An H engine is a piston engine comprising two separate flat engines (complete with separate crankshafts), most often geared to a common output shaft. The name "H engine" is due to the engine blocks resembling a letter "H" when viewed from the front. The most successful "H" engine in this form was the Napier Dagger and its derivatives. The name was also applied to engines of the same basic layout, but rotated through 90 degrees—most famously the Napier Sabre series. A variation on the "H" theme were the Fairey Prince (H-16) & Fairey P.24 Monarch, where the two engines retained separate drives, driving Contra-rotating propellers through separate concentric shafts. Although successful, they only existed in prototype form.
The H engine is a relatively rare layout, with its main use being in aircraft engines during the 1930s and 1940s. The 1966 Lotus 43 Formula One car used a BRM 16-cylinder H engine, and an 8-cylinder H engine was used for powerboat racing in the 1970s.
The benefits of an H engine are the ability to share common parts with the flat engine upon which it is based, and the good engine balance which results in less vibration (which is difficult to achieve in many other types of four-cylinder engines).[1]
However, H engines are relatively heavy and have a high centre of gravity. The latter is not only due to the second crankshaft being located near the top of the engine, but also the engine must be high enough off the ground to allow clearance underneath for the exhaust pipes[citation needed].
The British Racing Motors (BRM) H-16 Formula One engine won the 1966 US Grand Prix in a Lotus 43 driven by Jim Clark.[2] It was also used by the unsuccessful 1966 BRM P83 car driven by Graham Hill and Jackie Stewart. As a racing-car engine it was hampered by a high center of gravity, and it was heavy and complex, with gear-driven twin overhead cams for each of four cylinder heads, two gear-coupled crankshafts, and mechanical fuel injection.[3][4]
The Brough Superior Golden Dream motorcycle, first shown in 1938.[5] A 1,000 cc H-4 design and a few units were produced in early 1939. Any development planned was interrupted by World War II and subsequent years of austerity.
German firm Konig, who specialised in racing outboard motors,[6] built a few 1000cc H-8s in the 1970s, which were basically two of their VC500 flat fours mounted one above the other, with the direction of rotation reversed on one of them. Each half of the engine was a water cooled 2-stroke with rotating disc valve driven by a toothed belt via two 45/90 degree pulleys, plus two siamesed expansion chamber exhausts, fed by two single choke carbs. Both cylinders at each end of each engine fired at the same time, hence the siamesed exhausts for each pair.
Other engines named "H"
Subaru has marketed its flat-four and flat-six engines as "H4" and "H6" respectively. The letter "H" in this case refers to "horizontally-opposed", an alternative term for flat engines; these engines can also be said to look like a "H" or conjoined "H"s, albeit from the top and in schematic form.
The Saab H engine is a straight-four engine produced from 1981 to 2009. The letter "H" represents "high compression".
References
Wikimedia Commons has media related to H engines.
^Willoughby, Vic (1989). Classic motor cycles. Ivy Leaf. ISBN0-86363-005-7.
^Taylor, Roger. . Model Cars (July 1967): 327. Archived from the original on 26 March 2016.
^Taylor, Roger. . Model Cars (July 1967): 328. Archived from the original on 4 March 2016.
^Wilson, Hugo (1995). "Brough Superior Dream". The Encyclopedia of the Motorcycle. London: Dorling Kindersley. pp. 34–35. ISBN0-7513-0206-6.
^"Quincy vs Konig". www.quincylooperracing.us. Retrieved 16 November 2019.
