4 Inch Muffler [Archive] - Diesel Place : Chevrolet and GMC Diesel Truck Forums

: 4 Inch Muffler


Mitchagain
06-18-2004, 04:48 PM
Well I bit the bullet after the last trip to the hills pulling my big a$$ horse trailer and ordered the MBRP muffler. I called and asked if I could get just the muffler alone and it was delivered in just a few days (wait on the delivery man is the biggest pain!).


I have spent a few years paying close attention to all you guys that have gone bigger and the EGT questions and the noise factors. Being an old fart noise is a key ingrediant for me. Wanting this Dmax to last 250,000 is also. Some of you may remember that long steep pulls in 100 degree temperatures has drive my EGTs to the 1400+ for sustained hauls, and 1500 was possible if I was not paying close attention. Now I may be old, but I can learn from others, and tearing up my truck is not on the agenda.


Back to the theme of this post. I decided that there was not enough benefit to justify the cost of the full 4" system versus installing a 4" flow through type muffler in line with the 3.5" pipe from the factory. Once I had the new muffler in hand it didn't take much to cut and pound and weld the two ends down to a 3.5" size. I cut the OEM muffer out and install the MBRP in its place. About 2 hours and 3 beers later (okay, maybe 5 beers, I mean it was 105 degrees outside!), I fired up the Dmax and was pleasantly surprised at the low, throaty rumble. Even with throttling it, the sound was not objectionable.


Prior to the swap I ran some pre checks for temp comparisons. This is where I was really impressed. I run normal in level 4 on the Juice (may be old but I'm a kid at heart), and at every test I duplicated my EGTs are 175 to 200 degrees lower now. Way impressive! Now I haven't pulled the trailer yet, but if this is any indication, I am going to be very tickled over this!


Finally, I have driven about 150 miles now and there is a slight drone at the 1700-1900 RPM. You guys know that this is the optimum RPM for most driving. Now its not so bad that I couldn't live with it (the wife has noticed it and kinda wrinkles her nose a little), but I would rather not. So here I go again. Looks like I am gint to find a 4" resonator and install it either before or after the muffler, I haven't decided yet. Anybody have any suggestions on the brand, size, placement, etc., for a resonator?


Up side of this whole story is that the flow through 4" muffler did what I wanted and lowered the EGTs pretty dramatically without the expense of the whole 4" system.


On a side note. Before buying this unit I was as concerned as most about the high EGTs and how high was too high and how long is too long. I called Banks and talked to their engineering staff and then I called Hesco in AL and talked to Bennie. I got the same version from both. 1400+ is no problem for extended pulls and not to worry about the EGTsgetting too hot to do damage to the turbo. By the time the EGTs gets too hot to damage the turbo (they indicated way over 1500) that the pistons have already melted down, and turbo is the least of the problems. Well that was enough for me!

2MuchFun
06-18-2004, 05:59 PM
Good jobhttp://www.dieselplace.com/forum/smileys/Clap.gif





I think you can get a 'resonator' or 'drone killer' that clamps or welds onto the outside of the pipe.


My Ford -sorry- had this item.


It was basically a metal rod, maybe 1/2" diameter and 4" long?? That clamped onto the pipe and stuck out to the side. At the end of the rod was a big cylindrical part (maybe the size of a beer can) I think it was maybe rubber?


Anyway, it was there to kill vibration drone.





Sorry for the cruddy description, I try to forget my Ford days http://www.dieselplace.com/forum/smileys/Big Smile.gif

Tsckey
06-18-2004, 06:46 PM
Does your truck have cat? The reason I ask is that I had the same surgery and have no drone. There is a very slight resonance in about the same rpm range you mention where I can hear the sounds from the tail pipe, but it's not what I associate with drone, a frequency at which a number of structures hum along in sympathetic vibration. In all other respects it is almost unnervingly quiet. Even in closed spaces, as when driving into my parking garage with the window down, all I hear is the mechanical clatter of the engine. It has a nice basso idle tone, which I like very much, but the lion's roar is subdued, even towing. On the EGT front, I'm not sure how great the benefit, which might be due to the presence of the cat, another reason for my initial question. There is definitely a benefit, but not as much as you describe. At least I don't think so. I have never seen the really high temps you report, even with my very heavy TT attached and laboring up a steep hill. My problem from the analytical perspective is that the last time I towed before getting the new muffler, the weather was quite cool. The first time I towed after the muffler the weather was very warm. So, while I might be getting similar benefits they might be slightly masked by the warmer ambient temperatures.

Mitchagain
06-18-2004, 08:01 PM
Maybe I am using a wrong term. The noise that I am refering to is the tailpipe exhaust noise. Granted the tone is low and very nice (I like it, the tone reminds me of a hungry wolf looking for rice burners and mustangs for lunch!) but it is loud enough to notice with the windows up and the radio on. Though the tone is low it is still louder than I really want. My partner in crime here says I am being to sensitive, maybe I am.


