I have a "problem" and I'm seeking a solution. Here we go:
I recently bought a GMP 1/3 scale Laird Super Solution Biplane. It has the following:

Span - 76" (top wing)
Area - 1633 sq in
Wing loading - 24 oz / sq in
Length - 60"
Weight - 17lbs
Engine - 50-80cc

Previous owner used a G-62. Here's my "problem" I have a 3W 60, a Sachs 4.2 , and a Z-445 twin. All fit the firewall and the cowl (12 1/2" round, 8" deep). Which one would you use and why? Thanks in advance.

Looking at the engines from a power to weight standing the 3w60 or the Sachs 4.2 might be the better choices of the 4 engines listed . A lot also depends on what versions of the 4.2 and the 3w60 you have . If it is a Brison ,FPE , BME or any of the lighter versions of a 4.2 It would beat out the older 3w60k but may be closer power to weight to the newer 3w60. versions The z445 is heavy and not that powerful, it would be the first to eliminate. The G62 is awesome especially the lite version on ignition but still not as powerful as any of the other choices and would be the second to eliminate.
So if you have a newer lighter 4.2 vs an older heavier 3w60k go with the 4.2. If you have the newer lighter 3w60 and a older heavier 4.2 go with the 3w60. If you have the newer lighter versions of both the 3w60 and the 4.2 put them on a plane or on a bench and run them to compare .

Thanks CK1!!! I have an older 3W60 and the Sachs 4.2 is not as old and is lighter. It has the 6-bolt prop hub which is almost scale to the original used in the 1930's. A 24x10 prop should be about right. Thanks again!

I put both engines on the scale with mufflers and the 3W was .5 heavier. Going with the 4.2. Thanks again!