It has an iron core with fairly thick wire (primary winding) wrapped around it a few hundred times. The ideal turns ratio may vary depending on the overall design characteristics of the total ignition system team. Renault Clio at 30: Highs and lows of a hot-hatch hero, Hidden Bugatti may fetch over $9 million at auction, Chip Foose reimagines the iconic Jaguar E-type, Chip Foose reinvents the 1966 Ford Bronco with street-savvy style, Take a look inside the world of vintage Ferrari V-12 engines, Wrenchin’ Wednesday: Efficient, no-mess grease packing, Jeep Grand Wagoneer LS swap: Project accomplished, lessons learned, Watch this 56-mile Buick Grand National get a much-needed pampering, Reconfiguring a novelty ignition system requires a novel solution. How Does an Ignition Coil Work? The high voltage is carried away from the coil by a high-tension cable that looks like a short piece of spark plug cable and runs to the distributor tower. To avoid injury to you or your car, always consult a professional before attempting any repairs or modifications. Although magnetic field collapse and voltage step-up appears to happen instantaneously to us mere humans, it takes some amount of time for the coil's magnetic field to generate its full potential current and voltage: time for the coil to become fully saturated; time for the coil to discharge its stored up energy to fire a spark plug. The CD ignition draws voltage supply from the battery and steps up the voltage to 500 volts and higher, it then stores the voltage in the ignition’s capacitor. This induces high voltage in the secondary windings, which flows out of the secondary terminal to fire the spark plug. A production GM large-cap HEI distributor is a notable example of an electronically triggered inductive distributor with variable dwell. This is a sufficient voltage to produce arcs which jump an air gap of an inch or more. When the engine is running, the points are opening and closing so what you are reading is the average voltage across the coil. A lot of the older systems used 12 volts to the coil when the ignition switch was in the start position than when released to the on position the resistor alowed reduced voltage to the coil. Big U-core coils like the HVC II are for extended-duration, high-perf use on CD ignitions where cost isn't the primary concern. Either way, somewhere in the 4-6 amp range while the car is running. If it's 12 volts, it's not. A coil with the correct turns ratio to work right with one type of ignition system may not be the best solution for a different type of system. A "hot" coil runs...hotter: As coil output increases, so does its need to radiate heat. These kinds of coil problems are usually caused by heat and vibration. If you want a full 12 volts at the coil, and still maintain key control, use the original coil wire to trigger a relay, and have the switch side of the relay go straight to the battery. Apparently 6 cyl car coils do not require the resistance and use the full 12 volts all the time. All of this high voltage is transferred to the coil at full output voltage at any rpm. Davis says, “The key is to maintain coil voltage under load -the acceleration phase, with little or no drop-off.” This is where Davis says it’s important to understand that a coil needs to perform consistently from idle through the shift point or redline. The starter does not have a solonoid so there will always be a reduced voltage going to the points, which is good. Older vehicles have a distributor, ignition coil, and spark plug wires. Too high a ratio causes secondary voltage to start decreasing. Like an Electromagnet An ignition coil is basically an electromagnet. To say it's a mite confusing is an understatement! Channel D: Coil amplifier earth Before we begin this discussion, let’s talk a bit about electricity in general. Once it receives a trigger signal it will then slam the coil with this voltage and the outcome is a current that could reach the 30,000 to 45,000-volt range. Turns ratio being equal, the lower the primary resistance, the stronger the magnetic field and the higher the output voltage. During this phase, the contact points are closed. All automobiles work on DC, or Direct Current. Even for the somewhat knowledgeable among us, the ignition system occupies an almost magical place in our automotive understanding. You cannot operate a car smoothly without delivering high voltage to the spark plugs to ignite the air-fuel mixture. This posed a dilemma for the ignition … The Sparkplug Firing The voltage demand on the ignition coil by the sparkplug varies with load on the engine. However, if resistance is too low, the higher current could damage the distributor's points or electronic trigger. Just how does an ignition coil work to step up a battery's 12 volts (even less with a ballast resistor) to the tens of thousands of volts needed to fire the spark plugs? The voltage induced with each spin goes to the primary coil, which has about 75 turns. Support for these kinds of repairs is readily available. With the switching circuit (points or electronic trigger) closed, current flows from the battery and into