Exhaust mod gone bad.
10-12-2011, 12:21 PM
#11
JK Junkie
I lost a lot of low end when I swapped to a Cherry Bomb Extreme from my MBRP muffler. I wanted the noise, but at least I got a nice bump in mid-range power.
Maybe try getting a MBRP muffler only and put it on?
Maybe try getting a MBRP muffler only and put it on?
10-12-2011, 12:32 PM
#12
JK Enthusiast
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I have the same feeling after putting on a Gibson Dual Tip Muffler. Went to a local shop who specializes in performance exhaust and they recommend putting a resonator in front or the Gibson. I am trying that next week.
....Really, I would.
10-12-2011, 01:03 PM
#15
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Is it throwing any codes? If the cats arent working properly or the O2 sensors arent communicating properly your timing or fuel may be retarded. IF you have codes, try disconnecting the o2 sensors and zip tie to the frame. If the O2 sensors dont send a signal that they are warm the computer will ignore the emissions issues and not throw codes and not retard timing and fuel. I am not saying toyota guys take their cats off, but if for testing reasons they did, they always disco the O2 sensors for this reason.
10-12-2011, 01:23 PM
#16
JK Enthusiast
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Alright, thanks for all the input....
Sorry no sound clips.
No headers.... Stock manifolds.
The exhaust pipes are 2" off the manifolds to the 2 cats (not 4) to the Y-pipe then 2 1/2" to the muffler.
I went with 2 high flow mini cats from magnaflow. 2 1/2" pipe From manifold to cats to a flowmaster 40 (under the drivers seat) and a straight pipe about 24" long with a downturn just in front of the rear diff.
Well the loss of power after checking and researching is sure to lack of backpressure.
And although I do care about gas mileage, power is way more important than mileage (my choice)
Still talking and researching, probably going to change out the muffler and pipe after muffler to 2" & then make it longer.
Then go from there.
Sorry no sound clips.
No headers.... Stock manifolds.
The exhaust pipes are 2" off the manifolds to the 2 cats (not 4) to the Y-pipe then 2 1/2" to the muffler.
I went with 2 high flow mini cats from magnaflow. 2 1/2" pipe From manifold to cats to a flowmaster 40 (under the drivers seat) and a straight pipe about 24" long with a downturn just in front of the rear diff.
Well the loss of power after checking and researching is sure to lack of backpressure.
And although I do care about gas mileage, power is way more important than mileage (my choice)
Still talking and researching, probably going to change out the muffler and pipe after muffler to 2" & then make it longer.
Then go from there.
10-12-2011, 02:07 PM
#17
JK Newbie
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increasing exhaust gas velocity = more low end power = less high end power. the mod you performed is the same as increasing the diameter of your exhaust...which decreased exhaust gas velocity...which is bad for low end torque. it's hard to believe, but making your engine breathe easier can cost low end power
10-12-2011, 03:50 PM
#19
JK Junkie
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Thanks for the advise
Well I could go and pay for dyno pulls and hope I get at least three pulls with constant numbers, but they would be pretty much useless, unless I had some baseline numbers to compare with... but to be honest, it is real bad. You would not need a dyno print out to tell you there is a major loss.
now as far as a change, should I change from cat back, or cat forward, what about options...like mufflers? Or simply changing after muffler tail pipe to slow down the exit? Really would hate the expense of starting over and using smaller pipe thoughtout. Oh well.
Well I could go and pay for dyno pulls and hope I get at least three pulls with constant numbers, but they would be pretty much useless, unless I had some baseline numbers to compare with... but to be honest, it is real bad. You would not need a dyno print out to tell you there is a major loss.
now as far as a change, should I change from cat back, or cat forward, what about options...like mufflers? Or simply changing after muffler tail pipe to slow down the exit? Really would hate the expense of starting over and using smaller pipe thoughtout. Oh well.
10-12-2011, 04:51 PM
#20
JK Super Freak
Same thing happens when guys put straight pipes on their Harley's for sound and top end power. Unfortunately, most of us never drive in that power range in day to day driving. The straight pipes were made for drag racing and WOT, hi rev blasts. So these guys like the sound and the look but lose practical torque for daily driving. So a quick fix is to bolt baffles or restrictors inside the pipe to create back pressure. Some guys drill a hole into their pipes, thread a bolt through and weld a large washer to the bolt end which they can turn to adjust the amount of back pressure just by turning the bolt and changing the angle of the washer. Maybe you can rig something similar in your pipe to create needed back pressure.