Can you weld engines together?

[Boomerang1]

You could use love joy couplers (spider joints), this way the engines would not have to line up perfectly. They come in any shaft size and can hold more torque than those engines could ever supply. Twenty years ago , I was maintenance mechanic & welder at IBP. We used these on large electrical motors. All of your engines will run even, because the faster or stronger one will pick up the slack of the weaker one. Check out clearstreamco

 

[Boomerang1]

Another site rinomechanical

 

[chriswheeler]

Flex coupling joints is exactly what Detroit does with their 3000 HP V 20 diesels. They have a V8 in the front, a V8 in the rear, and a V4 in the center all bolted together with the crank shafts coupled with flex couplers. These make a locomotive sound quiet. 9 foot radiator fan with 8 blades that makes most small plane engines look small. 3 turbochargers. Radiator, without fan, weighs 8000 lbs and holds 250 gallons of coolant. Outside the noise they run smoother than some of the smaller cat V16s ( 3516), bottom line, not a new idea. Be fun to try.
Chris