This is the Ofna Force 28 Big Block Nitro engine. The Force big block engines started out as a .21 and then grew to a .25 displacement, then a .26, and now it has been punched out to a .28 displacement. This Ofna Force 28 nitro engine is rated at 2.7HP and 38,000 RPM. Another low cost big block choice for rc trucks or buggies (or even larger scale on road rc cars).

Here are some additional specs on the Ofna Force 28 engine:
CLAIMED HP: 2.7
RPM: 38,000
CARB TYPE: SLIDE
CRANK: SG
CONSTRUCTION: ABC
ENGINE SIZE: .28 cu. in.
TYPE: REAR EXHAUST