Mark,
Thanks. I also have the same info on the K-90, but I dont have tacho readings of it, so I dont know what revs it runs.
The A180V is based upon the same pistons, liners and rods used in the A-90HP. It has a single carb which feeds a chamber which has a disc at each end which goes into the case volume of each cylinder. The disc timings are 180 degrees each and set 180 degrees apart. This would limit max power, but everything else about the engine is built to race. I didn't get much running with mine, but even running way too lean (it would not richen up with the needle all the way out) it got up on pipe on a 8015 prop shop when mounted in a rigger. The engine would make good power if it could get enough fuel, and it revved very well.
Props are a limiting factor with the larger engines. Prop shop make some very large props (I have heard or 95mm props and own an 8517) but these tend to suit monos. The largest octura is a X482, (and a 3 blade version) which would suit monos okay, but may not be much good on a rigger. The largest hydroplane type prop from Octura would be a P775 or 1475, but neither of these would absorb the sort of power we are talking about.
There are other options for making props that I have not fully explored yet.
Are you talking about a multi cylinder engine to get 25000 rpm? My guess is the engine would have to show as pretty dominant for people to consider paying $3000 or more for. I presume you mean Aussie dollars? I am thinking about 12-14 hp from 20k to 22k would be realistic.
Tim,
I am still betting the problem is the 16% larger capacity in basically the same engine. Give me some time and I can do some testing to confirm my theory, but I am very busy at the moment.
What do you mean a strength issue?
Some of what has been said in that discussion is not that politically correct and may not be suitable for public consumption!
I would like to keep as much of the design discussion public as we can, that way we are open to the ideas of the boating community! There's no real secrets in engine design. Besides if someone or an engine company copies our ideas and makes another engine it is actually to our benefit! 8)
Ian.
