Harry's Replica Engines Gallery

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1/6 scale Profi V8, based on Cirrus aero engine

2 of my engines are based on the Cirrus 4 cylinder aero engine used with the DH-60 MOTH also known as "CIRRUS MOTH"

air cooled engine V8

[missing] [missing] [missing]

4 cylinder water cooled engine, 5 " High, 7 " long

I am fairly proud to have the pair, which I purchased from hobbyclub.com. They where made by PROFI Micro Engines. Alex Osovik represents a group of amazingly talented and dedicated engineers in the Ukraine.

Cirrus origins

In 1924 Geoffrey de Havilland was looking for a reliable cheap engine for use in a light sports aircraft. More particularly, he was looking for something like his favorite World War I aircraft engine: the 240 horsepower (hp) Renault V8, but with half the weight and half the power. Major Frank B. Halford gave it to him by building a 4-cylinder crankcase and adding to it half of the Renaults cylinders, several other of the Renaults components, and standard parts used in car engines. The result was a 60 hp (45 kW) in-line aircraft engine that, although it fell short of the promised horse-power, was still superior to all contemporary engines for light aircraft. Most importantly it was a true aircraft engine at a time where its competitors were more often than not motorcycle engines adapted to running at high altitude. The engine secured, de Havilland Aircraft commenced manufacture of the D.H.60 Moth and the combination of reliable power plant - the ADC Cirrus - and reliable training craft, the Moth, marked the start of serious sports flying in Britain. Major Halford was working at the British government Aircraft Disposal Company (Airdisco) where there were 30,000 surplus Renault V-8 engines, providing the pistons and cylinders for the Cirrus.

Strictly I.C. (Internal Combustion) magazine for the Miniature IC Engine 
published for 14 years starting FEB 1988.
Discontinued due to aging staff. all 84 back issues are available. 
1/6 SCALE DE HAVILLAND CIRRUS MK1, 4 - Cylinder, In-Line, Glow Ignition Engine.
Described by Eric Whittle, also did CAD Drawings
published in Strictly I.C. Feb 96, Issues: # 49, 50, 51 and 52
A 1/4 Scale CIRRUS MK.1, by Merritt Zimmerman - Built by Ron Colonna
Issue: # 30, 31, 32, 33, 34, 35 and 36

Strictly IC

Chester DuBiel, Parma, OH. who provided casting sets, mentions you can not keep a good design down. Following his construction article for SIC, Eric Whittle reduced the Cirrus to 1/9th scale and built one from bar-stock. This was serialized in the English magazine, Engineering in Miniature. This 1/9th scale Cirrus then formed the basis for his Aero V-8 that was serialized in the Model Engineer, thus reversing the full-size process where a WWI Renault aero V-8 was cut in half to produce the Cirrus Mk 1!

Eric whittle 10cc V8 Aero engine series in Model Engineer, April 1995,
download article with plans as 14 pd f's, patience required

Model Engineer article


The Zimmerman-Cirrus V8 is an overhead valve V8 engine based on the four cylinder Cirrus aircraft engine. The original Cirrus was used by such aircraft companies as GeeBee, DeHaviland and even Boeing in 1927. In order to make a running engine of this complexity. the fits of the parts is much more critical than in a single cylinder 2-stroke. All of the parts in the Cirrus V8 are made on Aero space quality computerized machinery. Even the assembly by an experienced technician takes many hours. Only a few years ago, the only engines of this type were made by a few highly skilled hobbyists and took years to complete. They were owned by the original maker or purchased by wealthy collectors for many times the price of this engine. The crankshaft, camshaft and valves are made from heat treated alloy steel. Sealed ball bearings are used front and rear. The center main bearing is "Oilite" bronze. A single cast iron piston ring is used. Each engine is test run before leaving the factory. Operation: While these engines are a beautiful display piece, they are also capable of producing enough power to fly an airplane. The power is equivalent to a modern sport .60 although the Cirrus V8 turns a larger propeller at a lower speed. The engine should be mounted right side up and used only in tractor (not pusher) applications. The engine should not be run on the ground for long periods of time and in the air avoid long periods of full throttle operation. While the engine will run without one, a Glow driver is suggested for ease of handling. The eight glow plugs will require about twelve amps at 1.5 volts. Make sure that your starter battery can handle this load. The propeller should be balanced before mounting it on the engine. IMPORTANT--- Before starting, Oil all of the external valve operating mechanism. Marvel LUBRICATING OIL is recommended. The fuel tank should be mounted level with the carburetter. STARTING Fill tank Attach plug wires Turn the propeller over 8-10 times Choke both carburetter while turning propeller until fuel is drawn into them. Turn on power to plugs Flip propeller vigorously counterclockwise. A power starter may be used but do not crank for a long period of time and do not press the starter on the engine any harder than is necessary to get it to turn over. AFTER RUN - IMPORTANT Wash the engine carefully with kerosene and oil it with Marvel Oil. Remember- there are a lot of moving parts in the Cirrus V8 and they should all be kept clean and lubricated. For long term storage or while the engine is on display, Hoppes gun oil is recommended. DISASSEMBLY This is not recommended unless you are an excellent mechanic and have all the proper size wrenches and other tools. All of the parts for one cylinder should be kept together and put back in the cylinder they were removed from. Remember, there are many more parts in this engine than your average 2-stroke airplane engine and they must all be in the right place for the engine to run properly.


 Type: Overhead valve,
 Air cooled, 90 Degree V8 Bore: .674 Stroke: .748 
 Displacement: .267 in cu X 8 = 2.14 in cu 
 Length: 7.1 in Ignition: Glow Plug (4-stroke type) 
 RPM: 1200-8000 
 Fuel: 80% Methanol - 20% Castor oil.
 Valve Clearance: .004 
 Propeller size: 16-6 Scale: 1/6

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