The Conley Stinger 609 supercharged four-cycle V8 gasoline engine - 6.09 cubic inches and 9.5 horsepower at 10,000 rpm
Giant-scale model cars (and airplanes) powered by small gasoline engines have been popular with adult racers for quite a few years now. The largest scale models available through conventional RC hobby outlets are one-fifth or one-sixth scale, but the serious racers go quarter-scale. Now the smallest (quarter-scale) blown V8 gasoline engine in commercial production is being turned out by Conley Precision Engines to power.
Why then is the racing community reacting with crackling excitement over the Conley Stinger 609, a new quarter-scale V8 with supercharging, 100 cc (6.09 cu. in.) displacement, and a power output of 9.5 horsepower at 10,000 rpm – especially with a list price over US$7000? Simply enough, other engines don't look or sound right.
If you are going to spend a significant portion of a year's salary on a scale model car, expecting to own a true scale model isn't unreasonable. For example, the 1969 Dodge Charger Daytona, one of the quintessential Detroit muscle cars, was 5.75 m (18.9 ft.) long, weighed about 1690 kg (3730 lbs), and had a 7.0 l (426 cu in) hemi V8 that put out 425 hp. Scaling to one-quarter the size would give a model 1.44 m (4.7 ft) in length and weighing about 26 kg (57 lb). The scaled engine would have a displacement of 109 cc (6.6 cu in) with an output of 6.6 horsepower.
Quarter-scale model of a 1923 roadster equipped with the Conley Stinger 609 V8
But a powered scale model of a car isn't just one with the right appearance, or even if properly scale performance is produced. A great deal of the enjoyment of racing is the sound of the car, and especially of the engine. Nothing else in the world quite sounds like a big block V8 turning over, then running up through the power curve. The rumble at low speeds is hypnotic, while the special screaming wail at high rpms adds greatly to the excitement of the race. In short, serious quarter-scale racers want their models to sound right, and this largely drives the demand for the Conley 609. It sounds like the real thing – only two octaves higher in pitch.
Internal parts of the Conley Stinger 609 V8 engine
Of course, a scale-model engine also encounters difficulties associated with simple scaling. A particular problem comes from lubrication – it is very hard to adequately lubricate the cylinder and piston walls to survive running at 10,000 rpm. This problem was eventually solved with the help of manufacturing engineers from Sunnen Products Co., a leader in precision honing who worked with Conley to make the engine's cylinder liners. It proved necessary to deeply hone a cross-hatched pattern in the cylinder liners, and then to plateau hone the liners to remove any lips and edges protruding from the first set of patterns. The cylinder liners then had sufficient excess oil capacity to adjust to the movements of the piston, and were smooth enough to significantly reduce the effects of those movements by maintaining closer tolerances between the pistons and the cylinder liners. The production models can be run for long periods at high rpm without excessive heating or wear.
The Conley Stinger 609 V-8 has an electric starter and a centrifugal clutch as standard equipment, and is available with or without the supercharger. The list price of the Stinger 609 in its naturally aspirated form is US$5695, although lower prices are available from some suppliers. The supercharger allows the engine to produce about 60 percent more power for an additional cost of US$1700.
Rear end of quarter-scale drag racecar equipped with the Conley Stinger 609 V8
Giant-scale model car racing is a high-tech sport which can be approached without having to put a new mortgage on the house. It also doesn't require "hold harmless" clauses in life insurance policies against accidents during races. The practitioners are an enthusiastic, outgoing lot who truly enjoy their hobby. More power to them.
Source: Conley Precision Engines via Gizmag