2U D8 Re-powers
I have been told that Peterson Engineering, a long-time Cat distributor in California, did the D17000 re-powers on the 2U D8's to give them more 'ooomph' for pushing scrapers.
Then there was another outfit that put the motors out of the Cat DW21's into the 2U and 13A D8's and I just can't think of the name at the moment. It'll probably occur to me about 2 minutes after I post this.
Then there is Don Mearnes from Ipswich, Queensland, Australia, who has dropped both Cummins and Cat engines into Cat D11's to boost their 'grunt'. I understand that he has a Cummins conversion with 1,100 hp and a Cat re-power with 1,300 hp. However, Mr Mearnes is a little secretive about his antics and I'm open to correction on this.
The D17000-powered 8R D8 mentioned above is still in the same condition. It has been fired up a couple of times since its first outing back in February, 2006 but is no further advanced toward completion. It lives about 5 crow-type miles from me and I work for the owner's family company.
If you want a Cat 60 that has a top speed of around 20 miles per hour, I think a V8 car engine and auto trans with lock-up would be a good way to go. The old 4-banger Cat 60 gas engines did about 700-800 rpm on a downhill run with a stiff tail wind. Most car V8's that I have had anything to do with run up in the 5-6,000 rpm range. Should make for some 'interesting' track wear figures, at the very least. Unless you govern it back a fair way.
Just my 0.02.
You have a wonderful day. Best wishes.