Shinpachi
thank you for sharing! That is a great translation, by the way.
Two things that I find interesting:
1. The translation suggests that the Homare 21 had both fuel injection and water injection, which does not agree with the TAIC report on the Ki-84. It may be that the Homare 21 used indirect injection, which is a form of fuel injection. I think a bowl-prime carburetor is classified as indirect injection since it primes the cylinder heads with fuel. Really interesting.
2. It looks like the Kasei 23 (or Ha-32-11 using the integrated naming system) was the first direct injection engine, unless it used indirect injection. It is not clear to me how to tell the difference between direct and indirect injection systems using the available data.