The Powertrain

Back in 2013, when I first purchased the bus, it was powered by a 50s-designed Ford 534 Super Duty truck motor connected to a Spicer 5 speed manual transmission. The 534 probably originally spec’d out at 266 horsepower and 490 lb/ft of torque, while achieving something like 8mpg in use.

Our repower consists of a 1999 Cummins ISB, sourced from a Freightliner XC motorhome chassis. The ISB, a 5.9L motor, delivers 275 horsepower and 660 lb/ft of torque, so once the turbo spools up it pulls pretty well. Others have put the larger 8.3L cummins into Visicoaches. Ours will do 11mpg on the highway, but climbs slowly on steeper grades. The Allison 6-speed automatic makes driving much simpler as well. An integrated exhaust brake does effectively preserve the service brakes on long downhills.

The Flxible catches cooling air for the motor through a scoop on the top-rear of the bus. The air is driven down through the radiator, over the powerplant, and out the bottom of the bus. The original engine (and the 534) had a cowl over it, and used the stock belt-driven fan on the rear to pull air down and over the block before exiting the bus. The factory also installed a set of metal fins, or dams, underneath the block to deflect oncoming air as the bus went down the road.

But there isn’t sufficient room with the longer ISB to keep that cowl in place, so instead we have a top-mounted, belt and gear-driven fan. The gear drive is from a grain harvester, and it works exceptionally well at keeping airflow moving. We also have a full-width mud flap behind the rear axle, which acts as an air dam as the bus is in motion.

I certainly hope that somewhere down the line, options for an electric or hydrogen powertrain come available.