Top Fuel
Because of the speeds, this class races a 1,000 foot (304.8 m) distance, not the traditional drag-race length of one-fourth of a statute mile, or 1,320 feet (402.3 m).
The rule was introduced in 2008 by the National Hot Rod Association after the fatal crash of Funny Car driver Scott Kalitta during a qualifying session at Old Bridge Township Raceway Park in Englishtown, New Jersey.
The International Hot Rod Association, which at the time sanctioned Top Fuel in Australia, dropped the 1/4-mile distance in September 2017 after a campaign by Santo Rapisarda, a car owner who often runs NHRA races in the United States.
The burnout also applies a layer of fresh rubber to the track surface, improving traction during launch.
At maximum throttle and RPM, the exhaust gases escaping from a dragster's open headers produce about 900–1,100 pounds-force (4.0–4.9 kN) of downforce.
The massive airfoil over and behind the rear wheels produces much more, peaking at around 12,000 pounds-force (53.4 kN) when the car reaches about 330 mph (531.1 km/h).
The engine of a Top Fuel dragster generates around 150 dB[2] of sound at full throttle, enough to cause physical pain or even permanent damage.
[citation needed] Since 2015, NHRA regulations limit the composition of the fuel to a maximum of 90% nitromethane; the remainder is largely methanol.
[3][4][5] Like many other motor sport formulas originating in the United States, NHRA-sanctioned drag racing favors heavy restrictions on engine configuration, sometimes to the detriment of technological development.
However, while some basic facets of engine configuration are heavily restricted, other technologies, such as fuel injection, clutch operation, ignition, and car materials and design, are under constant development.
The engine used to power a Top Fuel drag racing car is based on a second generation Chrysler RB Hemi, but is built exclusively of specialized parts.
There are three approved suppliers of these custom blocks; Keith Black, Brad Anderson, and Alan Johnson.
As such, they, too, lack water jackets and rely entirely on the incoming air/fuel mixture and lubricating oil for their cooling.
The piston is anodized and Teflon coated to prevent galling during the high thrust load operation encountered.
These superchargers are in fact derivatives of General Motors scavenging-air blowers for their two-stroke diesel engines, which were adapted for automotive use in the early days of the sport.
Mandatory safety rules require a secured Kevlar-style blanket over the supercharger assembly as "blower explosions" are not uncommon, from the volatile air/fuel mixture coming from the fuel injectors being drawn directly through them.
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.
As the increased engine speed builds up pump pressure, the mixture is made leaner to maintain a predetermined ratio that is based on many factors, especially race track surface friction.
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.
Normal ignition timing is 58-65 degrees BTDC (This is dramatically greater spark advance than in a petrol engine as "nitro" and alcohol burn far slower).
In late 2015, tests using sensors developed by AVL Racing showed peak power of over 11,000 hp (8,200 kW).
[citation needed] This calculation assumes an average racing engine speed of roughly 3,800 revolutions per minute over a period of 3.8 seconds.
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, shoes, and outer sock-like boots, 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.
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.
In the wake of a Gateway International Raceway fatality in 2004, involving racer Darrell Russell, the fuel ratio was reduced to 85%.
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.
[10] The NHRA also mandated that different rear tires be used to reduce failure, and that a titanium "shield" be attached around the back-half of the roll-cage to prevent any debris from entering the cockpit.
[18] Bob Sullivan's Pandemonium (a '65 Plymouth Barracuda) joined about six other nitro-fuelled early funny cars facing fuel dragsters in the 1965 season.
[19] In 1971, Don Garlits introduced the Swamp Rat XIV, a rear-engined Top Fuel dragster.
It was having trouble attracting full sixteen-car fields, leading to cutting back to eight-car rosters, while the International Hot Rod Association dropped Top Fuel entirely.
