Changing Mufflers on a cat c7

[n4hwl]

I have learned from experience with my Dodge truck (1998 cummins 5.9 isb) that when I added a 4 inch exhaust and a low restriction muffler that my exhaust temperature dropped some. I have a 2004 cat c7 in a 40 foot phaeton. I have the original exhaust and original air filter. I am wondering if anyone has tested the exhaust temperature change (if any) when going to a lower restriction muffler on these c7 engine in my type of application. Just wondering.

Ken

[RayChez]

Why add more power if you already have a powerful motor?

[John_S_]

I have an ISM and it is a huge difference. I get about .8 of a mpg better. I run a bit cooler and get two extra pounds of boost. It is better then 50hp stronger too. It is a bigger difference on the bigger motors but it works on the smaller ones too . Many FT owners are doing this now. They don't make my big can muffler and the Areo works great.

[down_home]

There is probably a hp and torque increase but not 100 hp or enough, to register, at seat, of the pants, in a MH. It should cool down the turbo causing part, of the increase.
Our 05 C7 has a cat, in the muffler. Why, I don't know because the chassis is an 04.
I've thought about the Aero muffler, a time or two but there is no 100% consensus one way or tuther.
If I change, it will be, for an 04 spec muffler or better, that is quiet.
I think more are no than yes, on the change, on the forums.

[TDInewguy]

I have a 2002 CAT 3126... and it had a HUGE stock muffler that probably had a catalytic converter or something in it. I have no idea for sure though.

I put on the famed Aero 5050XL and it was "cool" for a while as I'm also a car guy and my car crowd loved the noise, it really bugged me the drone. At 70-75 the drone was gone so I spent a lot of time at higher speeds, but at the expense of MPG.

So I went on a quest to find the ideal muffler. low backpressure and low noise. I ended up getting a stock style muffler for a semi truck from the local truck repair shop. Donaldson is the brand, and it's a 5" straight thru muffler that is about 5' long. it's very low backpressure, but a LOT quieter.

Lesson learned. If you are hard of hearing and your wife is too, then who cares, but the drone of the Aero muffler drove me nuts, and I'm only 38 years old.

[RayChez]

wny_pat wrote:

RayChez wrote:
I inquired about the Aero Muffler and the air cleaner that is also part of the deal when installed. 99% of the rvers that posted on that thread that I started said it was NO GOOD. First they said the filter would allow dust to get through harming the engine. And some said the Aero muffler did not increase the power at all on their coaches. So I decided not to invest on such a project. I saved myself $1200. I also saw the vendor at the FMCA rally in Indio, California.

But I know several who just removed the old muffler and installed just the Aero 5050XL resonator, who say that it has helped, but they had big horses, like 400 hp and more. Owner operator truckers have been getting rid of mufflers for years now to get rid of weight and gain power.

Pat, on 01-08-2014 I started a thread titled: K&N Filters. And it is on the Class A. You can check all the responses I got. Fact there were five pages of responses or 45 posts. The vendor who was trying to sell me the Aero muffler come together with a K&N filter for diesel engines. $1200. installed at the FMCA rally at Indio, CA.
You might want to read some of the responses. I was amazed at them because I was about to buy into it.

[wny_pat1]

RayChez wrote:
I inquired about the Aero Muffler and the air cleaner that is also part of the deal when installed. 99% of the rvers that posted on that thread that I started said it was NO GOOD. First they said the filter would allow dust to get through harming the engine. And some said the Aero muffler did not increase the power at all on their coaches. So I decided not to invest on such a project. I saved myself $1200. I also saw the vendor at the FMCA rally in Indio, California.

But I know several who just removed the old muffler and installed just the Aero 5050XL resonator, who say that it has helped, but they had big horses, like 400 hp and more. Owner operator truckers have been getting rid of mufflers for years now to get rid of weight and gain power.

[RayChez]

I inquired about the Aero Muffler and the air cleaner that is also part of the deal when installed. 99% of the rvers that posted on that thread that I started said it was NO GOOD. First they said the filter would allow dust to get through harming the engine. And some said the Aero muffler did not increase the power at all on their coaches. So I decided not to invest on such a project. I saved myself $1200. I also saw the vendor at the FMCA rally in Indio, California.