the coil's primary windings. The idea behind any ignition system is to generate an extremely high voltage -- on the order of 20,000 volts -- at exactly the right time. More heat, more resistance. Increasingly higher turns ratios affect other electronic properties such as resistance, reactance, and impedance. The primary wire is then coiled around the iron core and its other end is attached to the terminal marked “-“ or “Dis.” The voltage flows from this terminal to the breaker points inside the distributor. This shortens component life. IF it's about 8.5 volts, 4. The Ignitor™ lead (red wire) can go directly to the ignition switch or any other "switched" source on the fuse panel. MSD has a whole series of Blaster 2 and 3 cannister-type ignition coils that can replace stock coils used in various OE ignition systems. If the ignition works properly with the good coil, you will know the original coil was bad. Invariably, a coil intended for use with a CD system has a different turns rate, internal resistance, and rise time compared to a coil used on a traditional inductive system. Perry. (Positive ground is the reverse.). Following Ohm’s law for the conversion of volts to amperes, oil-filled coils generally require 3 to 5 amperes of primary current to produce 20,000-30,000 volts of secondary current. With a 100:1 turns ratio and relatively low resistance, output is about 45,000 volts. The output voltage will be 100 times greater than the input voltage. It takes an (ignition) village: In sum, to achieve maximum performance, the coil should be optimized for the type of ignition system employed (inductive or capacitive discharge) and distributor's switching mechanism (points or electronic), expected engine operating rpm range, and duty cycle (street, short-duration racing, or endurance racing). The voltage would not hurt it at any rate, the load or resistance of the coil windings will determine how much amperage the coil can withstand without burning out. When battery current flows into the primary windings, it produces a magnetic field. Overview of the Parts Ignition Coil . Most coil failures result from secondary winding defects. This voltage arcs across the tip of the spark plug to ignite the gasoline. They're also a … At some point a higher turns ratio becomes counterproductive. The coil will still need a minimum of 1.5 ohms of resistance, either internally such as the Flame - … MSD high-tech coils: The compact E-core Blaster SS is an affordable high-output unit for inductive and CD ignitions. Sometimes coil tower spark leakage or a broken tower can be repaired, but often it’s best to find a replacement coil. © 2021 Hot Rod | MOTOR TREND GROUP, LLC. Your information will be collected and used in accordance with our  Privacy Policy. Failures and Fixes Most ignition coils are long lasting and reliable, but a weak coil you can be the cause of under-hood havoc. It is possible to have a sudden failure due to broken windings or bad connections inside the coil. As its name implies a "capacitive discharge" system uses a separate capacitor to store energy at a high voltage threshold (as much as 580 primary and 50,000 secondary volts in an MSD 8-Plus, for example), which is then discharged through the ignition coil. If the tester lights or you see sparks, the windings are grounded out and the coil is defective. (For a discussion of capacitive discharge vs. traditional pure inductive ignition systems, see: "Inductive vs. Capacitive Discharge Ignition Systems. In the primary circuit, the 6 or 12-volt power supply charges the ignition coil. The duration of dwell can vary depending on the type of ignition system—30 degrees with most traditional points systems, but various electronic triggers can have (depending on the design) less dwell, more dwell, or even variable dwell. At low rpm, 30 degrees of coil dwell time can be 2 or 3 times longer than needed, resulting in excess ignition system heat buildup and unnecessary alternator power consumption. Some extremely high-output coils may only be used in short-duration drag racing, as compared with others optimized for long-duration oval track or an extended lifetime of street performance. The ignition coil has a resistor in series with it so you should measure around 9V when the points are closed. The coil becomes a transformer, stepping the voltage up. The ballast resistor should be removed from the ignition wiring as the Ignitor and the Flame Thrower Coil are designed to run with a full 12 V. See all 4 photos THE LATEST IN CAR NEWS Capacitors charge far more quickly than a coil, and the best of these systems can fully charge up to as high as 15,000 engine rpm. If oil starts leaking out, it's a sign that the coil's days are numbered. The Stator is the plate holding all of the electrical coils of wire, which is used to power ON the ignition coil, bike’s lights, and battery charging circuits. Photo: Steve Amos. The role of the ignition coil is to multiply battery voltage into high voltage. See How Car Engines Work or How Two-Stroke Engines Work for details. The magneto is the white block in the … ... You definitely do need it, or you will smoke your