Mike.
The R250 is an excellent engine that is excellently manufactured by a manufacturer that is an active control line flyer. Quality is carefully controlled and every engine produced is a good one.
Steve Rothwell also manufacturs a R320 3.2cc (.19cu in) engine in a limited numbers for combat use and they have more horse power than a 2.5 to pull a model through turns without washing off airspeed.
If you were thinking of buying an R250 then be advised that you will have to wait for over a year for it to arrive as there is a waiting list for orders.
Wanted to know what the 250 is equal to ?
I think that would depend on what aircraft you wanted to use it for.
Did you know that genuine Oliver Tigers are back in production in England and that John Oliver is involved with the manufacture?