Crosshead type engines are able to develop much higher power at lower rotational spieeds than trunk-piston type engines, because the space available for the crosshead bearings is greater than the space within the piston for the gudgeon bearing assembly. Trunk-piston engines have the advantage of requiring less head room than crosshead engines. Their working parts are fewer in number and much less costly to produce because their design lends itself to mass production methods. The gudgeon bearing assembly is not particularly suited for highly rated two-stroke engines unless special arrangements are made for its lubrication. Cheaper quality fuels may be used in crosshead engines as it is possible to isolate the cylinder space from the crankcase, thus preventing acidic residues entering the crankcase. The total cost for lubricants is less with crosshead engines than with trunk-piston engines of equivalent power.