[Visser]

My RE with a Hatz 1b30 performs alright.
It is happy to chug along at 50mph. I've read about another Englishman with a Hatz 1b30 who has tweaked his to go a bit over 60mph. I guess he put a larger front sprocket as well as some fine tuning that I am not aware of. I will try to wrestle a bit more speed out of mine one of these days.
If you look at www.dieselbike.net , there are some that have used Comet cvt's. I have no idea if they perform better or worse. Mine is a 4-speed right hand shift, and that works fine as far as I am concerned.

[seakayaker]

Performance ? Hardly any !  Well, that's not true, with only 3600 rpm to play with: You can ride is flat out in every gear without worrying about getting caught for speeding. 54 MPH maximum (GPS verified).  Or, you can ride using the torque and weighty flywheel to best advantage, and enjoy the scenery, and the massive economy.  Riding the diesel solo, is much like riding a 350 Bullet with a pillion: A little less power, and considerably more torque. And, a curious bonus is the noticable gyroscopic stability that the big flywheel give the bike !!!

[Blue Ridge Wheeltor]

I would think with all that torque, it would be unaffected by adding a hack. What a perfect combo.