I thought this might be useful for some Detroit owners down the road.
https://youtu.be/88efH_HdI2c
Good video of some OLD coaches. With the sidewinder on my 4107, the engine had zero belts of any kind and with the engine sideways, a big thermo controlled fan had no problem with the absolutely huge radiator. The AC compressor was two automotive compressors driven by the PTO with the condenser as big as the radiator on the 8V-71. In all the years I owned it, it never came off the thermostat. Didn't smoke either if I watched the mirror at altitude.
If you notice, none of the Detroit engines in the video have a hydraulic fan drive. The 12V-71T in the MCI has a single belt going up to drive the fans. I remember heading upgrade west just past Denver at about 35 mph in our 235 hp 8V-71 (Greyhound detuned 318 hp normally) when I was passed by one of those MCI Greyhounds with the 12V-71T at about 75 with a load of passengers. Absolutely like I was standing still. But 235 hp still pushed the Buffalo at almost 90 mph on the flat and got super fuel mileage..
Our Foretravel 6V-92TAs have a 5 inch out of the turbo into the 5" in and out muffler without much restriction. Foretravel changed the radiator type and installation three times trying to keep them cool but with the hydraulic horsepower draining fans and a radiator that's not big enough, they are bound to be marginal in summer mountain driving. Hey, 350 hp minus 60 hp for the fans only leaves 290 hp to drive the coach but you have to still cool for 350 hp.
I would think about replacing the muffler with a resonator but with the Jake and where we live, I like to keep the peace. Most buses in Mexico all had Detroits (still do in one form or another) and just had stright pipes that made a 90 and out the back. You could hear them for miles. 2400 rpm with a 2 cycle sounds like 4800 rpm. Then came the Mexican DDEC Detroits with the turbo that are the engines we have in our coaches today.
Pierce