Top-Fuel Racing is a class of drag racing in which the cars are run on a maximum of 90% nitromethane and about 10% methanol (also known as racing alcohol), instead of gasoline. Drag racing is a competition in which objects compete to be the first to cross a set finish mark usually from a dead stop and in a straight line Nitromethane is an Organic compound with the chemical formula CH3NO2 Methanol, also known as methyl alcohol, carbinol, wood alcohol, wood naphtha or wood spirits, is a Chemical compound The cars are purpose built race cars, with a layout superficially resembling open-wheel circuit racing vehicles - however, they are much longer, much narrower, and have very thin front tires, to optimize their performance exclusively in a straight line.
Like other standing start drag racing classes, these cars compete in a 1/4 mile (0. 4 km) race. They are the fastest such category, with the fastest cars reaching the end of the 1/4 mile in less than 4. 5 seconds at a speed of 341 mph (530 km/h) or more. A Top Fuel dragster accelerates from 0 to 100 mph (160 km/h) in less than 0. 8 seconds, subjecting the driver to a force about 5. 7 times their weight. This acceleration takes less than a tenth of the time needed by a production Porsche 911 Turbo to reach the same speed. The Porsche 911 (pronounced as Nine Eleven, Neunelfer is a Sports car made by Porsche AG of Stuttgart, Germany A fuel dragster can exceed 280 mph (450 km/h) in just 660 feet (0. 2 km). For further information and standards for drag-racing, including safety requirements, see NHRA. "NHRA" redirects here For other uses see NHRA (disambiguation.
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Facts about Top Fuel
Before their run, they do a burnout. A burnout (also known as a peel out or power brake) is the practice of keeping a vehicle stationary and spinning its wheels causing the tires to heat up This is done for three reasons (water is applied to initially break traction, allowing the tires to spin up). First, it heats the tires up, creating a sticky superficial layer of rubber on the tires. Secondly, it removes debris from the tires. Thirdly, and most importantly, it coats the track surface with rubber which greatly improves traction during the subsequent launch. A top fuel dragster's burnout alone can travel one quarter of the way down the track.
At top engine speed, the exhaust gases escaping from the open headers produce about 800-1000 pounds-force (3. This article deals with the unit of force For the unit of mass see Pound (mass. 6 kilonewtons) of downforce. The newton (symbol N) is the SI derived unit of Force, named after Isaac Newton in recognition of his work on Classical The term downforce describes the downward pressure created by the aerodynamic characteristics of a Car that allows it to travel faster through a corner by holding The massive foil over and behind the rear wheels produces much more downforce, peaking at around 12,000 lbf (53 kN) when the car reaches a speed of about 325 mph (523 km/h). The newton (symbol N) is the SI derived unit of Force, named after Isaac Newton in recognition of his work on Classical
Top Fuel dragsters are notorious for the deafening amount of noise their engines create at full throttle. They generate 120 dB of noise,[1] enough to cause some peoples' eardrums physical pain. The intense levels of sound are not only heard, but also felt as pounding vibrations all over one's body, leading many to compare the experience of watching a Top Fuel dragster make a pass to 'feeling as though the entire drag strip is being bombed'. Prior to the dragsters going down the strip, race announcers usually advise spectators to cover or plug their ears—indeed, ear plugs and even earmuffs are often handed out to fans at the entrance to a Top Fuel event.
The fuel
NHRA regulations limit the composition of the fuel to a maximum of 90% nitromethane (as of 2008); the remainder is largely methanol. "NHRA" redirects here For other uses see NHRA (disambiguation. Nitromethane is an Organic compound with the chemical formula CH3NO2 Methanol, also known as methyl alcohol, carbinol, wood alcohol, wood naphtha or wood spirits, is a Chemical compound However, this mixture is not mandatory, and less nitromethane can be used if desired.
Kenny Bernstein was the first drag racer in NHRA history (but not in the world) to break 300 mph (480 km/h) in the 1/4 mile in March, 1992. Kenny Bernstein (born September 6 1944 in Clovis New Mexico) is an American Drag racing driver Bernstein took his dragster over 300 mph (480 km/h) using a mixture of 90-to-100% nitromethane at the time. Despite nitromethane having a much a lower energy density (11. 2 MJ/kg) than either gasoline (44 MJ/kg) or methanol (22. 7 MJ/kg), its addition to the fuel mixture has the net effect of increasing engine output by around 2. 3 times compared to gasoline for the same mass of air.
