Something from the old forum


IHI turbo.
The VF series (VF22, VF23, VF24, VF29, VF30) are the most common direct replacement turbos. All VF-series turbochargers use the same roller bearing, water-cooled core assembly. The differences are in their wheels and housings to achieve different flows.

The VF22 has the largest potential for peak horsepower. In other words, in the IHI model range, the VF 22 supports the highes boost levels. It is capable of running up to 25 psi. Because it is a roller bearing turbo, turbo lag is minimal...the boost comes on around 3300 rpm. Expect to max out the VF22 somewhere in the 400-450 hp range.

The VF23 starts the middle ground. It comes on boost around 3100 rpm and is capable of running 20 psi of boost. Expect to max out the VF23 somewhere in the 300-350 hp range.

The VF 24 starts to come on around 2900 rpm and will significantly improve power through the midrange over the stock TD04 turbo. However, the VF 24 is only capable of running around 17 psi.

The VF23 and VF 24 are a great replacement for those who value drivability higher than maximum power.

The VF29 & VF30 delivers a very wide increase in torque over the standard TD-series turbos. It is important to note that the VF30 is not a roller bearing turbo.

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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.

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)
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.

After the TD04
+500rpm lag on VF24/28/35
+600rpm lag on VF29
+650~700rpm lag on VF34
+800rpm lag on VF23/30
+900rpm lag on VF22

all on the same 3" exhaust after removing the std TDO4

All the turbo's with P18 exhaust housing & BB has good off boost response (VF28/34), and top end power of the 34 is very impressive , only down 3 odd kw on the 22 and yet heap more down low .

The VF30 starts late and come on fast , it has poor ish off boost response and very strong mid and top end .

The 30/34 & 35 have very good compressor wheels that work very efficiently and run lower intake temps and this is where the good power comes from .

The power on the 23 & 22 come from the open P20 exhaust housing, better exhaust flow and scavenging up top and the cost of some low to mid range power .

VF35 has identical internals to the VF30 and it uses divided thrust bearings. However, the exhaust housing is a P15 which sacrifices top end performance compared to the VF28/30/34's P18 exhaust housing.

The gains from the P18 exhaust housing is of better scavenging of the exhaust stroke in the top end , down side is the loss of low rpm torque as it allows fresh charge to exit the exhaust valves on cam over lap , much the same as what bigger cams do.

Summing that lot all up changing from a VF28 to a VF35 will give slightly (if any) more lag, but you will gain mid range power due to the more efficient (and slightly bigger) 6+6 bladed compressor wheel giving a cooler intake charge.

J

also
TD05/L TB, PZ?? - WRX MY94-96
TD04/L TB, PZ?? - WRX MY97-08

VF22 BB, PZ20 ex.h/48.5mm c.h/5b c.w/0.71 A/R - JDM MY97 V3 STi/1998/ optional 22B
VF23 BB, PZ20 ex.h/46.7mm c.h/6b c.w/0.71 A/R - JDM MY97 V3 STi/1998/ 22B
VF24 BB, PZ18 ex.h/46.7mm c.h/6b c.w/0.63 A/R - JDM MY98 V4 STi

VF25 TB, PZ12 ex.h/38.2mm c.h/10b c.w/0.36 A/R - JDM MY00 Legacy B4 Primary turbo
VF26 TB, PZ14 ex.h/38.2mm c.h/0.48 A/R - JDM Legacy B4 Primary turbo
VF27 BB, PZ18 ex.h/38.2mm c.h/10b c.w./0.63 A/R - JDM Legacy Secondary turbo

VF28 BB, PZ18 ex.h/46.7mm c.h/7b c.w/0.63 A/R - JDM/OZ MY99/00 V5/V6 STi
VF29 BB, PZ18 ex.h/46.7mm c.h/7b c.w/0.63 A/R - JDM WRX MY99-00 V5/V6 STi
VF30 TB, PZ18 ex.h/47.9mm c.h/6+6b c.w/0.63 A/R - JDM MY01 V7 STi

VF31 ??, PZ11 ex.h/??????
VF32 TB, PZ?? ex.h/46.5mm c.h/10b c.w/0.70 A/R - JDM/OZ Legacy/B4 Secondary turbo
VF33 TB, PZ11 ex.h/46.5mm c.h/6+6b c.w/0.75 A/R - JDM/OZ Legacy/B4 Primary turbo

VF34 BB, PZ18 ex.h/47.9mm c.h/6+6b c.w/0.63 A/R - JDM V7/V8 STi RA Spec C
VF35 TB, PZ15 ex.h/47.9mm c.h/9b c.w/0.51 A/R - OZ/UK MY02-05 STi
VF36 BB, twin-scroll titanium wheel/shaft - PZ25 ex.h/47.9mm c.h/9b c.w/0.63 A/R - JDM MY03-06 STi RA Spec C
VF37 TB, twin-scroll - PZ25 ex.h/47.9mm c.h/9b c.w/0.63 A/R - JDM MY03-06 STi
VF38 BB, twin-scroll titanium wheel/shaft - PZ?? - JDM/OZ MY05 Legacy/Liberty GT
VF39 TB, PZ18 ex.h/47.9mm c.h/9b c.w/0.63 A/R - US MY04-06 2.5L STi
VF40 TB, PZ17 ex.h - US MY05-07 Legacy GT/JDM Forester STi
VF41 ??, PZ18 ex.h - JDM Forester STi
VF42 BB, twin-scroll titanium wheel/shaft - PZ25 - JDM STi S203/204
VF43 TB, PZ18 ex.h/47.9mm c.h/9b c.w/0.63 A/R - OZ/US MY06-07 STi
VF48 TB, PZ?? - OZ/US MY08+ STi
VF52 TB, PZ?? - OZ/US MY09+ WRX

BB = Ball bearing
TB = Thrust bearing/Plain Sleeve bearing
ex.h = Exhaust housing
c.h = Compressor housing
(x)b = (x) bladed compressor wheel
c.w = Compressor wheel
A/R = Area to Radius turbine housing ratio
JDM = Japanese Domestic Model

http://www.dune-buggy.com/turbo/turbo.htm
http://www.gcg.com.au/technical/technical.html
http://www.ihi-turbo.com/turbo_RHE-RHF.htm
http://www.rb5286.pwp.blueyonder.co....rbo%20comp.htm
http://www.vividracing.com/turbodata.pdf
http://www.automotivearticles.com/Turbo_Selection.shtml
http://www.stealth316.com/2-3s-compflowmaps.htm
http://not2fast.wryday.com/turbo/maps

mods - sticky?

got any specs for a vf39?

yep, this is old news, need some details on the 39/43, the 36 and the 37. Paticularly sizing..

__________________
K.E.R.S!!!1

Isn't the 37 just a twin scroll 34?

VF37 is a sleeve turbo but same size compressor housing and similar exhaust.

VF36 is the ball bearing but the same size as the VF37.

AFAIK.

__________________
[DBR]

so do we have any flow rates for the 39/43 yet? is it bigger than a 35 and or 30/34?

cfms needed for the 36/37 and the new 43..

__________________
K.E.R.S!!!1

Hey all

Does anybody know what VF turbo comes standard on the 02 spec STi? Also, does anybody know of where to go for the full specifications of the 02/03/04 etc Sti's? Many thanks

__________________
...He said Smooth Bee the skins is fat
I don't beg cause I'm not in begonia
I dress warm so that I won't catch pneumonia
My rhymes are stronger than ammonia
I'm a diamond, you're a cubic zirconia

The 02/03/04 STI's all came with the VF35.

__________________
[DBR]