Gear Head

iTrader: (2)

I have a standard sti 4 with a Blitz cat back exhaust and the vf24 turbo I believe. I will soon be purchasing an apexi power fc and was wondering if it would be a good time to upgrade my turbo, and if so, which one? Looking for around the 330bhp/ 330lb/ft mark initially before upgrading injectors, fuel pump/regulator etc.

TonyBurns

iTrader: (3)

A VF34 would suit you well here, roller bearing, and capable of 350bhp. Should be quite easy to come by also.
Avoid the VF35 though, not quite as good for your money.

Tony

mervil

iTrader: (5)

I bought a VF34 (STi8) which was a very good buy, spools up a lot quicker now! Think they're good for around 350bhp!!!

Paul

john banks

There isn't a huge difference between a VF24 and a VF34.

I don't think it is worth changing a turbo for <=10% power gain. When I've done this before I've regretted it.

I also prefer the VF35 to the VF34.

David MY99

John why do you prefer the 35 over the 34 ?
i've had them both and the VF34 spools earlier and can deliver a bit more topend power

RoRu

I all ways thought VF 35 =p15 exhaust housing and a slightly better spoll up but less top end and the VF 34 had a p 18 exhaust housing slower spool but top end delivery, (about to be corrected by the people in the know). In real world driving probably not much i it though.

TonyBurns

iTrader: (3)

VF34, rollerbearing turbo and lightened turbine, over VF35, sleeve bearing turbo... the VF34 was designed to be the quicker spooling of the 2.

Tony

john banks

VF35 spools earlier than VF34 because the smaller exhaust housing has more effect than the bearing, I feel the same between gear changes. I don't think the top end gain in the VF34 is worth the slight loss of spool up. I don't think the turbine housing is the big restriction, adds a little power but also raises the spool point, and I feel the balance is less favourable. Mark (EMS) has compared more of these VF3x series than me, and from what he has said he agrees. For a VF34 sized turbo I'd get a TD05-16G as the spool up : power is more favourable IMHO.

If you make the AR of the turbine housing bigger when it wasn't a big restriction in the first place then you don't improve the turbo so much (the turbine wheels are small on the on VF in relatively large housings, the P18 housing is bigger than a TD05 needs for 400 BHP).

So my batting order would be: TD04, VF35, 16G, 20G etc. Edit to say I would also take a few steps rather than just one in this order as an "upgrade".

john banks

http://bbs.scoobynet.co.uk/showthrea...ight=vf35+vf34

http://bbs.scoobynet.co.uk/showthrea...highlight=vf35

http://bbs.scoobynet.co.uk/showthrea...highlight=vf35

john banks

"I don't think the roller bearings will give you much of an advantage. It's more like a theoretical advantage in my opinion. How is the friction in the bearing compared with the rotational mass of the compressor and turbine wheel? I don't think it will be much of a difference."

"The last MY99 I did with the VF35, had 1 bar @ 2900 in 4th gear. Very responsive and it produced about 315 HP and 300 Lb/Ft. All this at moderate boost and with conservative mapping. The car only had free flow 2.5" exhaust, colder spark plugs and a Walbro fuel pump. I like this turbo more and more..... (the bad thing is that porting of the wastegate is needed)"

"We have tested on the GDB Group N cars the VF30/34/35, and my choice will be the IHI VF35 always ..... it will spool faster than anything else homologated, and at least with the 32mm restrictor it produces the same top end as the VF30/34."

TonyBurns

iTrader: (3)

John,
There should be considerably less friction on a rollerbearing turbo over a sleeve bearing turbo. As an engineering friend pointed out to me, roll a ball bearing in a cup and you get virtually no friction as it rolls freely with minimal contact, shove a tennis ball in there are you get 99.9% contact.
The lightened fins are probably an advantage, these seem to come with the rollerbearing turbos AFAIK, but the downside is that a rollerbearing turbo will be bigger, but should last (theoretically) much longer than a sleeve bearing turbo due to less wear (on the bearing).

