Liberty CRD 3" Exhaust Question

epimethius05 · **Posted:** Fri Feb 25, 2011 5:51 pm

Yes I'm a noob...
I have read several strings about owners putting 3" straight pipe and and 2 1/2 or 3" flowmaster mufflers on their CRD.

I got my 3" areo muffler today and tried to have it installed at a local performance muffler shop.
I was turned away because he said what I bought was too big. That it was too much to jump from the 2 1/8 exhaust to 3".

My question is do I remove the CAT and run 3" from the from the header/exhaust manifold flange or do I need to also get a 3" CAT? Which application is best? Also is there an adapter available to go from the stock diameter (whatever that is) to 3" ?

Any advice is greatly appreciated (bowing down to my Sensei)
John :JEEPIN:

ATXKJ · **Posted:** Fri Feb 25, 2011 9:00 pm

your 'local performance muffler shop' - just proved that they are totally clueless about turbo diesels.

2 1/2 is great 3" would be better - but unless you run it to the Turbo - not sure you'll tell the difference - although some folks have gone no muffler - the Turbo legally acts as one.

and FYI - you'll get a better response if you post in the general CRD - love that torque section

Tech is for solutions once the problem gets solved.

fastRob · **Posted:** Mon Feb 28, 2011 1:02 pm

I went 3" catback with a 3" muffler, did stainless.
I am happy but I did not notice any improvement, was planning on going to the turbo eventually.
Went to a custom guy after a chain shop really screwed it up.
Do an online search for 2 of the 3" 45 degree stainless sweeps for over the rear axle from Road Race Engineering, CA, $77.50 a few years ago.
Good Luck.

Glend · **Posted:** Mon Feb 28, 2011 5:37 pm

At least on my 'export model' the exhaust system is 2 1/2" (if you remove all the restriction flanges, ditch the stock muffler, and cut off the tube narrowing to the muffler). So you can retain the stock SS tubes just get rid of the narrow bits. There have been some older posts on this that suggest that 3" is actually less efficient than 2 1/2" on the VM due to the effect that the larger diameter has on 'laminar flow' of the gases. Try some searches.

GreenDieselEngineering · **Joined:** Sun Jun 07, 2009 5:10 pm **Posts:** 1111

The larger exhaust will have a very minimal effect on performance and fuel economy on the CRD (statistically insignificant). The majority of exhaust energy is absorbed through the turbo. If you remove the catalyst you will notice a huge increase in hydrocarbon and carbon monoxide. The HC causes the exhaust to smell very bad and is a bit painful on the eyes. Plus the catalyst has about $300 of platinum in it and you certainly do not want a new cat with 3" inlet and outlet due to the cost and it is very doubtful anyone would have the correct substrate structure, cell density or loading for the CRD.

LibertyCRD · **Posted:** Tue Mar 01, 2011 10:25 am

Wow, an exhaust shop that actually knows what they are doing. Don't see that often.

3" is way too big for a 200 HP application. Geez...my buddies '07 Cummins had that on it from the factory and it makes twice the power.

AJN · **Joined:** Tue Oct 19, 2010 12:42 am **Posts:** 53

A local muffler shop did the cat-back straight pipe mod in about 15 minutes with a piece of 2 1/2 pipe with the appropriate mandrel bends and solid weld - very clean work which eliminates the restriction from the factory muffler. I figured I'd try the straight pipe first and if I didn't like it I could replace it with a performance muffler.

The CRD now has a slight growl to it, and the turbo seems to spool up a bit more quickly. Definitely a good modification.

epimethius05 · **Posted:** Thu Mar 03, 2011 1:24 am

Got my 3" Aero Muffler/resonator installed today.
After talking with a diesel guy (muffler shop) for quite some time, he told me that replacing the OE CAT with a high flow CAT would not do much performance-wise as most of the restriction was caused by the OE muffler.
So I had a 3" adapter flange put on the CAT then, 3" pipe all the way back to the 4" tip.
So far I'm pretty happy with the sound and the quicker spool up from the turbo.
I have lots more mods still left to do. :shock:

Any input on what I should do next?
:JEEPIN:

warp2diesel · **Posted:** Thu Mar 03, 2011 8:41 pm

epimethius05 wrote:

Got my 3" Aero Muffler/resonator installed today.
After talking with a diesel guy (muffler shop) for quite some time, he told me that replacing the OE CAT with a high flow CAT would not do much performance-wise as most of the restriction was caused by the OE muffler.
So I had a 3" adapter flange put on the CAT then, 3" pipe all the way back to the 4" tip.
So far I'm pretty happy with the sound and the quicker spool up from the turbo.
I have lots more mods still left to do. :shock:

Any input on what I should do next?
:JEEPIN:

If you got rid of the 2 1/8" choke point in the cat flange, you did a good thing.
I ran and posted tests on back pressure by putting a boost gauge between the turbo and cat. When I got rid of the 2 1/8" choke point and 2 1/2" all the way back, the back pressure went to 0.0 PSI and stayed there. With your 3" as long as you got rid of the 2 1/8" choke flange should also have 0.0 PSI back pressure.

My stock turbo spools up much faster too.

As you can see by my mods, my CRD is strong & sweet, BUT NOT a VIRGIN, just better.

jrsavoie · **Posted:** Sat Sep 14, 2013 5:00 pm

This is along the lines of where I want to go with the exhaust. Now we have an 8 year old exhaust with 140,000 miles on the cat. I still think this is a necessary upgrade, at this mileage. A plugging cat will kill an engine as fast as anything. I've never seen exhausts from these Jeeps, but the exhausts I've seen from other diesels, with similar miles, reminded me of the EGR system. How long do these exhaust systems generally hold up in the salt belt?

Does anybody make a 2 1/2" stainless high flow exhaust for these vehicles that installs as effortlessly as the 4" exhaust kits install in the 6.5 diesels?

If you got rid of the 2 1/8" choke point in the cat flange, you did a good thing.
I ran and posted tests on back pressure by putting a boost gauge between the turbo and cat. When I got rid of the 2 1/8" choke point and 2 1/2" all the way back, the back pressure went to 0.0 PSI and stayed there. With your 3" as long as you got rid of the 2 1/8" choke flange should also have 0.0 PSI back pressure.

My stock turbo spools up much faster too.

As you can see by my mods, my CRD is strong & sweet, BUT NOT a VIRGIN, just better.[/quote]

DOC4444 · **Posted:** Sat Sep 14, 2013 6:55 pm

We have the Magnaflow cat back system with platinum delete option. However, Magnaflow is pretty bad in terms of warranty returns.

DOC

jrsavoie · **Posted:** Sat Sep 14, 2013 11:45 pm

DOC4444 wrote:

We have the Magnaflow cat back system with platinum delete option. However, Magnaflow is pretty bad in terms of warranty returns.

DOC

Is that stainless?

What are the warranty issues?

These are cat back gasser kits. All stainless with stainless hardware. Will they be a direct bolt on for the most part?

If these kits willo work I would go with Flowmaster 817608 $381.48
Magnaflow 15870 $497.68 or

MBRP S5510409 $314.50

Those prices are from autoanything.com
(800) 874-8888 ext 7116
Let me know what you think our best move on the exhaust is
These are all cat back systems for a gasser

Liberty CRD 3" Exhaust Question

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