Expected Power from a 2.5 with VF28
 

I have recently brought a car with the following spec which is a great stepping stone to greater things, but was wondering what power people have seen with something similar.

Current spec is a UK classic, running a 2.5 bottom end with forged internals, standard top end, Full decat, Uprated fuel pump, pressure regulator, 440cc injectors, performance headers, Standard intercooler, and a VF28 turbo, Motec M800 ecu.

I know the place to start would be bigger intercooler, injectors and turbo.

But the car is currently only boosting, 13psi, dropping back to 10psi quickly. I feel that the car has more potential in its current state with a careful map. But is anyone running something similar and what are you seeing in terms of performance.

With the very low boost levels, the car is currently 305bhp/320ftlb.

thanks in advance

Watch your gearbox if you do tune it further.

May be worth pricing one up before you decide you want much more torque from the car.

Spec (apart from the gearbox) sounds like it could make a comfortable 400+ with a change of i/c, injectors and turbo.


Bob


PS. I'm assuming its this one http://bbs.scoobynet.co.uk/showthread.php?t=469802

Yep that be the one, I know the gearbox is the weaklink, but do like the gearing that comes with the UK box, and don't bang gears or do 1/4 miles so although weaker than most it should last. But here what you say and do have it in my budget to replace if I ever had to.

With regards to performance I wanted to progressively do the mods, and my original post was asking whether the current state of tune could demand some more, by making turbo, injectors and intercooler work on the limit.

Have read various threads on the 2.5 and from what I can see most people have just gone balls out with 20gs front mounts etc. but there must be someone running similar modest mods to me.

Bigger Intercooler, injectors and turbo will come, but just not yet. But even when I do, I would wish to always retain a top mount ic. So probably and STI8 or hybrid of some description.

my mate has a sti version 4 wagon 2.5ltr with vf24 (original)turbo,sti topmount,3" aps system, powerstation headers, sbcid boost controller, autronics ecu and fuel pump/regulator.he was running 305bhp 360ftlb on the standard sti gearbox with 50.000miles(which wore out very quickly). he now has 345bhp 390ftlb with a six speed box.

the turbo you said you have is a vf28 but isnt the 22b turbo a vf22?

http://img.photobucket.com/albums/v7...y/100_0361.jpg


p.s...re. topmount i have almost the same set up but with a md321 20g and an aps duel entry top mount:)

http://img.photobucket.com/albums/v7...y/100_0353.jpg

pps one of my other mates wanted to buy your car but his missis wouldnt let him.......what a bargain:thumb:

That 344 BHP plot looks like a very very nice TDI. That is ideal for a road car.

R25 - the 22B turbo was a VF23, sam eas the ones off of the V3 STi

Russell

I will be going down the 2.5L route very soon, but will be using my existing VF22, Do you know what size injectors and boost your mate was using R25_Sti?.

Thanks

the car is very quick on the road but runs out of power as you get up the top end.we think its the turbo running out of puff,having said that he wouldnt change it.:)
the injectors are the standard sti version 4 one,s(whatever they are)and his max boost is 1.3 bar.

WUZ.....cheers i new it wasnt a vf28:)

my sti type r version 4 has standard 440cc injectors and boosts to 1.4bar all day baby, standard vf24

This is something I would like to acheive with mine, hence maybe sticking with the VF28/VF22 (will look at housing), I am not looking for 1/4 mile or a track car, I am looking for a good fast daily driver. Hence wondering if I could acheive this with what I current have and what will now soon be a STI top mount, and a remap.

It is a great car and even better already, after 'T' cutting that mark off the door (Now totally gone), and just put a set of 18" gunmetal Grey PFF7's on it so now looking the dogs. Have replaced the Firestorm with a Group 'N' backbox, and have a STI5 intercooler with OEM dump valve going on soon. (Its was toooo noisey for me)

THe price I got it for allows me to play with it a bit.

I now just want to squeeze some more from the car in its current state and would be very happy if I could get something like the 344bhp power readout your mate has. This would keep me happy for a fair while.

In conclusion it does sound like I can demand some more boost/power from my car in its current state and the addition of the STI5 ic will help a little. The car pulls like a steam train already especially low down but runs out a little at the top end, but then its only boosting 10psi.:)

Eventually I will go for a big turbo, etc,etc. But far too happy with it to start getting that serious already.

