Exhaust question....keep the cat or find a new home for it? If it goes 4" or 5"

[Bouma]

I just had my truck in and had the FCA replaced. However got a clean bill of health on everything else. With that said the mechanic told me when we were talking about EGT's "If it was my truck I would dump the cat" I have a 5" magnaflow cat back exhaust on the truck currently. It has been on there for 6+ years. It is loud enough for me. I have also read that with a 5" turbo back I may loose performance. So the million dollar question is, keep the cat or not? If everyone says it has to go should I do a turbo back 4" or 5"? My gut tells me a turbo back 4" magnaflow ss. I want to avoid the drone towing if possible. If the answer is yes then who makes a turbo back system that will not kill your ears? I am open to all brands. I just thought magnaflow because my old cat back system has held up nice and the band claps vs U bolts I like.

 

[NIsaacs]

We need more info on your truck... .

Nick

 

[Bouma]

We need more info on your truck... .

Nick

Please see sig, Basically as stock truck, no programmer, just a cat back 5" with a full set of gauges.

 

[AH64ID]

The biggest difference you will see is the turbo cools down quicker, I am not sure you will notice a difference on EGT's when towing, I didn't. The cat is a free flowing unit.

With the stock turbo the restriction is the turbo, so any restriction from the cat won't have much, if any, effect on cylinder temps/flow.

 

[MChrist]

I've heard consistently from people who have dyno tested exhaust systems that even a stock catalytic converter has almost zero restriction. Even at elevated levels, there may only be a two to five HP cost. The benefits are less diesel smell, it may be required by law, and quieter. . especially when towing.

On the other hand, I've heard consistently from people who HAVEN'T dyno tested anything "Ya gotta cut that thar thang outta there. . yer jest chokin' that engeen!"

Which camp would you rather be in? I still have my stock pipes and converter on my (approximately) 450 rwhp twin-turbo Smarty S06 truck. I could put any exhaust on my truck I want, and have the tools, shop, lift, and materials I need to alter my exhaust any way I want and I choose to leave mine stock, with the exception of a muffler from a Medium Duty truck.

Truck is quiet as stock, tows quietly, and runs 0-60 in 4. 5 seconds consistently. You have a 5" converter on a stock truck. I think you'll be just fine.

 

[SierraRam]

I have removed mine and went with the MBRP 5" turbo back, I did not do this for HP gain, I did it for lower EGT's and I wanted the semi exhaust note. I acheived both of these.

The problem is in CA I must smog check every other year and if you get caught without the CAT hear it is an $800 fine. Not sure what you state has in mind for future emission laws.

 

[MChrist]

I just read your first post and noticed you have a 5" cat back exhaust. I assumed you also had a 5" cat, not the stock 4" cat. Either way, you will be fine with the stock cat.
Also, are you the one who posted elsewhere that you had an EGT probe installed after the turbo and it was reading 800-1000 towing a 16' enclosed light trailer? If you are the same person, I meant to say that seems quite high, since Banks and several others report a 250-300 degree drop from pre turbo to post turbo temps. Those temps aren't too high for the motor, but too high for what you are towing. Keep in mind, you may have one cylinder running 1500 degrees and the rest at 1200. One is too high, the others can run there all day and night. There seems to be a problem elsewhere.

Only takes one cylinder meltdown to put a damper on your day...

 

[Bouma]

I just read your first post and noticed you have a 5" cat back exhaust. I assumed you also had a 5" cat, not the stock 4" cat. Either way, you will be fine with the stock cat.
Also, are you the one who posted elsewhere that you had an EGT probe installed after the turbo and it was reading 800-1000 towing a 16' enclosed light trailer? If you are the same person, I meant to say that seems quite high, since Banks and several others report a 250-300 degree drop from pre turbo to post turbo temps. Those temps aren't too high for the motor, but too high for what you are towing. Keep in mind, you may have one cylinder running 1500 degrees and the rest at 1200. One is too high, the others can run there all day and night. There seems to be a problem elsewhere.

Only takes one cylinder meltdown to put a damper on your day...

Yes that was me that posted about the EGT's being high. I took my truck to a company that only does diesel injection work. They checked the lift pump, CP3, injectors, injector return, etc. The only issue they found was the FCA. I towed the same trailer last night. I can get to 800-900 degrees accelerating hard. However running 75 I am between 600-700 degrees now. If I see a hill it will gain some but go back down. They told me the fuel system was in remarkable good shap. They gave me a print out of how many millilieter each unit has, all very good and way inside of Chrysler's "safe" area. They did recommend getting rid of the cat however. They thought there may be some blockage. I do have a 5" cat back with a stock cat. My thought was a 4" turbo back removing the cat. Not sure I am in danger of a cylinder meltdown if the fuel system is passing with flying colors. They did check temps on each cylinder as it warmed up. According to them it is a green light.

