Editing IMSA (section)

=== IMSA RS ===
The ''IMSA RS Series'' (for ''radial sedan'') began as the ''Baby Grand Series'', in 1971. Originally sponsored by [[BFGoodrich|B.F. Goodrich]] (therefore known as ''Goodrich Radial Challenge'') until they dropped sponsorship midway through 1975 (or 1976) and then by [[Goodyear Tire and Rubber Company|Goodyear]] (becoming the ''Goodyear Radial Challenge''), and later as ''Champion Spark Plug Challenge''.{{Citation needed|date=March 2009}}

The initial race held was in 1969 at [[Talladega Superspeedway]] Road Course. Gaston Andrey was first overall in an [[Alfa Romeo Giulia Super]] sedan.<ref>{{Cite web |url=http://touringcarracing.net/Races/1969%20Talladega.html |title=1969 IMSA - round 1 |access-date=2014-12-27 |archive-url=https://web.archive.org/web/20141228000229/http://touringcarracing.net/Races/1969%20Talladega.html |archive-date=2014-12-28 |url-status=live }}</ref><ref>{{cite web|url=http://www.ultimateracinghistory.com/race.php?raceid=17325|title=IMSA International Sedan race|website=www.ultimateracinghistory.com|access-date=2 July 2017|archive-url=https://web.archive.org/web/20160304095103/http://www.ultimateracinghistory.com/race.php?raceid=17325|archive-date=2016-03-04|url-status=live}}</ref>  The Series' first year was actually 1970 with only two races, the inaugural race was at the newly constructed [[Summit Point Motorsports Park]] on Memorial Day weekend; Rasey Feezell was first overall in an [[Alfa Romeo Giulia TI Super]] sedan;<ref>{{Cite web |url=http://touringcarracing.net/Races/1970%20Summit%20Point.html |title=1970 IMSA - round 2 |access-date=2014-12-27 |archive-url=https://web.archive.org/web/20160303230853/http://touringcarracing.net/Races/1970%20Summit%20Point.html |archive-date=2016-03-03 |url-status=live }}</ref><ref>{{cite web|url=http://www.alfabb.com/bb/forums/sedan-1962-1977/47867-autodelta-ti-super.html#post417895|title=Autodelta Ti Super - Alfa Romeo Bulletin Board & Forums|website=www.alfabb.com|access-date=2 July 2017|archive-url=https://web.archive.org/web/20170510074242/http://www.alfabb.com/bb/forums/sedan-1962-1977/47867-autodelta-ti-super.html#post417895|archive-date=2017-05-10|url-status=live}}</ref> the second race was held at the [[Montgomery Speedway]], Alabama, [[Red Farmer]] won in a specially prepared [[Datsun 510]].  Feezell didn't fare too well having to drive against the local four-cylinder "beater class" cars brought in to fill out the field, with their protruding wheels rubbing Racey's "immaculate" [[Alfa Romeo]]. Infuriated, Feezell quit and never ran another IMSA RS race after that.{{citation needed|date=February 2018}}

The idea was to attract racers who did not have the budgets that were required in the GT category as well as an emphasis on compact sedans such as the [[AMC Gremlin]] and the [[Opel Manta]].{{Citation needed|date=March 2009}} There were two classes from 1970 through 1973: Class A for under two liters and under 1.6 liters with [[overhead cam]] and Class B for over 1.6 L with overhead cam and over two liters up to the largest permitted engine being the {{convert|232|cuin|L}} AMC Gremlin. In 1974 all cars were placed in one class, with the only parity for the smaller engines being free [[carburetor|carburetion]] for under 1.6 liters. Limited preparation was permitted, and since the entrants were meant to be street-driven race cars, the original rules required the retention of headlights, seats, upholstery, window cranks, stock brakes and original springs and radial tires. Only the exhaust systems and shock absorbers were free. Later rules regarding headlights, seats, upholstery, window cranks, original springs, and other stock elements were loosened up somewhat.  From the beginning, engine modifications similar to [[Sports Car Club of America]] B Sedan were permitted, with the main difference being that over-boring cylinders was not allowed, and stock carburetors being required, but modifications allowed. The series was loosely based on rival SCCA [[Trans-Am]]'s Two-Five Challenge rules.<ref>{{cite web|url=http://www.bsedan.com/hist25.html|title=The history of the Trans-AM 2.5 Challenge |website=www.bsedan.com|archive-url=https://web.archive.org/web/20140224132453/http://www.bsedan.com/hist25.html|archive-date=February 24, 2014|url-status=dead}}</ref><ref>{{cite web|url=http://www.grmotorsports.com/news/012005/potent-pintos-these-drivers-have-no-worries-about-being-hit-from-behind.php|title=Grassroots Motorsports » Potent Pintos: These Drivers Have No Worries About Being Hit from Behind<!-- Bot generated title -->|access-date=2 July 2017|archive-url=https://web.archive.org/web/20070221080035/http://www.grmotorsports.com/news/012005/potent-pintos-these-drivers-have-no-worries-about-being-hit-from-behind.php|archive-date=2007-02-21|url-status=dead}}</ref>

The series became dominated mostly by [[Mazda]]'s [[Mazda Wankel engine|rotary-powered]] [[Mazda RX-2|RX-2]] and [[Mazda RX-3|RX-3]] prompting IMSA to specify heavier weights than piston-engined cars and prohibited any modifications to the rotors and more importantly to intake and exhaust ports.<ref>{{cite web|url=http://www.mazdausa.com/MusaWeb/displayPage.action?pageParameter=mazdaSpeedMotorsportsRacingHeritageCommon&sectionParameter=heritage01|title=Mazda Motorsports – Mazda Motorsports Development|website=MazdaUSA.com|access-date=2 July 2017|archive-url=https://web.archive.org/web/20160304112742/http://www.mazdausa.com/MusaWeb/displayPage.action?pageParameter=mazdaSpeedMotorsportsRacingHeritageCommon&sectionParameter=heritage01|archive-date=2016-03-04|url-status=live}}</ref> [[Datsun]] also had a fair share of success within the series with cars such as the [[Datsun 510|510]] and [[Nissan 200SX|200SX]]. Many drivers would cut their teeth in this series such as Don Devendorf, of [[Electramotive]] fame, [[Jim Downing]], of Kudzu, and [[Bobby Rahal]]. The final season was run in 1984 before it was replaced by the [[IMSA Showroom Stock]] class the following year, while retaining its sponsor until 1988.{{Citation needed|date=October 2022}} As with most now-defunct racing classes, there are revival races run for this category and the [[SCCA]] sanctions events for mostly-stock and all-stock cars.
{{Expand section|date=May 2008}}