Allison V-1710 (and others)

[Thorlifter]

Many planes used the V-1710 and some rebuilt/newly built warbirds (and tractors) that didn't use Allison engines are being fitted with them. Are all the engines surplus? If so when was the last V-1710 made? How many times can an engine be rebuilt?

Are there any WWII era engines that have been newly tooled?

 

[Shortround6]

I believe that all Allison V-12 engines are surplus.

How many times an engine can rebuilt depends on the wear and the spare parts. Some engines when torn down have some parts still within specification and others show enough wear that that they need to be either reground/resurfaced or replaced. On some engines you were allowed to regrind the crankshaft bearing surfaces twice for example. Assuming you had suitable bearings to fit and that each regrind took care of the problems, (pits/scoring/imperfections) but each regrind had to stay within certain limits.

It would be totally uneconomic to tool up to build a WW II engine today. Turbo shaft engines have much longer overhaul times (3-5 times even a commercial big piston engine), are much lighter for the power given. Are able to operate at a higher percentage of full power for much longer periods of time and actually are fairly close in fuel consumption, and don't require fuel that is now unobtainable.

Without a commercial market that would leave only a very, very small specialty market for such an engine and not only do you have to build it, you have to certify it, and you have to insure it.
For US engines you may be able to use the old type certificate, but any foreign engines would be starting from zero.