 Roller Bearing 46.7 B 9.4 PZ20-H 94001 0.71 6 11 C395 8psi TBA
VF 24 Roller Bearing 46.7 B 9.4 PZ18-H 94001 0.63 6 11 C418 8psi H, S4, 66
VF 30 Bronze Bearing 47.9 C 9.4 PZ18-H 94001 0.63 6 11 C484 H, S4, IC F55
VF 34 Roller Bearing

Garrett 400 Ball Bearing 53 - - Outlet Dia 51.5 - 7 9 11 psi
Garrett 450-500 Ball Bearing 53 Outlet Dia 46.9 - 7 10 14 psi




Turbo Type ----------- Approx flow @ pressure
Stock Turbo ---------- 360 CFM at 14.7 PSI
IHI VF 25 ------------- 370 CFM at 14.7 PSI
IHI VF 26 ------------- 390 CFM at 14.7 PSI
T3 60 trim ----------- 400 CFM at 14.7 PSI
IHI VF 27 ------------- 400 CFM at 14.7 PSI
IHI VF 24/28/29 ----- 410 CFM at 14.7 PSI
========= 422 CFM max flow for a 2 Liter at .85 VE pressure ratio 2.0 (14.7 PSI) 7000 RPM =======
IHI VF 23 ------------- 423 CFM at 14.7 PSI
FP STOCK HYBRID -- 430 CFM at 14.7 PSI
IHI VF-30 ------------- 435 CFM at 14.7 PSI
SR 30 ----------------- 435 CFM at 14.7 PSI
IHI VF-22 ------------ 440 CFM at 14.7 PSI
T04E 40 trim -------- 460 CFM at 14.7 PSI
========= 464 CFM max flow for a 2.2 Liter at .85 VE pressure ratio 2.0 (14.7 PSI) 7000 rpm =======
PE1818 -------------- 490 CFM at 14.7 PSI
Small 16G ------------ 505 CFM at 14.7 PSI
ION Spec (stg 0) --- 525 CFM at 14.7 PSI
========= 526 CFM max flow for a 2.5 Liter at .85 VE pressure ratio 2.0 (14.7 PSI) 7000 RPM =======
Large 16G ----------- 550 CFM at 14.7 PSI
SR 40 ----------------- 595 CFM at 14.7 PSI
18G ------------------- 600 CFM at 14.7 PSI
PE 1820 -------------- 630 CFM at 14.7 PSI
20G ------------------ 650 CFM at 14.7 PSI
SR 50 ---------------- 710 CFM at 14.7 PSI
GT-30 ---------------- 725 CFM at 14.7 PSI
60-1 ----------------- 725 CFM at 14.7 PSI
GT-35R -------------- 820 CFM at 14.7 PSI
T72 ------------------ 920 CFM at 14.7 PSI