The Cox Tee Dee has long been the standard of the 1/2A engine class, for, very good reasons: It’s
readily available, it’s economical, and performance is good, However, new 1/2A engines incorporating
present-day technology have recently become available. The BV Shurlken and the Chinese are beginning
to push the Cox in racing events. What are these now engines7 Where do we get them? What about the Cox?
The most advanced form of the COX engine that’s commercially available is marketed by Kustom Kraftmanship.
This is a remanufactured engine. The transfer ports have been remachined, a pressure tap added, and a larger
venturi is available. A precision needle valve assembly is included, and the crankshaft has been mated.
Most important, the engine has been dimensionally optimized.

Optimization is accomplished with a Set Of brass shims between the crankcase and the cylinder.
These shims have become the identifying mark of a KK engine. KK makes a re-machined Cox grow plug,
which boosts performance considerably. The company also sells the Glow Bee 1/2A glow head, which adds
additional rpm if you know how to work with it. The basic mistake most modelers make with Cox engines is
to use a racing fuel. Other commercial fuels don’t lubricate properly, producing irregular mixture settings.
For racing purposes, the Cox’s only disadvantage is that it uses e steel piston with a ball joint. While they
are Cute durable at speeds under 20,000 rpm, the piston and connecting rods simply do not last at speeds
over that threshold, old, where the Cox develops More power.

The Shurlkon engine by BV Competition Engines employs all the most advanced technology in engine
design, including a new porting concept and a lightweight piston, The ABC piston/sleeve system reduces
reciprocating mass in the engine, which Increases efficiency- The lightweight piston also allows the engine
to operate at higher rpm for increased horsepower. This powerful little package been Derisively tested in
prototype form in & variety Of applications- The Shurlken will run at over 20,000 rpm vary happily,
and even turn UP to 30,000 rpm when necessary.

The design of this engine is unique, functional, and creative. Especially original is the Shurlken engineers’
approach to exhaust stock styling. Traditionally something of a fixation with engine designers. The Shurlken
exhaust just occurs and it works. A planned production version will be fitted with an exhaust outlet to which
a resonating pipe or muffler can be attached, the Shurlken is nicely filleted, completely anodized, faired. The
engine has no screws; all necessary seals, such as the crankcase and head, are threaded. A spanner wrench
is provided with the kit. The Shurlken weights only 2.25 oz. The engine has a .400 stroke and .3999 bore,
which results in .5000 cube inch displacement (it’s also available at .0608 cube inch) The crankcase width is
slightly larger than that of the Cox, but mounting hole span is the same (with a little Dremel tool work, it’ll fit
your Four most mount).

The Shurlken has twin ball bearings. Unfortunately, the AMA rules prohibit engine equipped with ball
bearings in 1/2A Pylon Racing. For optimum performance, the manufacturer suggests a high-ratio nitro fuel
formula that will produce 24,000 rpm on a 6 x 3 Cox gray prop, I have run a type at 25,000 rpm on a Cox 5 x 3
with Cox rating fuel, These are good number.

With its advance design, look far this Shurlken to be the future Of 1/2A engine technology. For the sport
fliers, it means no more Marginally powered models. For the Speed flier, It means record-setting potential.
For those like myself, it simply means a strong and engines that will last and last. To inquire about the
Shurlken engines, write BV Competition Engines. 1163 Country Club Road, IN45234

The CS engine is another new 1/2A engine from China. You won’t find it at your local hobby store, but
with a little patience it’s possible to acquire it. The CS is an engine of modern design with dual ball bearings,
Schnuerle porting, and ABC technology. It runs well in the 28,000-40,000 rpm range, velocities suitable for
competitive Speed flying.

The garbage pail-sized Venturi and stock spinner of the CS is both highly polished and contrast nicely
with the aluminum crankcase, which is coarse appearing but functional. The CS bigger and heavier than
the Cox or Shurlken. It’s taller (though the small head makes it appear shorter), wider, and longer. The rear
exhaust isn’t easily accommodated in most model airplanes. You can’t just drop a CS into a Taper-wing
with a Four most mount. (See my article "RC Taper-wing l/2A Pylon" in the January 1989 Model Aviation.)

A friend, Larry Hutson, has worked extensively with the CS engine, Creating special head and pipe designs.
With optimized timing, his modified CS puts out considerable horsepower at over 40,000rpm.

Inquiries about the CS may be addressed to CS in the USA (James Zhou). The CS engines come in normal
and speed types. The Speed version is timed for a pipe, which adds considerable power. The pipe is also
available. Speed Times, newsletter of the North American Speed Society, reports that at least one person
(Nick Sher) thinks the CS 049’engine is capable of record setting in Control Line Speed.

The 1/2A scene is growing more competitive and exciting as newer technologies in engine design come
Into use, With more power and options available, we can expect see greater and greater interest category
of flying.

James' note: A new version 049 under GZ brand with improved quality and investing mold case is on way.
It will be the real championship engines. Meanwhile we will still keep on selling the  CS 049 N/S engines.