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
