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03-10-2014, 04:41 AM | #1 |
Scooby Newbie
Member#: 106163
Join Date: Jan 2006
Location: Miami, Fl
Vehicle:2004 sti Blue |
turbo intake question, could this be the cause of my problem?
i have a modded 04 sti, built block, (carrillo rods cp pistons, acl bearings, cosworth pump high flow high volume. built and ported heads, cossy avcs cams 278/274)
precision 6262 .82 A/R rotated, 1200 cc injectors dual in tank walbros. dual plate exedy clutch, short shifter, bushings, coil overs. etc etc rotated cosworth intake mani, custom fabbed all my piping. basically "the works" and it is running 3 inch dp all the way out. no cats no muffler or silencer. it is a little loud but i can bare with it. the car is in south america, so noise or speed is not big a deal here. hydra ems for engine management. what is curious and my question is that i fabricated a 3 inch intake for the turbo and used a 4 to 3 inch silicon adapter. i have a rotated setup, it goes from turbo to fender obviously 90 degree bend, to another 90 small straight pipe and a final 90 degree to a filter that i placed a behind the plastic cover that has the sti sticker under the headlight. on the street i run it cover on, on the track cover off, could this be the cause of my power drop after 6200-6400 rpms? what makes it worse, is that @ 18 psi the power keeps climbing the way it should. i looks like a proper dyno graph. i increase the boost and the car makes the same power in some places and fluctuates a lot and makes more power on the mid range but not much gain as expected 10 hps per 2 psi. and over 6200 rpms it drops hard. and if i give it timing it it drops even harder. i revised the tune. different afrs different timing combined them. you name it, and it did not make a difference. tried cover on and off a little change on afrs but not on total power delivery. i am sure there is a choking point on the system, i know heads are not. and exhaust system could not be since it is basically a straight pipe. running out of ideas, any help would be greatly appreciated.
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03-22-2014, 11:12 PM | #2 |
Scooby Newbie
Member#: 379237
Join Date: Jan 2014
Chapter/Region:
VIC
Location: Sechelt
Vehicle:2010 GRB STI SWP |
Sounds more like a fueling problem. Fuel cut? Or fuel pressure problem maybe?
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03-22-2014, 11:22 PM | #3 |
Scooby Specialist
Member#: 283134
Join Date: May 2011
Location: AZ
Vehicle:2015 STi LE EFR7163 500whp/550wtq |
What silicone intake adapter are you using? A few years back I was using a weak turbo inlet, and above 21psi it would start to collapse because it was sucking in so much air. It didn't have any ribbed supports inside of it. This happened at a boost threshold and not an RPM like yours.
What is your IDC at 6000+rpm? How much timing as well? |
03-22-2014, 11:41 PM | #4 | |
Scooby Specialist
Member#: 322963
Join Date: Jun 2012
Location: upstate NY
Vehicle:04 wrx psm |
Quote:
Last edited by 02nismokiller; 03-23-2014 at 12:15 AM. |
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03-23-2014, 12:50 AM | #5 | |
Scooby Newbie
Member#: 106163
Join Date: Jan 2006
Location: Miami, Fl
Vehicle:2004 sti Blue |
Quote:
time to start hunting the problem. |
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03-23-2014, 02:30 AM | #6 | |
Scooby Specialist
Member#: 250152
Join Date: Jun 2010
Chapter/Region:
MAIC
Location: Pennsylvania
Vehicle:2006 WRX Limited OBP |
Quote:
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03-23-2014, 03:41 AM | #7 | |
Scooby Newbie
Member#: 106163
Join Date: Jan 2006
Location: Miami, Fl
Vehicle:2004 sti Blue |
Quote:
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03-23-2014, 09:22 AM | #8 | |
Scooby Specialist
Member#: 250152
Join Date: Jun 2010
Chapter/Region:
MAIC
Location: Pennsylvania
Vehicle:2006 WRX Limited OBP |
Quote:
Regardless of that, I doubt its a fueling problem. If a stock engine and turbo can creep on up to 22-23 psi without the "proper" fueling, then theres no reason you shouldnt be able to see the same thing. Its a boost control issue. Why is it that you have 23 psi wg spring pressure? Is your goal to run 44-46 psi of boost? You want your wg spring pressure to be roughly half of your desired boost pressure..... Last edited by 2Fast4U1DAY; 03-23-2014 at 09:45 AM. |
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03-23-2014, 01:46 PM | #9 |
Scooby Newbie
Member#: 187648
Join Date: Aug 2008
Chapter/Region:
International
Location: Finland
Vehicle:2007 WRX |
Exedy twin plates suck ass.
