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K&B .18

PostPosted: Fri Aug 26, 2011 1:52 am
by PLaurence
Purchased a K&B .18 from MECOA.

This is my first U.S. Made engine in twenty years.
Pros: lots of power. Started on first flip of the prop.Easy to break in.

Cons: Prop shaft should be a little longer. tried to mount an APC 8X4. The shaft is 5mm and the prop hole is approx 1/4 inch. APC sent me plastic bushings to bush the 5mm to 1/4 inch. Unfortunately, the bushing has a sloppy fit. I subsequently found out after talking to the owner of MECOA, that a shoulder nut should have come with the engine. The shoulder nut solved the problem but after mounting the prop there are no threads beyond the the nut. Not acceptable.
And certainly no room to place a spinner.

I ended up placing a Zingali plastic prop which allowed 2 threads beyond the nut. Placing a spinner creates the no thread beyond the nut problem. :!:

Re: K&B .18

PostPosted: Wed Dec 21, 2011 8:49 am
by Jakob01
CH is correct; the fine print is for a hi nitro with tuned pipe. Even then, I have doubts that the K&B .18 can come anywhere near those figures. I bought one to use on a Combat Mustang (this was to be used just for sport flying, not combat). It would only turn a MAS 8x4 at 15,500RPMs. That's only about 400RPMs more than a $15 Enya 15-IV (bought on EBAY) that I have. Tried 33% nitro, & the increase in performance was only marginal. Inquired with MECOA, & the rep said that the real limitation with this engine was in the exhaust. The thing was so loud, that I just assumed the muffler was nothing more than a header. Removed the muffler assembly, & the RPMs jumped to 16,900. I separated the muffler from the manifold, & checked the Rs again.... About the same as with open exhaust. Checked in with MECOA again, & asked for the speed secrets on how to get the performance that they advertised this engine at. Reply was "GO TO THE MACS SITE". I would think that if a company used these figures in their advertising, that they would be able to tell their customer (more precisely) how he can get those results. SO, I go to the Macs site, buy a header, buy a pipe, follow instructions, & get nowhere. I'm not saying that you can't get this engine to run on pipe. I'm just admitting that I don't know what I'm doing when trying to use a pipe, & I sure ain't getting any help from MECOA. Turned out a adapter on my lathe & mounted a small mousse can to the exhaust manifold. Runs about 16,700, & is fairly quiet. This was a lot of $$$, & time spent to get what a good hi perf. engine should get, off the shelf. A lot of .15s run well on 7" dia props, but it's pretty hard to find one that will spin an 8x4 at 17,000. The Cox Conquest will do that on 10% (and more if you want to go to higher nitro, but I stay with 10% unless I'm using smaller props.) I have never owned a CV-A, but have never heard anything bad said about them. ...................... George K.