ORIGINAL: MarkGrabowski
Matt, et al, I'm just thinking aloud here... Todd seems willing to make some modifications to this engine in order to maximize it's performance (for our use in pattern applications anyway...SAP 180-F3A???). I've only seen photos but at first glance, I'd like to ask if it's feasible to do a bit more machining around the crankcase and possibily loose an ounce or two. I think that if he could incorporate some threaded tabs near the front for nose ring install, cool. Lastly, since the liner is chromed (is it Nikasil or some other process?). porting jobs could get a bit hairy so it would be cool if the engines could be ported at the factory to maximize power when using a pipe. Wouldn't hurt to bump up the compression just a bit to pick up some low-end (but only up to say a 91 octane level). Are these engines being run on gas that includes the 10% ethanol mixed in that many cities mandate?
Mark,
Engines don't have liners as do glow engines. It's aluminum alloy casting that does have some extra material for additional bore. That's the easy part. I don't recall discussing with Tod what the plating is. Maybe Ed did and could chime in. A small amount of weight saving could be had by machining the fins and such on the outside, however, the current finish aids heat dissipation. Smooth finish will not help here. It would make the engine very pretty, almost too pretty considering what the rest looks like, but it would probably hurt heat removal. It's a positive compromise and believe me Todd has thought of that. Designing a new piston diameter the fit the new bore is a small obstacle
The major obstacle is in stroking the engine which requires new crankcase, rod and shaft. More specifically, the case would require new programming to CNC the new dimensions. But as we discussed with Todd, we believe that some, perhaps many Pattern folks would not even blink an eye if the cost jumped to 500$ or more to get the reliability of gas power. That's the main reason I am looking at gas, the reliability they seem to have compared to glow. Power wise I believe the engine has the necessary beans. If we stroked it just a little, maybe 3mm, and bored it maybe another 1 mm, we'd pick up displacement which wouldn't hurt anything
I've been very successful with my Webras. But even with that, there are features or characteristics I don't like such as downline brakes. Gas will give these in spades and also give the year after year with no maintenance what so ever that YS 4 strokes and all the 2 strokes simply can't compete with.
Ed knows several former IMAC' ers that are ready to make the move to pattern but can't work with glow and can't stand electric. I think this is an excellent alternative. I've just purchased some woodies in the size this engine should turn and I will report in this forum. I found a test bed I am setting up also Vince, so if the weather holds over the next couple weeks, I should have a report for ya
Matt