If Toki didn't see fit to install a turbo plug onto their motor,, uh, engine, then I'm inclinedto agree that maybe they just threw something together. Case in point is that they use a SOLID brass rod??? Cheap to make, but adds huge amounts of stress to thereciprocationparts. I don't know what the Toki's piston pin is like but the Picco'shas a larger than usual outside diameter and is HOLLOW by a large measure, as in, it's a LIGHT, thin walled, TUBE.With the larger diameter, you get more surface area to resist the high, reciprocating loads and wear. Well thought out all around the Picco is, to paraphrase Yoda. I was very much impressed.
BUT,,, I have a Brodak with the bits of an old Norvel AAN stuffed into it. And it's using the stock, Brodak crank. And it does 19.9K on 25% fuel on a 6 X 3 Tornado. I haven't yet got to putting a timing wheel onto it. It just went good from the get go. As Dave suggests, I think that at least some of this has to do with the portpassages cut into the liner instead of the case. This way, you get it exactly right every time. In fact, the VA does it that way too, MK1 AND MK2. and so is the Picco/Brodak hybrid.
Maybe next up is to use the Picco crank in the Norvel/Brodak hybrid and stick on a 4 or 5 x2 APC. I didn't dare do that with the stock, Brodak crank. I broke two running 8 x 4s on diesel fuel. This is not a negative against the Brodak engine, it handles its glow chores just fine. Its just that no Norvel .06 or .049 has ever broken a crank when run with the 8" prop on diesel. But, the thing is, the Picco crank and the Brodak crank are both 7mm while the Norvel crank is 7.5. Even small increases in diameter make any shaft or tube far stronger than you might think. BUT, this IS a PICCO and the other is, well, it is what it is. So I'm speculating that Picco has made a small crank just as strong as the larger, Norvel crank. Next up is the Picco crank stuck into the two hybrids to run teeny little props
and big lumber,,, just to see what breaks first.
About timing. I also have a stock, Norvel Revlite .06 that does 11K on an 8 x 4 prop.
http://www.youtube.com/watch?v=57WTJ...eature=channelThat is one huge prop for an .06 but on diesel it just hauls *ss and sounds very happy doing it. The same engine has been tested on the benchmark, 6 x 3 Tornado on 25% glow fuel and it delivers 19500 RPM. No timing changes were made and that marvelous little Norvel handles the various sizes of props just fine. In fact, I did put a 5.25 x 2 APC on to a stock Norvel with 10% fuelandopen exhaust and got 26K.
http://www.youtube.com/watch?v=Cyvb7...eature=channelThis wasn't the very same engine but WAS stock. I'm sure that tweaking the timing to maximize the potential of each size would be of much benefit but I'm real super happy just the way things are. What a versatile, incredible engine it is. Then again, I recall the VA behaving the same way. Put a pipe on it with no attention paid to "pipe timing" and got 1.5K with no deterioration in throttling. I really need to get a YouTube video of that one done soon.
Some of this may sound like I'm being contradictory but this is what I get when I try this and that. I'm not a serious competitor so my lack of precision isn't costing me anything, However, If I DID compete, I can see that there would be a lot of engaging experimentation that could keep a guy with too much time on his hands, real busy.
Oh,
And here are the new numbers.
4.2 x 4 at 37.4K APC
.204 HP
107.58 MPH
.71lbs static
Finally, what if, with no changes to the timing, but with a far lighter overall engine, we could get numbers that exceed the stock Picco. I have some ideas (one of those are the D shaped crank port mentioned by Dave ) that will be tested, one at a time, to determine what effect each change has. AND,,, this one will be run as glow and dieseland the stock Picco will get the stinky treatment too. The neatthing is that the diesel head will fit both.
Maybe Picco will make a thousand batch run, of this thing that I have in mind. I've got dibs on the first ten,, or more. 