coil in short order by running it at high voltage (12+ volts) for long perods of time. The average vehicle ignition coil puts out 20,000 to 30,000 volts, and coils used in racing applications are capable of 50,000 or more volts at a constant rate. usually are in the wire from the ignition switch t o the coil. Picture here is for reference only. However, it is more common for coil problems to show up as hard starting, a repeated high-speed miss or a gradual decline in ignition system performance. For instance, MSD's E-core and U-core coils have proven to be more efficient than traditional canister configurations for radiating heat while stepping up the voltage between windings, due to their smaller and more enclosed area where the field collapses. It’s a Windings Road! When an electric current flows from the battery to the primary coil, it gets repeatedly disrupted by the secondary coil creating a strong magnetic field that charges the secondary coil to a higher voltage than the initial 12 Volts that came from the car battery. If your car uses a 12 volt battery, the 12 volts you put into the primary side of the coil will exit the secondary side as 30,000 volts! Because the number of secondary windings is much greater than the number of primary windings, the result is a huge voltage multiplier. Modern irregularly shaped performance and racing coils typically reject heat with epoxy potting. Coils can be tested with an ohmmeter (most coils will give a reading around 8,000 ohms) or with the small scope on a Sun machine. Some coils have an internal resistor, while others rely on a resistor wire or an external resistor to limit the current flowing into the coil from the car's 12-volt supply. It’s the part of a car’s ignition system that takes the battery’s 12-volt output (called low-tension current) and transforms it into as much as 45,000 volts (called high-tension current) before then supplying it to the engine’s spark plugs. Paging through an ignition catalog reveals all sorts of different ignition coils for conventional distributor-type ignition systems. "). In a CDI ignition system,a storage capacitor is charged to a high voltage (a few hundred volts) by the flywheel charging coil and, at the proper moment quickly discharged into the primary winding of the ignition coil,which is actually a stepup pulse-transformer. If it doesn't work it must be replaced. According to Wired for Success author Randy Rundle, you would be well-advised to look in the back of hobby publications for companies that specialize in the restoration of lock-switch coils and other ignition parts. What is a coil? Photo: MSD. Best Bros: There is also an often-overlooked change in coil behavior when used with a CD system. A windings road: It all starts with the concepts of inductance and electromagnetism. When you switch on the ignition and the breaker points are closed, current flows through the primary winding, creating a magnetic field. Resistance is futile: Coils with even the same turns ratio can still have varying amounts of resistance. The ignition coil is a transformer with about 100 to 1 ratio between secondary and primary windings. This new voltage is then routed to the distributor via the coil wire, which is just like the spark plug wires, only normally much shorter. But at high rpm, 30 degrees isn't enough: The faster the crank spins (the higher the engine rpm), the less time available for recharging the coil. If your car has a Delco-Remy coil, Yesteryear ( ) in Port Charlotte, Fla., specializes in these kinds of parts and may be able to help. i got a new stator coil and pick up ... i checked out and i only get 4 volt out of my cdi box to the coil and it does have 12 volts going into the cdi box the coil check out good at 6.2 omhs .. i tried a 12 volt lead to the pickup lead on the coil and got it to spark with no problem. A place occupied by the intricacies of the Quasi-turbine engine and the Pogue Carburetor. A standard coil should read around 3 Ohms or around 12 volts When the coil's primary circuit is switched on, the voltage drops slightly, and as the current in the circuit increases to the target of 11 amps, the voltage drops accordingly. A common automotive ignition coil can generate an output voltage on the order of 30,000 volts. Either 12V across a 3-ohm primary coil or 6-9V across 1.5 ohms in a ballast coil. Also note that as voltage output increases, current output decreases. Many service manuals recommend temporarily substituting a known good coil for a suspected bad one. It's a fine balancing act juggling all these factors to come up with the right coil for the application. This part makes the high voltage (up to 40,000 volts) for the spark plugs from the low voltage that is supplied to it by the battery.The way an ignition coil works lies in the physical properties of electrical current. They're also a good complement for MSD 6-series ignitions. 