David MY99

Hi guys,

My VF35 is broke so i've ordered a VF34 instead.
Can anyone tell me what i can expect from this turbo
What kind of boost can i run and do i need a remap with this turboswap?

Spec's of my 99 Impreza:

Walbro fuel pump
Hybrid Fmic
Apexi air filter
HKS SSQV
3" invidia exhaust
Spark plugs NGK PFR7B
Tek3 mapping
VF35 (which will be replaced by the VF34)
Supersprint Exhaust header
Apexi AVC-r

Boost settings:
0-5500rpm 1.4bar
6000 rpm 1.3 bar
6500 rpm 1.25 bar
7000 rpm 1.20 bar

Can the VF34 handle these boost settings
Any info is appreciated

Tia

97 rExy

Running simmilar boost settings although you will need 550cc injectors or bigger.
Not sure the bhp but it did trap 114mph at the dragstrip.
My time: http://www.freewebs.com/lil-rapa/images.htm

David MY99

I ran a 12.700 at the 1/4 mile with the VF35 with 330hp and 420NM
This was before i placed the exhaustheader and FMIC
After the latest ecutek i've had 365hp and 480 NM @ 18 degrees celcius
Running on the stock 440cc injectors.
I ran last weekend a 12.8 but the turbo was allready gone an could not create more boost then 1.15 bar. A bit dissapointing.
The car is mapped bij Mark Verhoeven (EMS)

The main question is, is the VF34 beter voor more power and same spoolup and do i have it to get remapped ? After the last remap the injector dutycycle had even more space but the VF35 was to small. I Think the VF34 an VF35 are almost the same. I think the VF34 has a bit more top end power

Here's the Deltadash run
http://www.2xceler8.nl/guests/Naughty/dyno13-5-2004.jpg

97 rExy

VF34 has P18 and VF35 P15 housing.
At your boost settings my 550cc(injectors) with VF34 running 85% duty cycle.
What is your trap speed ?normally the best indication of hp, and since both classic shape = same weight , it would be a good comparison.
Best trap I ve see for VF35 is around 108-109mph with VF34 110-114mph
ps.114mph = very low 12s ,high 11s with good driver.

David MY99

It's a bit offtopic but oke
Our classic weights with airco, ABS and airbags with spoilers etc 1300 kg empty

Our run of 12.700 had an trapspeed off 110 mph (174 km)
http://www.2xceler8.nl/guests/Naughty/12-700.jpg
An other run with ET of 12.7xx had een trapspeed off 111 MPH (178 km)

With our new setup we've had an 1/8mile in 7.7 Sec
Unfortunately was the turbo broke and couldn't we make a descent run on the 1/4 mile

I hope that the VF34 is a bit bigger than the VF35 an can hold it's boost a little better at the top. If that's the case i can hardly wait to break our own record and go into the low 12's

97 rExy

7.7 for 1/8 mile & 110 trap is well in to low 12s or better.
Vf34 with supporting mods , does low 12s(1.6-1.8 60') allday everyday!!!

Here:http://www.scoobymile.com/index.php

RB5_245

yes the VF34 is bigger. you're going to loose a bit of spool up but gain where the 35 would start to run out of puff at the top.

I don't know much about the avc-r but to keep the boost down at the top of the rev range you may need to reduce the wastegate duty cycle, I assume it will do this anyway but it may need a little help if it was orginally set up for a vf 35.

As for the extra airflow a 34 can provide, just be sure all the lights work on the knocklink.....

Dave

CustomScoobyIOM

VF34 is also a roller bearing turbo is it not so spool up is greatly improved?

David MY99

setting up the AVC-R is not a big deal
I'm running the car pretty much on the edge of it's capabillity. This setup was to much for the VF35. I don't want ot buy another Turbo each week.
So what is a safe pressure setup for the turbo with in mind the supersprint exhaustheader which drops the pressure by 0.15 - 0.2 bar.

I didn't adjust the boostcontroller, so the VF35 ran 1.55-1.6 in the midrange and at the top 1.35 which is to much for it.
I think i'll run the VF34 at 1.35 in the midrange and at the top i'll go to 1.1 till rev limit (7300rpm).
I think this turbo can cope with these settings but i'm not sure.
In the netherlands nobody has the VF34 and i'll be the first (-as i was with the VF35 also ;-) ) So i'll have to trust on the experience of the guys here.

And do i need another remap for the VF34 or can i just swap it and watch the AFR and knocklink

97 rExy

Lots of ppl here(Oz) running VF34 and is regarded as the best street turbo.
ppl swap to VF34 from TD04,TD05,VF35(new age STi),VF2X.
I was running VF23 for 2yrs .Although VF23 has P20 housing and suppose to be bigger, VF34 which i m running for more than 18000kms is simply outgunning it in everything,numerous dyno runs -drag strip-spool up-efficiency.
I m yet to see any VFXX including VF22 outperforming VF34 on any of the group dyno
days .
All "turbo group buys" here are:VF34

I run 1.4bar up to 6000rpm dropping to 1.25 @7000rpm
PS.Although my VF34 is not suffering from boost creep its best to port wastegate before installing it.AVC-R normally wouldnt solve boost creep with VF34.
Old dyno run,M line is for boost>>http://au.geocities.com/aretir2000/My97.html

RB5_245

What exactly went on the turbo? was it a product of huge egt?

the VF34 should be able to take you pretty much to the limits of the 440 cc injectors.

With the bigger turbine giving less backpressure egts should also be reduced and allow the same power at lower boost.

The boost you are suggesting though looks to be very low. I don't have the compressor maps for the vf range of turbo's though, so I'm not going to suggest anything

Dave

David MY99

The VF35 has run to much boost.
First i noticed an slower spoolup but blamed the summer, the next thing waht happend was "compressor stall' for a few seconds.
Adjusted the boostsettings and kept on annoying Porsche's etc.
Finaly it could not make more boost than 1.1 bar in the midrange with quiete some lag
Finaly broke down when i made a road kill on an old Porsche turbo .
could not get any more boost than 1.05 en at 5k rpm it started to whistle quite loud.

Have to take the VF35 off and see wat exactly happend. I'll have to wait for 2 day's, 'cause than the VF34 is here and i use the car as a dailydriver.
Wastegate is now lose so it don't make any boost at all at low revs

RB5_245

how long did the turbo last for then?

I'd have to agree with 97 rExy's set up. In fact that's what I run on the TD05/06

Dave

David MY99

Final question
Today arrived the VF34.
At what rpm does this turbo has 1.4bar?
My old VF35 had at 2900rpm 1.0 bar in 4th and 5th
The turbo lasted for 35000 km and has run 7500km with the supersprint header

i bought the VF35 second hand with 12000 km on it

97 rExy

TD04 was making full boost @2800rpm 4th,5th
VF34 full boost @3000-3100rpm.
PS.1bar @2900rpm with VF35 is tops!! and would say VF34 will hit full boost around the same with your set up.

David MY99

Spoolup seems to be equal. Only the VF34 spools quicker once you're above 3500 rpm and go to wot. This is probably the advantage of the rollerbaering vs the thrust bearing
The car delivers now the same power at 1.2 bar as the VF35 at 1.4 bar
Dutycycle is much lower at the same boost. The VF34 seems to have more potential.

i Need to get it remapped and will post the final outcome

PS 1bar @ 2900 rpm was with the standard exhaustmanifold. The supersprints delay's it with aprox. 3-400 rpm