The high temperature of vaporization of nitromethane also means that it will absorb substantial engine heat as it vaporizes, providing an invaluable cooling mechanism. The laminar flame speed and combustion temperature are higher than gasoline at 0. 5 m/s and 2400 °C respectively. Power output can be increased by using very rich air fuel mixtures. This is also something that helps prevent pre-detonation, something that is usually a problem when using nitromethane.
Due to the relatively slow burn rate of nitromethane, very rich fuel mixtures are often not fully ignited and some remaining nitromethane can escape from the exhaust pipe and ignite on contact with atmospheric oxygen, burning with a characteristic yellow flame. A flame is often defined as the visible (light-emitting part of a Fire. Additionally, after sufficient fuel has been combusted to consume all available oxygen, nitromethane can combust in the absence of atmospheric oxygen, producing hydrogen, which can often be seen burning from the exhaust pipes at night as a bright white flame. Hydrogen (ˈhaɪdrədʒən is the Chemical element with Atomic number 1 In a typical run the engine can consume as much as 103 litres (22. 75 gallons) of fuel during warmup, burnout, staging, and the quarter-mile run.
Top fuel engines
Like many other motor sport formulas originating in the United States, the NHRA favors heavy restrictions on engine configuration, rather than technological development. "NHRA" redirects here For other uses see NHRA (disambiguation. This restricts the teams to using many decades old technologies.
The engine used to power a Top Fuel drag racing car has its roots in the second generation Chrysler Hemi 426 "Elephant Engine" made 1964-71. A Hemi engine (from hemisphere) is an Internal-combustion engine in which the Combustion chambers are of hemispherical form Although the Top Fuel engine is built exclusively of aftermarket parts, it retains the basic configuration with two valves per cylinder activated by pushrods from a centrally-placed camshaft. The engine has hemispherical combustion chambers, a 90 degree V angle; 4. 8" bore pitch and a 5. 4" cam lift. The configuration is identical to the overhead valve, single camshaft-in-block "Hemi" V-8 engine which became available for sale to the public in selected Chrysler Corporation (Dodge, DeSoto, and Chrysler) automotive products in 1952.
The NHRA competition rules limit the displacement to 500 cubic inch (8194 cc). A 4. 19" (106. 4 mm) bore with a 4. 5" (114. 3 mm) stroke are customary dimensions. Larger bores have been shown to weaken the cylinder block. Compression ratio is about 6. 5:1, as is common on engines with overdriven (the supercharger is driven faster than the crankshaft speed) superchargers.
The block is CNC machined from a piece of forged aluminium. The cylinder block or engine block is a machined casting (or sometimes an assembly of modules containing cylindrically bored holes for the Pistons of a multi-cylinder The abbreviation CNC stands for computer numerical control, and refers specifically to a computer "controller" that reads G-code A forge is the workplace of a smith or a Blacksmith. A forge is sometimes referred to as a smithy. It has press-fitted ductile iron liners. There are no water passages in the block which adds considerable strength and stiffness. Like the original Hemi, the racing cylinder block has a long skirt (to reduce piston "rocking" at the lower limit of piston travel); there are five main bearing caps which are fastened with aircraft-standard-rated steel studs; with additional reinforcing main studs and side bolts. There are three approved suppliers of these custom-made after-market blocks, from which the teams may choose.
The cylinder heads are CNC-machined from aluminum billets. In an Internal combustion engine, the cylinder head sits atop the cylinders and consists of a platform containing part of the Combustion chamber and the Billet refers to a cast Semi finished product. It is also referred to as Ingot, particularly for smaller sizes As such, they have no water jackets and rely entirely on the incoming air/fuel mixture for their cooling. The original Chrysler design of two large valves per cylinder is used. The intake valve is made from solid titanium and the exhaust from solid Nimonic 80A or similar. Titanium (taɪˈteɪniəm is a Chemical element with the symbol Ti and Atomic number 22 Seats are of ductile iron. Ductile iron, also called ductile cast iron, spheroidal graphite iron, or nodular cast iron, is a type of Cast iron invented in 1943 by Beryllium-copper has been tried but its use is limited due to cost. Beryllium (bəˈrɪliəm is a Chemical element with the symbol Be and Atomic number 4 Copper (ˈkɒpɚ is a Chemical element with the symbol Cu (cuprum and Atomic number 29 Valve sizes are around 2. 45" (62. 2 mm) for the intake and 1. 925" (48. 9 mm) for the exhaust. In the ports there are integral tubes for the push rods. The heads are sealed to the block by copper gaskets and stainless steel o-rings. In Metallurgy, stainless steel is defined as a Steel Alloy with a minimum of 11 An o-ring, also known as a packing or a toric joint, is a mechanical Gasket in the shape of a Torus; it is a loop of Elastomer with Securing the heads to the block is done with aircraft-rated steel studs.