Tony

Gear Head

iTrader: (2)

How much do these turbo's retail at?

Andy.F

I have dismantled TD05's that have done well over 100k miles and the bearing wear (sleeve) is just not measureable, sometimes with new bearings there is more clearance than with the old used bearings, this is just the tolerance during manufacture.
Your crankshaft main and big end bearings are sleeve type, there is no bearing to shaft contact, the shaft floats on an oil film wedge, same as the turbo.

Andy

john banks

Tony, I've had enough of marketing hype about ball bearing turbos that supposedly spool up in a light breeze. I couldn't give a toss which I have, it is the power band matched to the engine that is important. Best matches I've found happen to have all been sleeve bearing, best one I've had that spools up well but makes high power has been sleeve bearing. This is nothing to do with them being sleeve bearing though, just coincidence. Yes there may be an advantage to ball bearing technology, but it is wildly overstated as marketing hype.

WTF is the point of discussing tennis ***** in cups when we are talking about turbo bearings? Is this Play School or a technical forum based on experiences of people that have swapped these turbos, mapped them extensively and heavily tested them?

PSML at you telling him to avoid the VF35, what experience and knowledge do you have of this turbo? How many cars have you setup with it on?

Bob Rawle

The only problem I've had with a VF35 is keeping it right sided of the surge line (as per TD05/06), never had a problem with boost creep but that depends on what boost you want to hold at high revs I guess. Not much to choose between the TD05 and the VF35.

bob

David MY99

John,

The spoolup is a bit better with the VF35 to the VF34, i stand correct. The difference is only a 100rpm or so. Once your'e actualy on boost the VF34 come's earlier on boost is my experience.

The topend is also a bit better on the VF34.
On the roaddyno which i have from mark/EMS you can see that the car delivers 365hp around 5500 rpm and hold that figure till the redline. The VF34 has it's max power around 6200 rpm and delivers 20-30hp more. The 20-30 hp more is without a remap which should make it a bit more responsive and should keep its boost a bit better.

I'll choose a VF34 over a VF35 everyday now.
But it's always difficult to advice turbo's. Anything falls or stays with a propper remap and supporting mod's

john banks

If you get either at good money they are nice choices. But I would upgrade from a VF24 to neither, they are all too similar, yes the VF24 is an earlier generation, but there is not much in it. For the hassle of changing a turbo, and the purchase cost you may as well get something that makes a nice difference?

VF22-35 sit in the 310-370 BHP range from what I've seen. The dyno and the other mods/octane/tune differences make up a lot of this c.20% range I would say, bringing the real differences between the turbos to within 10%.

stevebt

iTrader: (8)

if your getting a vf34 , i have a friend who has just had his car r&R'd with one of these on and it made about 425bhp/370lbs torque but he mentioned something about the snail was ported and polished ?? he is running 1.5 bar on a gems and reckons its really quick but he drives like a nutter anyway

P20SPD

iTrader: (1)

steve, 425 from a 34?

David MY99

on a VF34 you max out around 375+bhp says the seller
A 425bhp is very unlikely. But then again i'm aiming also for a 400bhp setup with the VF34 with supported mod's as a powerdigger Fmic, GT spec gen II, link ECU etc

stevebt

iTrader: (8)

as hard as it is to believe it is true

john banks

You can port and polish the snail as much as you like But I don't believe 425 BHP on Optimax, without nitrous, on a factory Subaru 2.0 engine running a single VF34 and no other supercharging device. Can produce all the rolling road printouts you like, it isn't plausible. I thought we'd had this joke already?

