The 645 usoro engines banyere mmepụta na 1965. Dị ka 567 usoro ruru ya ókè na horsepower na-abawanye, a ibu ibuga mkpa; Emezuru nke a site n'ịba ụba site na 8 + 1⁄2 na (216 mm) na usoro 567 ruo 9+1⁄16 na (230 mm) na usoro 645, na-ejigide otu ọrịa strok na elu elu. Ezie na crankcase e gbanwetụrụ si 567 usoro, 567C na mgbe e mesịrị engines (ma ọ bụ 567 engines nke gbanwetụrụ na 567C nkọwa, mgbe ụfọdụ na-ezo dị ka 567AC ma ọ bụ 567BC engines) nwere ike na-anabata 645 usoro ọrụ akụkụ, dị ka ike mgbakọ. N'aka nke ọzọ, engine 567E na-arụ ọrụ 645E usoro ngọngọ na 567 usoro ike mgbakọ.

Igwe igwe 645 niile na-eji ma ọ bụ ihe na-afụ mgbọrọgwụ ma ọ bụ turbocharger maka ịkwanye cylinder. Maka engines turbocharged, a na-eji turbocharger na-ebugharị ma nwee njide na-emebiga ihe ókè nke na-enye ya ohere ịrụ ọrụ dị ka onye na-agbapụta centrifugal na ọsọ ọsọ dị ala (mgbe ikuku gas na-ekpo ọkụ na okpomọkụ naanị ezughị iji kwọọ turbine) na turbocharger na-ekpochapụ kpamkpam. na oke ọsọ. Turbocharger nwere ike ịlaghachi n'ọrụ dị ka nnukwu chaja n'oge a na-achọ nnukwu mmụba na ike mmepụta engine. Ọ bụ ezie na ọnụ ahịa dị oke ọnụ karịa ndị na-efe efe mgbọrọgwụ, EMD na-ekwu na imewe a na-enye ohere "n'ụzọ dị ịrịba ama" belata oriri mmanụ na ikuku, rụọ ọrụ elu dị elu, na ọbụna ruo pasent 50 na-abawanye na ike ịnya ụgbọ elu kachasị elu n'elu ígwè ọrụ mgbọrọgwụ maka otu ihe ahụ. mgbanwe engine.