The camshaft is billet steel, made from 8620 carbon steel or similar. It runs in five oil pressure lubricated bearing shells and is driven by gears in the front of the engine. Mechanical roller lifters ride atop the cam lobes and drive the steel push rods up into the steel rockers that actuate the valves. The rockers are of roller type on the intake side, high pressures on the exhaust limits its use to the intake side only. The steel roller rotates on a steel roller bearing and the steel rocker arms rotates on a titanium shaft within bronze bushings. Intake rockers are billet while the exhausts are investment cast. The dual valve springs are of coaxial type and made out of titanium. Valve retainers are also made of titanium, as are the rocker covers.
Billet steel crankshafts are used; they all have a cross plane a. The crankshaft, sometimes casually abbreviated to crank, is the part of an Engine which translates reciprocating Linear k. a. 90 degree configuration and runs in five conventional bearing shells. 180 degree crankshafts have been tried and they can offer increased power, even though the exhaust is of open type. A 180 degree crankshaft is also about 10 kg lighter than 90 degree crankshaft, but they create a lot of vibration. Such is the strength of a top fuel crankshaft that in one incident, the entire engine block was split open and blown off the car during an engine failure, and the crank, with all eight connecting rods and pistons, was left still bolted to the clutch.
Pistons are of forged aluminium, 2618 alloy. A piston is a component of Reciprocating engines Pumps and Gas compressors It is located in a cylinder and is made gas-tight by Piston They have three rings and aluminium buttons retain the 1. A piston ring is an open-ended ring that fits into a groove on the outer diameter of a Piston in a Reciprocating engine such as an Internal combustion 156" x 3. 300" steel pin. The piston is anodized and Teflon coated to prevent galling during high temperature operation. Anodizing, or anodising, is an electrolytic Passivation process used to increase the thickness of the natural Oxide layer on the surface of metal In Chemistry, poly(tetrafluoroethene or poly(tetrafluoroethylene ( PTFE) is a synthetic Fluoropolymer which finds numerous applications The top ring is an L-shaped Dykes ring that provides a good seal during combustion but a second ring must be used to prevent oil from entering the combustion chamber during intake strokes as the Dykes-style ring offers less than optimal combustion gas sealing. The third ring is an oil scraper ring whose function is helped by the second ring. The connecting rods are of forged aluminium and do provide some shock damping, which is why aluminum is used in place of titanium, because titanium connecting rods transmit too much of the combustion impulse to the big-end rod bearings, endangering the bearings and thus the crankshaft and block. In a reciprocating Piston engine, the connecting rod or conrod connects the Piston to the crank or Crankshaft. Each con rod has two bolts, shell bearings for the big end while the pin runs directly in the rod.
The supercharger is a 14-71 type Roots blower. A supercharger is an air compressor used for Forced induction of an Internal combustion engine. The Roots type Supercharger or Roots blower is a positive displacement pump which operates by pulling Air through a pair of meshing lobes not It has twisted lobes and is driven by a toothed belt. A timing belt, timing chain or cam belt is a part of an Internal combustion engine that controls the timing of the engine's valves. The supercharger is slightly offset to the rear to provide an even distribution of air. Absolute manifold pressure is usually 3. Manifold vacuum, or engine Vacuum in an internal combustion engine is the difference in air pressure between the engine's intake manifold and 8-4. 5 bar (56-66 PSI), but up to 5. 0 bar (74 PSI) is possible. The manifold is fitted with a 200 psi burst plate. Air is fed to the compressor from throttle butterflies with a maximum area of 65 sq. A throttle is the mechanism by which the flow of a fluid is managed by constriction or obstruction in. At maximum pressure, it takes approximately 400 horsepower (300 kW) to drive the supercharger.
These superchargers are in fact derivatives of General Motors scavenging-air blowers for their two-cycle diesel engines, which were adapted for automotive use in the early days of the sport. General Motors Corporation ( GM) ( is a multinational automobile manufacturer founded in 1908 and headquartered in the United States. A diesel engine is an Internal combustion engine which operates using the Diesel cycle (named after Dr The model name of these superchargers delineates their size; i. e. the once commonly used 6-71 and 4-71 blowers were designed for General Motors diesels having six cylinders of 71 cubic inches each, and four cylinders of 71 cubic inches each, respectively. Thus, the currently used 14-71 design can be seen to be a huge increase in power delivery over the early designs.
Mandatory safety rules require a secured Kevlar-style blanket over the supercharger assembly as "blower explosions" are not uncommon. The absence of a protective blanket exposes the driver, team and spectators to shrapnel in the event that nearly any irregularity in the induction of the air/fuel mixture, the conversion of combustion into rotating crankshaft movements, or in the exhausting of spent gasses is encountered.
