Swapping VF35 for VF34
 

I know that the VF34 is Roller Bearing with a slightly bigger turbine wheel but I have a VF35 as standard and would like to know if its worth spending £500 on a VF34.

What will I get for my money?

My VF35 makes

0.2bar boost at 1500rpm
0.5bar boost at 2000rpm
0.8bar boost at 2500rpm
1.5bar at around 3000rpm

It appears to hold boost pretty well and not noticed any tail off but I'm not normally looking when theres over 300hp driving me forward.

I would have thought that it would spool sooner and be stronger up top but not having any experience with the VF34, I dont know.

Long term, I want to fit a 2.5 motor in the car so this is a consideration for me also, would the VF34 work with the 2.5.

Thanks for any help.

The turbine wheels are the same, it's the VF35 exhaust housing that's smaller.

I doubt you'll get any power gains with a VF34, just a little more lag, and to be honest, if you intend to go with a 2.5lt at some point, I would stick with what you have, and change the turbo to suit your goals with the bigger engine.


Mark.

Half of me knida hoped somebody would say that and the other half wanted someone to say the VF34 would make 1.5bar at 2000rpm lol.

Cheers Mark,

why will the vf34 have more lag ?
surely a roller bearing will spool up quicker if the compressor and turbine are the same, as a roller bearing has less resistance than the sleeve bearing ?

Northan Nick who have you managed to get 1.5 bar at 3000 rpm what car are you running and to what spec?
I'm interseted as my 2003 sti dosn't make 1.5 bar till around 3500 rpm thats with tubular heades and 40mm uppipe.

Ian,

The smaller the turbo, the less difference there will be between the baring types, especially when in this case the size is the same, and the VF35 is also a very current design.

So the main difference is the size of the exhaust housing, and the VF35 uses a P15, over the VF34's bigger P18, which negates any advantage the ball baring core may have had.


Mark.

just buy an MD321T and be happy ALWAYS ;)

That would be nice but my VF34 gets to 1.45bar at about 3000rpm

These usually effect (slow) the response/spool by about 500rpm, although they are more efficient at the upper rpm range..;)

IMHO the VF35 is an excellent turbo, with very good low down response and capable of 320 to 350 bhp depending on supporting mode etc..:norty:

VF35 to VF34 will result in approx +10bhp and +100rpm spool.

Works well on a 2.5, very similar to the VF43 on the 2.5Sti, the 43 has a larger wastegate but the 34 wastegate can be ported to suit the increased flow of the 2.5.
A std 34 or 35 will normally boost creep on a 2.5.

Andy

The man above mapped the car only the other week, he's done a great job, Hello Andy.

Type UK STi V7

I slightly strayed on that as I've been logging a bit of info today, I have 1.45bar at 3050rpm but 1.5 at 3000rpm isn't far off.

I also dont have .5bar at 2000rpm but at 2200rpm but my figures aren't far off.

My boost does tail off at around 6000rpm, dropping to 1.25-1.3 at 7000rpm but I'm normally changing up at 6250rpm so not to much trouble there.

My mods are 3" full decat turbo back kakumei system, TSL WRC panel filter with Northern Nick's intake resonator mod, PFR7B's, walbro pump, earthing kit, oil catch can (Total VTA), throttle body coolant bypass & Northern Nick's automatic water spary kicking in at 0.9bar boost.

My mod on the res box made a massive difference to the turbo spool, but when you cut the box off, dont leave the in & out pipe linked as you may as well leave the box on if you do imo.

do you get these boost figures in 4th gear ?

mine made 351 bhp and 350 lbs torque with sports cat and vortex zorst, panel flter, tubular headers

I will try mine and campare boosting figures. your seems to spool quicker though !

It kinda does the same in 3rd 4th 5th and 6th apart from it tends to spike in 5th and 6th gear jusyt ever so slightly for a split second as the boost gauge give a short beep to say 1.5bar has been past.

You have some good figures there, mine made on Delta Dash 335hp 320lbs/ft.

Tried it last night in 4th made 1.5 bar at 3400 ish drops to around 1.25 up to around 5800-6000rpm then 1.0-1.1 at 70000

Have you still got your intake resonator box fitted?

yes if thats the snokel that fits in the inner wing

Its the big Y-piece and box set up the lives behind the driver sides wheel arch plastic.

Get it removed, cut the whole thing off so your only left with the two seperate pipes coming through the inner wing and the securing, thr rest in the bin. Keeping the 2 stubs allows you to refit the intake pipe and stops it rattling.

I should have taken photo's when I did it but I didn't think to.

Doing that to my made a huge differance to turbo spool time, but amd I will add, it does alter the characteristics of the turbo and may cause spikes at max torque due to the better air flow through the airbox, i.e. may need a remap to make 100% right.

Cheers.

thanks going to have a look at it this weekend :thumb: