[pastorscott]

Question
on my 97 TJ 2.5 with 5 speed.. I went to a borla high flow cat plus a turbo muffler with 2.5 inch pipes.. problem is its way too loud and feels more slugish taking off... is that possible

 

[UnlimitedLJ04]

yup, thats possible. your 2.5L doesn't need a fancy exhaust. it can't even move enough air to use it.

 

[redneckpunk]

Sounds like you lost some of your low end torque. Unless you engine is tuned for a more free flowing exhaust, you won't be able to get full advantage from it, but it should free up some higher end HP.

 

[krisbman]

Bigger pipe equals less backpressure which equals less torque to an extent.

 

[tabber02]

Bigger pipe equals less backpressure which equals less torque to an extent.

^^ spot on there. :thumb: only way to "get back" the back pressure is to increase the baffling in the larger diameter pipes... but that defeats the purpose (typically) of throwing them on... sound.

 

[Robertsk1]

The "happy medium" in exhaust piping size is something we generally always try and find when it comes to vehicles. Finding a good pipe size where there is enough back pressure from the atmosphere, but also enough room for the exhaust to flow out unrestricted is tough with some vehicles. However, jeep got it pretty damn good putting 2.25 diameter piping on our 97 jeeps, and the intake is also pretty unrestrictive stock. Some vehicles benefit much more from CAI and aftermarket exhaust systems because the stock ones were restrictive, but this is not the case with our wranglers. Your best bet is to find an exhaust system that maintains that 2.25 diameter piping.

Anything smaller is going to be too restrictive and make the engine work harder to push the exhaust fumes through, and anything bigger will cause a loss of the backpressure krisbman alluded too.

 

[jeepinmike]

Yes, 2.5" on a stock 2.5L will lose low end, but should gain a little near redline, but most of us don't care about that end of the spectrum.