[wny_pat1]

And that Aero 5050XL is probably quite a bit lighter than your present muffler.

[keepingthelight]

As Fireup stated, the Aero Muffler is louder. I installed a 5" resonator in front of the Aero Muffler which toned it down. As Brett has stated, the turbo does spool up quicker than before. This muffler will also lower EGT's. According to my CAT specs on this engine, my EGT's were running around 1300 degrees consistently throughout the power band. I do have a picture and I am unable to down load it.

Good luck;)

[wolfe10]

Ken,

Which of my Seminars did you attend?

Your chassis maker chose and installed the muffler, not the engine maker. You may be able to get the make and model number off the old muffler and look up its CFM ratings on the muffler manufacturer's website.

Drilling, tapping and installing a temperature probe and running that to the driver's area would be quite a job. And, as already stated, if your engine is stock, you do not need to worry about EGT's.

A freer flow muffler will likely allow the turbo to spool up a little quicker, but very unlikely that max boost will change.

[n4hwl]

Brett

This is the original exhaust and muffler that came with this cat c7 in 2004. I have no reason to think it is restricted more than it was new. I just saw some open type mufflers at the FMCA rally and I just got to wondering. Where could a person get a exhaust temperature probe and be able to run it all the way up front to the dash on these things.

By the way I also enjoyed your talks this past week at the FMCA. Thanks for doing them.

Ken Tenpenny

[ScottG]

With stock fueling there's probably nothing to be gained with a different muffler. Your EGT's wont get too high so there's no need to lower them.

[wolfe10]

Ken,

The answer really depends on how restricted your present exhaust system is, compared with the one you are fitting.

Many muffler websites give technical data on CFM at particular pressures. I would start there along with a call to Caterpillar to see how the muffler compares with their air flow requirements for your engine.

Caterpillar RV Hotline: 877 777-3126

[FIRE_UP]

n4hwl wrote:
I have learned from experience with my Dodge truck (1998 cummins 5.9 isb) that when I added a 4 inch exhaust and a low restriction muffler that my exhaust temperature dropped some. I have a 2004 cat c7 in a 40 foot phaeton. I have the original exhaust and original air filter. I am wondering if anyone has tested the exhaust temperature change (if any) when going to a lower restriction muffler on these c7 engine in my type of application. Just wondering.

Ken

Ken,
Well Sir, I've changed the muffler on our '04 CAT C-7 and I'm going to tell you what I experienced. First off, the muffler I changed to is called the Aero 5050XL Stainless Steel muffler. It's a 5", straight through unit. I do not have an exhaust temp gauge, anywhere in line. So, that I can't help with. But, in all reality, I don't really feel any more power gain what so ever.

What both the wife and I did notice was one heck of a lot more NOISE! Our rig, an '04 Itasca Horizon, 36GD, has the CAT exhaust empty out at the rear, about a foot or so inboard from the right rear corner of the body. It's turned down and, blows towards the corner of the coach. So, in that, it's blowing the exhaust in a direct line, away from the driver.

So, you can't get any better in terms of directing the exhaust noise, away from the driver is what I'm saying. Now, "SUPPOSEDLY", one of the main benefits of this muffler is less back pressure which, is supposed to decrease exhaust temps and, again, supposedly, since there's less back pressure, the turbo is supposed to spool up earlier in the RPM range and therefore, you're AGAIN, SUPPOSED to get earlier torque than normal.

Well, I knew this rig pretty well before I installed it and, I've ran many of the same grades, towing the same weight, at the same temps, in the same conditions and, well, lets just say, for me, it was a waste of money. Others will argue and, that of course, is their choice.

In my personal opinion, because these rigs are so darn heavy and accelerate like a drunk dinosaur anyways, the only real and true test would be to put your rig on a dyno and get the readings. Then, install that type of muffler, WITHOUT DOING ANY OTHER CHANGES, and re-run the dyno and that, will tell you right then and there, if, there's any real change, other than NOISE!

Again, this is all my personal experience and opinion. Good luck.
Scott