What is the purpose of the dent is the exhausts

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03-08-2012 | 10:37 AM

#31

djb383

CF Veteran

Joined: Nov 2009

Posts: 8,172

Likes: 17

From: The Republic of TEXAS

Year: 1998

Model: Cherokee

Engine: 4.0L HO

Wouldn't the dent/restriction cause more heat ahead of the restriction and less heat after?

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03-08-2012 | 10:45 AM

#32

kissthis66

Senior Member

Joined: Apr 2010

Posts: 720

Likes: 1

From: Marshall, WI

Year: 1994

Model: Cherokee

Engine: 4.0L i6

Quote:

Originally Posted by djb383

Wouldn't the dent/restriction cause more heat ahead of the restriction and less heat after?

Seems that way to me.

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03-08-2012 | 10:53 AM

#33

ZINGGG

CF Veteran

Joined: Oct 2011

Posts: 4,440

Likes: 3

From: Seal Beach, CA

Year: 1996

Model: Cherokee

Engine: 4.0 HO Straight Six

Quote:

Originally Posted by djb383

Wouldn't the dent/restriction cause more heat ahead of the restriction and less heat after?

That's what seems logical to me but I'm by no means an expert on this stuff

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03-08-2012 | 12:59 PM

#34

gpeade

Seasoned Member

Joined: Jan 2012

Posts: 401

Likes: 1

From: Smithfield, VA

Year: 1997

Model: Cherokee

Engine: 4.0

Quote:

Originally Posted by 413maxwedge

Just so people ask ? about it.

I think you are right! 3 pages in 2 days, Curious to see how long this debate runs.

Gotta wonder if (short of the enginer that made the design) we will ever no for sure or just speculate.

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03-08-2012 | 01:26 PM

#35

bheath

CF Veteran

Joined: Jul 2011

Posts: 4,521

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From: JOCO

Year: 1999

Engine: 4.0 Inline 6

X2 ^

i think i'll just stick with my "...stick/log/branch shoved up in there.'' theory... im in mo way an expert on exhaust systems and the reasoning behind the way they are designed, so you could tell me that its there to deadened the sound and i'd believe you. Maybe thats why?.?.?.

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03-08-2012 | 05:35 PM

#36

cruiser54

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Joined: Aug 2011

Posts: 43,971

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From: Prescott, Az

Year: 1990

Model: Cherokee (XJ)

Engine: 4.0

Well, I've done this on 3 Renix Jeeps and a 99 XJ. Performance increase and throttle response were noticeable. As to getting into all that theory stuff, it only stands to reason that if you restrict the heat before the dent, it's gonna be hotter after the dent than it would be if you had no dent.

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03-08-2012 | 06:02 PM

#37

5-90

CF Veteran

Joined: May 2008

Posts: 3,018

Likes: 17

Year: 1988

Model: Cherokee

Engine: AMC242

Quote:

Originally Posted by cruiser54

Here's my .02 FWIW. Jon, correct me if I'm wrong.

I'm thinking the dent is there to help the converter heat up faster from a cold start. Therefore, by the time you had your emissions test, the cat would be plenty warmed up already.

Entirely possible - see previous comment on exhaust ports in the 0331 head.

Methinks the jury is still out. Either way, my opinions and thoughts on emissions control are well known - there are better ways to solve the problem, with less equipment, that is more reliable, without harming performance to do so (improved fuel efficiency generally = improved fuel economy. Improved combustion efficiency = improved fuel economy.)

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