The oil system has a wet sump which contains 16 quarts of SAE 70 mineral or synthetic racing oil. The pan is made of titanium or aluminium. Titanium can be used to prevent oil spills in the event of a blown rod. Oil pressure is somewhere around 160–170 lbf/in² during the run, 200 lbf/in² at start up, but actual figures differs between teams. The pound per square inch or more accurately pound-force per square inch (symbol psi or lbf/in² or lbf/in²) is a unit of
Fuel is injected by a constant flow injection system. There is an engine driven mechanical fuel pump and about 42 fuel nozzles. The pump can flow 100 gallons per minute at 8000 rpm and 500 PSI fuel pressure. In general 10 injectors are placed in the injector hat above the supercharger, 16 in the intake manifold and two per cylinder in the cylinder head. Usually a race is started with a leaner mixture, then as the clutch begins to tighten as the engine speed builds, the air/fuel mixture is enriched. As engine speed builds pump pressure the mixture is made leaner to maintain a predetermined ratio that is based on many factors, one of which is primary one of race track surface friction. The stoichiometry of both methanol and nitromethane is considerably greater than that of racing gasoline, as they have oxygen atoms attached to their carbon chains and gasoline does not. Stoichiometry (sometimes called reaction stoichiometry to distinguish it from composition stoichiometry is the Calculation of Quantitative (measurable This means that a "fueler" engine will provide power over a very broad range from very lean to very rich mixtures. Thus, to attain maximum performance, before each race, by varying the level of fuel supplied to the engine, the mechanical crew may select power outputs barely below the limits of tire traction. Power outputs which create tire slippage will "smoke the tires" and the race is often lost.
The air/fuel mixture is ignited by two 14 mm spark plugs per cylinder. A spark plug (also very rarely nowadays in British English: a sparking plug) is an electrical device that fits into the Cylinder These plugs are fired by two 44-ampere magnetos. The ampere, in practice often shortened to amp, (symbol A is a unit of Electric current, or amount of Electric charge per second This article is about the Engine component For other uses of the term see Magneto (disambiguation. Normal ignition timing is 58-65 degrees BTDC. Ignition timing in an Internal combustion engine is the process of setting the time that a spark will occur in the combustion chamber (during the Power stroke) relative In a Reciprocating engine, the dead center is the position of a piston in which it is farthest from or nearest to the Crankshaft. (This is dramatically greater spark advance than in a gasoline engine as "nitro" and alcohol burn far slower. ) Directly after launch the timing is typically decreased by about 25 degrees for a short time as this gives the tires time to reach their correct shape. The ignition system limits the engine speed to 8400 rpm. The ignition system provides initial 50,000 volts and 1. 2 amperes. The long duration spark (up to 26 degrees) provides energy of 950 millijoules. The joule (written in lower case ˈdʒuːl or /ˈdʒaʊl/ (symbol J) is the SI unit of Energy measuring heat, Electricity The plugs are placed in such a way that they are cooled by the incoming charge. The ignition system is not allowed to respond to real time information (no computer-based spark lead adjustments), so instead a timer-based retard system is used.
The engine is fitted with open exhaust pipes, 2. 75" in diameter and 18" long. These are made of steel and fitted with thermocouples for measuring of the exhaust temperature. Steel is an Alloy consisting mostly of Iron, with a Carbon content between 0 In Electrical engineering and industry thermocouples are a widely used type of temperature sensor and can also be used as a means to convert thermal Potential They are called "zoomies" and exhaust gases are directed upward and backwards. Exhaust temperature is about 260 °C at idle and 980 °C by the end of a run. A night run provides visual excitement with slow-burning nitromethane flames many feet above this screaming spectacle of acceleration. A "good run" is over in just 4. 5 seconds, the noise ends, and braking parachutes are seen in the distance, after a speed of over 325 miles per hour has been reached.
The engine is warmed up for about 80 seconds. After the warm up the valve covers are taken off, oil is changed and the car is refueled. Rocker Covers, in relation to the Internal combustion engine, are covers that are bolted on over Rocker arms Called a valve cover in the United States The run including tire warming is about 100 seconds which results in a "lap" of about three minutes. After each lap, the entire engine is disassembled and examined, and worn or damaged components are replaced.