 

[Bouma]

I also am surprised at the number of guys that say to leave the cat. I figured for sure the response would be cut it off... .

 

[MChrist]

Your new, improved EGTs sound correct now. Glad the FCA is all it was. Could've been much worse!
The cat is up to you. I haven't heard of any diesel cat plugging up, but I'm not an authority. I do know that they are different from gasoline vehicle cats. They DO plug up/melt.

Anybody out there ever heard of a diesel cat plugging up? I know there are guys on this forum with hundreds of thousands of miles with a factory cat and no problems. .

 

[cerberusiam]

If one runs a tuner with too high EGT's for a length of time it can melt the honeycomb in them and they will be a big cork. Stock it is doubtful they will melt or plug as they quite open.

 

[Bob4x4]

I would love to see a pic of any Ctd cat that has plugged

I have not seen this yet,built many at many different power levels,so far all good

 

[Bouma]

Your new, improved EGTs sound correct now. Glad the FCA is all it was. Could've been much worse!
The cat is up to you. I haven't heard of any diesel cat plugging up, but I'm not an authority. I do know that they are different from gasoline vehicle cats. They DO plug up/melt.

Anybody out there ever heard of a diesel cat plugging up? I know there are guys on this forum with hundreds of thousands of miles with a factory cat and no problems. .

Sorry I had to point this out... I don't post nearly as much as you. I am more of a reader. If I don't understand something I don't want to give advice that may be wrong. Others such as yourself are more versed in this than I am. However new? I actually have been a member since 2006 you joined in 2008..... Sorry couldn't resist. I do however greatly appreciate your help and advice. Just the smart ***** in me comes out every now and then... Have a great day.

 

[Bouma]

If one runs a tuner with too high EGT's for a length of time it can melt the honeycomb in them and they will be a big cork. Stock it is doubtful they will melt or plug as they quite open.

I have heard that since i have owned a diesel. When I saw the numbers I backed out of it and slowed down. Last thing i need to do is cook this thing.

 

[Bouma]

I would love to see a pic of any Ctd cat that has plugged

I have not seen this yet,built many at many different power levels,so far all good

So Bob your saying that I should leave it alone? With the new EGT numbers I posted you feel that I am good? I would rather not do anything with it, I would rather have the sound muffled. Thanks again for the help

 

[MChrist]

Sorry I had to point this out... I don't post nearly as much as you. I am more of a reader. If I don't understand something I don't want to give advice that may be wrong. Others such as yourself are more versed in this than I am. However new? I actually have been a member since 2006 you joined in 2008..... Sorry couldn't resist. I do however greatly appreciate your help and advice. Just the smart ***** in me comes out every now and then... Have a great day.

I wasn't implying that YOU were new... I said "Your new, improved EGTs sound correct. ". Your previous EGTs were much higher than they are now. That's a good thing.
And I don't mean to sound like a smart *** either, but if I wanted to imply that YOU were new, I would've typed "You're" new...
Have a nice day as well.

 

[Bouma]

I wasn't implying that YOU were new... I said "Your new, improved EGTs sound correct. ". Your previous EGTs were much higher than they are now. That's a good thing.
And I don't mean to sound like a smart *** either, but if I wanted to imply that YOU were new, I would've typed "You're" new...
Have a nice day as well.

You got me on that one. One thing I love about the TDR and it's members, on other sites someone would have taken my comment in a way not intended. MChrist PM sent. Thanks again.

 

[Bob4x4]

So Bob your saying that I should leave it alone? With the new EGT numbers I posted you feel that I am good? I would rather not do anything with it, I would rather have the sound muffled. Thanks again for the help

Yes keep the Cat. I have one of most responsive crd's I have driven,it tows great the temps are good,power is good and the cat is in place

 

[AH64ID]

If one runs a tuner with too high EGT's for a length of time it can melt the honeycomb in them and they will be a big cork. Stock it is doubtful they will melt or plug as they quite open.

I am not as worried about tuner EGT's as most tuners lower then for sustained operation. The reason mine is not as operational as it once was is the added soot, and lower EGT's. With more soot and less heat the cat can become plugged easier, and then it can cause issues.

I also didn't like the smell with the cat, it didn't smell like a diesel.