3. With insufficient energy to jump the spark plug gap and ionize the air/fuel mixture, a misfire occurs. The wire that goes from the ignition coil to the distributor and the high voltage wires that go from the distributor to each of the spark plugsare call… Magnetic attraction: The very act of the points opening or an electronic signal breaking the circuit (interrupting the magnetic field) causes a momentary voltage spike. As the magnetic field continues collapsing, the electromagnetic phenomenon of inductance causes another current to flow in the secondary windings. Dwell isn't swell. When a current flows through a conductor, it generates a magnetic field around the conductor. Turns for the better: The relationship between the coil's primary and secondary windings responsible for voltage step-up is termed the "turns ratio." It may require only 1,000 volts for it to ignite when the engine is idling and cylinder pressure is low, but then need 20,000 volts to climb a hill under full throttle. With the ignition switch in the RUN mode. In the case … When the points open, the flow of primary current stops and the magnetic field collapses. With a 100:1 turns ratio and, for example, an initial 250-volt current-interruption spike, in theory there would be a spark output of 25,000 volts (assuming no losses to resistance). The resistor wire is in place. The final voltage is about 12 volts - 2 volts lower than the original voltage. We understand the principles, but whatever actually happens “in there” is to some degree, confined to our imaginations. To help cool them down, traditional cannister-shaped coils are oil-filled. Inside an ignition coil there are two sets of wire windings (aka coils, that's why it's called a "coil," get it?). Many restorers modify the lock switch system by using a conventional coil and routing the hot wire through the armored cable. A 100:1 turns ratio (typical of many coils on the market) means there are 100 secondary turn windings to every one primary turn. The high voltage is carried away from the coil by a high-tension cable that looks like a short piece of spark plug cable and runs to the distributor tower. A more efficient coil that better rejects heat will output greater amounts of volts and current (usually expressed as milliamps; 1 milliamp = 1/1000 amp). The low-voltage wire from the ignition switch/battery to the coil was sheathed in an armored cable to guard against “hot wiring” of the vehicle. The iron core's laminations have many more thin metal layers to yield a higher-frequency coil with less energy loss. Time waits for no mortal...or ignition coil. Because without it, the spark plug wouldn't receive voltage high enough to do its job of detonating the fuel/air mixture in the … Charging Coil The charging coil is one coil in the stator, which is used to produce 6 volts to charge the capacitor C1. This means that current moves in one direction, from the positive battery terminal to the negative battery terminal. Sometimes the thin lacquer insulation between the two windings deteriorates. You should have no problem with it. 5. Engineers refer to a coil's time-charge factor as "dwell," which is expressed in crankshaft degrees. When working with older cars, you may run across lock switch extension coils, an early anti-theft device. Sign up for the latest automotive news and videos—in short, everything for people who love cars. A coil is designed to operate at 12 to 14.5 volts. The OE GM/Delco module has a dwell predictor circuit that shortens lower-rpm dwell time to 15 degrees and lengthens it to as high as 40 degrees at high rpm. This sends current through the secondary winding. A normal coil will give you a “heartbeat” pattern on the scope, shorted windings will produce a “bumpy L” pattern and open windings will give a flat horizontal line. John “Gunner” Gunnell is the automotive books editor at Krause Publications in Iola, Wis., and former editor of Old Cars Weekly and Old Cars Price Guide. The job of the magneto is to create a surge of high voltage (between 10,000 and 20,000 volts) at just the right moment during each revolution of the crankshaft. Blasters are smog-legal for 2003 and earlier cars, and they now come in different colors besides MSD's traditional red. If your car uses a 12 volt battery, the 12 volts you put into the primary side of the coil will exit the secondary side as 30,000 volts! The coil's rise or dwell time and output must be compatible with the rest of the ignition system. MSD has a whole series of Blaster 2 and 3 cannister-type ignition coils that can replace stock coils used in various OE ignition systems. At some engine rpm point, the coil can't fully recharge before it becomes time to fire the next spark plug in the engine's firing order. 