Volvo B58 THD100 power upgrade

[WUNDY]

Hello, we have a 1980 B58 Volvo city bus from Adelaide which has been converted to a motor home. It is really great and a heap of fun to live and travel in but long slow inclines and very steep ones can be challenging. We are thinking of an engine upgrade and wondering if you or any of your readers might have some suggestions.The rear axle ratio has been changed to provide a cruising speed of 100kph at around 2100 engine rpm. Transmission is a ZF 4 speed auto with a hydraulic retarder on the rear of it.
Some information suggests that the early THD100 crankcase is unsuitable for higher torque ratings.

Many thanks
Geoff

[boronia]

I think B58 coaches had the option of a turbo engine.