ive got a my99 rb5 and was wondering what turbo i should upgrade to and what psi i can run . ive had suggestions of vf22,23,24 and 28's .any ideas whats best

also is nitrous a good mod for the scoobys

the car will be getting a custom remap after the turbo has been fitted but do i need any other parts . ie boost controllers or fuel pump etc etc etc

 

How much power do you want?

How much lag can you put up with?

How much are you willing to spend?

 

ill take as much power as i can get but i dont want front mount intercoolers or changing engine internals if that makes any sense . oh and i dont want it to go bang!!!!

my budget is pretty flexible ,just looking for a good value upgrade

 

its wanted for power up the box and the odd trackday. no more crails etc for me i think

 

Keeping stock engine and gearbox then, and particularly allowing the latter to stay likely in one piece for a decent time, I would suggest a VF35, full exhaust - choose backbox to determine noise levels, STi panel filter, resonator removal, new age STi top mount IC and larger scoop, ported OEM headers, fuel pump, 3 port solenoid, remap. This should give you a nice reliable free breathing motor that doesn't have too much lag, about 320 BHP, not too much torque to trash the gearbox, and not too much power to need bigger injectors.

If you don't mind replacing the gearbox and more lag, as above but a TD05H-16G (340 BHP) or 20G (390 BHP), 550cc or 740cc injectors, clutch, induction kit, aftermarket headers.

Power levels are estimates only, depends on rollers, reasonable for Star which is probably your nearest? Decat MY00 on these rollers about 220 BHP.

 

john, i got you to remap my 99 impreza (s300bty) about 18 mths ago.

anyway the car has full decat and panel filter with full prodrive but i dont think its as good as my tec2.5 i had before . awd suggested a vf23 turbo £725, and a custom remap £600 with a boost controller£100 ,fuel pump£130 and a reg £98 plus fitting . they said this would give me 330-350bhp @ 22psi . is this rubbish or an accident waiting to happen .any ideas where and what i should do

 

why not try another turbo and remap 1st, i took someone for a spin in my car when it had a td05 turbo and was running 1.6/1.7bar he was shocked at my car and amitted to someone i know that my car is much faster than his V6(2.5ltr) polo with 150bhp shot of nitrous

 

Looking at John's post above I think we should ask the Mods to make it a "sticky" ..............

Midlife.........

errrr with John's recommendations mapped by Bob Rawle

 

<cough> surely you mean andyf

 

Apologies for not remembering your user name

Re AWD recommendations, that is one way of doing it. My personal opinion is that the VF23 is a little outdated, the VF30/34/35 range or TD05 are a better choice these days I think unless the VF23 is very cheap, although I'm not saying it is a bady choice. Just thinking spool up to top end trade off here. All the other stuff sounds OK, main differences are that I suggested the intercooler and scoop to control heat, and produce more power at lower boost for reliability, same with porting the headers. The 3 port with a remap means you don't need the boost controller. As always there is more than one way to do it, a lot of it is opinion. 22 PSI is likely to produce quite a lot of torque (=trash your gearbox in short order IMHO), but the VF23 won't hold this to the top, and some of the older VFs have a habit of exploding compressor wheels over 20 PSI. So the boost level quote is more relevant to torque than power. 22 PSI at the top on a turbo breathing correctly is 400 BHP+ territory IMHO. If you roll off the VF23 to say 17 PSI at the top you might get about 330 BHP at Star with good intercooling.

 

Hi there

i was under the impression that the stardard injectors would max out way before this sort of power , but if the stardard injectors are fine for this sort of power it looks like you might have saved me a few £'s as i was gonna get 550cc injectors to go with a VF34 turbo but it looks like i might not need them now

Cheers
Granby

 

Standard 440cc injectors at 4 bar pressure with a pump can run a TD05 or VF34 to a decent level on Optimax without quite going static.

 

What's the best way to get 4 bar fuel pressure

 

by turning up the fuel pressure, on an aftermarket fuel pressure reg

 

On a decent one that can handle it - ie SX not FSE, and with an uprated fuel pump.

 

hi john,
a little off topic here, but since you're more knowledgable with various turbos, how much power can i get out a VF34, would it be much different from a VF28? I want to use the car everyday but also have a decent quarter mile time and reliability. How reliable are these turbos and whats the max bhp i can get out of one considering i do all the mods required?

cheerz,
suhail

 

oh,
forgot to mention, my97wrx runs on a fuel pressure of 3.8bar at idle, and rises to roughly 4.5bar when i put my foot down, it has the standard td04 turbo but alot of mods...

cheerz

 

Some VF28s on some cars on some rollers will get more than a VF34 on others. But most think the VF34 has a small edge, probably less than 10% though. They will both probably be in the 300-350 BHP range.

Your fuel pressure is not responding correctly if your 4.5 bar is on full boost, if it is at atmospheric that would be right if a little high. Perhaps your (uprated?) fuel pump is overwhelming the return capability of your (standard?) fuel pressure regulator?

 

Sorry john,
i misrepresented my figures yesterday, fuel press is 2.9bar at idle and 4bar at full throttle, my apologies . How much different is the VF34 from a TD05/06 20g turbo? Is there a huge difference in torgue and top end power? What is a better turbo for day to day use and to maintain reliability

 

About 50 BHP difference. Torque depends on boost mainly. Either will do enough to destroy a non-STi gearbox. This is your main concern before the engine.

 

cheerz john,
the car i'm looking to fit either turbo on is an sti ver6 with a 3000pound rally spec gearbox fitted, apparent with a 4:4 ratio don't know what that's all about, if there's a big difference in actual driving terms between the turbos i'd go for the more powerful one, but if it's merely on paper, (50hp gain but you can't really tell) i'd stick with the VF34.

 

VF35's aren't cheap to come by though!

 

You can tell a 50 BHP gain, but less so in twisty work, depends what you want the car for.

If you are upgrading to get more power, the 20G will offer far more of a difference than the negligible difference you'd get from VF28 to VF34.

Some people like to stop at 16G or VF34 (ie c.340 BHP) size on a 2.0, with an STi rev limit you can go a bit bigger. Some people don't mind a 20G even with a non-STi rev limit (ie c.390 BHP).

 

you can say that again
nor are they easy to come by

 

What does the 16G and 20G mean in relation to the TD05 turbo?

 

IMO the 20g holds boost far better and its power is more felt as you go over 5000rpm the td05 16g feels flat after 5000rpm but the td05 20g still pulls well to the redline line

 

U WOT!, it is the compressor wheel size.

 

How do you know which one u've got is it stamped on it somewhere??

 

The turbo type is usually stamped on the compressor cover.

 

Cheerz john,
thanks for all the info, i'm looking to upgrade for more power, all i don't want is my engine to go boom! As i mentioned earlier the car is already fitted with a rally spec gear box so thats no problem, will the TD05/06 damage the engine internals in the long run?