Straight piped my Mack.

[Truckie]

Well this weekend I straight piped my Mack.

Its a 2000 CL 713 with a E7 460hp engine. Well it sounds sweeeeeet while under throttle but thats it, this is the first rig I have had that is plane just obnoxious while using the jakebrake while straight piped. It dose sound good while in the 1600 to 1000 rpm range any thing past 1600 is just crazy loud. Its so bad I have to find something to quiet it down or put some type of muffler back on it, if not I'm going to rattle my truck apart.

Any one out there ever have this problem with a Mack? and what did you put on to quiet it down a bit.

Thanks.



MIKE

 

[bmoeller]

The '95 CH (E-7 350) at work has a stack on it. It isn't that loud to me, though. I run with the pass. side window down quite a bit. It can be a bit annoying at around 1900RPMs, but not there, except for shifting or running hill. Generally in the 1400-1600RPM band.



Do you have a sleeper on it? If you do, Dynaflex makes a resonator that works nicely. Have one on my Ram. 5" in/out, straight-through. Approx 9" dia. x 16" long. Don't know that there would be enough run it under the cab. Kinda tight.



There is also an internal muffler that is made to slide up into a stack. You have to have dual exhaust to run them though.



The Iowa 80 truckstop sells both. www.iowa80.com

 

[n5ifi]

I think the owners of those trucks nearly single handedly have caused all the local municipalities to make city ordinances against engine brakes. I see the signs up everywhere around the East Texas area. There are lots of old Mack Log trucks as well as other types around here. You can hear those trucks for miles when they get on the brake with no muffler.

 

[RThompson]

Years ago a log trucker that had his work done at my Dad's shop had a 10" -12" stack rolled about 8' long and put in place of a muffler. I remember my Dad cutting into the pipe and putting a 4 or 5 half baffles in it. This was an old KW with 235hp Buda engine. Sure had a neat sound! This was before turbos and I am not sure if it was supercharged or not. Maybe some other grey beard knows about the Buda whether it was naturally aspirated or had an iron lung.

 

[Truckie]

Well today was an experience in its self with my Mack.

I was running up 79n bound early this morning and passed a farm and was on the down side of hill, and I cracked the Jake and I literally scared the I TRIED TO BY-PASS THE CUSSING FILTER out of a horse. After driving 350 miles to day and most of the day with paper towels stuffed in my ears I stopped off and got a cheap resonator, 42 inches long about 10inches round 5" in 5" out. Its made by walker, but I don't remember the part number I will post it for ya.

The truck is a day cab and I always have the passenger window up.

The only way I can explain how loud the Jake brake was is try to remember hearing the loudest straight piped Harley and Imagen it being about 10 times worse. Like I said before I like straight piped trucks as long as they sound good. This one was absolutely obnoxious. Ill let you know how tomorrow goes with the new resonator.



MIKE

 

[bmoeller]

I do have to agree that a stacked Mack engine doesn't sound as nice as a big Cummins or Cat. Not to shabby though either. Jake sounds better on those also. Could be because the displacement isn't as big as a 14L+ Cummins/Cat. E-7 is in the 11-12L range.

 

[Truckie]

Well heres the up date. I put on the muffler/ resonator which was made by Walker, which was the only one the dealer handled where I stopped off to pick up a muffler. The P/N is 22920

I ran it for two days and after that it to came off because of the HORRIBLE sound that it had. Any thing over 1500 rpm while loaded sounded like a molecular death ray sound. It was just as bad and annoying as the straight pipe that was on there. So I called my local MACK dealer and just settled for a stock muffler that they handle. It is a OEM replacement muffler, made by Donaldson. I had 3 different exhaust systems on this truck with in a week, I could not get the sound I wanted and had to do something so I settled and opted to go back to stock for now :{ :{ .

Quote by bmoeller:



"I do have to agree that a stacked Mack engine doesn't sound as nice as a big Cummins or Cat. Not to shabby though either. Jake sounds better on those also. Could be because the displacement isn't as big as a 14L+ Cummins/Cat. E-7 is in the 11-12L range. "Quote



bmoeller I do have to agree with you on that.



MIKE

 

[RollOver_Pete]

My first new truck was an 86 Superliner. Power came from an E9 rated at 500hp. 6" straights sounded sweet from that V-8. 12th @ 1200 rpm got you 65 mph. Didn't have to think about dropping a gear untill 1000 rpm's... . which is when the boost would drop off. That Mack was one of the finest trucks I ever owned. Any V-8 (3408, E-9, 8V92TA) sounds awsome with straights. On the other hand, I-6's almost always need a small muffler of some sort to make life bearable... and keep the noise tickets down.

 

[bmoeller]

The engines built prior to the E-Tech series came out in '98 (?), sound better anyways. From a distance, the E-Tech engines, at idle, sound a bit like a gasser with a stuck lifter.



One guy near here has a stacked mid-'80s RW613 Superliner. Sounds great!



The pre- ETs, still had a Bosch in-line pump. New ones look like they just have a low psi fuel rail, with electronic injectors.