Dynomax Cat Back - JeepForum.com

 
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post #1 of 11 Old 10-02-2009, 11:04 PM Thread Starter
befumo
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Dynomax Cat Back

Plan on buying this soon, was wondering if there is any gain in power or fuel economy? Heard some people say yes, some people say no, etc.

I know it sounds good and is cheap.


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post #2 of 11 Old 10-03-2009, 11:39 AM
mightydog78
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all the exhaust will do for you is make it sound better. I RARELY ever here of increases fuel economy, but maybe a tiny bit of power gain (not enough to notice)

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post #3 of 11 Old 10-03-2009, 11:57 AM
InfernoGirl
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None that you are likely to notice, with any exhaust really.

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post #4 of 11 Old 10-03-2009, 12:45 PM
alecmcmahon
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it sounds nice, i went with the dynomax cat back last year... I ripped the tail pipe off in the woods, then later rippped then the muffler broke off at the welds, roadside treasure somewhere. now im running a 25 dollar muffler i found at a 4wd shop, sounds the same if not better.
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post #5 of 11 Old 10-03-2009, 01:12 PM Thread Starter
befumo
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Really theres no real gain in horsepower? I dont get that, how come? I mean other cat backs on other vehicles give you a gain in horse power.

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post #6 of 11 Old 10-03-2009, 02:31 PM
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Why do you think putting a different muffler on would give you a horse power boost?
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post #7 of 11 Old 10-03-2009, 03:56 PM Thread Starter
befumo
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Quote:
Originally Posted by alecmcmahon View Post
Why do you think putting a different muffler on would give you a horse power boost?
Excuse me, never really thought about it. Thought it was more free flowing then stock, plus the diameter was larger also.

Hm, well was under the impression that cat backs give you a gain in horsepower. Then how do you gain horsepower from the 4.0, doesnt it basically have headers now.. and upgrading from 2.5'' to 3'' will cause a loss in torque correct.

School me.

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post #8 of 11 Old 10-03-2009, 10:46 PM
mightydog78
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im pretty sure increasing the diameter can mess with the backpressure and decrease the torque. There really isnt any big way to increase horsepower from what I've heard excepts getting an LS1 engine swap

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post #9 of 11 Old 10-04-2009, 12:33 AM
ClimbStuff
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The head in the 4.0L is so restrictive, that even opening up the sir ways doesn't yield much gain... mostly because the camshaft duration is so short. These things are out of breath at 5000rpm... if you could get a .500/.500 with 242 dur @.050, im sure it would breath pretty heavy.

I've removed the air box and intake tube and run the engine hard under load with just the throttle body and let me tell you, it wants to breath hard, it really does. I've been messing with engines for going on 17yrs now and I can hear a work horse trying to come out of its shell. If there was a 200cfm head available, I bet 300hp would be cake with this hoss.
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post #10 of 11 Old 10-04-2009, 07:57 AM
alecmcmahon
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Quote:
Originally Posted by befumo View Post
Excuse me, never really thought about it. Thought it was more free flowing then stock, plus the diameter was larger also.

Hm, well was under the impression that cat backs give you a gain in horsepower. Then how do you gain horsepower from the 4.0, doesnt it basically have headers now.. and upgrading from 2.5'' to 3'' will cause a loss in torque correct.

School me.
Not a problem, if your looking for more power & you have bigger tires, IMO the most effective way is to re-gear.
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post #11 of 11 Old 10-04-2009, 09:56 AM Thread Starter
befumo
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Nah just have 30 inch tires and 3.73s with automatic. Just want a little more power, nothing major.

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