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hehe my xforce 'high flow' cat filled up with crap and sort of fused itself towards one end of the shell due to my Microtech not running an 02 sensor and running excessively rich, it would probably be worth checking out to eliminate the possibility, especially if the car's had a really crappy tune at some point.

Well it did have a REALLY crappy tune, the cat was a fairly pricey item but I might ask my tuner to take a look.

Would his longer intake pipe going under the engine bay really cause the car to lag?

No longer an issue anyway, it has since been moved into the engine bay.

drop the exhaust and see if the restriction is there... your tuner probably should have suggested this.

I run a hks 2835 (garrett 3071 based turbo) and see 20psi by 3400 revs and make 390rwhp (432rwhp on e85)

a 3071 /3076 is what you are after... (but either way a 30xx turbine housing)

anyone suggesting a GT35xx turbine for someone after response and sub 300rwkw on an unopened RB25 has no idea / or a good deal on a gt35xx that they want to flog

i'd reccomend a new tuner

I take his words with a grain of salt because he is always looking towards big power and big $$ engine builds, he is correct in that if I buy a GT30 based turbo then I am limited if I wanted to go further down the track. That is most likely the reason for his suggestion. However, it's true that he should be listening to what I want better.

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Not a good plan, we had a bad storm here while I was driving, went through a puddle. Wet afm, which screwed it up, had to get towed, shit afternoon.

Good for top end power if its a racecar or something like that I guess..

My mate had a unopened 25 with GT35r .63 housing

Full boost (18psi) by 3800rpm and 400rwhp

very smooth and linear power, how much more response could a GT30 give?

you could always just change the rear housing if you want to shift the power band to a .82 or 1.06?

Lots more response is the simple answer. When quoting full boost by rpm, you need to specify gear as well as it varies with each gear due to load.

A nicely matched GT3076R with 0.82 housing is always going to be better then a mismatched GT35R with 0.63 housing on an RB25.

Geeze a GT35 with 0.82 or 1.06 is going to be quite laggy on a stock RB25! I would only choose the GT35R if I was going to use the 0.82 housing and shoot for big peak power figures.

My mate had a unopened 25 with GT35r .63 housing

Full boost (18psi) by 3800rpm and 400rwhp

very smooth and linear power, how much more response could a GT30 give?

you could always just change the rear housing if you want to shift the power band to a .82 or 1.06?

You are right about the response. My last setup was a gt35 with .63, 16psi by 3500-3800. But i would NOT recommend that sized turbo if you wanted something sub 400hp AND you wanted better response. I'm not a qualified mechanic. But if i wanted 380hp with the best response i could get i wouldnt even be looking at a gt35r. Thats like buying a 1000hp supra, when an evo can do 10sec 1/4 ,more efficiently.

  • 3 months later...

For those that are interested.. I ended up fitting a HKS GT-RS, it is getting tuned on Wednesday :D

Never got a chance to fiddle with the old setup because I got a yellow sticker, and had to remove the intake plenum, fuel rail, turbo and manifold etc and revert to stock parts(except for the turbo, hehe)

I also found the cause of the lag.. the wastegate was welded completely open!! The guy that fitted is has revealed himself as more and more of a f#ckwit every day.

Watch this space 8)

^^^^ :D

HKS should go real nice, you wont know yourself...

run a GT2871R 52T CHRA in a .86 OEM Bolt patterned T28 turbine housing and .60 comp housing. Full boost at 3000RPM and max out around 260rwkws.

AVO recomended me much the same....

For those that are interested.. I ended up fitting a HKS GT-RS, it is getting tuned on Wednesday :D

Never got a chance to fiddle with the old setup because I got a yellow sticker, and had to remove the intake plenum, fuel rail, turbo and manifold etc and revert to stock parts(except for the turbo, hehe)

I also found the cause of the lag.. the wastegate was welded completely open!! The guy that fitted is has revealed himself as more and more of a f#ckwit every day.

Watch this space 8)

he welded it open??

can u get the number of his crack dealer? sounds like a good batch

Well now I am questioning the legitimacy of that :)

Never mind, tuner reckons it will easily make my power goals on about 16psi once the fuel pump is sorted.. Could be a clogged fuel filter or a voltage issue, if not I will whack a bosch motorsport pump in.

For those that are interested.. I ended up fitting a HKS GT-RS, it is getting tuned on Wednesday :)

Never got a chance to fiddle with the old setup because I got a yellow sticker, and had to remove the intake plenum, fuel rail, turbo and manifold etc and revert to stock parts(except for the turbo, hehe)

I also found the cause of the lag.. the wastegate was welded completely open!! The guy that fitted is has revealed himself as more and more of a f#ckwit every day.

Watch this space 8)

LOL WTF!

Well now I am questioning the legitimacy of that :down:

Never mind, tuner reckons it will easily make my power goals on about 16psi once the fuel pump is sorted.. Could be a clogged fuel filter or a voltage issue, if not I will whack a bosch motorsport pump in.

Try the fuel pump direct re-wire...its in the DIY section

  • 3 weeks later...

Just got word from the tuner.. made 260rwkw :worship: . Boost rises to 16psi and tapers to 14.5 towards the top end. Apparently it has more in it but my tuner advises not to go any further without installing a catch can.

Also had to fit 550cc injectors as the stockies maxed out around 280rwhp.

Pick it up in half an hour, cant wait!

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