Straight-piped my diesel again....

LibertyCRD · **Posted:** Tue Dec 20, 2005 10:11 pm

Well after all the talk about you guys ditching your stock mufflers, I decided to try straight-piping my diesel again. I straight-piped it back in May right after I bought it, but got some CELs and at the time thought it was associated with the muffler being gone. It turns out those CELs may have been because of something else actually.

So anyway, a local shop cut my muffler off and welded in a good piece of pipe for $30 today. My stock muffler would actually bang against the frame because of the tight tolerances in there, so I eliminated that problem too with the pipe. At idle it has a mean rumble to it now. When you hit the throttle it spools up much faster. The turbo whistle is louder. It has a little drone at cruising speed but not bad. So far no CELs. It doesn't seem to have lost any power...in fact I think it has just a tad more power now. Over the next week or so I will see if the pipe has any positive effect on fuel economy.

I think I'm going to really like it. It may turn out to be the best $30 I ever spent on this Jeep so far.

MrCRD · **Posted:** Wed Dec 21, 2005 12:24 am

Would you happen to be able to get a sound clip of what it sounds like with the muffler gone? I have heard different opinions as to what it sounds like.

Thanks
Chris

:shock:

LibertyCRD · **Posted:** Wed Dec 21, 2005 8:49 am

I will try to get a sound clip but I'm not sure I will be successful at it. The best way I can describe it is if you have ever heard a 1980s model, small-medium sized farm tractor at work in the field. This CRD straight-piped with the cat still on sounds identical to an old farm tractor....with the exception that the CRD has a turbo whistling in the background.

Some people would hate it, long-time diesel guys would love it. Personally, I'm still on the fence. I can't really decide. There is no doubt it's running better now. It's just pretty loud. If I see an increase in fuel economy I'll leave it this way I guess. If I don't see any change in fuel economy I'll probably end up installing a straight-through muffler eventually.

One note of interest...when the stock muffler was removed, it was totally sooted up inside. Black as coal. That muffler will never go back on my Jeep again. Too restrictive.

Guest · **Posted:** Wed Dec 21, 2005 9:09 am

I'll be watching your progress reports like a hawk! The stock muffler on my CRD hangs pretty low and out on the job sites I'm sure to damage it when I bottom out. If I can solve the issue I'll be all the happier...

MrCRD · **Posted:** Wed Dec 21, 2005 10:02 am

Yep, I agree, I thought that the muffler looks really low down there as well. If I remember right it is only a little over 6 inches off the ground with that front lip just waiting to catch on something.

On a side note. Do Diesels have to have a CAT on them? I was thinking that not all diesels do. I was thinking of doing a straight pipe as well but had not decided on either removing the CAT altogether or getting one of those less restrictive ones that are for sale.

Thanks
Chris

LibertyCRD · **Posted:** Wed Dec 21, 2005 10:39 am

Most diesels do not have a CAT. They have started putting them on these newer trucks these days because of the stupid govt. regulations made by people who don't understand diesels.

The muffler is indeed low, and I frequently would bottom out on mine while off-road and cover it in mud. Not it is gone....thank goodness.

retmil46 · **Posted:** Wed Dec 21, 2005 11:33 am

Guy that installed my AT muffler asked me when we were looking at the exhaust system, "do you want to get rid of the cat too? You don't need it on a diesel."

I said no, for two reasons. One, just replacing the muffler shouldn't raise any warranty or legal issues, but doing away with the muffler AND the cat altogether could be getting into territory where they might have grounds to revoke the warranty. It's against the law to remove, disconnect, or otherwise disable emissions control equipment. That alone could be grounds for them to revoke the warranty, regardless of whether or not it's actually required on a diesel. For all we know, this beast might be designed to need that cat to meet current emissions requirements.

Second, the EPA '07 regs are going to require cats on even the 18 wheelers. We've already seen a mockup at Freightliner of the EPA '07 engine setup. It has a huge cat mounted in the frame rail, and the intake and EGR systems look like a supersized version of what's already on our CRD's, same system and controls configuration. DC may have actually been ahead of the curve and designed these CRD's to already be EPA '07 compliant, that way they don't have to do any major mods for the next model year.

IMHO, I'd hang onto the cat for another year, until the new regs come out, and we know for sure whether or not our little rig is going to be required to have a cat by law.

retmil46 · **Posted:** Wed Dec 21, 2005 11:41 am

LibertyCRD wrote:

One note of interest...when the stock muffler was removed, it was totally sooted up inside. Black as coal. That muffler will never go back on my Jeep again. Too restrictive.

Amen! It's the same muffler they use on the 3.7 V6, and probably on the 4 banger gas engine as well. Bean counters saving money by using the same muffler on all 3 engines. The inlet and outlet are necked down to 2". Mine was the same way, 3600 miles and so much soot it was unbelieveable, so restricted you couldn't blow it out with WOT accel no matter how hard you tried.

IMHO, doesn't matter what you replace it with, just get rid of that stock muffler!

&JUSTICE4ALL · **Posted:** Wed Dec 21, 2005 12:16 pm

I'm having a Super series 40 installed this mourning. Keep us posted on the straight pipe.

oldnavy · **Posted:** Wed Dec 21, 2005 6:08 pm

Here come da Judge, here come da Judge, rumbling down the road like a freight train. :lol:

Hehehe I couldn't resist. :twisted:

Does it sound much different??? :?:

Come on Judge it's after 4 pm in the real world (CST), where are you? :?:

Informed people want to know.

