So I bought another big lot of "stuff" off the bay.... sometimes I'm not too sure why ...anyway one of the engines in the lot was an ST G20 .15 in the box.  Its got 1960 cast on the bottom and a smooth head, no fins.  Is this the/a Speed engine?  it came with an exhaust block with a slide valve, not sure if that is home made or standard fare for a speed engine though.  If that's the case is it reasonable to assume it probably wouldn't be a good fit for a stunt ship?  Would I be best to either sell it or  build a .15 speed ship for it 

Also got a real clean Holland Hornet .049 with its tank and back plate and  a couple of un-run Pee Wee's and an un-run baby Bee.  I was gonna flip some of em on the bay but darn I'm thinking I might keep a few more than I had planned.. who was me

Matt, I didn't think about combat   I have most of a Super Swoop kit would that be too big for it?

A great Classic speed engine. Prototype won the 1959 Criterium, "production" (in the hands of Rossi), controversially won the 1960 World Champs? - A slight case of whipping!

I have one that was gifted to me installed on an extended wing Sig Akromaster.  With a Master Airscrew 8-4 and just into a full two stroke, it does 4.5 second laps on 55 foot lines.  Actually, it's just about right, the lines stay tight and it will do anything.  For some reason, it is very hard to hand start, maybe not enough flywheel from the very light prop?  Once it's running it is great and the little airplane is a blast.

Browsing through a pal's speed file today I came across a report that Bob Lauderdale had done over 170mph with his G20/15. (1963)