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A wasted spark system is a type of ignition system used in some four-stroke cycle internal combustion engines. In a wasted spark system, the spark plugs fire in pairs, with one plug in a cylinder on its compression stroke and the other plug in a cylinder on its exhaust stroke. The extra spark during the exhaust stroke has no effect and is thus "wasted". This design halves the number of components necessary in a typical ignition system, while the extra spark, against much reduced dielectric resistance, barely impacts the lifespan of modern ignition components. [1] In a typical engine, it requires only about 2–3 kV to fire the cylinder on its exhaust stroke. The remaining coil energy is available to fire the spark plug in the cylinder on its compression stroke (typically about 8 to 12 kV).
Perhaps the most significant advantage of the system, compared to a single coil and distributor systems, is that it eliminates the high-tension distributor. [2] This significantly improves reliability, since many problems with a conventional system are caused by the distributor being affected by dampness from rain or condensation, dirt accumulation, and degradation of insulating materials with time. Although plug-top coil systems would later offer this same advantage, they were not available for another 30 years. Plug-top systems increase the number of coils required, increase the heat that these coils must survive and thus require more sophisticated and expensive materials to survive routine usage.
Wasted spark systems still require a timing signal from the crankshaft. In a conventional four-stroke engine, this signal must also observe the phase of the camshaft relative to the crankshaft, so contact breakers are normally driven from the camshaft and distributor drive. With a wasted spark, the crankshaft can be used instead, as the system fires on both upward strokes. It simplifies the mechanical arrangements since there is no distributor drive and the contact breaker cam can be fixed to the crankshaft. Although a 2:1 reduction gear is still required to operate the camshaft and valves, the precision of this drive is now less critical (ignition timing is more critical for engine performance than valve timing): engines continue to run adequately even with worn camshaft drives and imprecise timing.
This system has been widely used, including such engines as the MG MG6 1.8T engine; Mitsubishi Evolution 4G63 engine, Fiat 126 engine, Mercedes-Benz inline sixes (M104.94x, M104.98x, M104.99x); Buick 3800 engines (LN3 and newer); Harley-Davidson V-Twin; air-cooled BMW Motorcycles; Citroën 2CV, Mazda B engines; Chrysler V10s; GY6 engine; Volkswagen Golf Mk3 2.8 VR6 (other than 2.0); Saturn Corporation four cylinders; Toyota 5VZ-FE V6s; Toyota 5E-FE and Chrysler 1.8, 2.0 & 2.4 engines. Some Ford engines also do. Many Honda and Kawasaki motorcycle and PWC engines also follow a similar design, to allow for a smaller number of more powerful coils to replace a larger number of smaller coils in the same limited space.
In practical use, a V-6 engine would only need three coil packs instead of six. The coilpack fires the spark plugs in two cylinders simultaneously so for example 1&4/2&5/3&6 cylinders fire together, the spark plug in one cylinder on a compression stroke is where the power comes from, and the spark plug in the other cylinder on an exhaust stroke does nothing. Coils in a wasted spark system may be in pack form, or they may be in Coil-On-Plug (COP) form, with a spark plug cable attached to each COP unit, which connects to another spark plug.
Most single cylinder [four-stroke] engines use the wasted spark system in order to capitalise on the simplicity and reliability of the flywheel magneto. These engines need a flywheel to run smoothly, and the heavy current-generating magnets help provide the momentum while delivering a zero-maintenance drive to the ignition system. Bolted to the end of the crankshaft, this flywheel rotates twice for each compression stroke.
As well as the build-weight and maintenance advantages of this system, there is a tuning advantage. Mounted directly on the end of the crankshaft, all the stress that spark generation would otherwise place on the camshaft chain (or another special purpose half-speed drive) is avoided, while there is virtually none of the strain that necessarily degrades the ignition timing in systems relying on chains or gears.
Unlike the multi-cylinder systems noted above (which fire two plugs simultaneously from a double-ended coil) the coil in this system has only a single HT lead running to the single plug. The flywheel magneto provides other services in, for instance, small motorcycles, as it can easily be built to provide direct-current battery-charging power at almost no additional cost or weight.
In modern conditions, this method has a very small impact on the length on the service intervals of the vehicle and the longevity of individual components. Modern ignition systems do not have breaker points, which have been almost entirely replaced by electronic systems. Modern ignition coils outlast most other components of the vehicle and modern spark plugs have excellent service life, though there is a slight-difference between the two plugs as to erosion suffered at the center electrode. Because the spark jumps in opposite directions on the companion plugs, one bank will erode the center electrode more, and the opposite bank will erode the ground electrode more. Spark plugs used in wasted spark systems should have precious metals, such as platinum and/or iridium, on both the central and ground electrodes in order to increase the average service interval time before replacement is needed. [3]
Since the earliest gasoline engines twin spark systems have been used, with two spark plugs for each cylinder. Each set of plugs is supplied separately. Reasons for this include reliability (especially as a failsafe in aircraft engines), for improved starting, and for better combustion performance by initiating the flamefront at opposing points simultaneously (e.g. Alfa Romeo). These are not considered as wasted spark systems since their sparks all take place after the useful compression stroke rather than "wasted" in the exhaust stroke.
