Tidgy

ok, been having a look around to try to see if anyone has got the 400ftlb i was on about earlier, and i came across someone claiming ot get 302bhp at the wheels out of a vf34.

now according to rough calculation thats near 400bhp at the fly.

how the hell do you manage that? all the tuners Andyf, API, scoobyclinic, powerstation etc say its good for 350bhp.

any ideas?

Tidgy

right think i may have asnwered me own question, but i hope someone can say if im correct or not.

Seems to be that all the different dynos used vary figures wise. they always state which dyno was used (its a thread on nasioc) and they seem to read all over the place. is this just cos companies are trying to make things seem better than they are and the customers don't mind cos they just want a higher figure?

bighead

iTrader: (1)

i had 362bhp on the fly out of mine on two different dyno dynamic rollers , if you up the boost abit you will get more but it will shorten the life of the turbo/engine !
if you want 400 get the md321h/t turbo

APIDavid

iTrader: (4)

John, there are too many " it depends upon's " to get a really sensible answer to this. 302 hp at the wheels is not a high figure per se. BUT I think it is optimistic on a VF34. Typical tranmission losses factored in are 22 / 23 % usually. BUT, if you increase or decrease that figure, the power read out will go up and down all over the place.

BUT as any rolling road tuner might tell you - you can largely produce a result that suits what you need to tell the customer.

One of our 2.5's went to one of the lesser-known-for-Subaru rolling roads The car is on a MD321T and STi 3 cams and is quick....... Certainly in the region of 430 odd hp; genuine. { Clinic's rollers show that ] But this customer got 390 and was rightly disappointed. "Shall we fix it for you?" Was the question. "Yep get on, then we can see."

SO, they took out timing, lowered the boost and weakened the mixture and GAINED 22 hp. ON Pats map ?? I don't think so !! AND Pats mapping is not questionable.

Jeez if it was easy, we'd be doing more of that to see if we could get it up to 450........ By changing the load factor, or going from usual rolling road data logging into 'shoot out mode ' and back again you can get different readings back to back.

It also depends upon which gear they choose.

It also depends upon air temperature.

It depends upon wheel slip on the rollers.

And so on.

A rolling road is a very dangerous piece of kit to trust blindly, as it can be easily abused. We don't have a rolling road, BUT I was trained on them when I was at Ford, many, many years ago and l know the tricks that can be pulled.

For diagnostics it can hardly ever be beaten for speed and ease. BUT when used to produce power figures it is very easy to 'diss' another tuners work and 'prove' that your work is better...................

As for the 2.5 guy he is now wiser, as the settings used at the rolling road place were dangerously weak and I merely questioned; whose fault it would have been and who would take responsibility for a blown engine? , should it all have gone wrong on 'their ' mapping. I tell you what; it wouldn't have been me......

David APi

APIDavid

iTrader: (4)

Huh ! Double post.
.........

scoobyhoobydoo

Why not? If work on the principle that a engine gives X amount of power and with addition of boost pressure Y the two added together give a result is Z.

If you improve the engine output X then add the same amount of turbo pressure Y the result Z should be higher. Some people choose not to open up the engine as other results such as larger turbo, mapping and injectors/fueling give result at a "cheaper" cost. It all depends on what you want and as David said the rolling road used, none are the same and some tell you good and others not so good news.....rolling road readings are a can of worms.

APIDavid

iTrader: (4)

Algebra doesn't work in practice. a VF series can only shift a finite amount of air. Ditto the exhaust and induction system. ANy standard VF just runs out of capacity anywhere from 340 to 350 hp. That is not enough with transmission losses to make 302 at the wheels.

Cars making any sort of power shift huge amounts of air. Can't move enough air? [exhaust ] then power will be lower.

David

The Fixer

302 ATW relates to approx 380 AFW in Dyno Dynamics, top of the range for a VF34 but as Mike pointed out above 360+ is possible on the VF34 with high boost but it surges all over the place and is not nice at all, the turbo wont last long at that either.

Andy.F

Have seen this sort of level from a VF34 or 35 when mapped for NF octane booster and/or 10% methanol. VF34's seem quite hardy in comparison to some earlier VF's and not nearly as surgy as the VF35.

https://www.scoobynet.com/private-sa...i-type-uk.html

Andy

jasonius

iTrader: (1)

I really rate my VF35 and can honestly say I wouldn't change it for anything else as it ticks all the right boxes for my needs (a real world fast road 2.0 05 WRX). At around 1.5bar peak it produces near 350hp @ fly, with 1 bar @2800 and peak ~3100 and holds over 1.3bar at 6k.

Been running this for 18mths/18k miles without a problem. It is a noisy turbo, which I actually like..

However, IMHO the figure of 302whp was probably calculated using a silly loss factor, say ~15%..! The yanks do seem to claim some 'high' output figures for the specs they have..!

Tidgy

it was on 93 ron (not a typo 93 Ron, us pump gas) Andy

so the ups and downs of it is it sounds very much like a dyno tweek rather than a realistic figure.

there seems so many figure brandished about that claim silly figures and while i did realise you can change the figure on the dyno, (toasty's 1.6gl made 276bhp on clinics rollers you know ,,,, pmsl )

tbh i'm trying to understand the US method of tuning, seems to be chuck the largest set of injectors at it you can (seen cars running 300bhp running 850cc injectors) then remap it and claim high figures, that sound about right?

Tidgy

yeah i get what your saying, very easy to please a customer by giving silly power thats just unrealistic for the car

sssssteeeee

hi merry xmas all.

just had a vf34 fitted and mapped on v power with a dash of nf, we got 312 @ 6000 rpm. 260 ftlb with various mods . trying to work out is that good as we thought 320 plus was the aim, i think so far its good in terms of safety 1.4 bar. engine standard 2L , 5 Speeder.