Sparkplugs
Modern Formula 1 engine is an incredible thing, with a spec sheet that makes car geeks like me queasy. The basics are incredible. From just 2.4 liters and 8 cylinders-without horsepower-enhancing turbocharging or supercharging-an F1 engine makes about 800 horsepower. It does this by revving to an incredible 19,000 rpm, or more than double what a rev-happy Honda S2000 engine spins to.
To keep the pistons and connecting rods from flying apart at those revolutions, an F1 piston travels only about 40 millimeters. The bore is roughly 90 millimeters (called supersquare bore).
Those are estimated dimensions of an F1 engine gleaned from Peter Wright's fantastic book, Ferrari Formula 1: Under the Skin of the Championship-Winning F1-2000. The book was written about the 2000 Ferrari F1 racer, and it's impossible to acquire the specifics of current engines because those are well-guarded secrets within each team.
F1 fans are curious beings, though, and I wondered what kind of interesting technical details are housed in the usually not-so-glamorous spark plug.
Apparently, F1 spark plugs aren't all that secret because Federal-Mogul's global director of ignition technology, Richard Keller, talk openly about this item and research. Federal-Mogul is an owner of Champion.
Sparkplugs, left to right- F1, GP bike, Ford Focus
Spark-plug sizes vary, but a basic one used in a current production car is about 85 millimeters long, with a maximum diameter of roughly 15 to 20 millimeters. The bottom third of a plug's length is covered by a sleeve of steel threads, there's a metal stud on the top, and the white part is called the insulator, and it's ceramic. If you cut a plug in half down the length, you'll see an internal metal rod that extends from the top to a point near the bottom of the steel threads. A small piece of metal that looks like a hook extends from the bottom of the threads and comes close to-but doesn't touch-the lower end of the internal metal rod. That space is called the "gap," and it's across this area that the sparks occur to ignite the fuel-and-air mixture in the cylinder. (By the way, the metal surfaces on either side of the gap are "electrodes," and the hook is commonly referred to as the "ground electrode"). So, spark induced by high voltage transformer jump from center rod to ground electrode.
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Champion's basic Formula 1 plug that was used in the 1990s was similar in length to the one described above, but half the diameter. Then in 1999, one of the teams told McMurray that for the amount of space the spark plug inhabited, it was the heaviest part on the car (that plug weighed only 25.9 grams) because it was located very high on engine. Unless Champion could reduce the weight of the plug by 20 percent every year until the team told them to stop, Champion was going to be out.
The plug Champion produced in response, is smaller than your pinky. It's only 35 millimeters long, and the diameter of its threads is 7.6 millimeters, or roughly half the diameter of a conventional plug. It also requires a special tool for installation so that the spark-plug hole in the cylinder head can be made as small as possible. Empty space in an F1 combustion chamber is a precious because any space taken by the spark plug leaves less room for the valves, and as we all know, the larger the valves, the greater the airflow, and the greater the potential power output. The plug weighs 10.7 grams.
Besides its tiny size, another interesting feature of the F1 plug is that there's no protruding hook on the bottom. That's because there simply isn't room for one. A normal ground J shaped electrode doesn't have a chance of surviving in an F1 motor, It would get crushed by the piston or simply shaken loose by the intense vibration. When an F1 piston is at the top of its stroke, it just about touches the cylinder head. The combustion-chamber volume is mostly made up of the recessed parts in the piston tops that are there to provide room for the valves. Without that hook, the ground electrode is simply the bottom edge of the threads. This design is known as a surface-gap spark plug.
To get an idea of the precision of the components of an F1 engine, when Champion builds its F1 spark plugs, the length varies minutely from plug to plug. This is known as manufacturing tolerance; for the F1 plugs, the difference from the longest to the shortest plug is only 0.05milimeters, or about the same as the thickness of the hair. If a spark plug is on the long side, the piston might hit it, so teams machine a divot in the piston or shim the spark plugs with washers.
Over the course of a year, Champion produces about 10,000 of these special units, and they're not cheap. Whereas you or I might pay two bucks for a spark plug, an F1 team spend between $35 and $50 each, or as much as $500 per engine.
We all know the old racing saying: "Speed costs money. How fast do you want to go?"
Main suppliers for F1 teams are US based Champion, Italian Magneti Mareli and Japan based NGK.
5.8 Electrical systems :
5.8.1 Ignition is only permitted by means of a single ignition coil and single spark plug per cylinder. The use of plasma, laser or other high frequency ignition techniques is forbidden.
5.8.2 Only conventional spark plugs that function by high tension electrical discharge across an exposed gap are permitted.
Spark plugs are not subject to the materials restrictions described in Articles 5.13 and 5.14.
5.8.3 Other than for the specific purpose of powering KERS components, the primary regulated voltage on the car must not exceed 17.0V DC. This voltage is defined as the stabilized output from the on-car charging system.
With the exception of any KERS or capacitor circuitry or coils being used solely to provide ignition, any device with a current requirement greater than 50mA or a power requirement greater than 1W may only be supplied at or below the primary regulated voltage.
Only capacitor discharge ignition systems (those which generate a spark by means of closing a switch which then discharges a capacitor through the primary side of the ignition coil), are permitted to provide a voltage higher than the primary regulated voltage to an ignition coil.
Other than any parts being used to supply a higher voltage to devices such as those described in the previous paragraphs, no device may step up or increase the primary regulated voltage.
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