Today my 6 inch exhaust pipe came UPS
So this evening I spent a couple hours putting it on. I discovered that although I like loud big diesel trucks........this engine, without a turbo on it, is just too loud straight piped. Even though it wasn't too loud for me personally inside the cab, it is just plain embarrassing to drive when it is straight piped. Ha ha. Everyone would turn and stare, not because it was a cool Army truck, but instead to see what was causing all that horrid noise!
So what I did, since I didn't have a 4 inch to 6 inch reducer/adapter anyway, and needed to go from 4 inch to 6 inch somehow, and also wanted to quiet it down a little bit, I decided to just modify the stock muffler and use it effectively as a reducer.
The stock muffler is way too quiet for my liking, but no muffler at all was no good either, so I cut the 4 inch pipe out of one end, and stuffed the 6 inch pipe down inside there and welded it in place, and then used my plasma cutter to cut a big section out of the inside on the other end, so that it works more like a resonator and has very limited flow restriction.
I wanted the stack to stand up straight, so I had to modify the brackets, which required, not only moving the bottom one out, but also putting it at an angle, since the further you push the bottom of the muffler out from the truck, the further forward it moves because of the angle of the exhaust pipe coming from the engine.
And because I was too cheap to go buy a 6 inch exhaust clamp (them things ain't cheap!), I just made my own by welding two long bolts on the ends of a piece of metal strap and bent it around the pipe. Forgive my ugly weld on the top of the muffler. Ha ha. All I have is an arc welder right now, and that muffler is made of pretty thin stuff. Besides, the plan is to eventually modify the muffler guard, and put it back in place, and it will hide that weld a little better.
The whole exhaust is going to get painted with flat black wood stove paint as soon as I go to the store and get some. And the stack is not going to be that tall when I'm done. The idea, is to cut the stack and weld it into this style
when I can figure out how to cut the angles right. I know that one cut needs to be 22.5 degrees and the other needs to be 45 degrees. But I don't know how to do it without a big band saw with a big miter box or something. I've never seen a sawzall blade that long, and my plasma cutter would make an absolute mess of the cuts.
The stack makes a nice low rumble now, and is just about right. No longer deafening, yet it sounds good.
I also installed one of those Auber 1812 digital Pyrometers to see what my exhaust temps are running. Gets up to just over 1000 degrees under heavy acceleration, and in the 700-800's when running level at 55. I've got a number 20 fuel button in right now. Haven't put my turbo in yet.
Put about 120 miles on it since installing the new cylinder liner and piston, and all seems good! I have owned many diesel big rigs and other diesel vehicles, and never have I had one where the engine oil stayed so perfectly crystal clear as the engine oil still is in this truck right now. I'm sure after a few hundred more miles it will start turning black like normal, but it trips me out that it is still so perfectly clear. Every other truck I've ever owned, the oil would be completely black again within a day of changing the oil and filter. Very very happy with this truck so far!