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01-17-2006, 02:26 AM | #1 |
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Join Date: Nov 2002
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VIC
Vehicle:06 WRX |
Headers on a 2.5i?
Has anybody replaced (and hopefully dyno'ed) headers on the 2.5i?
I know in previous years, using a equal length header freed up about 10hp, but this year my understanding was that subaru already included an equal length header. Does this mean that there is not much else left to be gained by swapping out the headers?
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01-17-2006, 04:32 PM | #2 | |
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Vehicle:2011 Mitsu Outlander Sport (Ex-Suby owner X3) |
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01-17-2006, 05:06 PM | #3 |
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Vehicle:2000 JDM Impreza SRX w/ AVCS Silver |
This is interesting, since from 99, full unequal 4-2-1 that came w/ EJ204 and EJ254, all 2.0/2.5L NA engines like mine came w/ them and it makes you wonder.
I can tell all of you who have AVCS (can be corrected here)in the 2.5i, increasing pipe size from the mid of the car to the exhaust will yield more torque below 3K rpm. I have to test a full 2.5 piping from the mid to the header and see whats happens. I have one problem now. With more flow, I am pinging more in the 1900-2500rpm and I cannot fix this until a reflash which is in developement. My last task is an adjustable Fuel Pressure regulator and see whats happen in the maps that learns. From idle to 3800+ is close loop, so the fuel controller do not work . I hope that RalliTek and others who have a TWE or any other header can it. Last edited by west_minist; 01-17-2006 at 05:38 PM. |
01-17-2006, 06:00 PM | #4 |
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no headers are out there yet, and the old ones will not work from what ive seen
i think stock headers are prob as good as it could really get with your car |
01-18-2006, 01:00 PM | #5 |
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Vehicle:2016 WRX Ugly Sedan |
Interesting, I was wondering the same thing last night about my 06 2.5i wagon and header fittment / power benefit.
So I was out on the Rallitek forum and it sounds as if thier new header may fit on the 06 2.5i, sounds as if thier looking for an 06 in the area to test it on. Sean also said he should have some dyno sheets up for the various model years they put them on. I sent an e-mail to Rallitek regarding thier new EL headers fitting an 06 2.5i, as well as any expected power increase. Of course I also inquired as to the full exhaust and the new UniChip(due in late Feb.) which should be available for N/A 2.5. I'll post the reply when I get it. Check the Rallitek forum, the should hopefully have some dyno sheets regarding this issue in a month or 2. |
01-18-2006, 01:14 PM | #6 |
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west minist??
west minist, interested in your statement regarding AVCS in the 06 2.5i and a cat back exhaust add on.
Is this benefit due strictly to the AVCS in the 06 2.5? Most of the research I've done on the forums regarding cat backs for N/A (all pre 06/AVCS cars) say minimal if any gains without a header from a cat back on N/A. And regarding the additional torque below 3k (where I want my gains ) is there any penalty anywhere else in the RPM range? Would an intake be required to reap these benefits?(I have a desnorked airbox but hesitant about a CAI due to the rumors of low end tourque loss). Thanks for any info you can shed on this for me, new to the Suby scene and still learning. |
01-18-2006, 08:42 PM | #7 | |
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01-18-2006, 08:47 PM | #8 |
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no pre 06 is dual ports. maiin reason for gains i say is the maf intake and avcs.. far superior technology compared to the older stuff
difference in header is cause the rs is slow, its not a secret subaru wanted to get all the power out of it that they could and changin the headers helped them |
01-18-2006, 09:13 PM | #9 | |
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Join Date: Jan 2004
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Vehicle:2000 JDM Impreza SRX w/ AVCS Silver |
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I have a:- JDM Non-Turbo Auto (4EAT) Impreza Variable Intake Manifold - Kicks in after 5krpm. Its on/off MAF Coil per Spark Plug AVCS Ground Kit HVC system 7K+rpm limit, car very willing to rev to 9K. Stock box w/ K&N Filter Stock unequal Length Header HKS Carbon Ti for NA Sweet ECU for performance driving, but bad close loop (Hydra for the future, once I get the auto sorted out) Innovate LC-1 & XD-1 running stock ecu o2 sensor input Now, change my piping from the header to exhaust using 2.25" piping w/ 1x 14" 2.5" internal magnaflow to keep noise down. All around results. Added another magnaflow and acceleration increase from 2K to 4K. Added a HKS Fuel Controller and had more torque in the 3.5-5k rpm range. Above 3800rpm is open loop. Playing ground for me. Added 18" 2.5" internal Summit Racing resonator w/ 2.5" piping from the outlet to the HKS Carbon TI. That resonator was place just before the rear diff. More torque from 2 to 4K. Excess of 8+tq. Now, for a car with 155ps 196n*m stock 2.0L engine should not be behaving like this. Even shop rally experience owner and my prodive mechanic was surprise. Why am I having more torque and not losing it, when this is the normal case. The only reason was AVCS. No lift. Toyota's, Honda's do not behave like this. I am a dummy @ mechanics and engine dynamics, but it seems that w/ a more open system, the avcs is making more torque. I do not know where the limit is, but more performance is have from 2-4Krpm and some increase above 5.5K+rpm. But the major improvements are in the AVCS on range. AVCS graph produce using 2nd gear. What I must added, is that the Ground and HVC system added more torque for me. So I'm not sure if the AVCS w/ a proper voltage system is causing it, but thats how the car is. The car do not sound drowny, which is also surprising, but screams, really screams w/ that HKS. I look forward to see some dyno graphs for the 06 w/ upgrades. My piping is custom made w/ crush bends. I have lose my comparison graphs of before the changes. Since then, I have ran mixtures of toulene and race gas. Those comparisons would have shown before and after. I can say that to date, becuase of the power robbing auto, I have 107ps @ 6358 & 134n*m @ 4300avg @ the all wheels. All test was road dynos. Haven't run my Gtech pro in a while to compare to EcuTek. Last edited by west_minist; 01-18-2006 at 09:58 PM. |
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01-18-2006, 09:43 PM | #10 |
Scooby Specialist
Member#: 53451
Join Date: Jan 2004
Location: Caribbean
Vehicle:2000 JDM Impreza SRX w/ AVCS Silver |
Since I cannot attach stuff, you will have to join http://www.tari.co.za/cgi-bin/yabb2/YaBB.pl to see posted logs.
But from my analysis, especially and the max. gradient,t he car runs lean. I guess this is for low emissions If I can added some fuel in there, the torque would be better. Driving the car, I do not even have to go to 2500, not even 2000rpm. Honestly. Do not know why that is so lean. The flow goes so quick, that the no fuel is added. See lean readings, sometimes in 15, but mostly around 14.7+ . I am not sure if I had fuel correction, if it would have work. It should. Last edited by west_minist; 01-18-2006 at 10:00 PM. |
01-20-2006, 03:20 PM | #11 |
Scooby Specialist
Member#: 53451
Join Date: Jan 2004
Location: Caribbean
Vehicle:2000 JDM Impreza SRX w/ AVCS Silver |
Can you all try the tari software to see if it can log your 06 cars!
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