Performance
Measuring the power output of a top fuel engine directly is not feasible. This is not, as is sometimes stated, because no dynamometer exists that can measure the output of a Top Fuel Engine; in reality, dynamometers capable of measuring tens of thousands of horsepower at the appropriate shaft speeds are in widespread use. For the dynamometer used in railroading see Dynamometer car. A dynamometer or "dyno" for short is a machine used to measure Rather, it is because a Top Fuel engine cannot be run at its maximum power output for more than about 10 seconds at a time without overheating (or perhaps exploding) as would be necessary to take a reliable power reading. Instead, the power output of the engine is usually calculated based upon the car's weight and its performance. The calculated Power output of these engines is most likely somewhere between 7000 and 8300 horsepower (approximately 4500-6000 kilowatts), with a torque output of 5100–6750 N·m (3760–4980 lbf·ft) and a brake mean effective pressure of 80–100 bar (0. In Thermodynamics, motive power is an agency as Water or Steam, used to impart motion. A torque (τ in Physics, also called a moment (of force is a pseudo- vector that measures the tendency of a force to rotate an object about The foot-pound force, or simply foot-pound (symbol ft·lbf or ft·lb) is a unit of work or Energy (a scalar The mean effective pressure is an abstraction of the Pressure exerted into the combustion chamber of an Internal combustion engine. 8–1. 0 MPa).
For the purposes of comparison, a 2008 SSC Ultimate Aero, the world's fastest production automobile, produces 1,183 bhp (882 kW) horsepower and 1094 lbf·ft (1483 N·m) torque. The SSC Aero is an American -built mid-engine Sports car by Shelby Super Cars.
Engine weight
- Block with liners 85 kg
- Heads 18 kg each
- Crankshaft 37 kg
- Complete engine 225 kg.
Mandatory safety equipment
Much of organized drag-racing is sanctioned by the National Hot Rod Association. Since 1955, the Association has held regional and national events (typically organized as single elimination tournaments, with the winner of each two car race advancing) and has set rules for safety, with the more powerful cars requiring ever more safety equipment.
Typical safety equipment for contemporary top fuel dragsters: full face helmets with fitted HANS devices; multi-point, quick release safety restraint harness; full body fire suit made of Nomex or similar material, complete with face mask, gloves, socks and shoes, all made of fire-resistant materials; on board fire extinguishers; kevlar or other synthetic "bullet-proof" blankets around the superchargers and clutch assemblies to contain broken parts in the event of failure or explosion; damage resistant fuel tank, lines, and fittings; externally accessible fuel and ignition shut-offs (built to be accessible to rescue staff); braking parachutes; and a host of other equipment, all built to the very highest standards of manufacturing. Nomex (styled NOMEX) is a registered Trademark for flame resistant meta- Aramid material developed in the early 1960s by DuPont and first marketed Any breakthrough or invention that is likely to contribute to driver, staff, and spectator safety is likely to be adopted as a mandated rule for competition. The forty year history of NHRA has provided hundreds of examples of safety upgrades.
In 2000, the NHRA mandated the maximum concentration of nitromethane in a car's fuel be no more than 90%. In the wake of a Gateway International Raceway fatality in 2004, the fuel ratio was reduced to 85%. Gateway International Raceway is a race track in Madison Illinois, USA just minutes from Downtown St Complaints from teams in regards to cost, however, has resulted in the rule being rescinded starting in 2008, when the fuel mixture returns to 90%, as NHRA team owners, crew chiefs, and suppliers complained about mechanical failures that can result in oildowns or more severe crashes caused by the reduced nitromethane mixture. [2]
The NHRA also mandated that different rear tires be used (in both Top Fuel and Funny Car) to try to prevent them from failing and that a titanium "shield" be attached around the back-half of the roll-cage in Top Fuel Dragsters (although some Funny Car teams adopted this) to prevent any debris from entering the cockpit.
At present, final drive ratios lower than 3. 20 (3. 2 engine rotations to one rear axle rotation) are prohibited, in an effort to limit top speed potential, thus reducing the perceived level of danger.
References
- ^ http://www.rlengines.com/tech/Acceleration.pdf
- ^ NHRA News: Nitro percentage to be raised to 90 in Top Fuel, Funny Car in 2008 (9/15/2007)
- "The Top Fuel V8", Race Engine Technology, #009, p60-69
- "Running The Army Motor", Race Engine Technology, #008, p18-30
- "Top Fuel by the Numbers, By John Kiewicz, Motor Trend, February 2005
- "Drag Racing: It's Like Plunging Your Toilet with a Claymore Mine, By John Phillips, Car and Driver, August 2002.
External links
- Restored Top Fuel Dragsters from the 60s & 70s
- NHRA National Hot Rod Association Website
- WSID Website
- IHRA International Hot Rod Association Website
- Santa Pod Raceway - the home of European Drag Racing
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