The spark-ignition engine (SI engine) was invented over a hundred years ago, and is getting better and better all the time. Now, with modern electronics we are entering the era of “smart ignition”. For instance, at low speeds, multiple sparks can be created, making the starting easier and the idling speed lower. The ignition point can be adjustable for best possible performance over the entire operating range, advancing (and retarding if need be) as engine speed is increased. We can make an ignition system that is truly optimized for different types of engines, different compression ratios, different fuels and so on.
The RUNTRONIC SPARK IGNITION SYSTEM can do everything outlined above. Conceived and perfected by Rune Svenningsson in Sweden, it is now available to engine lovers also in USA. Rune is a genius in the field of electronics and a former world champion in racing model airplanes. By now he has learned all the tricks in the book - and a few more. (His latest invention has just been patented in USA - No 6,668,780.) What Rune has come up with here is truly outstanding: unmatched compactness and ruggedness, very low weight and extremely high efficiency.
What we are talking about is a highly developed CDI system (Capacitor Discharge Ignition) with a built-in, dual-spark ignition coil. An induction-type pulse generator is used as standard. Triggering is done via a small magnet on the crankshaft or on the camshaft, passing over a stationary sensor. With the induction-type pulse generator, the advance curve can be modified by the positioning of the magnet and the sensor. At low speeds, two, or three sparks are obtained. A special sensor can back off the advance curve towards the top end. This simple set-up can be used in the majority of cases.
The small size and low weight of the ignition module is a result of the designer’s thorough understanding of spark ignition in general: that it is more important to have a very short voltage rise time and a sufficiently long spark duration, than just ”brute force” in terms of volts and amps. Thus it has been possible to drastically reduce the power consumption at the same time as a better responding system has been obtained.
The same ignition module can be used for firing one or two spark plugs. When used with only one plug, the output connector to the other plug is shortened internally. Several models are available, developed for different applications: a super small, general purpose unit (”Z”), a somewhat larger unit, giving more spark energy (”S”), units with a built-in voltage converter, units with two separate coils, etcetera.
The extremely small dimensions, the light weight and the low current draw of the RUNTRONIC unit makes it ideal for flying models. Four-cycle engines especially, benefit a lot from being run with spark ignition, but also large two-cycle model engines are well suited for a conversion from glow to ignition. True spark ignition makes the small engine much more like a ”real” one. With optimized compression ratio and proper spark advance, it is possible to get more power than with the crude type of ignition provided by the glow plug. With gasoline, the fuel economy becomes fantastic. There will be no worries any more about corrosion in the engine. (You can still run your engine on methanol, if you like.) A special kind of freedom is experienced when you do not have to carry along a heavy battery and a starter out to the flying field. Just fill up, turn on the ignition, flip the propeller by hand (thanks to the automatic spark advance, large engines can also be started that way) - and off you go!
For boat models, the complete insensitivity to vibrations, dirt and moisture makes this system a pure delight to use. The same goes for model cars of different kinds.
For builders of scale models with working SI engines, the small dimensions of the unit, the absence of external coils and the possibility to fire two plugs from one unit make the installation very compact. It is often possible to ”hide” the ignition components in a way that will not spoil the scale appearance.
In the world of ”real” engines, the RUNTRONIC system can bring new life into old machines. Take a vintage racing motorcycle, for instance: what a relief to get rid of the whole complicated and touchy magneto! Where flywheel magnetos are used, they can be replaced by a much lighter impulse generator (a disc with a magnet) plus a RUNTRONIC ignition module. You will get easier starting, better acceleration, more power and much improved reliability. For high speed two-cycle engines, that require reduced advance at the highest speeds, the advance curve can be tailored to a specific engine and a specific application.
The weak point of old boat engines is often the ignition system. If you happen to be the lucky owner of an antique boat engine, here is the chance to make a runner of it again!
If you are building your own SI engines, you will find the
RUNTRONIC system to be an easy-to-use,
bolt-on unit, that will breathe sparkling life into your creation.
FIGURE: BASIC COMPONENTS
Basic design: CDI unit with all electronic parts potted in a block of epoxy
Advance range: Zero degrees (at start) to 35 degrees
50 degrees with new “flux sensor”.
Operating voltage: 3.6 to 6 V (6 to 24 V can be
handled by means of an optional,
built-in voltage converter).
Current consumption: at 5 V input: 12 mA at 0 RPM
(stand-by), 120 mA at
5 000 RPM, 225 mA at 10 000 RPM, 350 mA at
20 000 RPM.
Spark rise time: 7 microseconds.
Max spark frequency: Z: 25 000 sparks/min; S: 40 000 sparks/min
Firing voltage: 24 000 V with 5 V input, 28 000 V with 6 V input.
Dimensions: Z: 1.2 X 1.2 X 1.0 ” (30 X 30
X 25 mm)
S: 2.0 X 1.4 X 1.0 ” (50 X 35 X 25 mm)
Weight of ignition
module, incl. dual-
output coil: Z: 1.4 oz (40 g); S: 2.0 oz (55 g).
Included in basic set is:
Electronic module with dual-output coil
Sensor and trigger magnet
Ignition cable with spark plug boot (for ¼” plugs or for full-size plugs)
Power leads (S-model only)
Warranty: 6 months
Optional accessories are available, see price list.
a registered trademark, owned by
Modeller & Elektronik AB, Karshult 5, 33291 GisLaved, Sweden.
RUNTRONIC SPARK IGNITION SYSTEMS
are marketed in the U.S. exclusively by