2MuchFun, never heard of a unit like this but it makes sense that a vibration dampener like you describe would do the job, but vibrations and harmonic issues isn't my problem


Tsckey, the only cat I have on my unit is the fuel filter under the hood http://www.dieselplace.com/forum/smileys/Clown.gif. I like you, like the nice bass and waiting to pull a load before I order any resonator. I have no harmonics rattling the rafters, just the exhaust noise that seems louder than I would like. The advertisement guarranteed that the increase would only be 3dB, and I have to believe that the increase is about that (no meter) so its not like I am upset, just spoiled from 38,000 miles of stock muffler. I have to say I was very surprised with the decrease in EGTs. I was hoping for 100-125 decrease, but see what I am seeing is quite surprise. I understand the ambient temp influence, I think the surprising temp issue to me how the engine temp never got above 200 but the EGTs were bouncing 1200-1450 depending on the grade/speed/gear.

Zeeb
06-18-2004, 08:11 PM
Hmm...


Seems like I saw a post around here somewhere saying Garrett had told a member that 1320 degrees F sustained, was all they wanted to see...http://www.dieselplace.com/forum/smileys/Ermm.gif


Going to have to go looking for that post...http://www.dieselplace.com/forum/smileys/Geek.gif

OC_DMAX
06-18-2004, 09:30 PM
The VVT turbocharger on the LLY is made by Garrett. The turbocharger on the LB7 is made by IHI. Each probably has their own spec.


The following link has some info on the IHI turbos. My "assumption" is the model in our trucks is the RHE version (sure looks similar). In the spec table, you will notice a max exhaust gas temp of 1382 deg F.


http://www.ihi-turbo.com/turbo_RHE-RHF.htm





If it were my truck, I would not run it anywhere close to 1400 deg F in a sustained hauling environment. Probably would start "getting nervous" when it got close to 1200 deg F and start backing off the throttle or force a downshift. Just my opinion though.Edited by: OC_DMAX

2MuchFun
06-18-2004, 10:08 PM
Well it sounds like you have a good sound and just need to get used to it.


When I first installed my system ~Magnaflow; pretty quiet~ , it was very noticeable and now I almost wish it were louder because I cant discern it anymore.

Mitchagain
06-20-2004, 04:38 PM
OC_DMAX - Cant argue with your logic. The only thing that ever concerned me with the original package from the GM was the EGTs. In stock form I saw at least 1500 on more than one occassion (thanks to the Autometer!). So, with that in mind (there are a lot of OEM trucks out there with no pirometer in place to monitor the EGTs) I knew it was time to open up the breath tube with a flow through type muffler. Those temps used to scare the hell out of me, now I should have it under control. BTW, whenever I do see temps over 1250 these days, I push the ODLO button and if that still isn't enough to maintain the speed and keep the EGTs down, then I manually shift down to 3rd. Climbing some of these 6-8% grades pulling heavy, its what you got to do to stay safe. I don't want anyone to think that the speed limit is only the criteria for my happiness, but its close! http://www.dieselplace.com/forum/smileys/Big Smile.gif

Mitchagain
06-21-2004, 04:54 PM
Has anyone had any experiences with a 4" resonator? I found this one from Air Flow Systems Inc on thier web site. Looks like it'll fit between the 4 bolt flange and the new 4" muffler I installed last week.


"Standard 4" resonator. Use for additional quieting in an exhaust system. Straight through design. Body length is 10", overall is 16.5"


http://www.dieselplace.com/forum/uploads/1_Air_Flow_Systems_Inc_Resonator_4.jpg

ratlover
06-21-2004, 05:20 PM
IMO the muffler has the biggest effect on resonance. Maybe switch to a different muffler and se what happens, although I have heard of talk from some dodge guys about band clamping lenghts of angle iron to parts of thier exhaust(before the muffler I believe) and it helping with resonance. My straight piped truch has less resoance at cruise speeds below 80 or so than when it had a muffler. Although over 80 or so and it gets pretty loud.


You sure your EGT is correct? That sounds pretty high to mehttp://www.dieselplace.com/forum/smileys/Confused.gif

Mitchagain
12-06-2004, 09:07 PM
Has anyone had any experiences with a 4" resonator? I found this one from Air Flow Systems Inc on thier web site. Looks like it'll fit between the 4 bolt flange and the new 4" muffler I installed last week.


"Standard 4" resonator. Use for additional quieting in an exhaust system. Straight through design. Body length is 10", overall is 16.5"


http://www.dieselplace.com/forum/uploads/1_Air_Flow_Systems_Inc_Resonator_4.jpg
Ok, I finally had enough of the noise and bought the unit above for $85. (Sorry MBRP, just could not justify the stainless steel units). I have to tell you that I now have a truck that is as quiet (maybe quiter) than original. Yes it was a pain to install (the OD on the can is 10") trying to fit in between the flange and the MBRP muffler. The inlet/outlet of this resonator is 4" and I still have the original 3.5" exhaust pipe, but with the welder and time (and rearranging a bit of the english language) its in place and out of the way. This unit did more than I ever expected and there is absolutely no noise in the cab except the engine noises now.

I had to do something, the 'drone' between 1600 & 1900 rpm was more than we could take, hauling or city driving, now its completely gone. I don't have empirical data, but I think the EGTs are down a little more also, but that could be just me wishing it too! Anyway, if'n you want quieter, take it from me, this one (and probably the unit from MBRP) will get the job done.