Tiago, I didn't believe you until I went to the ZDZ USA distributor and looked up the ZDZ80 single and twin. The single does put out more power.
Twin -
http://www.rcshowcase.com/html/engines/zdz80B2.html
Single -
http://www.rcshowcase.com/html/engines/zdz80.html
I got my information from the AI site. The 3W-48B2 puts out more power than the 3W-50i.
Lanier says that the engine should be a 3.2 to 4.2 gas. While 3.2 is 52CC, the extra power of the twin (an more torque) should make up the difference. I guess it depends on the manufacturer.
ORIGINAL: TD1
You should expect the performance of the 3w 48 twin to be similar to the 3w 42 single if not less the twins generate less power than the singles, the prop for the engine will probably be a 22x8 at the best or a 20x10 .
you can use that engine on the Hangar 9 80" Cap or similar planes, at least you will have better results than with the Lanier Edge. JMHO
Tiago Dias