&JUSTICE4ALL · **Posted:** Wed Dec 21, 2005 6:20 pm

Walt, the super series 40 does not sound any different than the stock did. You were right about that Walt! The guy at the shop couldn't believe that it sounded the same either. In fact he mentioned right up ft as though he thought I might be disappointed :shock:

Thanks for your report Walt

I'm in centeral Idaho. I was IdahoTDI on fred's page and purchased one of your milled CCV filters for my 01 NB that's why I think I know you some my friend.

oldnavy · **Posted:** Wed Dec 21, 2005 6:45 pm

I had decided you must be someone from Fred's and that you either had bought a CCV filter or we had met at a GTG.

I have had no luck in finding someone to make a CCV filter similar to TDI CCV filter for the CRD and this one would be even easier to make and mount then the TDI CCV filter. So I guess I'm stuck with the over engineered and priced ProVent. :cry:

LibertyCRD · **Posted:** Thu Dec 22, 2005 8:11 am

I think you guys that are going with the straight-through mufflers are doing the right thing. The stock muffler is too restrictive. But the straight-pipe is just a tad too loud. You can actually hear the exhaust over the engine now. So a good straight-through muffler or cat-back kit would be ideal for the CRD in my opinion.

jinstall · **Posted:** Thu Dec 29, 2005 6:05 am

Any of you thought about using a SuperTrapp?

oldnavy · **Posted:** Thu Dec 29, 2005 9:12 am

Yes, too many $$$$$ for the same effect as a cheaper muffler.

LibertyCRD · **Posted:** Thu Dec 29, 2005 9:17 am

Well I had a Magnaflow muffler installed yesterday, and all I can say is WOW. Normally this muffler would make a lot of noise and turn a V8 into a hot-rod. but not on the CRD. It's honestly nearly as quiet as stock. I can't believe it! There is still a little rumble under throttle, but it's MUCH nicer inside the Jeep with the windows up now. Turbo spools a tad quicker than stock muffler. And I swear it seems like it has a little more power now. Maybe it's my imagination but I swear it feels like it's got more get up and go! I think this Magnaflow muffler is a great cross between the straight pipe performance and the stock noise levels. I'm loving it!!

jinstall · **Posted:** Tue Jan 03, 2006 7:02 am

oldnavy wrote:

Yes, too many $$$$$ for the same effect as a cheaper muffler.

Yeah but you get hat you pay for and there is no other "cheap" muffler out there that gives you a "tunability". I have run these on all of my race cars and a few other peoples as well. SuperTrapps are not cheap and cheap has never gotten me to the checkered flag.

oldnavy · **Posted:** Tue Jan 03, 2006 9:22 am

jinstall wrote:

oldnavy wrote:

Yes, too many $$$$$ for the same effect as a cheaper muffler.

Yeah but you get hat you pay for and there is no other "cheap" muffler out there that gives you a "tunability". I have run these on all of my race cars and a few other peoples as well. SuperTrapps are not cheap and cheap has never gotten me to the checkered flag.

Had my first Super Trap Muffler 25 years ago and I am well aware of their quality and what and how they work. What I'm saying and have mentioned here several times is this is just a soccer grandma's Jeep and not something that need's any real performance mod's. I just wanted to relieve the back pressure to lower EGT's and improve mpg's in the process.

As a general rule I do my mods based on who the vehicle is driven by (me or wife), how long I plan on owning the vehicle, and what I want out of the vehicle. I don't have a Super Trap on the Magnum because the plan is to give it to the daughter when '07 models come and I will then have an AWD, diesel if available as rumor says it will be, Dodge Magnum. If the Jeep had been my vehicle I would have straight piped it and not even used a muffler, because mufflers are big hp/torque killers on diesels and not really needed for sound levels under most use needs. My wife hated the slight drone my diesel VW New Beetle had, but it was music to my ears.

I am rambling here sorry about that.

Sure would like to hear that CRD with a Supper Trap and prospect of an audio file???

jinstall · **Posted:** Tue Jan 03, 2006 12:52 pm

Well see here lies the problem with that, my wife. I am buying the CRD for her and I will use it for towing the racecar to the tracks. Now IF I can get the Trapp on the CRD I will but I will have to hide it carefully. Yeah I know that the turbo will pretty much kill the sound. That was the great thing about the ML400CDi with the 4.0L V8. Basicly and open exaust and was great when you floored it. Good V8 rumble but not really loud. OK loud for a MB. The only thing is I have to really look at the way the exaust is configured. SuperTrapp does not make anything in 4", only 3.5" inlet with a 3" core. Waht I like is that if I have a problem with inspection, I can just cap it. I think 3.5" should do the trick. Highspeed runs should be done on a open-flow exaust. I get out on the Autobahn with the race car and it loves being "uncorked", it likes the Nuerburgring uncorked as well. The track officials don't care for it though. Good to hear that someone else knows that SuperTrapp has been around more than 30 years. I used it back in 1988 on the first toy.

oldnavy · **Posted:** Tue Jan 03, 2006 2:29 pm

My first ST was in late '83 on my last two wheel toy and later 4 wheel toys, including my 86 CJ7 4cyl Jeep.

Straight-piped my diesel again....

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