Pro Stock - AbsoluteAstronomy.com

Pro Stock Drag Racing is a class of drag racing

Drag racing

Drag racing is a competition in which specially prepared automobiles or motorcycles compete two at a time to be the first to cross a set finish line, from a standing start, in a straight line, over a measured distance, most commonly a ¼-mile straight track....

featuring 'Factory Hot-Rods'. The class can be known as "all motor," as the cars cannot use artificial induction such as turbocharging, supercharging, or nitrous oxide, and there are very strict rules governing the modifications allowed to the engines, and the types of bodies used.

History

The National Hot Rod Association

National Hot Rod Association

The National Hot Rod Association is a drag racing governing body, which sets rules in drag racing and host events all over the United States and Canada...

Pro Stock class emerged from the production-based Super Stock class in 1970 with a more liberal set of rules and an absence of handicaps. Rules initially favored big-block V8s but by 1972 had changed to favor small-blocks to reflect contemporary trends in the American auto industry. In 1982, the NHRA implemented a new engine formula that allowed the big-blocks to return, due to the popularity of the Mountain Motor IHRA

IHRA

IHRA may refer to:*International Human Rights Administration*International Hot Rod Association*International Hotel & Restaurant Association*International Human Rights Association*International Harm Reduction Association*Illinois Human Rights Act...

Pro Stocks with unlimited displacement in the late 1970s. However, NHRA still limits the size of the engine to no more than 500 cubic inches(about 8100 cubic centimetres) in displacement.

The 1972-81 small-block formula (358 cubic inches - about 5,900 cubic centimetres) would reappear from 1998 until 2001 in the Pro Stock Truck class that used compact pickup truck bodies instead of sedan bodies.

Engine

The engine must be manufactured by the same company as the car body. Though no engine currently being raced in Pro Stock is used on any manufacturer's assembly line, all of the raw components are available to anyone. Engine blocks and cylinder heads are often provided in a "raw" condition with only approximate dimensions and rough machining. Each team will continue to machine and modify the part to their own standards.
Engine capacity is restricted to a maximum 500 CID single-camshaft, 90-degree V8
V8 engine
A V8 engine is a V engine with eight cylinders mounted on the crankcase in two banks of four cylinders, in most cases set at a right angle to each other but sometimes at a narrower angle, with all eight pistons driving a common crankshaft....

.
- Some non-NHRA bodies will have different rules. The American Drag Racing League (eighth-mile) and Mountain Motor Pro Stock Association (quarter-mile) do not have a 500-cubic inch rule, and some engines exceed 800 CID, known as "mountain motors."

Pro stocks are limited to dual 4-barrel carburetor
Carburetor
A carburetor , carburettor, or carburetter is a device that blends air and fuel for an internal combustion engine. It is sometimes shortened to carb in North America and the United Kingdom....

(naturally aspirated
Naturally-aspirated engine
A naturally aspirated engine is one common type of reciprocating piston internal combustion engine that depends solely on atmospheric pressure to counter the partial vacuum in the induction tract to draw in combustion air...

) intake systems. The four-barrel carburetors can be "split" (i.e. sawn in half) so that each of the halves can be more accurately positioned over the slightly staggered intake runners. The intake manifold
Inlet manifold
In automotive engineering, an inlet manifold or intake manifold is the part of an engine that supplies the fuel/air mixture to the cylinders...

and head
Cylinder head
In an internal combustion engine, the cylinder head sits above the cylinders on top of the cylinder block. It closes in the top of the cylinder, forming the combustion chamber. This joint is sealed by a head gasket...

s are open to modification. The most effective intake manifold configuration has continued to be the "tunnel ram" for nearly 40 years. The carburetors are raised above the engine; the length and configuration of the intake passages ("runners") is critical to horsepower output. The tall intake manifolds predicate the large hood scoop that is a signature of the Pro Stock class.

The rules that forbid forced induction of any sort, plus allowing head modifications have resulted in Pro Stock heads being the most sophisticated in any drag racing category, with valve lifts in the 1" region.

Pro Stock engines generally produce around 2.5 hp/in³ (114 kW/L). A complete Pro Stock engine normally costs more than $80,000.

Drivetrain

Pro Stock clutch
Clutch
A clutch is a mechanical device which provides for the transmission of power from one component to another...

es utilize multiple discs. These must be serviced after every run to maintain critical tolerances that can mean the difference between a good run or severe tire shake.
Since 1973, the most popular transmission was the Lenco planetary design, first used as a four-speed and now as a five-speed. Although the five-speed unit (usually air-shifted) is still used in ADRL and Mountain Motor Pro Stock Association and in Air-Shifted three-speed units in Pro Modified
Pro Modified
Pro Modified, also known as Pro Mod, is a class or division in the sport of drag racing used in the NHRA and the American Drag Racing League .-Overview:...

, NHRA Pro Stocks utilize a Liberty or G-Force five-speed clutchless manual transmission.

Body

NHRA Pro Stock racers are no longer required to use modified stock steel bodies from the respective manufacturers' cars. Instead, NHRA-approved bodies that resemble the stock bodies are utilized.
Some have complained that the "Stock" portion of "Pro Stock" is not really all that accurate anymore, because so little, if any, of the race cars' bodies having their origins in the respective manufacturers' factories.

Chassis

Pro Stock chassis are welded 4130 chrome-molybdenum alloy steel tubing, with an integrated "funny-car style" cage around the driver that, combined with the safety restraints and helmet produce a very rigid and safe driving environment.