February 04, 2023
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An H engine is a piston engine comprising two separate flat engines complete with separate crankshafts most often geared to a common output shaft The name H engine is due to the engine blocks resembling a letter H when viewed from the front The most successful H engine in this form was the Napier Dagger and its derivatives The name was also applied to engines of the same basic layout but rotated through 90 degrees most famously the Napier Sabre series A variation on the H theme were the Fairey Prince H 16 amp Fairey P 24 Monarch where the two engines retained separate drives driving Contra rotating propellers through separate concentric shafts Although successful they only existed in prototype form Animation of an H engine For the EMD V12 V16 H Engine see EMD 265 The H engine is a relatively rare layout with its main use being in aircraft engines during the 1930s and 1940s The 1966 Lotus 43 Formula One car used a BRM 16 cylinder H engine and an 8 cylinder H engine was used for powerboat racing in the 1970s Contents 1 Design 2 History 2 1 Aircraft engines 2 2 Formula One racing engines 2 3 Motorcycle engines 2 4 Powerboat racing engines 3 Other engines named H 4 ReferencesDesign EditThis section needs additional citations for verification Please help improve this article by adding citations to reliable sources Unsourced material may be challenged and removed November 2019 Learn how and when to remove this template message The benefits of an H engine are the ability to share common parts with the flat engine upon which it is based and the good engine balance which results in less vibration which is difficult to achieve in many other types of four cylinder engines 1 However H engines are relatively heavy and have a high centre of gravity The latter is not only due to the second crankshaft being located near the top of the engine but also the engine must be high enough off the ground to allow clearance underneath for the exhaust pipes citation needed The U engine layout uses a similar concept placing two straight engines side by side History EditAircraft engines Edit Napier Sabre H 24 engine starboard side Lycoming US Lycoming H 2470 H 24 hyper engine 1930s 2 300 hp Fairey Aviation UK Fairey Prince H 16 1939 1 500 hp Fairey Monarch 1939 H 24 2 240 hp Klockner Humboldt Deutz DZ 720 H 32 102 9 litres diesel D Napier amp Son UK Napier Rapier 1929 H 16 air cooled vertical 8 83 litres 340 hp Napier Dagger 1934 H 24 air cooled vertical 16 85 litres 890 hp a development of the Rapier Napier Sabre 1938 H 24 water cooled horizontal sleeve valves 36 7 litres 3 500 hp Pratt amp Whitney US XH 2240 H 24 liquid cooled XH 2600 H 24 liquid cooled XH 3130 H 24 liquid cooled XH 3730 H 24 liquid cooled Rolls Royce Eagle 1944 H 24 46 2 litres 3 200 hp Formula One racing engines Edit The British Racing Motors BRM H 16 Formula One engine won the 1966 US Grand Prix in a Lotus 43 driven by Jim Clark 2 It was also used by the unsuccessful 1966 BRM P83 car driven by Graham Hill and Jackie Stewart As a racing car engine it was hampered by a high center of gravity and it was heavy and complex with gear driven twin overhead cams for each of four cylinder heads two gear coupled crankshafts and mechanical fuel injection 3 4 BRM H 16 engine 64 valve version BRM H 16 engine in a 1966 BRM P83Motorcycle engines Edit Brough Superior H 4 motorcycle engine The Brough Superior Golden Dream motorcycle first shown in 1938 5 A 1 000 cc H 4 design and a few units were produced in early 1939 Any development planned was interrupted by World War II and subsequent years of austerity Wooler built a motorcycle prototype with a similar configuration to the Brough Superior Golden Dream and exhibited it at the British International Motor Show at Earls Court Exhibition Centre in 1948 and again in 1951 This was replaced by a flat four engined prototype at the 1953 show Powerboat racing engines Edit This section needs additional citations for verification Please help improve this article by adding citations to reliable sources Unsourced material may be challenged and removed November 2019 Learn how and when to remove this template message German firm Konig who specialised in racing outboard motors 6 built a few 1000cc H 8s in the 1970s which were basically two of their VC500 flat fours mounted one above the other with the direction of rotation reversed on one of them Each half of the engine was a water cooled 2 stroke with rotating disc valve driven by a toothed belt via two 45 90 degree pulleys plus two siamesed expansion chamber exhausts fed by two single choke carbs Both cylinders at each end of each engine fired at the same time hence the siamesed exhausts for each pair Other engines named H EditSubaru has marketed its flat four and flat six engines as H4 and H6 respectively The letter H in this case refers to horizontally opposed an alternative term for flat engines these engines can also be said to look like a H or conjoined H s albeit from the top and in schematic form The Saab H engine is a straight four engine produced from 1981 to 2009 The letter H represents high compression References Edit Wikimedia Commons has media related to H engines Willoughby Vic 1989 Classic motor cycles Ivy Leaf ISBN 0 86363 005 7 BRM engines H16 Members madasafish com Retrieved 2010 09 12 Taylor Roger Lotus 43 amp B R M 83 Model Cars July 1967 327 Archived from the original on 26 March 2016 Taylor Roger Lotus 43 amp B R M 83 Model Cars July 1967 328 Archived from the original on 4 March 2016 Wilson Hugo 1995 Brough Superior Dream The Encyclopedia of the Motorcycle London Dorling Kindersley pp 34 35 ISBN 0 7513 0206 6 Quincy vs Konig www quincylooperracing us Retrieved 16 November 2019 Retrieved from https en wikipedia org w index php title H engine amp oldid 1076808813, wikipedia, wiki, book, books, library,
