I ordered a VMAR Tomahawk (trusting the stories of their better quality and flyability than in the past) and am planning a .61 for it. (6000 ft plus here in CO, need all the ooomph I can get). I was considering the Tower, cheap, but have ruled it out considering some "shutdown" issues et al. My old Magnum 40GP ABC runs decent in my Eagle2, nothing super tho. Seems OS, TT and Magnum all have decent followings, but not a lot of listings on this forum in the .61 size. I'm looking for a BB, non ringed.
Opinions?
Thanks

Dave

It always depends on how much you are willing to spend. The engines you have mentioned are fine, Though I have not run a Magnum since the '80's, I know they are better now but...

I would try to find a YS-45, a Webra, or a used Jett if you need performance at high altitudes...(MVVS also??)

Keep us posted,
james

Do yourself a favour and look at the MVVS units. The 61 and 77 are the same size and can be run either side or rear exhaust. A comprehensive range of mufflers and pipes is also available.

I want to like the MVVS medium 2strokes too, especially the .91, which is based on the .60 case and very lightweight. However, after an experience with muffler bolts broken off inside the cylinder head, I'm very leery with any "bolt-on" style muffler. With a "bolt-thru" muffler, the worse is that the muffler bolts would break clean off and slide out of the engine block.

Anyway, as far as brands go, OS, TT, Magnum and Irvine all share the same bolt pattern I believe. TT and Super Tigre are both a little porky, so they aren't too good if weight is an issue for you. Plus the ABC version of the ST is not out yet. Otherwise, they are great engines.

Don't know if the Tomahawk is a 40 size plane or not. If it is, consider an Irvine .53 as a far lighter weight alternative to going with a .61 or bigger engine. At 18 Oz., the Irvine .53 can swing as big a prop as most .61 can and puts out darn near as much power, especially if you couple it with a tuned muffler like the Tower or Ultrathrust.

I run 3 ST 61's (1 ring and 2 abc's) in King Kobra, TF (red box) P-51B mustang, and GP arf FW-190. They all run superb regardless if inverted, side-mounted, or semi-inverted. I use 11x7.5 or a 12x6 prop and 10% Cool Power. I also have a TT-Pro 61, it was on the FW-190 but was replaced with a ST-61. The TT-Pro 61 required tuning, retuning, etc and never gave a consistent performance. However, I must say the ST 61 ring or abc is a dying horse because of production down-time. All the new 61's at our field are OS 61FX and although there are more and more coming to the flight line I don't believe they perform any better than my ST -61's.

Moki makes a 61. Advertising is mostly the big 1.35-2.1 engines, but maybe worth looking for.