Ki-83 test performance
 

I did find some photos of ki-83 in test flights,but couldn't any Allies test performance report.So, the statics 762km/h max speed tested by Allies is not confirmed or anyone can give me a link of Ki-83 performance report by Allies.It's very strange 762km/h is widely used instead of 702km/h which was provided by Japan.Many thanks.(English is my third language, please tell me if my expression is not right)

Re: Ki-83 test performance
 

One of the possibilities for the difference in top speed may be from the fuel used during American testing.
America had a higher octane avgas than Japan. With the higher octane avgas, the Americans were able to get more power out of the engine (higher manifold pressure).

or

Perhaps it was just a typo that has been repeated over the years?

This article uses 705kph.
https://oldmachinepress.com/2013/09/...heavy-fighter/

Re: Ki-83 test performance
 

Just filling the tanks with 100 octane will not make any individual aircraft go any faster unless the engine is rated at a higher boost than it previously could achieve on the design petrol. This seems a curious design trait.

I've seen, earlier on this site, postings describing a Japanese habit of quoting a maximum speed at something less than the absolute maximum power setting. I don't recall the details, or even whether this was confirmed.

Re: Ki-83 test performance
 

I agree.

I just mentioned the avgas as Japan had limited sources of the "good stuff" during the war. Depending on what avgas was used for testing in Japan compared to what was commonly available from the USA "could" have made a difference.

There are numerous variables that may explain the difference, one being a simple typo replicated over the years. Who knows?