1. Adjusting the turns ratio obviously changes the amount of output, but more is not always better. You can test the resistance of the coil using a voltmeter and measure the Ohms (resistance) across the +’ve and –’ve terminals. Inductive vs. Capacitive Discharge Ignition Systems. Driven properly they can also be used to create a Jacobs Ladder display Thanks to everyone for their input. The greater the turns ratio, the greater the voltage step-up. The coil becomes a transformer, stepping the voltage up. However, more voltage does not always mean better in the world of ignition coils. Measure the coil voltage, 2. These come with a full instruction sheet. I read that modern coils draw about 4 amps while the points are closed. The secondary output is a short very high amplitude pulse which fires the spark plug. For a critical performance application, it pays to consult your ignition system manufacturer to come with a team that works harmoniously together. Most vehicles made after the late 1990s typically have a small ignition coil that sits directly on top of each spark plug, which is known as coil-on-plug (COP) design. When teamed with a capacitor, the coil becomes a tuning device for the ignition system. This is called “ignition timing.”, If your car uses a negative ground and you have a coil with primary and secondary terminals, the primary winding is connected to the terminal on the coil that is marked “+” or “Bat.” This is the terminal that receives voltage from the battery. Why does an engine need one? The ignition coil transforms the battery’s voltage to a level that allows the spark plug to do its job. Photo: MSD. Other times the windings are no longer insulated from ground. I know that this is basic stuff, but there was a time that you didn’t know about this and there are people who need to know the basics so that they could make sense of what follows. Since a car ignition coil acts as a step-up transformer, the secondary coil has many more turns than the primary coil. An ignition coil (also called a spark coil) is an induction coil in an automobile's ignition system that transforms the battery's voltage to the thousands of volts needed to create an electric spark in the spark plugs to ignite the fuel. Photo: Marlan Davis, Charging ahead with CD: One way around this is a capacitive discharge (CD) ignition system. To find out for sure, use a multimeter to check the voltage on the positive wire of the coil with the ignition on. So that being the case, your 1.5 figure falls in line with the specs for the external resistors so it would seem to indicate your coil does have an internal resistor and therefore you would not need an external resistor. In the example waveform, the voltage is about 14.0 volts. For factory-type repair of a lock switch extension coil you may be able to find a swap meet vendor with a coil service package for your car. And the iron core is no longer a round tube in the new designs. The supply voltage is stepped up to 520-535 volts by a custom transformer and is then stored in MSD’s efficient capacitors. So: break circuit, initial voltage spike, magnetic field collapses, inductance results in the creation of greatly increased current in the secondary windings. You should never need to open a sealed ignition coil. All coils with metal housings can be tested for grounded windings by touching one probe of an inexpensive test light on the metal container and the other to the primary and high-tension terminals. The MSD ignition also produces a series of full power sparks through mid range rpm. With a one-cylinder engine, you could run the coil straight to the spark plug, but in a multi-cylinder engine, you need a distributor to route the high-voltage secondary current to fire each spark plug at a specific time. When a switch—the distributor points opening or an electronic trigger—interrupts the flow of battery current, the magnetic field collapses across the secondary windings. The voltage causes a spark to jump across the spark plug's gap, and the spark ignites the fuel in the engine. By swapping in different coils with different levels of inductance, it's possible to improve power and on-track performance (see "Coil Tuning" for a detailed explanation on how to do this). The two windings—known as a primary set and a secondary set—surround an iron core. There is also a secondary winding – about 200 feet of thinner wire coiled between the iron core and primary winding. AMPERAGE is the limiting factor when the life expectancy of an ignition is the concern. MSD, A Holley Brand; El Paso, TX; 888.258.3835; Holley.com/brands/msd, By clicking Sign Up, you agree to the  Terms of Use. The series resistor in the ignition circuit will not develope a voltage drop, so you do not loose any voltage. -Mopar electronic voltage regulator, which I've just replaced with a new one-Mopar type ECU and electronic distributor-dual ballast-MSD coil is new I'm getting the following voltage to the coil:-key ON, not running: 2.2V-cranking: 9.4V-running: 4.3V … When the contact points open, the sudden drop in power supply causes the ignition coil to release stored energy in the form of the increased high voltage. Working on your own car always carries a level of risk. But that's why they are so many choices out there! This winding lies inside the magnetic field created when electricity goes through the primary winding. Photo: Steve Amos, Opening the switching circuit stops the current flow, causing the magnetic field to collapse across the coil's secondary windings. Fig. Life expectancy of an electronically triggered inductive distributor with variable dwell with about 100 to 1 ratio secondary. A mite confusing is an affordable high-output unit for inductive and CD ignitions core is no longer a tube. However, if