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Old 08-06-2004, 03:40 PM   #1
RoC_Pooh
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Default STI with just a UTEC or UTEC+VF34......

What kind of performance it will gain with just the UTEC or UTEC+ a VF34 on a 05 STI without any other mods?

I know I read most people want or suggest a TBE but I really don't like the idea of TBE or just swap the muffler.

Thanks
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Old 08-09-2004, 02:11 PM   #2
RoC_Pooh
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anyone?
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Old 08-09-2004, 02:15 PM   #3
happasaiyan
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probably a good 40whp or so. thats my edjucated guess.
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Old 08-09-2004, 02:22 PM   #4
big_adventure
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You will be really, really limited by the exhaust backpressure with two cats meowing behind the turbo. I HIGHLY doubt that a UTEC alone will give you a consistent 40whp on an STi.

-Sean
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Old 08-09-2004, 04:32 PM   #5
happasaiyan
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Quote:
Originally Posted by big_adventure
You will be really, really limited by the exhaust backpressure with two cats meowing behind the turbo. I HIGHLY doubt that a UTEC alone will give you a consistent 40whp on an STi.

-Sean
i think the utec alone would yield 25-30whp...and then an extra 10-15whp more topend on the vf34 vs vf39. thats my guess.
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Old 08-09-2004, 07:05 PM   #6
hippy
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I wouldn't think it's worth getting a vf34 given the turbo you're starting with is so close in size.
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Old 08-10-2004, 08:59 AM   #7
big_adventure
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People seem to have mixed results with the vf34/39 transfers. The vf34 should hold a little more boost to redline than the 39, thanks to the larger exhaust side, and flow a little bit better up there, but you're maxing and going beyond maxing both of those turbos on that engine. If you are going to upgrade the STi turbo, go for AT LEAST a vf22 or 18g. Otherwise, the upgrade may not be worth the price of a new uppipe gasket.

-Sean
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Old 08-12-2004, 09:59 PM   #8
Subiemax
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I would also like a backed up answer to this question.
I want a little more hp and smoother acceleration for my sti.
But want to be able to go back to stock if I need service.
Anyone with first hand experience with UTEC on stock STI.
"NMYETI" or maybe "TurboXS(Pete)"
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Old 08-13-2004, 07:48 AM   #9
Abe Froman
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Smile

My car had only a catback on it when I got my UTEC. Are you willing to tune it yourself? If not your gains will be minimal(it's not really plug and play).

Mostly stock, what you will really gain with the UTEC is torque, I upped the boost on my car to 19psi(+5) tapering down to 14ish(+2) with zero knock on 93 octane with some self tuning of timing. With the stock ECU in control I was getting 14ish peak tapering down to 12ish. The VF39 really doesn't like to hold boost near redline and I don't like to force it so I let it taper the way it wants to. With the stock fuel curve your injectors will be running a high duty cycle.

In layman's terms the gains come mostly in midrange torque and drivability, the power comes on smooth and it pulls from lower rpms with much more authority but you will likely have hesitation issues near the transition point from ECU to UTEC and back to ECU(I did).

If your willing to shell out $ for a proper tuning(or tune it yourself like I did) the hesitation issues can be lessened and I would say 25hp is reasonable w/tuning but the torque is the real gain and it's easy to get with minimal tuning.

Oh and flat shifting is so much fun it's almost worth the price of the UTEC alone...ok maybe not but it's a blast!!

Hope that helps.
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Old 08-13-2004, 08:18 PM   #10
Zornorph
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did you check the thread about 50% of sti's coming with the 18 hot side? It is a VF34!
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Old 08-14-2004, 07:35 AM   #11
TheMadScientist
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If you are going to upgrade the turbo on an Sti. Stay away from the IHI junk. Go get a real turbo. MHI, garrett, rotomaster, anything other than IHI.

My $0.02

TMS
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Old 08-14-2004, 12:13 PM   #12
xtian67
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Quote:
Originally Posted by Zornorph
did you check the thread about 50% of sti's coming with the 18 hot side? It is a VF34!
Link please!
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Old 08-14-2004, 04:44 PM   #13
Abe Froman
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Quote:
Originally Posted by xtian67
Link please!
Not quite 50% but pretty freaking high!!
http://forums.nasioc.com/forums/showthread.php?t=606432
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