Maybe its slipping a little at higher boost/torque. But you should notice it pretty easily. |
03-23-2014, 04:31 PM | #10 | |
Scooby Newbie
Member#: 106163
Join Date: Jan 2006
Location: Miami, Fl
Vehicle:2004 sti Blue |
Quote:
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03-23-2014, 04:33 PM | #11 |
Scooby Newbie
Member#: 106163
Join Date: Jan 2006
Location: Miami, Fl
Vehicle:2004 sti Blue |
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03-23-2014, 04:49 PM | #12 |
Scooby Specialist
Member#: 250152
Join Date: Jun 2010
Chapter/Region:
MAIC
Location: Pennsylvania
Vehicle:2006 WRX Limited OBP |
Either the wg is bad or you have a tune problem. My guess is the latter considering you say the boost fluctuates a lot. TD is probably off along with other parts of the tune
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03-23-2014, 05:02 PM | #13 |
Scooby Specialist
Member#: 181617
Join Date: Jun 2008
Chapter/Region:
MAIC
Location: frederick, md
Vehicle:2004 wrx Dom3/IAG built hybrid |
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03-23-2014, 05:08 PM | #14 |
Scooby Newbie
Member#: 187648
Join Date: Aug 2008
Chapter/Region:
International
Location: Finland
Vehicle:2007 WRX |
We just had one slip last month, swapped it out and it wasn't badly worn.
We've had more than one slip btw, once you start getting into +500ft/lbs they start going at around peak torque. Sometimes they let go significantly earlier. The TRIPLE plates, haven't had any issues thus far over here. Last edited by DisoDisp; 03-23-2014 at 05:15 PM. |
03-23-2014, 09:04 PM | #15 | |
Scooby Newbie
Member#: 106163
Join Date: Jan 2006
Location: Miami, Fl
Vehicle:2004 sti Blue |
Quote:
Today took it to the track, lot of traction issues ran 11.7 easy on the launch. 1.77 60 ft |
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03-24-2014, 12:04 AM | #16 | |
Scooby Specialist
Member#: 250152
Join Date: Jun 2010
Chapter/Region:
MAIC
Location: Pennsylvania
Vehicle:2006 WRX Limited OBP |
Quote:
Hmmm and you said you tried different MBC's to verify that the problem isnt in fact the MBC? Have you tried a different gate or tested the current one to verify that the gate is functioning properly? Did you try running a different rotated intake to see if you can see your target boost? In theory it *shouldnt* be the problem but in reality the stepped down coupler may be just enough restriction that you are choking the flow to the compressor... I see more now why you could think its the intake, but I cant seem to make sense of why its not supplying the compressor inlet with MORE air and not less... now I am stumped too hmmm Last edited by 2Fast4U1DAY; 03-24-2014 at 12:14 AM. |
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03-24-2014, 03:07 AM | #17 | |
Scooby Newbie
Member#: 106163
Join Date: Jan 2006
Location: Miami, Fl
Vehicle:2004 sti Blue |
Quote:
i read on some other forum that the pressure that the compressor housing sees is not the same as the intake mani. made enough sense to try, and apparently it worked.. i will keep testing a report back. thanks everybody for the input |
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