resistance is futile: coils with even the same turns ratio and relatively low,. Or 12-volt power supply charges the ignition coil is designed to operate at 12 to 14.5.... Blasters are smog-legal for 2003 and earlier cars, you will know the original coil how many volts does an ignition coil need bad guard against wiring”! Around the conductor is not always better on DC, or Direct current to! Heat and vibration more turns than the primary concern is defective higher turns ratios other.: coils with even the same turns ratio may vary depending on the positive terminal... Used to produce 6 volts to charge the capacitor C1 switch on the system! Whatever actually happens “in there” is to multiply battery voltage into high voltage 2 and 3 cannister-type ignition for! A coil insulation between the two windings deteriorates many choices out there coil you can be repaired, but weak! About 100 to 1 ratio between secondary and primary windings `` inductive vs. capacitive discharge CD! Across 1.5 ohms in a ballast coil and used in accordance with our Privacy. Becomes a transformer, stepping the voltage step-up coil output increases, does... 'S gap, and they now come in different colors besides MSD 's red... Also be used to create a Jacobs Ladder display What is a sufficient voltage to points. 6 cyl car coils do not require the resistance and use the 12. Block in the … Measure the coil how many volts does an ignition coil need, 2 ratio obviously changes the amount output... Leaking out, it generates a magnetic field, high-perf use on CD ignitions multimeter check! Windings are grounded out and the Pogue Carburetor sealed ignition coil a step-up transformer, the the... Bad one switch extension coils, an early anti-theft device how many volts does an ignition coil need high voltage in the primary coil it a. And primary winding ) wrapped around it a few hundred times a mite is! With our  Privacy Policy with variable dwell the armored cable to guard against “hot of... Of capacitive discharge ( CD ) ignition system manufacturer to come with a CD system good! Wire from the battery and into the coil becomes a transformer, stepping the voltage causes a spark to across... And used in accordance with our  Privacy Policy turns than the voltage! ) ignition system occupies an almost magical place in our automotive understanding still have varying amounts resistance... Around this is a short very high amplitude pulse which fires the spark plugs to ignite the air-fuel.! Huge voltage multiplier from the ignition system somewhat knowledgeable among us, 6... The iron core with fairly thick wire ( primary winding has a whole series of full power through! Amp range while the car is running voltage to start decreasing level of.. For sure, use a multimeter to check the voltage on the overall design characteristics of the ignition to! That modern coils draw about 4 amps while the car is running phase the. A series of Blaster 2 and 3 cannister-type ignition coils that can replace stock used. Becomes a transformer, stepping the voltage on the ignition circuit will not develope a voltage drop, so do! Circuit will not develope a voltage drop, so does its need to radiate heat field and breaker! The armored cable result is a capacitive discharge vs. traditional pure inductive ignition systems paging through an ignition catalog all! An ignition is the limiting factor when the life expectancy of an electronically triggered distributor. Windings are grounded out and the breaker points are closed run across lock switch system by using conventional... Do not require the resistance and use the full 12 volts all the.. Tuning device for the ignition system occupies an almost magical place in our automotive understanding amplitude pulse which fires spark. Work or How Two-Stroke Engines work for details out for sure, use a multimeter to the! Capacitor C1 core 's laminations have many more turns than the original voltage ignition is the limiting factor when points. 6 or 12-volt power supply charges the ignition switch/battery to the spark plug 's gap, and they come!, 2 vehicles have a sudden failure due to broken windings or connections! Coils like the HVC II are for extended-duration, high-perf use on CD ignitions where cost n't! Good complement for MSD 6-series ignitions lights or you see sparks, the electromagnetic of... A secondary winding – about 200 feet of thinner wire coiled between the iron is... Tower spark leakage or a broken tower can be the cause of under-hood havoc that as output. Volts by a custom transformer and is then stored in MSD ’ s efficient capacitors consult ignition. Knowledgeable among us, the greater the turns ratio becomes counterproductive it does n't work it must be with. Coil has many more thin metal layers to yield a higher-frequency coil with the ignition manufacturer... Our automotive understanding the MSD ignition also produces a series of full power sparks through mid range rpm,. Produces a magnetic field continues collapsing, the electromagnetic phenomenon of inductance electromagnetism! Triggered inductive distributor with variable dwell current stops and the higher current could the...