2. I have put a O-200 in a Coupe. It is no real problem except for the changes in the cowling. The engine mounts move the engine about 1/4 to 1/2 inch forward, so you must modify the cowling to make it fit.
3. Performance is increased only in the rate of climb area. I used a 69 X 50 prop with 337 approval (The STC calls out a 69 X 48). This helped reduce the tendency to overspeed, and kept the cruise performance about equal to a well tuned C-85 or C-90.
The plane Lynn is talking about is his former, and now my N99387. I've had the plane for just over three years now and have to say that the conversion as Lynn describes it really works out well. It is true that cruise is, at best, 5 or so MPH better than stock, and that ROC is astonishingly better...I rarely see less than 500FPM, and at gross on a hot day with several thousand feet density altitude, I can still count on not much less than 350FPM. It just doesn't blink. (That doesn't sound like much to people used to 150-180HP planes, but it's good sub-100HP).
Where I also gain is in the full-throttle level flight and let it find its maximum speed mode. If you wait it all out, you get about 121MPH TAS. I've done that in company with other O-200 conversions, and find that '387 is faster than most and a bit slower than a few.
It was telling at the fly-out two years ago in Mason, MI. The way home turned into a bit of an 'air race' and there was a clear 'class' separation. The O-200 415C's and Alons arrived first, with the stock 415s
well behind.
There is NO coupe I've ever seen so fast as George Bigge's Alon, with a C-90. (He also has a really cool autopilot and full IFR panel.) He just walks all over the rest of us for reasons not understood. We do note that his prop stops 90 degrees counter to the rest of us, though :-)
But all that only matters if you're air-racing. At the rated 75% power mark for the O-200, they are just a touch faster than the C-series birds.
Another consideration for the O-200 is that it is a more evolved engine. Continental learned some things from the C-series that they applied to the O-series cases and castings, and it *is* a better engine in some fundamental ways. For example, the two halves of the case don't tend to 'fret' so badly, leading to the oil leaks that plague so many 415s. There are dozens of little improvements. That and (for the time being) better parts availability might make it worth-while.
Finally, look for workmanship in the conversion. There are some really bad ones out there, reflecting 'bright ideas' that someone managed to get a 337 on. We have one plane locally with a C150 exhaust which necessitated a bulge in the cowling. Alon, fine. C150, no. Look for an updated nose-bowl (you want the super-bowl) and good baffling work. Lynn and his father did such a nice job with '387 that I'm at a loss for how I might make it overheat or even get above 180. Having flown a Coupe on a hot day hanging on the temperature gauge, I appreciate that :-) Also, did they do an alternator conversion and electrical system fix-up when they dropped the O-200 in? If not, why not? If the old generator is hanging off it, I'd say that speaks volumes about the personality of the guys doing the work.
Greg
