An introduction to the IMSA GT Championship (part 1) #blogpost

After the success of my last blogposts, about Super GT, I was given a few suggestions about other series I could do. The one I most wanted to do was this, so I did it first. Hope you enjoy :)

There will be four parts to this:
Part 1 - General history, tracks
Part 2 - Cars of GTO
Part 3 - Cars of GTU
Part 4 - Cars of GTX and GTP

So, onto the actual article.

IMSA (International Motor Sports Association) was a governing body set up in 1969 by John Bishop and Bill France (yeah, the NASCAR guy) to run professional road racing (circuit racing to normal people) in North America. The first season of GT racing was in 1971, with six races held. GTO and GTU were the two main categories. Camel cigarettes was the main sponsor from 1972, and turbochargers were permitted in 1977.

In 1978, the GTX class was introduced, for FIA Group 5 cars (Special production cars, e.g Porsche 935), and in 1982, was replaced by the GTP class, with rules similar to those of Group C. The series enjoyed much success with these three classes for the next 17 years, until the championship split into the American Le Mans Series and Grand-Am in 1998.

In the early years of the GTO class, the most competitive car was the Porsche 911, followed by the Chevrolet Corvette, and in GTU, Porsche also dominated, with the 911 (again) and 914/6. GTO had been the highest class, but the introduction of GTX changed that. The Porsche 935 was immediately competitive, taking a 1-2 at its first IMSA event.

In 1979, the Mazda RX-7 was introduced to GTU, where it immediately took the place of Porsche as class leader.

When GTP was brought in to replace GTX, the 935 was still allowed to compete, and was successful for a number of years until the 962 was brought out, which made it pretty much redundant.

In this era there were many privateers racing alongside the factory teams, and, unlike in Europe, they were actually quite successful. They weren’t exactly privateers in the traditional sense, since they were manufacturing their own race cars, but they didn’t make road cars and therefore didn’t really have the budget of factory teams. Porsche was, again, at the front of the field, this time with the 962, just in front of Jaguar and Nissan. In 1989 Mazda entered the 767B, though it couldn’t quite keep up with the rest of the GTP cars.

By 1994, most of the factory GTP teams had left for one reason or another, leaving only the semi-privateers. The GTP cars were therefore replaced by WSC cars. Ferrari did enter at this point with the 333 SP, but they were the only real factory team.

For 1995, GTU was abolished and became a subclass of GTS (new name for GTO). So the classes were now WSC, GTS-1, and GTS-2. To confuse matters some more, GTS-3 appeared in 1997. As previously mentioned, the championship split in 1998.

In 2014, however, it was reunited, to form the TUDOR United SportsCar Championship, which is now the Weathertech Sportscar Championship.

The tracks

The IMSA GT Championship raced on a lot of the most famous American tracks. The 12 hours of Sebring were held in 1973 and from 1975 until 1998, and the 24 hours of Daytona from 1975 to 1997. Indianapolis, Road Atlanta, Watkins Glen, Talladega, Lime Rock Park, Mid-Ohio, Laguna Seca, Road America - that isn’t even half of them.

Since I did this in the Super GT post, here is the calendar of events in the championship that sort of derived from the one we’re talking about here:

Daytona 24 hours - January 30/31
Sebring 12 hours - March 19
Long Beach - April 16
Laguna Seca - May 1
Belle Isle - June 4
Watkins Glen - July 3
Canadian Tyre Motorsport Park - July 10
Lime Rock Park - July 23
Road America - August 7
Virginia International Raceway - August 28
Circuit of the Americas - September 17
Road Atlanta - October 1

If you’ve got any suggestions for other championships, please comment below. Thanks for reading all this, and hopefully part 2 will be out sometime soon :)