Hey Jan.... the 25SF weighs the same amount as the 25FP. They're almost the same engine other than the SF has ball bearings whereas the FP is bushing'd instead. Also, I'm going to be running 3 bladed Master Airscrew props so the extra power of the SF should be absorbed by the slightly less efficient 3 blade props. All in all I think it'll work fine.... and if it doesn't I can always sell the 25SF's and buy 4 smaller engines for it. ;-)

But thanks for the comment. This B-17 project is still sitting on my backburner for now as I'm in the middle of scratch building a delta wing canard pusher plane.

Finally, for all the criticism I see of these rotary Wankle engines they must be one of the most sought after engines on Ebay! Good God, but used Wankle's go for well over $250 on Ebay almost every time!!! Wish I had a crate full of them cause they're worth their weight in gold it seems. I'd still like to try one someday and I went ahead and purchased the RCM plans for that seaplane that was designed for a Wankle.... the Northrop Eagle II. Might build it this winter and try to get a Wankle for it just for the experience.

Regards!

- Michael