lancerswimmer89 Posted January 19, 2014 Share Posted January 19, 2014 Hey guys, so i just added a catless midpipe to my car the other day, and it kinda feels like i've lost power. So i am now running a Weapon R secret weapon intake w/ the metal intake box, a speedyracer header, tsudo catless midpipe w/ resonator, and a 2.5" catback magnaflow exhaust. Does anyone know how I would get the power or torque back? does it need a tune? or do i need to turn off my rear o2 sensor now that the catalytic converters are gone? Any and all help would be greatly appreciated. Link to comment Share on other sites More sharing options...
Zues Marine Posted January 19, 2014 Share Posted January 19, 2014 2.5" is too big, you're losing backpressure and without grinding your cams and a bore...2" is the biggest you should be running Link to comment Share on other sites More sharing options...
Kennyfvholla Posted January 19, 2014 Share Posted January 19, 2014 On a 2.5 liter motor, a 2.5" exhaust you're going to lose part throttle power throughout the power band, but you'll gain throttle response. You are also shifting the power band towards the top end a bit. I don't think the "power problems" with the exhaust are because it's too big, I believe it's just the motors themselves.. My 3.0 V6 actually works extremely well with a 3" to dual 2.5" catback (catless, no resonator) exhaust system. The best results with my motor have been seen with a single pipe 3" catback (catless, no resonator) system. I believe a more powerful 2.5 would run optimally with a 2.5" catback system. I think anything smaller would restrain it. It's all about how much air the motor is flowing. If you have a 2.2 liter engine, 2.25" is the absolute biggest the piping should be PERIOD. The SOHC EJ22 heads literally flow HALF as well as SOHC 2.5 heads. Link to comment Share on other sites More sharing options...
robinlsb Posted January 19, 2014 Share Posted January 19, 2014 Hey guys, so i just added a catless midpipe to my car the other day, and it kinda feels like i've lost power. So i am now running a Weapon R secret weapon intake w/ the metal intake box, a speedyracer header, tsudo catless midpipe w/ resonator, and a 2.5" catback magnaflow exhaust. Does anyone know how I would get the power or torque back? does it need a tune? or do i need to turn off my rear o2 sensor now that the catalytic converters are gone? Any and all help would be greatly appreciated. Downpipe???? "Belief does not make truth. Evidence makes truth. And belief does not make evidence." Link to comment Share on other sites More sharing options...
lancerswimmer89 Posted January 20, 2014 Author Share Posted January 20, 2014 i don't have a downpipe, my car is n/a... Link to comment Share on other sites More sharing options...
IrishLt Posted January 20, 2014 Share Posted January 20, 2014 Could always try to disconnect the battery for a bit to see if the ecu needs to relearn fueling maps after the cat delete.......but I wouldn't be surprised to hear that a cat delete and larger pipes caused you to lose some low end torque. Ass-dynos tend not to always be reliable either....remember that you've screwed with the power-band by altering exhaust. Might not have lost the power but have moved it further up the band. Link to comment Share on other sites More sharing options...
Bassnectar Posted January 20, 2014 Share Posted January 20, 2014 You essentially made your car louder without adding any performance. I wonder why it would "feel" slower? Wink wink nudge nudge Sent from my SGH-I337M using Tapatalk Link to comment Share on other sites More sharing options...
DGR81 Posted January 20, 2014 Share Posted January 20, 2014 [ame=http://www.youtube.com/watch?v=SOsEuScaT78]Subaru Impreza Horsepower Increase - Wheeler Dealers - YouTube[/ame] I don't know if this would apply to your situation. Link to comment Share on other sites More sharing options...
DOHCEJ22E1 Posted January 20, 2014 Share Posted January 20, 2014 You lose or gain engine response by changing exhaust piping diameter. What YOU (the OP) felt was actually a loss of low-end TQ when you decided to straight-pipe it. If you put the cats back on, you will regain the low-end that you lost. However, as a trade-off for your low-end shrinking, your mid-to-top range powerband has increased, making your car less capable for the street & more for the highway. If you have a stock 2.2, 2.25 is the top diameter than you should be running but our computers hate it when there are no cats around & they tend to run rich as a way to compensate for the loss. Messing with your O2 sensors will make you rue your fuel gauge. Put a high flow cat on (they ARE available), don't mess with your O2 sensors, & you will be just fine. Link to comment Share on other sites More sharing options...
spooln30 Posted January 21, 2014 Share Posted January 21, 2014 Maybe you were just expecting too much from adding these parts. These engines won't net big gains from bolt-ons verse say a turbo engine. But yes NA engines need a certain amount of backpressure and too little will equal less overall power. Link to comment Share on other sites More sharing options...
spooln30 Posted January 21, 2014 Share Posted January 21, 2014 Honestly I think the best exhaust set up would be a UEL header with stock cats and a OEM STI axle back muffler. This would be the set up I would use on my LGT if I were staying NA. Link to comment Share on other sites More sharing options...
boostedgrocerygetter Posted January 27, 2014 Share Posted January 27, 2014 On turbo cars there is no such thing as "too big" of an exhaust. But on N/A cars you have to be careful you can't just run the biggest exhaust you can find. You shouldn't be running anything larger than about 2inch unless you have a built motor. Link to comment Share on other sites More sharing options...
Zues Marine Posted January 27, 2014 Share Posted January 27, 2014 unless you have a built motor. yeah, like cams and such.. not a cone filter and LW pulley system lol Link to comment Share on other sites More sharing options...
DJBRANDER Posted January 29, 2014 Share Posted January 29, 2014 damn, I knew I went too big. It's ok... im finally sick of the noise. Time to quiet it down Link to comment Share on other sites More sharing options...
Bassnectar Posted January 29, 2014 Share Posted January 29, 2014 Leave it 2.5 inch but put a restriction in the middle. Sent from my SGH-I337M using Tapatalk Link to comment Share on other sites More sharing options...
Kennyfvholla Posted January 29, 2014 Share Posted January 29, 2014 Throw two universal high flow cats in and see what happens. You'll quiet down and regain some back pressure. Link to comment Share on other sites More sharing options...
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