Two-cycle V-engine with integrally cast exhaust manifold

A unitary cast cylinder block for a water cooled, two-cycle crankcase compression outboard motor engine, said unitary block comprising:

• A. a plurality of cylinders arranged in first and second vertical banks, said banks forming a V having an included angle of approximately 74.degree., each of said cylinders including an inlet port means for transferring inlet gases from a crankcase to the interior of said cylinders;
• B. first and second vertical exhaust gas chambers between said cylinder heads, said exhaust gas chambers opening downwardly;
• C. exhaust gas passages connecting each of said cylinders of said first and second banks with said first and second exhaust gas chambers, respectively;
• D. walls between said exhaust gas chambers and said cylinders to define a vertically extending central core cooling passage;
• E. first and second upper cylinder cooling jackets surrounding said cylinders at their head ends;
• F. a manifold cooling passage partially defined between said first exhaust gas chamber and said first upper cylinder cooling jacket and between said second exhaust gas chamber and said second upper cylinder cooling jacket, said manifold cooling passages extending along the full length of said exhaust gas chambers;
• and
• G. first and second walls on the outside of said first and second cylinder banks, respectively, said walls spaced from said cylinders to define first and second outside cooling chambers on the outside of said V, said outside cooling chambers located near the apex of said V.