Have looked closer, That is a mental plot from the specification. If I could get any thing like this I would be seriously chuffed. As John sais as a daily driver this must be awsome. Mindue I would need to factor a 6 speed myself with that torque figure. I can't see the UK box lasting long even with a driver that don't push it hard all the time, and its a little older and wiser.;)

hope you achieve what your after.you will have to put up your results....cheers.

Not been in Robs car yet, but he sounds pretty pleased.
I will have a looksie at the turbo to identify what it is, as there apeears to be a little confusion.
I was under the impression ot was a VF28, but 22B didn't have one of this only P1/STi 5&6

From what Rob has said to me, it's running about 12psi at present.

What would be nice to know is the efficiency of a VF28 (or whatever) when blowing into a 2.5L as opposed to a 2.0L.

I know the VF28 can run 1.3 to 1.4(max) dropping to 1.2 at 6,000(ish). So assume somiwthing like a 25% reduction in boost due to the 25% increase in capacity.
But then I'm no expert on flow rats / efficiencey when it comes to turbo's, I just ren/map them to the recommended levels.

Once we know these I can hook up to the motec and start playing.

The Turbo was a VF23, and currently maxing out the injectors at under 1 bar pressure.

Therefore 740cc's going in soon.

I have just aquired a TD05/06 20g, but beginning to think that perhaps I should have stuck with the VF23 and take boost to 1.3bar and from what I can see would give me about 350/350 with the other supporting mods I have.

I think I might see more horses with the 20g but at a cost of low down drivability. :(

Won't know until I try but might hold back from fitting the 20g yet and see what the VF23 is capable of doing.

The way I understand it is that turbos can flow a certain amount of air, so if a VF23 can make 320HP on a 2.0, it won't make that much more on a 2.5.

Good thing about extra capacity is you don't need as much boost to get the same volume of air, which usually means the charge is cooler / turbo is more efficient, hence a bit more power and less stress on the turbo

A properly built and ported 20G will not have any low down driveability issues. Should be more than a match for your VF23.

Andy

Although there are a few dodgy examples on the market at the moment, a properly built and ported 20G will not have any low down driveability issues. Should be more than a match for your VF23.

Andy

im confused as to what the spec was on the 390lbft car? was that achieved with a VF23??

Here what you say ! - I hope the one I got is a good one. A bit off topic but whilst not ideal, have you had any experience putting a 20g on a standard MY98 Intercooler. ?. I am not looking for top BHP and don't do track work, and really don't want the hassle of a STI8 IC upgrade or hybrid for a while. I am looking for about the 350/350 mark, and was working on the theory if the 20g is not working hard, the charge temps will be lower than say the VF which will be like a hairdrier at 1.3 bar, and therefore the 20g on standard MY98 IC might suffice. Also I won't have several feet of pipework than if I used say a front mount to create lag.

what is the better turbo as my m8 has 330bhp with 380lb torque from a vf22 and top mount! (2.5)
dyno proven (steve simpson).....

This is mine:
http://img.photobucket.com/albums/v4...rprograph1.jpg

Its a 2.5 on standard UK heads, VF28 turbo, Sti injectors, sytec pump, standard regulator, standard headers, FMIC, Unichip Ecu, exhaust and induction.
Its on an AP organic clutch and STANDARD UK 5 speed gearbox.
Done about 6000miles, some of them on track (and off)

Olly are the STi injectors the 440cc sized version? and is your exhaust a 2.5" or 3" setup. Very good figures by the way.

Thanks.

What boost are you running Olly?

Looks like 350 is about the limit from what I can see even with a VF23 which is larger than the VF28. But just brought and fitted a 20g, just waiting on the 740 injectors and remap and heyho, what should hopefully be well in excess of 350/350.

the VF23 would have probably got close to where I wanted to be, but the 20g insures it. Good so see someone else running a UK with relatively big BHP and torque, and its still going.

Anyone wana buy a VF23 ?

That is immense torque!! i'm guessing that is due to the headers and 2.5 Converision?? I'm not a techy person so correct if im wrong!

Must be a bit of a handful on the road.

Stiver3

Btw: how much for the VF23??

Yep, there yellow tops from Grade A Subaru, 100squid with the rails.
Not sure on the exhaust. Its an H&S open neck downpipe custom centre and backbox.

1.2 bar.

Cheers. You've done well getting those figures. :)