Finland’s second aircraft engine factory was built in Linnavuori, a village in Siuro Nokia in 1942. The main mission of the factory was to function as a core place for reparing aircraft engines.
Since Europe was threatened by outbreak of war, the engine department of State Airplane Factory, located in Tampere, had been relocated to Kokkola in Western Finland. The difficulty by the distance created need for founding a new factory for airplane engines. Prehistoric Linnavuori (castle mountain) near the village of Siuro in Nokia was selected. The mountain offered good opportunity for underground caves, railroad was nearby and electricity could be easily arranged. The building started in November 1942.
The production was started in partly unfinished premises in March 1944. The first product was the assembly of 30 fuselages for VL Myrsky II (Storm) fighter. This was shortly followed by rework of airplane propellers and at the end of summer bearing foundry started operation. The initially intended operation, rework of airplane engines, could be started only after the war in 1947.
After the end of world war II the factory was fully transferred for production of war reparations. Since the engines were nearest, production of nearly all diesel engines as well as air compressors were selected for Linnavuori. The extremely tight delivery schedules offered no time for own development, but licensing was seen as only alternative, luckily these could be sourced for Sweden. Totally 60 units of June-Munktell crude oil engines were manufactured for schooners built for war reparations. With license from Skandiaverken diesel engines were manufactured for locomotives and air compressors with license from Atlas Diesel. Only these compressors remained in production until 1960’s.
Production of diesel engines based on own development and design was started in 1946, when small series of 440 and 648 type engines were made mainly for propulsion and power generation applications. Part of them were delivered already for war reparation and after them yet for ships sold to Soviet Union by Valmet Shipyards. In 1947 also the development of 4 cylinder otto-engine was begun with intention for powering the first Valmet tractor, fueled either by gasoline or petroleum.
In late 1940’s State Rail Roads had need for light rail car that should be powered by diesel engine. Rail cars would be manufactured by Valmet Airplane factory in Tampere and the natural selection for engine supplier was Linnavuori Works. So the decision for development of a larger diesel engine was made. It was to be an inline 8 with 12-liter displacement developing 180 bhp. In further development it was made also mainly for power generation application featuring charge air cooler and twin turbocharger technology and developing 250 bhp.