New Finnish Boat Engine
Original author: Kari Hermola
First published in Vene magazine, August 1981
Translated from the Finnish, with permission, by Mauri Lindholm (2004)
Engine manufacturing hasn't yet died in Finland. The struggling Valmet Jyska works has brought to market a 12 hp big brother to the old well-known Vire 7. Is there still room for a 2-stroke petrol engine in this diesel era? A Vire is about half the price of a corresponding diesel engine. Just calculate the difference - for how many years could you cover the extra fuel costs?
For many years the Vire engine has divided boat owners into two groups. One group thinks it's not reliable, noisy and stinks! The other likes its simple construction and small size and especially its low investment price. There is no denying that some faults occur repeatedly in Vire engines but they result, without exception, from neglected maintenance. Users seem to have the strange attitude that a cheap engine deserves less maintenance than a costly one.
For a long time, Vire fans have been looking for a more powerful model that would serve as an auxiliary engine for bigger sailing boats, or even for a small fishing vessel. Bearing in mind the typical brief use of a yacht engine, a petrol engine remains a more economical alternative to a diesel, in spite of the higher fuel costs. In practice auxiliary engines are driven briefly and occasionally. The engine is driven too cold, and a two-stroke engine tolerates cold running better than a four-stroke.
A Vire engine is often criticised for its loud exhaust noise which carries far - several kilometres distance on a calm summer evening. However, the exhaust noise is reduced by using an exhaust pipe and a silencer of rubber, which are common today.
At first sight the new Vire 12 doesn't differ much from the old engine. A closer look reveals a number of differences: -
Although many of the old faults have been remedied in the new Vire, some more improvements could have been made: -
The Vire 12 started easily and ran at idle in a reliable manner. After some warming-up, the speed of a "Myrsky-Janne 700" with two people aboard was measured at 7.1 knots. The engine was clearly over-powered, as the boat accelerated fast and the maximum speed was already reached at 2/3 throttle lever position.
Exhaust noise was very low although there was only a standard rubber silencer. However, the noise from the air intake was annoyingly high.
The engine ran reliably too when hot. Neither longer running at low power nor running at idle caused stopping as before.
Overall the Vire 12 functioned pleasantly. As it's easy to install and low-cost it will certainly find its place as a common drive unit in small craft.
|Operation principle:||Single-cylinder, piston ported, 2-stroke Otto motor|
|Cylinder bore:||70 mm|
|Piston stroke:||70 mm|
|Cylinder displacement:||269 cm3|
|Shaft horsepower:||12 hp at 4500 RPM|
|Cooling:||Water cooled, by a rubber impeller pump driven by extension of the crank shaft|
|Carburettor:||"Bing" float carburettor, fuel bowl type|
|Fuel pump:||Separate diaphragm-type pump powered by pressure fluctuations from the crankcase|
|Electrical system:||A combined starter-generator, starting 0.5 kW, charging power 150 W. Hand cord pull as secondary back-up starting system|
|Fuel:||Petrol + 2% oil (or alternatively petrol+paraffin (kerosene) 50%+50% mixture + 3% oil)|
|Gearbox:||Forward - Neutral - Astern. Gear ratio 2.8:1 forward; 2.5:1 astern|
The above text is an unofficial translation of an article issued in August 1981 in a Finnish boat magazine "Vene" (vene = boat). Permission was granted by the Vene magazine for use and free translation of the article. For more information about the magazine see http://www.vene-lehti.com
As to fuel, the Br.Eng. term 'petrol' or Am.Eng. 'gasoline' corresponds to 'benzin' in German, 'bensin' in Scandinavian languages (Swedish, Danish, Norwegian) or 'bensiini' in Finnish.
A curiosity: The alternative mixed fuel component that has been translated 'paraffin / kerosene' refers to 'petrooli' in Finnish, 'petrol' in Swedish. It is a vanishing fuel type, hardly available any more. As to its composition and viscosity, as a fuel it is between 'petrol' and 'diesel fuel oil', like the kerosene for aircraft or 'lamp oil'. Motor enthusiasts who need this type of fuel, once so common, for their old time engine can make their own "kerosene" by mixing petrol and diesel fuel oil.
The price indication 5950 FIM (Finnish marks) in the year 1981 corresponds to a figure twice that high in 2004 (average annual inflation presumed 3%) and expressed in Euros makes about 2000 EUR.