coleman

iTrader: (3)

I'm very confused about all these turbos for Imprezas!

Vf23-24-32-34-36? Does the 23 denote thats its the smallest of the lot and grow in size from there?

TD04-05-06? 16g-18g and 20g? I take it the g denotes the size of the compressor housing?

I'm use to T2-T25-T3-T34-T38-T4-T66!

And all this 20g VF talk i havent got a clue about!
Would be very greatful if someone could take a little time to explain Subaru turbos to me in laymans terms.

Thanks
Rich

brownstain85

Confuses me half to death to!

midnight

iTrader: (10)

There are loads of threads on here regarding turbo specifications if you hit the search bar ,but here is a rough guide for the vf series:


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

The king

Here you go - all those turbos explained pretty good. http://forums.nasioc.com/forums/show....php?t=1141476

Fro

Can anyone tell me how a vf23, vf24, vf28 would compare to a td04 in terms of spool time/lag on a smaller engine?
Would i be right in saying the vf24 would spool quicker than the vf23 due to the different exhaust wheel?

Thanks in advance for any help.

midnight

iTrader: (10)

I had a brand new td04 fitted on my 99 uk turbo & that would start hitting boost at 2200 rpm, however once you were above 5200 rpm it had nothing left to offer . It is one of the smallest turbo in the Subaru range therefore offers quick spool up and lots of low down grunt. The vf23/28 don't spool up as quick (2800 rpm),but offer a good bit more mid range torque and able to produce more power than the td04,and hold boost much longer (above 6400 rpm).
To be honest A properly mapped turbo with decent supporting mods, should not feel that laggy,& even with the td04 you still need to be in right gear/rpm to get the best out of the turbo

joz8968

iTrader: (13)

Best way to try to choose a turbo, is for you to tell us what your absolute max bhp goal is - certainly for the foreseeable future (as you'll invariably catch the moddiing bug! )

Then that way, we'll be able to tell you the best in terms of quickest spool, price, robustness, age, etc, etc...

Fro

Cheers for that.
So the td04 is smaller than the vf24 and vf23?
The td04 will be going on my toyota starlet and will be relatively laggy, just wondered if any of the vf series would offer quicker spool up

joz8968

iTrader: (13)

The TD04 is the smallest/quickest spooling OEM turbo on the Impreza. It makes around 280bhp on the Impreza's EJ20 motor.

There also an even quicker spooling hybridised version of the TD04 sold by Andy Forrest.

The VF28/29 will be laggier but can make up to 330bhp on a 2.0L. (It's also still an impressively lively turbo on the EJ20, to boot.)

BTW, I sold my VF28 to a Starlet owner and he got it mapped to 302bhp

scubbay

iTrader: (61)

Quite a few Starlets local to me running vf23 with good success. Theres even one on an APS sr55 which is massive in comparison. The vf23 turned out to be the choice of the vf units after a few back to back tests. TD05 is another option.

Fro

Yeah, alot of people run the td04 on the starlet and with a whack of boost can see 260+ with not that much lag.

Due to not being forged ill be looking to run about 1-1.2bar but thought if there wasnt going to be much difference in lag with a vf series turbo id consider it for the extra kick

Thanks again for the info lads

joz8968

iTrader: (13)

Fro, I still have the chap's phone number, whom I sold the VF28 to. If you want, I'll quite happily PM it you so you can converse with him about how he finds it.

He had the ubiquitous TD04 on before, so is gonna be a great reference for a comparitor, between those 2 turbos, on a Starlet.

He's a friendly chap (and is well into his Starlets lol ) so I'm sure he won't mind you ringing -- just tell him you got his number from John, the seller of his VF28...

Fro

yeah feel free, no harm!

joz8968

iTrader: (13)

Done it!