A four-strokeengine is an internal combustion (IC) engine in which the piston completes four separate strokes while turning the crankshaft. A stroke refers to the full travel of the piston along the cylinder, in either direction. The four separate strokes are termed:
Engine tuning is the adjustment or modification of the internal combustion engine or Engine Control Unit (ECU) to yield optimal performance and increase the engine's power output, economy, or durability. These goals may be mutually exclusive; an engine may be de-tuned with respect to output power in exchange for better economy or longer engine life due to lessened stress on engine components.
Ignition systems are used by heat engines to initiate combustion by igniting the fuel-air mixture. In a spark ignition versions of the internal combustion engine, the ignition system creates a spark to ignite the fuel-air mixture just before each combustion stroke. Gas turbine engines and rocket engines normally use an ignition system only during start-up.
A contact breaker is a type of electrical switch, found in the ignition systems of spark-ignition internal combustion engines. The switch is automatically operated by a cam driven by the engine. The timing of operation of the switch is set so that a spark is produced at the right time to ignite the compressed air/fuel mixture in the cylinder of the engine. A mechanism may be provided to slightly adjust timing to allow for varying load on the engine. Since these contacts operate frequently, they are subject to wear, causing erratic ignition of the engine. More recent engines use electronic means to trigger the spark, which eliminated contact wear and allows computer control of ignition timing.
A distributor is an electric and mechanical device used in the ignition system of older spark ignition engines. The distributor's main function is to route electricity from the ignition coil to each spark plug at the correct time.
A W8 engine is an eight-cylinder piston engine with four banks of two cylinders each, arranged in a W configuration.
The Hyundai Beta engines are 1.6 L to 2.0 L I4 built in Ulsan, South Korea.
Alfa Romeo Twin Spark (TS) technology was used for the first time in the Alfa Romeo Grand Prix car in 1914. In the early 1960s it was used in their race cars (GTA, TZ) to enable it to achieve a higher power output from its engines. And in the early and middle 1980s, Alfa Romeo incorporated this technology into their road cars to enhance their performance and to comply with stricter emission controls.
An ignition coil is used in the ignition system of a spark-ignition engine to transform the battery voltage to the much higher voltages required to operate the spark plug(s). The spark plugs then use this burst of high-voltage electricity to ignite the air-fuel mixture.
The Toyota S Series engines are a family of straight-four petrol engines with displacements between 1.8 and 2.2 litres, produced by Toyota Motor Corporation from January 1980 to August 2007. The S series has cast iron engine blocks and aluminium cylinder heads.
The Toyota E engine family is a straight-four piston engine series, and uses timing belts rather than chains. The E engines were the first multi-valve engines from Toyota designed with economy, practicality and everyday use in mind. Like many other Toyota engines from the era, the E engine series features a cast iron block, along with an aluminium cylinder head. E engines are lighter than earlier Toyota engines, due to the hollow crankshaft, thinned casting of the cylinder block, and several other reductions in auxiliaries as well as in the engine itself. Carbureted versions include a newly designed, variable-venturi carburetor. All of these changes improved economy and emissions. The members of the E engine family, range from 1.0 L to 1.5 L. The E family supplanted the K engines in most applications. A large number of parts in the E engine series are interchangeable between each other.
Capacitor discharge ignition (CDI) or thyristor ignition is a type of automotive electronic ignition system which is widely used in outboard motors, motorcycles, lawn mowers, chainsaws, small engines, turbine-powered aircraft, and some cars. It was originally developed to overcome the long charging times associated with high inductance coils used in inductive discharge ignition (IDI) systems, making the ignition system more suitable for high engine speeds. The capacitive-discharge ignition uses capacitor discharge current to the coil to fire the spark plugs.
In a spark ignition internal combustion engine, ignition timing is the timing, relative to the current piston position and crankshaft angle, of the release of a spark in the combustion chamber near the end of the compression stroke.
A hit-and-miss engine or Hit 'N' Miss is a type of stationary internal combustion engine that is controlled by a governor to only fire at a set speed. They are usually 4-stroke but 2-stroke versions were made. It was conceived in the late 19th century and produced by various companies from the 1890s through approximately the 1940s. The name comes from the speed control on these engines: they fire ("hit") only when operating at or below a set speed, and cycle without firing ("miss") when they exceed their set speed. This is as compared to the "throttle governed" method of speed control. The sound made when the engine is running without a load is a distinctive "Snort POP whoosh whoosh whoosh whoosh snort POP" as the engine fires and then coasts until the speed decreases and it fires again to maintain its average speed. The snorting is caused by the atmospheric intake valve used on many of these engines.
The following outline is provided as an overview of and topical guide to automobiles:
Trionic T5.5 is an engine management system in the Saab Trionic range. It controls ignition, fuel injection and turbo boost pressure. The system was introduced in the 1993 Saab 9000 2.3 Turbo with B234L and B234R engine.
Internal combustion engines come in a wide variety of types, but have certain family resemblances, and thus share many common types of components.
A trembler coil, buzz coil or vibrator coil is a type of high-voltage ignition coil used in the ignition system of early automobiles, most notably the Benz Patent-Motorwagen and the Ford Model T. Its distinguishing feature is a vibrating magnetically-activated contact called a trembler or interrupter, which breaks the primary current, generating multiple sparks during each cylinder's power stroke. Trembler coils were first used on the 1886 Benz automobile, and were used on the Model T until 1927.