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08-21-2009, 11:47 PM | #1 |
Increasing backpressure?
I recently installed the nitto midpipe on my car along with the stock header and a tanabe madallion axleback. It feels like I dropped a lot of torque from 2-4k RPM and I usually don't rev higher than 4k Is there an easy mod I can do to temporarily inscrease some backpressure to regain some of that torque until I am boosted? Also for those of you who have the midpipe are you getting 100% success on getting rid of a CEL with that anti fouler deal the garm sells on his website?
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08-22-2009, 03:59 AM | #2 |
"Stealth Runner"
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what is the diameter on your exhaust?
i believe the general rule of thumb is 2'' up to 120 hp, 2.25" up to 180hp, 2.5'' up to 250hp, 3'' up to 300-350ish, and 4.5'' for anything beyond please dont quote me on this. its just general hearsay from my years around other forums. |
08-22-2009, 11:01 AM | #3 |
Drives: '08 Yaris Join Date: Oct 2008
Location: SoCal (Jamul)
Posts: 97
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If you don't usually rev above 4k, then exhaust modifications are the wrong thing to do. Over the years, I have installed various exhaust modifications on vehicles I've owned and without exception, every one that reduced back pressure (on a stock engine) also reduced mid-range torque, sometimes by a substantial amount.
Most of these systems increased power in the upper RPM range, but for most street driving, that's pretty useless. If you have a big motor with lots of torque, it probably won't matter. But on a little engine like the Yaris has, a mid-range torque hit can be very noticeable. |
08-22-2009, 11:08 AM | #4 |
ULTIMATE
Drives: 07 Yaris Turbo Join Date: May 2007
Location: Canoga Park, CA
Posts: 14,859
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yes on the anti-fouler question.
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Micro Image forums, online store and shop are now closed. It was a great eight year run, but it was time to focus on other things. I'm still selling parts on eBay under micro*image seller ID and customers can still make requests for anything specific. |
08-22-2009, 11:23 AM | #5 |
Drives: Vitz RS Turbo Join Date: Nov 2008
Location: ML
Posts: 576
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When I completed the 2.5" exhuast from the downpipe to the rear I really felt the difference in torque especially on the 3rd gear compared to the downpipe only. From this experience I understood well how much back pressure makes a big difference...
Last edited by Parmas; 08-22-2009 at 12:55 PM. |
08-22-2009, 04:36 PM | #6 | |
Start another Oil Thread!
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it has less to do with back pressure, and more to do with velocity and/or laminar flow of the exhaust gasses. the higher the exhaust gas velocity, the more "smoothly" it flows through the exhaust pipe.
if you want more "back pressure" put in a smaller exhaust pipe.
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08-23-2009, 05:01 PM | #7 |
Also, did you reset the ECU? I just installed the DC header and had a similar issue. After an ECU reset I got most, if not all, of the mid-range power back.
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08-24-2009, 07:38 PM | #8 |
08-24-2009, 07:45 PM | #9 | |
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08-24-2009, 07:48 PM | #10 |
Banned
Drives: LB Join Date: Jul 2006
Location: OH
Posts: 7,787
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Take it from me... on the subject of power, never make decisions based on "feel." Why don't you go dyno that thing and make sure you're not just feeling what you expected to happen rather than what actually is?
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08-24-2009, 07:56 PM | #11 |
The power feels smoother throughout the whole RPM range it just lost a lot of "pep" at low RPMS It probably is making more power overall just less power where I typically use it on the street.
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08-24-2009, 08:28 PM | #12 |
Drives: 2006 yaris Join Date: Oct 2008
Location: Puerto Rico
Posts: 536
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Not using a straight thru muffler will help the back pressure, like a dynomax turbo muffler or similar style.
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08-24-2009, 08:44 PM | #13 |
Banned
Drives: LB Join Date: Jul 2006
Location: OH
Posts: 7,787
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I guess it is hard to justify spending money on a dyno visit to find out if you're gaining/losing 3 foot pounds at the wheels. Either way good luck with the decision.
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