Jim's comment about the RE Rossi is spot on. They're next to impossible to find. I started a thread recently (on RCU I believe) to discuss this engine as I happened to be lucky enough to find one. I suspect it will be perfect, given the header I have for it, for a Citation 45.

On the other hand, I have had plenty of success sourcing YS 45's both in side and rear exhaust configurations. A simple wanted ad should produce one or two within a short time and the YS 45 is perhaps the most powerful RE 45 still around.

Another pair of options for RE configurations are: 1) at the high end, a Jett 60 could be used as this engine is specifically built into a 45 size case. It is also designed to turn smaller props (10") at high rpm and I suspect it would be another ideal light candidate for the Citation. 2) At the other end of the spektrum, in terms of cost and performance, is the MVVS 40 which is indeed a very good engine by all reports but it is a 40 and is likely not in the same power league as the YS, OS or Rossi. The nice thing about the MVVS is that it can be setup as SE or RE before its first run. Once the configuration is chosen, it should not be changed.

I mentioned OS above and certainly the OS 40 and 46 VF (-P) are other well known options that were commonly used by the Japanese in their designs. These are harder to source than the YS (in my experience) but not impossible. I have been able to locate a 40 VF-P and I believe the engine can probably be turned into a 46 by transferring the guts (crankshaft, piston and sleeve) of a 46 SF into the 40 VF crankcase. This is really just a theory but I believe it might be possible. The ramification of course is that parts for your VF can be easily had by sourcing SF engines. On the downside, the 46 SF seems to be the rarest of the great SF line with the 61's, 40's, and 25's being more readily available in that order (from high to low).

There may be other options out there that I'm not aware of and would be interesting to hear about. OPS and Picco made a RE 46 (now very rare) but from what I know Webra never did.

David