Has this been tried

[zzrodder]

Chain drive blowers used to be common in the early days of drag racing, but they were only going a 1/4 mile at a time. Dirt and wear would be a big issue for full time operation of an external chain drive. So then if you lubricate it, it will get flung all over plus the fan will be blowing it back onto yer window...
Torchman's idea of frame rails running tight to the oil pan is a workable, you could bolt the engine to the frame rails using the oil pan bolts via a flange running along each rail. They would still have to jog out around the bellhousing though..

 

[Dr Crankenstein]

Eddie Hill build a twin Pontiac engine dragster using the engines as a member in the top frame tubes. I don't remember if the bottom tubes tied in to the engines. It can be done, and in fact, I've considered it myself.

Overhead cams are chain drive. You can do it on the outside of an engine as well. Need to decide where to put the idler(s) and definitely have a guard around the whole works.

I saw the original Howard's Cam twin sbc dragster when it had chain drive 6-71 blowers. It was a top runner at the time.

The Eddie Hill car...

..

 

[old lady's mad]

on the early tractors like mine the oil pan is part of the strength to be able to do it. there is a co. called awsome henry that makes a kit to put a v8 flat head ford on a 8n tractor. the major part of the kit is the fabricated frame/oil pan. i think Jesse james done it when he built the monster trike on monster garage. using a big rig diesel engine

 

[R Pope]

I helped a guy put a double-60 chain drive 4-71 blower on an Olds engine in a '36 Ford coupe. Home made manifold with no pop-off valve. He punched it at a light, and it backfired and snapped the chain at about 2500 rpm. The free end of the chain whipped around and sent the front fender up into the overhead bus wires. Not a fan of chain drives......
One thing we learned, a GM- blown engine will idle with the blower not turning. He managed to limp it home under its own power.