copperclad Elite Veteran Location: ..
| hi Peter i know that the taper used on the Zenoah engines is a common metric taper , it is used on small honda engines and i am sure a number of others as well , i spent a bunch of time looking to see if i could source a reamer for this taper as that would be the best way to convert straight bore fans , it would be easy to just chuck them up and run the proper bit in and be done
when i first started following the R-90 conversion threads , i would always post asking , "how are you dealing with the taper" , of coarse with my lathe i understand that i can bore the taper with a small boring bar and by setting the cross slide to the right angle , and i also know i can use a discarded Zenoah crank and a dial indicator to get this angle perfect , but i shy away from this as making ten or twenty would be a pain
i like the idea that with the right parts , and perhaps some simple machining , the conversion can be practical , for instance the Predator hub has a slight lip on the front and , it is easy to chuck it up and take the lip off in about a minute , and once you setup for one , running twenty would be easy
the other problem i worry about , is even with the taper bore solved , i would still need to source a fanshroud , for the smaller fan , and it is not so hard to make a mold and produce shrouds , it is not something i really want to spend my time doing
this is where it all gets back to tradeoffs , the predator stuff is nice , because it is a complete system , designed for the gasser engines , and only needs minor mods to work with the G-20 , the downside is it runs about $150.00 US shipped for the Fan hub , fan , shroud and shroud mount
so it is perhaps spendy , but i wonder if by the time you get cheaper parts and do more work to make them work , you might not have been just better off with the $150.00 out front
and then the last thing is , with this machine as a proof of concept , it doesn't really matter and i am not really locked into basing the kit on all the parts i used here
say the machine flys and holds up and i am still grinning ear to ear , it would not be a big deal to tweek the frames to except a different fan and shroud setup and run with a completely different setup , as it is possible that the machine will need a serious V2 mod to even be close to what i want , and i will find out once this one is up and running , i am still seeing that there is no sense in getting locked into this being the only way to go this early , and that is why you see my trying to flag people off with " don't buy anything yet , let me finish this and see if it even works first  " , cheers , dana  |