{{Short description|Early 1940s American air-cooled aircraft engine}} {{Use mdy dates|date=March 2022}} {{Use American English|date=March 2022}} <!-- This article is a part of [[Wikipedia:WikiProject Aircraft]]. Please see [[Wikipedia:WikiProject Aircraft/page content]] for recommended layout. --> {{infobox aero engine |name= O-300/6AC-298 |image = |caption = |engine_type= [[Piston]] [[aircraft engine]] |national_origin = United States |manufacturer= [[Franklin Engine Company]] |first_run= 1941 |major_applications= |number_built = |developed_from = |developed_into = |variants_with_their_own_articles = }}

The '''Franklin O-300''' (company designation '''6AC-298''') was an American air-cooled aircraft engine of the early 1940s. The engine was of [[Flat-six engine|six-cylinder, horizontally-opposed layout]] and [[Engine displacement|displaced]] {{convert|300|cuin|L|abbr=on|0}}. The power output ranged between {{convert|130|hp|kW|abbr=on|0}} and {{convert|175|hp|kW|abbr=on|0}} depending on variant. The '''6ACG-298''' featured a [[Propeller speed reduction unit|geared propeller drive]].

An enlarged displacement version was known as the '''O-315, 6A3''' or '''6AL-315.'''

==Variants== ===O-300=== ;6AC-298: ;6AC-298-F3 (O-300-1):{{convert|130|hp|kW|abbr=on|0}} at 2,600 rpm

;6ACT-298:{{convert|150|hp|kW|abbr=on|0}} at 3,000 rpm ;6ACT-298-J4 (O-300-3):{{convert|150|hp|kW|abbr=on|0}} at 2,930 rpm ;6ACT-298-35 (O-300-11):{{convert|150|hp|kW|abbr=on|0}} at 2,930 rpm

;6ACG-298-P5 (O-300-9):Geared propeller drive 0.63:1, {{convert|160|hp|kW|abbr=on|0}} at 3,200 rpm

;6ACTS-298:Supercharged, {{convert|160|hp|kW|abbr=on|0}} at 3,200 rpm ;6ACTS-298-K4 (O-300-7):Supercharged, {{convert|175|hp|kW|abbr=on|0}} at 3,000 rpm

;6ACV-298:Vertical installation for helicopters,{{convert|160|hp|kW|abbr=on|0}} at 3,250 rpm

===O-315 (6A3)=== ;6AL-315:{{convert|175|hp|kW|abbr=on|0}}

;6ALG-315:{{convert|175|hp|kW|abbr=on|0}}

==Applications== ===Direct drive=== *[[Aeronautical Products A-1]] *[[Aeronautical Products A-3]] *[[CNNA HL-6]] *[[Culver Cadet|Culver XPQ-9]] *[[Culver PQ-14 Cadet|Culver XPQ-14, YPQ-14A, XPQ-15]] *[[Bell 30]] *[[Bellanca 14-7|Bellanca T-14]] *[[ERCO Ercoupe#Variants|Erco XPQ-13]] *[[Fleetwings 33]] *[[Hockaday Comet]] *[[Piper PT-1]] *[[Troy A]] *[[Zodiac Libra-Det]]

===Geared drive=== *[[Culver PQ-14 Cadet]] *[[Republic RC-3 Seabee|Republic RC-1 Thunderbolt]] (O-315)

===Supercharged=== *[[Northwestern XPG-1]] ([[Waco CG-4]] twin-engine conversion)

==Specifications (6AC-298)== {{pistonspecs |<!-- If you do not understand how to use this template, please ask at [[Wikipedia talk:WikiProject Aircraft]] --> <!-- Please include units where appropriate (main comes first, alt in parentheses). If data are missing, leave the parameter blank (do not delete it). For additional lines, end your alt units with </li> and start a new, fully-formatted line with <li> --> |ref={{fact|date=December 2017}} |type=6-cylinder air-cooled [[flat-6|horizontally opposed]] aircraft piston engine |bore=4.25 in (108 mm) |stroke=3.5 in (88.9 mm) |displacement=297.9 in³ (4.88 L) |length= |diameter= |width= |height= |weight=260 lb (118 kg) |valvetrain= |supercharger= |turbocharger= |fuelsystem= |fueltype= |oilsystem= |coolingsystem=Air-cooled |power=130 hp (97 kW) at 2,600 rpm |specpower= |compression= |fuelcon= |specfuelcon= |oilcon= |power/weight= }}

==See also== {{aircontent <!-- include as many lines are appropriate. additional lines/entries with carriage return. --> |see also= |related= |similar engines= *[[Continental O-300]] |similar aircraft=<!-- similar or comparable aircraft --> |lists=<!-- related lists --> *[[List of aircraft engines]] }}

==References==

;Notes {{reflist}} ;Bibliography {{refbegin}} * Gunston, Bill. (1986) ''World Encyclopedia of Aero Engines''. Patrick Stephens: Wellingborough. p.&nbsp;57 {{refend}}

{{Franklin aeroengines}} {{US military piston aeroengines}}

[[Category:Franklin aircraft engines]] [[Category:1940s aircraft piston engines]] [[Category:Boxer engines]] [[Category:Six-cylinder engines]] [[Category:Air-cooled aircraft piston engines]]