View source for Hiro Type 91

{{Short description|W12 piston aircraft engine}}
<!-- This article is a part of [[Wikipedia:WikiProject Aircraft]]. Please see [[Wikipedia:WikiProject Aircraft/page content]] for recommended layout. -->
{{about|the engine|the Hiro Type 91 flying boat|Hiro H4H}}
{|{{Infobox Aircraft Begin
|name= Type 91
|image=
|size=
|alt=
|caption=
}}{{Infobox Aircraft Engine
|type =W-12 water-cooled piston engine
<!-- The type of engine, eg: Air-cooled rotary, High-bypass turbofan -->
|national origin =[[Japan]]
<!-- The country where the engine was first manufactured. Use the main nation (ie. UK), not constituent country (England); don't use "EU". List collaborative programs of only 2 or 3 nations; for more than 3, use "Multi-national -->
|manufacturer =[[Hiro Naval Arsenal]]
<!-- The firm which manufactured the engine. -->
|designer =
<!-- The person or persons who designed the engine. Only appropriate for single designers, not project leaders -->
|first run =
<!-- The date that the engine was first run. If this hasn't happened, skip this field - don't speculate. -->
|major applications =
<!-- aircraft (or other vehicles) that were powered by this engine -->
|produced =
<!-- Years in production (eg. 1970-1999) if still in active use but no longer built -->
|number built =
|program cost =
<!-- Total program cost -->
|unit cost =
<!-- Incremental or flyaway cost for military or retail price for commercial aircraft -->
|developed from =[[Hiro Type 90]]
<!-- The engine which formed the basis for this engine -->
|variants with their own articles =
<!-- Variants OF this engine -->
}}
|}

The '''Hiro Type 91''', (full designation '''Hiro Type 91 520&nbsp;hp water-cooled W-12'''), was a 12-cylinder, water-cooled, [[W engine]] developed for aircraft use by the [[Imperial Japanese Navy]] in the mid-1930s. Power was in the 450&nbsp;kW (600&nbsp;hp) range. Its design was derived from the [[Hiro Type 90]]. An enlarged more powerful engine, the [[Hiro Type 90]] 600 hp water-cooled W-12 had also been developed, producing 600&nbsp;hp.

==Applications==
* [[Aichi E10A]]
* [[Aichi E11A]]
* [[Hiro H4H]]
* [[Kawanishi E7K]]
* [[Mitsubishi Ka-9]]

==Specifications (Type 91 500hp-1)==
{{pistonspecs
|<!-- If you do not understand how to use this template, please ask at [[Wikipedia talk:WikiProject Aircraft]] -->
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|type=12-cylinder water-cooled [[W engine|W-block]] (3 banks of 4 cylinders) aircraft piston engine
|bore=135 mm 
|stroke=160 mm 
|displacement=27.5 L 
|length=
|diameter=
|width=
|height=
|weight=
|valvetrain=
|supercharger=
|turbocharger=
|fuelsystem=
|fueltype=
|oilsystem=
|coolingsystem=Liquid-cooled
|power=<br>
*620 PS for takeoff
*520 hp for max continuous
|specpower=
|compression=
|fuelcon=
|specfuelcon=
|oilcon=
|power/weight=
}}

==See also==
{{aircontent
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|see also=

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|related=

<!-- relevant lists that this engine appears in: -->
|lists=
*[[List of aircraft engines]]
<!-- Engines that are similar to this design: -->
|similar engines=

}}

==References==
*{{cite book |last= Gunston |first= Bill |title=World Encyclopedia of Aero Engines |year=1986 |publisher=Patrick Stephens |location= Wellingborough |pages=74 }}
*{{cite book |last1=Goodwin |first1=Mike |last2=Starkings |first2=Peter |title=Japanese Aero-Engines 1910-1945 |date=2017 |publisher=MMPBooks |location=Sandomierz, Poland|name-list-style=amp |isbn=978-83-65281-32-6}}

{{Hiro Naval Arsenal}}

{{DEFAULTSORT:Hiro Type 91 (Engine)}}
[[Category:1930s aircraft piston engines]]