Italian aircraft suffered from low power engines when compared to allied aircraft. Alfa Romeo later was licensed to build DB 601/605 engines, but it was too little too late. Not sure if the Germans just gave the Italians MG151 20mm cannons or it it was built under license. The combo of the 605 engine and 20mm cannons made the final generation of Italian fighters at least at par with Allied planes. The Macchi C-205, Fiat G-55 and Reggiane Re-2005 were all equipped with a DB605 engine and 2-3 20mm cannon along with a pair of 12.7 machine guns. All were fine looking aircraft.
Excellent info, thank you.
One of the reasons for the poor performance of Italian aircraft engines was the use of lower grade gasoline. The engines were designed for inferior fuel because Italy was dependent on imports. IMO Mussolini's greatest failure was the lack of effort to develop the Libyan oilfields. The oil was known about before 1920.
The Axis in Europe had to make do with 87 octane gas for aircraft. The US produced 100 octane aircraft gas and shared it with the British; both got the extra performance from it. The DB601/605 engines would've been designed even better if aviation gas was available to the Germans.
I don't knw what the Russians used. My guess is lower grade.
Here's an article on 100 octane gas. Developed by a Frenchman but used by the US. It says the Germans had 89 octane gas and the Japanese 87 octane fuel.
https://sofrep.com/news/filler-up-how-high-octane-gasoline-saved-untold-allied-pilots-during-wwii/
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