Question about Tumansky M-89

[Hardrada55]

What was the bore/stroke of the Tumansky M-89? I've seen 146/165 and 146/152.5. M88 was 146/165.

 

[wells]

Kotelnikov's book, "Russian Piston Aero Engines", gives 146/165, but then he says the displacement is 35.7 L. It doesn't make sense that if they were trying to improve on previous versions, that they would make it smaller, even if it had higher compression.

 

[Hardrada55]

I've got 35.7 liters and 2179ci for the M89 with 146mm bore and 152.5mm stroke. I have seen Kotelnikov's book, which I appreciate very much. It is what started me digging around for the actual fact of the matter.

 

[rinkol]

Kotelnikov's book, "Russian Piston Aero Engines", gives 146/165, but then he says the displacement is 35.7 L. It doesn't make sense that if they were trying to improve on previous versions, that they would make it smaller, even if it had higher compression.

They might have been trying to reduce frontal area and allow increased rpm to offset the loss in displacement. I have the impression that the Soviet designers were more willing than most to go to the trouble of tweaking stroke size.

Aside from this, there are measurement issues. Radial engines use master and slave rods and these will differ slightly in stroke. Murphy's Law has the corollary that all constants are variables.

 

[Aurum]

What was the bore/stroke of the Tumansky M-89? I've seen 146/165 and 146/152.5. M88 was 146/165.

It definatly had the same bore/stroke that all its pecessors M-85-88 had for sure.