924 Carrera GTS/GTR
There was a GT, GTS and GTR. The motors were: M31.50/ 210hp/ 8.5CR, M31.60/ 250hp/ 8.0CR, M31.70/ 375hp/ 7.1CR. A GTS number would be wpozzz93zbn71nnnnn. A GTR is numbered wpozzz93zbn72nnnnn.
The GTP for 1981 was the proto944 motor with some significant differences.
The twin cam had a fixed tension belt driving the intake cam, much more reliable than the
production 944S. It was closer to a 924 in most ways. I have pictures as well. It has a
hybrid 935 5-speed transaxle(similar to the 956/962). There were GTRs built with the 2.0
924 engine, but the intercooler and intake were very similat to the 944 as was the
location and exhaust system with turbo. The engines for all mounted to the bodies with
rigid mounts.
Take a look at the brochure which
describes the Carrera GT technical details. Thanks to Jim Rogers for this fascinating
document.
Peter Utzon has some pictures of a naked GTR motor up on his site: http://hem.passagen.se/utzon/937/924E.html As you can see it ain't exactly stock turbo. The GTR is not a trivial undertaking should you want to try to duplicate.
Here's a couple of shots from the original technical manuals:
The 924 Carrera GTS represented the fastest road-going 924 you could buy anywhere. An upgraded chassis was matched by a re-worked engine putting out 250hp. Bodywork was nearly identical to the Carrera GT, excepting the fixed headlights, fixed plastic side windows with sliders, and revised front lower spoiler. The hood scoop was retained for better engine compartment cooling. The fixed headlights were necessary to accommodate the larger intercooler, which was moved to the front. The intake manifold was also reshaped to a log-style manifold, resulting in a system which looked much like the upcoming 944 Turbo (951). Ironically, according to GTS owners, the fixd headlights were a real compromise for function - the resulting headlight beam output was severely limited, cut off by the bumper, and not very helpful.
If you really wanted to have some fun with your GTS, you could get the Club Sport edition, with further weight reductions and a factory alloy bolt-in cage, for competition:
Pictures of the GTR Intercooler
The GTR was, without question, the ultimate evolution of the 924 (still using the 2.0L block). The GTP which followed was badged as a 924, but used the prototype 944 2.5L alloy block. How much power did the GTR motor make? Only God and Ferry Porsche know! Quoted numbers indicate 375hp, but that's sure to be a conservative estimate, and boost would regularly be adjusted as required. Longevity required was another major factor.
The GTR benefited from much development to date. The intercooler was relocated to the front, as with the GTS, but was much larger than the GTS, filling much of the nose of the car.
Bodywork has been much of an unknown at large, due to many variations and limited documentation. The bodywork shown on the red car above and below was the original factory customer bodywork. It greatly resembles the bodywork currently in vogue in the DTM touring car series.
The following gold and black car was used for rallying. Because of this fact, and since it remained with the original GTR bodywork, the original GTR bodywork is often referred to, mistakenly, as rallye bodywork.
The teams using the GTR quickly decided to develop their own bodywork. I'll be back later to document these better, and fill in some of the blanks of technical content. For now, I will mention that some of the major points were boxed rear fender quarters as seen on the 935's, and 1-piece noses. These cars also saw much service in the Trans Am series.
