Continuing La-5 development, Semyon Alekseyevich Lavochkin installed more powerful engine M-82F (later renamed to ASh-82F).
   The Ash-82A was very sensitive to cylinder head temperature for safe running and optimum performance best conditions were achieved between 200 and 220 degrees Celsius whereby if pilots allowed temperatures to exceed this the resultant overheating often caused loss of cylinder head or indeed complete disintegration of the cylinder its self. It also suffered a short spark plug life substandard oil pump capacity and a tendency for exhaust pipes to burn through. This led to the joint development of the Ash-82F, Ash-82FN & Ash-82FNV engines. The Ash-82F first appearing on La-5 planes in December 1942. The new engine produced improved performance above 1500metres (4921 ft) but was still aspirated by a conventional carburetor.
   Semyon Lavochkin likewise saw tremendous development potential in the La-5 (which he considered a hastily put together stop gap). After putting forward improvements re aerodynamic efficiency, better cockpit view, control enhancement and weight reduction, government decree was issued on the 9th December 1942 authorising further development work. This work was carried out by the TsAGI (Central Aerodynamic and Hydrodynamic Institute).
   Production of the La-5F had ceased by the end of 1943 in favour of the La-5FN.