![]() The rules that exclude 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 inch region. In the NHRA, an electronic control unit (ECU) will be implemented on the EFI systems, including a 10,500 RPM limit, with modern engines approaching 12,000 RPM.The NHRA formula (starting in 2016) requires, and the PDRA extreme pro stock permits, cars to use electronically controlled throttle body fuel injection systems.(The hood scoop is illegal in the NHRA because of EFI) The tall intake manifolds necessitate the large hood scoop that is a signature of the pro stock class. The carburetors are raised above the engine the length and configuration of the intake passages ("runners") is critical to horsepower output. The most effective intake manifold configuration has continued to be the "tunnel ram" for nearly 40 years. The intake manifold and heads are open to modification. sawn in half) so that each of the halves can be more accurately positioned over the slightly staggered intake runners. Those that use two four-barrel carburetors may allow them to be "split" (i.e.Depending on sanctioning body and class, engines may either be four-barrel carburetors or throttle body electronic fuel injection and must be a naturally aspirated intake system.The Australian National Drag Racing Association and IHRA have a 400 cu in (6.6 L) maximum displacement engine limit.The NHRA limits engine displacement in Mountain Motor categories to 843 cu in (13.8 L). "Mountain Motors", run by the PDRA (eighth-mile) and at selected NHRA events in 2019, do not have a 500-cubic inch rule, with some engines exceeding 800 cu in (13.1 L), to upwards of 1,000 cu in (16.4 L). NHRA pro stock engines are restricted to a maximum 500 cu in (8.2 L) single-camshaft, 90-degree V8.Each team will continue to machine and modify the part to their own standards. Engine blocks and cylinder heads are often provided in a "raw" condition with only approximate dimensions and rough machining. All raw components must be available to anyone for general public purchase.Except in the NHRA 500 ci formula (starting in 2018), the engine must be manufactured by the same company as the car body.Hood scoops and double four-barrel carburetors were eliminated and replaced by electronic fuel injection, an overhaul designed to reflect modern automotive trends, as all automobiles being produced for sale in North America have used electronic fuel injection for over 20 years.ĭual 4-barrel carburetors on a "tunnel ram" intake manifold In 2016, the NHRA implemented a major overhaul to the engine formula. Lee Shepherd won the second of four championships in a row in 1983, the year he also won IHRA's title, making him the first driver ever to do so he repeated the feat in 1984. In 1982, the NHRA did away with the weight break system and implemented a 2,350 pound minimum weight, 500 cubic inch maximum rule across the board, due to the popularity of the Mountain Motor IHRA pro stock cars, which have unlimited displacements. Over the 19 seasons, Bob Glidden became the first driver to win two pro stock championships. record with a 9.33, while Bill Jenkins turned in a record 148.76 mph (239.41 km/h) speed later at the same event, Nicholson made a 9.01 second/150.50 mph (242.21 km/h) pass, breaking both his and Jenkins' records. įollowing a 1973 NHRA rule change to allow records to be set at any national meet, at the 1973 NHRA Winternationals, "Dyno Don" Nicholson set the first official pro stock e.t. On 1 July 1973, the NHRA required pro stock drivers to have competition licences, just like blown or fuel dragsters and funny cars. The NHRA attempted to balance the playing field for 1972 and introduced rules allowing for small displacement V8, compact cars carrying favorable weight. Rules initially favored big block V8s with Chrysler Hemi engine powered cars winning the world title the first two years. The National Hot Rod Association pro stock class emerged from the production-based super stock in 1970 with a more liberal set of rules and an absence of handicaps. The class is often described as "all motor", due to the cars not using any form of forced induction such as turbocharging or supercharging, or other enhancements, like nitrous oxide, along with regulations governing the modifications allowed to the engines and the types of bodies used. Pro stock is a class of drag racing featuring "factory hot rods". Allen Johnson's Mopar Dodge Avenger Pro Stock
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