Suspension

Pro Stock cars are required to use automotive-type suspension systems.
Since the 1970s, front suspensions have utilized MacPherson strut
MacPherson strut
The MacPherson strut is a type of car suspension system which uses the axis of a telescopic damper as the upper steering pivot. It is widely used in modern vehicles and named after Earle S. MacPherson, who developed the design.-History:...

s with control arms; for rear suspensions, the design of choice is the four-link.
Coil- over shock absorbers are used at both front and rear.

Brakes

The primary means of slowing the cars from their top speeds of around 200 mph are the dual drag chutes.
Four-wheel disc brake
Disc brake
The disc brake or disk brake is a device for slowing or stopping the rotation of a wheel while it is in motion.A brake disc is usually made of cast iron, but may in some cases be made of composites such as reinforced carbon–carbon or ceramic matrix composites. This is connected to the wheel and/or...

s made by aftermarket manufacturers are also used.
The brakes have single caliper
Caliper
A caliper is a device used to measure the distance between two opposing sides of an object. A caliper can be as simple as a compass with inward or outward-facing points...

s on the front and double calipers on the rear.

Fuel

The factory hot rods may use only racing gasoline (octane rating
Octane rating
Octane rating or octane number is a standard measure of the anti-knock properties of a motor or aviation fuel. The higher the octane number, the more compression the fuel can withstand before detonating...

: 118), which is tested and certified by chemical analysis at NHRA, ADRL, or MMPSA events.
Pro Stock fuel systems flow the gasoline
Gasoline
Gasoline , or petrol , is a toxic, translucent, petroleum-derived liquid that is primarily used as a fuel in internal combustion engines. It consists mostly of organic compounds obtained by the fractional distillation of petroleum, enhanced with a variety of additives. Some gasolines also contain...

at 7.5 US gallons per minute (0.5 L/s).

On top of all of these specifications, each car must:

Weigh a minimum of 2350 pounds (1,066 kg), including driver.
In NHRA competition, the cars must be produced within the last five model years (2007–2011). In the late 1980s and into the 1990s, car sizes increased as mid-size family sedans had become the car of choice, but cars shrank by the 2000s as compact cars, banking off the popularity then of the sport compact class, became the trend, as General Motors and Chrysler began using compact cars (similar to Pro RWD except for the engine). Current NHRA rules require the Ford Mustang
Ford Mustang
The Ford Mustang is an automobile manufactured by the Ford Motor Company. It was initially based on the second generation North American Ford Falcon, a compact car. Introduced early on April 17, 1964, as a "1964½" model, the 1965 Mustang was the automaker's most successful launch since the Model A...

or Dodge Avenger
Dodge Avenger
The Dodge Avenger is a front-wheel drive, mid-size sedan, built by the Chrysler Corporation for the Dodge marque. In its initial debut, the Avenger was produced from 1995 to 2000 as a 2-door coupe...

, with the Chevrolet Camaro
Chevrolet Camaro
The Chevrolet Camaro is an automobile manufactured by General Motors under the Chevrolet brand, classified as a pony car and some versions also as a muscle car. It went on sale on September 29, 1966, for the 1967 model year and was designed as a competing model to the Ford Mustang...

scheduled to come later in 2011.
Rear spoilers cannot be longer than 13 inches (33 cm), measured from the body-line-to-spoiler transition point to the tip.
Complete stock headlights, parking lights, and taillights must be retained in original factory location.

This makes for some incredibly tight racing; the front runners in the class can reach speeds over 200 miles per hour (89 m/s) in 6.6 seconds (approx). The qualifications rounds are separated by less than a tenth of a second across all competitors. In a particularly tight qualifying roster, the difference from #1 to the final #16 qualifier may be only .05 seconds.

MMPSA cars, because of their 800+ cubic inch mountain motors, dip into the 6.30's at almost 220 miles per hour (98 m/s). Recently, a few cars have dipped into the 6.20's, with Brian Gahm being the first with a 6.29 second pass at Grand Bend Motorplex

Grand Bend Motorplex

Grand Bend Motorplex is a dedicated multi-use motorsports facility located southeast of Grand Bend, Ontario, Canada. It features IHRA Championship Drag Racing on its 1/4 mile dragstrip as well as two competitive Motorcross tracks and is home of the annual IHRA Mopar Canadian Nationals, Canada's...

NHRA Pro Stock Champions (1974-2010)

1974 - Bob Glidden

Bob Glidden

Bob Glidden is an American drag racer. He was retired from Pro Stock racing in 1997 and returned in 2010. Glidden retired as the driver with the most wins in National Hot Rod Association history at that time , and he is currently the third most successful drag racer in the history...

,
1975 - Bob Glidden

Bob Glidden

,
1976 - Larry Lombardo,
1977 - Don Nicholson,
1978 - Bob Glidden

Bob Glidden

,
1979 - Bob Glidden

Bob Glidden

,
1980 - Bob Glidden

Bob Glidden

,
1981 - Lee Shepherd

Lee Shepherd

Lee Alan Shepherd was an American drag racing driver . He began racing for car owners Reher & Morrison in 1978. The team campaigned Chevy Camaros through most of their career. The Arlington, Texas native won the National Hot Rod Association's Pro Stock championship in four consecutive seasons from...

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1982 - Lee Shepherd

Lee Shepherd

,
1983 - Lee Shepherd

Lee Shepherd

,
1984 - Lee Shepherd

Lee Shepherd

,
1985 - Bob Glidden

Bob Glidden

,
1986 - Bob Glidden

Bob Glidden

,
1987 - Bob Glidden

Bob Glidden

,
1988 - Bob Glidden

Bob Glidden

,
1989 - Bob Glidden

Bob Glidden

,
1990 - Darrell Alderman,
1991 - Darrell Alderman,
1992 - Warren Johnson

Warren Johnson