DB601 / Ha-40 Engine Question

Thanks JPC_Aero, The J-aircraft link was very helpful. I wonder if putting Bosch 601 injectors into the Ha-40 will improve operation? Or even if they will fit. I have some DB601 sparkplugs, I’ll try fitting them to the Ha-40 first and see if it’s achievable. Jerry Yagen has a Ki-61 close to completion at Precision Aero Productions in Australia. He has a reasonably good Ha-40 for it, but they are having difficulty finding needed parts. Given the DB601 is more common, with some parts availability, perhaps re-engining it with a DB601 would make more sense

I don’t have a DB601 handy to compare, but I can say that the only difference I can see between a DB605 & a Ha40 is that the accessory drive gear on the DB is thicker by about 10mm… diameter, number of teeth etc is the same though. I know the DB605 is of greater capacity, but externally & internally (visually) everything is the same.

Also, as 43-2195 mentions, I recall reading somewhere that there was a lubrication issue with the Ha40/Atsuta (am thinking valve gear?) that was caused by an undersight during the licenced production by the Japanese? I’ve also read that the Ha40 was a more reliable engine that the Aichi Atsuta, as the Kawasaki tolerances were better, but some Japanese engines suffered crankshaft failures due to bearing tolerance issues?… not sure if this was both engines or just the Atsuta’s?

Both the DB’s & Japanese engines use the same externally fine splined nuts (as opposed to common single hex nuts) to retain their main & conrod big end caps, so unless one has the correct tools it’s practically impossible to disassemble them without damaging the nuts (which of course wouldn’t be done). Also, having correct tools machined up is not as simple as it may sound… I’d be very interested to know what people working on DB’s around the world are doing for tooling?

Anyway… interesting thread on a VERY interesting engine!

Sorry, can’t claim any experience with DB or Ha engines, but the Ki-61/Ki-100 has been an interest of mine for awhile (though more from an aerodynamic perspective of crafting a radial engine onto a in-line fuselage interface).

Here’s a link to an old discussion on the J-Aircraft website. The Ha-40/DB601 discussion and the respective manufacturing prowess of the Aichi and Kawasaki companies is about half-way down the page. http://www.j-aircraft.com/faq/M6A.htm

I also recall past comments – attributed to Japanes pilots – who were impressed by the European-manufactured engines relative lack of oil leaks compared to the Ha-40. Though I’ve not been able to track down the reference in my notes, so perhaps put that one down as hearsay or bad memory for now.

Regards,
…geoff

Thanks low’n’slow. I suspect Kawasaki’s ability to manufacture aircraft engines in 1941, 1942 and 1943, was far superior to the restoration companies of 2014 building new components to original drawings. I also believe that materials available during that period were not (yet) affected by war shortages. If they had Daimler Benz drawings, then I cant understand why parts would not be interchangeable. High performance engines work to very fine tolerances, so Kawasaki must have produced quality products, or the Ki-61 would never have achieved the margin of success which it did.
I am vaguely aware of an internal engine fault whereby a lubricating or cooling port was either missed entirely, or poorly placed which contributed to engine failures. But I believe this was a stand alone error, not indicative of the overall engine manufacture quality.
I would certainly welcome input from anyone with experience of DB601s (or Ha-40s, he adds hopefully).

Given the fact that the two engines were being produced 10,000km apart, with a war raging at the time. I wouldn’t bet on it.

In fact, if you were to try, I suspect you will have been the first.

I understand that drawings and specimen engines were sent from Germany. However it would be hard to be sure that the resultant Kawasaki design drawings were identical and the materials available in Japan will almost certainly not match the originals.