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well, i realise dyno's are only a means of measurement, but i'm convinced that my setup has seemingly less power than almost everybody elses thats similar, so im just trying to figure out what the restriction could possibly be.

here's a list of what's been done:

unopened s1 rb25det

ems stinger ecu

hks gt2835 pro-s

3" flexi pipe intake hose

nismo 740cc injectors

walbro pump

hybrid cooler

stock coils

exhaust that goes from 2.5" to 3", 2 mufflers no cat

18psi - 315rwhp

13.1 @ 109mph on 205 rubber

compression test came up as 150psi across all 6 cylinders

it holds boost through to redline, and im assuming the coilpacks are working as it doesnt miss. it has a stock fuel pressure regulator.

the most obvious thing i can think of is either the exhaust is restricting it, or my tuner isn't putting any timing into it?

any thoughts please punt them at me

cheers in advance

Edited by bj0rn
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2.5" exhaust - your issue is staring you in the face.

3" or bust at a minimum.

Also 230rwkw/109mph, is pretty close. So it's not down on power, its just restricted to the heavens.

You'll probably get 20-30rwkw out of an exhaust change easily.

What will go pop?

The motor?

Mate - get the exhaust fixed. Drive sedately to tuners (or have them do the work on-site if possible), run it up and have a look.

There is no way around this. Your motor will simply not just up and die from an exhaust change, however the tune MUST be looked at with such a restrictive exhaust. You will hit load points that you weren't previously.

Also that tune, is honestly looking pretty average. The curve should be much smoother. Is the right axis is toruqe, then its 100% a poor tune as its dropping around 104-120, but then that could also be the exhaust.

Overall moral of this story? Get the exhaust fixed, and get the tuner to have another look at it all.

That often doesn't work, or give you a good idea.

Cause it's louder, you've made a change - often a bit of placebo kicks in.

Hence on the same dyno/tuner etc, you'll soon see whats going on.

That turbo is good for 260-280rwkw, and should be up around 112-114mph once you get that power.

I was racing regularly years ago with 220rwkw and I was running 12.9 @ 109mph consistently.

nismoid: funnily enough, its only 2.5" where the hks dump flange meets the front pipe. and its only that small for about an inch, then immediatgoes to 3 inch. it has a hollowed out cat, then two mufflers. are you sure it'd be the exhaust?

heres a photo;

DSCF0217.jpg

harey: the intake has wire which stops it from flexing. im fairly positive thats not the issue.

nismoid: funnily enough, its only 2.5" where the hks dump flange meets the front pipe. and its only that small for about an inch, then immediatgoes to 3 inch. it has a hollowed out cat, then two mufflers. are you sure it'd be the exhaust?

heres a photo;

harey: the intake has wire which stops it from flexing. im fairly positive thats not the issue.

That looks terrible. Is that 2.5" section part of the dump pipe or the front pipe? Either way it is most likely the cause and should be changed immediately.

The intake wont be causing the issue yet at that low power level. I had a flexi intake with wire and it still twisted and did nasty things above 250rwkw.

The exit of the HKS dump is 70mm from memory. Redo that to be something a little nicer than what youve got, yours looks more like 65mm ID, even if it were 68mm it could potentially hold back a lot of power.

The other issue is the flexi intake pipe, its GOT to be an issue.

Redo both ASAP. You WILL need a retune.

+1

for getting the 2.5in section replaced.

On my WRX years ago the owner had a terrible exhaust on it, pieces were 3in, some still had stock mufflers and resonators. it was all welded together horribly and the dump pipe had a big dent in it from where it was bent into shape. after i had the catback section replaced the car was louder, but still didnt gain any power because of the dent in the front pipe. this dent was quite big and was definitely restricting it.

The exhaust bloke said its like when you step on a garden hose, the amount of water that comes out the end is less because it cant flow past the restriction of your foot on the hose.

moral of the story,

had the dent fixed, welded in a new 3in section and gained power all over the power band.

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