RB5263

I'll let you know after christmas whether 400bhp+ is achievable with a VF34. Just waiting for the injectors. Admitedly I think my 399bhp figure was a tad high due to RR slip however I am sure you cannot dispute that currently I have atleast 380bhp and the torque figure of 382ft/lbs @4400rpm cannot be doubted, can it
http://www.proactive-it.co.uk/scoob/dyno031204.htm
The map had to be restricted due to the maxing out of the 440 injectors so therefore boost was dropped off at the higher end of the rev range. I am sure that with bigger injectors and boost levels held as far as they can be I shall be pushing a genuine 400bhp.

john banks

If the plot is flawed for any reason, it belongs in the bin and nothing can be inferred from it.

Before switching fuel injectors, I hope you were monitoring the fuel pressure. Wouldn't be the first person (or even expert) to go swapping out injectors when the fuel pump, upgraded or not, is what is struggling, or dealing with a dodgy regulator.

From most people's understanding of a VF34, you really shouldn't be needing bigger than correctly setup and regulated 440s if not using methanol and carefully setting up with a wideband....

RB5263

Richard Bulmer from TSL will be doing all the mapping after TSL have fitted the injectors. I have implicit trust in him.
If he's good enough to work on a certain Mr Sainz's car then he's more than capable of working on mine lol.

john banks

Indeed, but can he magic up >400 BHP from a VF34 when the 333 package doesn't often reach target, and is as we have heard up to about 20 BHP behind? This is no insult to TSL, Richard Bulmer etc, I just think 333 is a bit optimistic for some rollers, I'd rather understate the figures and ALWAYS exceed them on ANY rollers, especially with such confrontational advertising

stevebt

iTrader: (8)

i know i stated a figure above but its a friends car, and thats what he said he got , as for richard at tsl , he mapped my car when it had a td05 on. it was ok then i took it to andyf and it was amazing IMHO i think john can map the cars better than richard

RB5263

I guess its all about opinions and such like. They have done ALL the work on my car with the exception of the six speed box (Roger clark did that). I am more than happy with the results I have achieved so far. They know what they have done to my car they know its limits and its capabilities.

I will never have the fastest scoob out there but what I will have will be quick reliable and I'll be happy knowing that. I am just trying to get the best out of what I have.
Alot of you guys are pro's and do this stuff all day everyday. Sadly I don't have the technical expertise or the expansive tool kit so rely on professionals like yourselves. The target figure since the car spun a bearing in standard form has always been 400bhp. I'm not far off and genuinly believe I can get that with my current build with new injectors and a proper map. If I don't then its GT35 hybrid time.
However give me a computer/ I.T related issue and then we'll see who the technical daddy is .

I would just like to say that I value all your opinions and genuinly make my decisions about the next step to the RB5 based on them. Keep up the good work.

stevebt

iTrader: (8)

you cant assume your car will reach a figure due to your mods etc i have the spec of most 400bhp cars and run boost that would take my car over 400ish but i assume my car is around 370bhp which isnt a bad figure and seems about right

RB5263

Steve my spec is as follows:
STI 9 Tuftrided, Cross drilled Crank:
JE Forged Pistons (0.5mm oversize)
Carillo Rods
ARP Rod bolts
Heads Polished flowed and ported
Cylinder block Over bored
TSL Uprated Oil Pump with oil pressure release valve,
TSL Equal length tubular header pipe
Group A Down Pipe (3 inch)
TSL decat centre section
TSL Firestorm back box.
Turbo smart BOV
1.2mm Metal Head gaskets
WRC lead copper bearings
WRC head Bolts
Ecutek Remap (1.5 bar Boost)
IHI VF34 roller bearing Turbo.
APS Cold Air Induction kit
Walbro Competition fuel pump
Samco Hoses ( turbo, coolant, ancillary and induction)
Cross drilled and grooved brake discs.
Ferrodo Racing DS2500 brake pads


Transmission
STI 8, 6 speed gearbox conversion
Roger Clark Motorsport Lightweight Flywheel (4.5 kg compared to 11.5 kg for standard)
AP Racing Clutch
Uprated Clutch release bearing.