Putting a high flow low restriction muffler on a mechanical diesel

Back in the day we would hack saw the ends off a car drive shaft , grease it up and drive it down through the muffler.

 

There isn't a diesel engine out there that runs better with a restricted exhaust flow. What usually happens is guys just bust the baffles out and put the mufflers back on. When it opens up from 5" to 10" then goes back down, it create turbulence which creates even more back pressure than if it was just the baffles in there. It's one of the worse things you can do to a muffler. Slide a piece of 5" pipe into the muffler and you're good to go.

 

Exhaust flow (speed) is somewhat dependent on temperature.

Temperature and Pressure can be seen as the same.

Too great a drop in temp from engine to exhaust tip means pressure flow reduction.

As above, the flow starts to fight with itself (as it’s always seeking to equalize to atmospheric pressure).

I doubt anyone insulates the pipes (past engine rooms where personnel are working), but this has always been the thinking behind using double-wall tubing:

Retain the heat without restricting the flow.

Properly sizing the tubing is the “normal” answer. No press-bends in order to maintain constant interior diameter, and step down the sizing as distance increases (all to maintain heat).

Cylinder scavenging. Dependent on NOT hitting cold air too close to the engine. Farther downstream, the better.

One can easily size for a constant load. That’s where the trade-offs begin

That a TC diesel is less sensitive to this than gasoline doesn’t change the traveling waves pattern.
.