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Old 08-04-2004, 09:33 AM   #1
notraceready
Scooby Newbie
 
Member#: 64556
Join Date: Jun 2004
Location: Carbondale, Illinois
Vehicle:
2003 Stg 4 WRX sedan
silver

Default Why is torque so low after stage 4 and tune?

Hey fellas/gals. I've had my Vishnu stage 2 (typical stage 4 set-up) and after a custom tune, I feel like I'm getting good hp (276) but low torque (224 lbs/ft). My tuner said he thought that he could get me more torque but thought that there might be a problem with the wastegate either being "over ported" (had Deadbolt treatment) or the wastegate arm not being tight enough. He thought this becasue he had to set the wastegate duty cycles pretty high (like 95% or so) to get the numbers he got. He also thought that this might be why he couldn't get as much boost as he normally does with this set-up as he could only get a little over 15 lbs. on the dyno (I am, however, getting 16.7 or so on the road according to my stock gauge).

Anyway, I was going to send the turbo off the Deadbolt (Jerry there has been great about helping me. Fabulous service) to have it checked out but my tuner said to try to pass a light trough the intake and see if there is any light that passes through the flapper. If there is, then it needs a bigger wastegate flapper. However, he said that if the light can't be seen it could just be that the wastegate arm might need tightening and that this might make it easier to tune for more boost and more torque.

I'm having the turbo pulled and checked today and/or tomorrow but am curious if anyone has any ideas as to why my torque numbers are so low. I'm not sure if I should even worry about it since on the road on a cool day I see 16.7-16.9 lbs. of boost and the car does seem to run great. But I'd love to have more torque. I've posted elsewhere and folks suggest to not worry if I'm getting good boost numbers. But does having to set the wastegate duty cycles so high indicate some problem and why so little torque?

Any suggestions/feedback would be appreciated. Thanks.
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Old 08-04-2004, 06:16 PM   #2
bikerboy
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Member#: 5477
Join Date: Apr 2001
Chapter/Region: MWSOC
Location: in the garage!
Vehicle:
2007 R171.473
2009 SWP Spec B

Default

Wish I saw this earlier, you can put a helper spring on the arm to see if it is blowing open the flapper. IMHO I would guess that is it since if the WG hole is to large you would not build good boost at all.

As for duty cycle that would again support not enough spring preasure on the flapper.

On my 39 I opened it up so much I had to use a flashlight method as well. I really doubt deadbolt would do something like that. You might have got the wrong actuator on reassembally.

Also I would check to make sure the pill "restrictor" is in the hose from the compressor discharge to the "T"

Last edited by bikerboy; 08-04-2004 at 06:24 PM.
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Old 08-05-2004, 09:33 AM   #3
notraceready
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Member#: 64556
Join Date: Jun 2004
Location: Carbondale, Illinois
Vehicle:
2003 Stg 4 WRX sedan
silver

Default

Thanks bikerboy for input. Believe it or not, the port job was "overdone" as my mechanic told me he could see light coming from the wastegate upon inspection. I'm surprised but Jerry at Deadbolt will take care of it. Just a hassle sending it out again. BTW, I had contacted Shiv at Vishnu previously and he brought up the pill "restrictor" positioning and it was correctly situated. So, I'm just glad to have the issue diagnosed and hope that now I can get the most out of my mods. Thanks again for posting back. Gerry
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