New motor for a cabover

I don't see why you couldn't use 1 of the larger bore engines with the proper engine mounts,cooling systems,etc. Anything is possible it's just nuts and bolts

 

And money, lots and lots of money.

 

I'm sure that those cabovers came out of the freightliner factory with n 14's or detroit series 60's maybe even 3406e or c-15 cats.I'm sure you could buy a complete parts truck for the same money as a complete engine then still have all the small nickel and dime parts that you need on those swap projects

 

They all fit. My FLA (same can as yours) has 60 series. Flb at the shop has a 3406b in it.

 

There is a post on here somewhere about one with a K series Cummings. Saw an Astro with V12 and Ozdriver has a 3408 in a KW. Don't see why those won't fit in yours as well.
Surely not the best chose doing those swaps but you asked what is the largest that will fit. There is no other sound like a buzzing dozen.

 

Or shortages of oil stains under it lol.

 

If there isn't a puddle oil under those 2 stroke detroits,there probably ain't no oil in it haha

 

For a buzzing dozen with the right running gear that was external lubrication for the slip stream before the jump to light speed. An old man had a butterfly hood 4000 White, extended frame to make room for it plus mount the bumper and radiator forward. Hood looked like two cut and welded together with a torch and coat hanger with special paint brush effects. Everyone laughed at it. He said: "When the fenders get to going this away and the head lights get to going that away, with hand motions, all it needs is more road." Probably not much out there today that could run with it or use that much fuel. LOL

 

Ahhhh..... the Cummins K series, those where engines back in the day. You could sometimes spot them in certain trucks, Freightliner had the bigger grill.