H engine

From MedBib.com - Medicine & Nature

This article does not cite any references or sources. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. (February 2007)

The BRM H16 Formula One engine in its final, 64-valve incarnation.

An H engine (or H-block) is an engine configuration in which the cylinders are aligned so that if viewed from the front, they appear to be in a vertical or horizontal letter H.

An H engine can be viewed as two flat engines, one atop or beside the other. The "two engines" each have their own crankshaft, which are then geared together at one end for power-take-off. The H configuration allows the building of multi-cylinder engines that are shorter than the alternatives, sometimes delivering advantages on aircraft. For race-car applications there is the disadvantage of a higher center of gravity, not only because one crankshaft is located atop the other, but also because the engine must be high enough off the ground to allow clearance underneath for a row of exhaust pipes. The power-to-weight ratio is not as good as simpler configurations employing one crankshaft. There is excellent mechanical balance, especially desirable and otherwise difficult to achieve in a four cylinder engine. ^[1]

Two straight engines can be similarly joined to provide a U engine.

Notable H engines

Aircraft engines

Napier Sabre H-24 engine. The two starboard 6-cylinder banks can be seen in this view

• Napier & Son, UK.
  • Sabre H-24, 36.7 litres 3,500 hp, 1940 - by 1944 in the Hawker Typhoon, the most powerful inline configuration piston engine ever.
  • Dagger H-24, 16.85 litres 890 hp, 1934 - air-cooled.
  • Rapier H-16, 8.83 litres 340 hp, 1929 - air-cooled.
• Lycoming H 2470 hyper engine.
• Rolls-Royce Eagle H-24, 46.2 litres, 3,200 hp - first ran 1944.
• Fairey Aviation Fairey H-16 "Prince", 1,500 hp

Other engines

Brough Superior H-4 motorcycle engine

A BRM H16 engine, mounted in the back of a BRM P83 Formula One car.

• The British Racing Motors (BRM) H-16 Formula One engine won the 1966 US Grand Prix with Jim Clark in a Lotus 43.[1] 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.
• The Brough Superior Golden Dream motorcycle, first shown in 1938.^[2] A 1000 cc H-4 design and a few units were produced in early 1939. Any development planned was interrupted by WWII 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 in 1948 and again in 1951. This was replaced by a flat-4-engined prototype at the 1953 show.

Other uses of H term

Subaru produces water-cooled flat-4 and flat-6 "Horizontal" engines that are marketed as H-4 and H-6 (also thought to represent the configuration of the cylinders from a 'top down' POV as opposed to the traditional 'head-on' POV), despite the fact that their configuration has nothing to do with a real H engine.

References

This article is licensed under the GNU Free Documentation License.
All material adapted used from Wikipedia is available under the terms of the GNU Free Documentation License.
Seeking health information online: does Wikipedia matter?