Experiments in hope of extreme power...

Hi Guys,

Some of you know that I have been using a Shuriken engine to power my 1/2A profile protospeed model. The Shuriken is a quite old, out of production engine that has not been made or supported for many years now. I figured that until I broke it, it was still useful to play around with. I accidentally acquired aluminum and a ceramic coated cylinder liners in an Ebay acquisition of (mostly no good) parts.
The originally designed cylinder/liner assembly started out being made from Iron (piston) & steel ( cyl. liner). I don't know if many of these were made, but I have one.
Although it's WAY better than it's TeeDee rival, with a wrist pin rather than a ball-socket joint, it was not at all optimal for the time.

The next step was to go to a much lighter aluminum piston and run it in a chromed brass cylinder. Known as ABC. The next advance was to run an aluminum piston in a chromed Aluminum liner, that if nothing else yielded a lighter engine. Known as AAC (and boy the sturdy Shuriken is relatively heavy). The final stage of design yielded a Ceramic coated aluminum liner using an aluminum piston. This was known as AAO.  Ceramic feels kind of slick, not quite that of teflon. Teflon coated pistons and parts have been used successfully in high performance model engines, but were not ever featured on any 1/2A production engine (other than Norvel) that I'm aware of. Engine modifiers generally sent out parts to a shop for coating, which would then require a re-fit in order to get them back into the engine. If fitted incorrectly, they worked poorly. I never came across published data on this coating procedure, so those that tried these things were truly pioneers, going out on a limb & often ruining parts and engines...
Nonetheless, in the quest for the holy grail of speed, failures are often expected along the journey. If not expected, they'll happen anyways!

I personally never tried the Iron/Steel combo because I knew the ABC was superior. That being said there was a great variance in the performance of my ABC piston/cylinder units. The reason being is that several cylinders had different porting (my parts were experiments by somebody). But, more importantly the fit and profile of the cylinders were different. With the  tolerances in the tenth of a thou. (or less) I didn't have the instruments (+ knowledge of use) to do consistent measurements.

So I reverted to the tried and true "cut and try" method. Essentially meaning run the combo's & see what works best. In the end, I had my friend from California & master modeller John McCollum custom build me a few (one off) ABC piston / cylinder sets. Because John KNOWS the proper tapers + used a superior German Mahle ( high silicon alloy) aluminum for his pistons, his sets turned out to be the very best performers, even with MUCH less radical porting. The difference between best & worst being about 4,000 RPM!! ( 29,000 -> 33,000).  It's hard to call a 29,000 RPM .049 a failure, but it really is when compared to a 33,000+ RPM engine. The inflight difference being ~ 20 MPH!!  
At the end of the bench testing day, the promising Ceramic cylinder was a failure ( at 31,000 RPM), but it could very well be because the critical "fit" is off, not necessarily because of the Ceramic itself.  Or maybe it is the Ceramic...?? I don't really know much anything other than what my trusty tach tells me.  There are other maddening issues like bad / semi-failed bearings that have interfered with what might have been a superior result. Sadly, with no spares or spares with quality...my research is stopped for the time being.  BTW, DO NOT tell me to use Boca Bearings, because that's a route to very bad results....ask me how I know?  

I'll add photos later when I return from an appointment...

Cheer,

Paul