K&B 18 performance

[mtntopgeo]

I recently purchased a K&B 18 from MECOA. Great compression, easy starting, good transition, but mediocre top end performance. Followed break-in procedures, used 20% castor, & 10% nitro, got about 1 hr of running time on the engine now. Getting 15,500 with a MAS 8x4 prop. Bumped the Nitro up to 30% just to get a tach reading; 16,000 on that run. Are the tach readings, (and prop sizes) in MECOA's specs realistic? The performance that I'm getting is very close to that of my ancient, cast iron baffled piston, Enya! Considering the large carb, & ports, & port timing, & the terrific compression, along with the easy starting, I would expest more top end power?????? ............. George K.

[MECOA]

Drop the oil to 18%, it should be in the 15,500 to 16,500 range.

The limiter is the muffler, it will run better with a tuned pipe.

I think an Enya probably put out more like 14,000.

[mtntopgeo]

I tried the 18% oil fuel, & got no mesurable increase in RPMs. My Enya 15-IV actually runs at 15,100 with a MAS 8x4, but your comment about the Enya probably running at 14, 000 RPMs (along with your comment about the muffler being the limiting factor on the K&B's performance) lit a light bulb. I had always run the old Enya with a goofy looking, Buck Roger's,art deco style, twin exhaust pipe muffler. Decided to give the K&B a try with that same muffler. Couldn't use the adater, spacer (because of a curved cut-out to fit the Enya) and, the fit wasn't quite right, but I did manage to clamp it on to the K&B. Fired the K&B up, adjusted the needle, checked the RPMs, & was pleasantly surprised with a 600 RPMs increase. !!!!!!!!!
(and a lot more quiet than the K&B muffler). I checked the Mecoa site, but no tuned pipe/mufflers were listed. Any suggestions? Thanks for pointing me in the right direction. ....... George K.

[MECOA]

http://www.macspro.com

All the late model .15 side exhaust stuff will fit the K&B 18

[Ryan350]

What brand of Tune Pipe And Header did you use get thes specs.