924 Carrera GT Technical Summary

The 924 Carrera GT uses a turbocharged version of the 924's 1984cc engine with an intercooler. A normally aspirated 924 makes 125bhp, the type 931 turbo 175bhp, and the addition of an intercooler brings the 924 Carrera GT up to 210bhp. Apart from lighter pistons, most of the engine internals are common to the Porsche 924 Turbo, which itself shares the majority of its parts with the 924.

911 parts were also used on the 937 that were not used on the 924 or 931: The 924 Carrera GT's 210 BHP goes through a 911 clutch plate, the transaxle is strengthened using 911 syncromesh rings, and the Fuchs wheels are lifted from the 911. The brakes and the Koni front dampers are shared with the later 944.

Externally the 924 Carrera GT is similar to a 931, but with wider polyurethane wings at the front and rear, and a polyurethane hood scoop. These, slightly lowered suspension, and the Fuchs alloys give the 924 Carrera GT a much more purposeful stance than a standard 924 or a 931. Inside the cabin the 924 Carrera GT is surprisingly comfortable, with electric mirrors and windows as standard, and A/C and a large lift out sunroof (UK models only) as options.

Only red, black, and silver 924 Carrera GTs were made, the 924 Carrera GTS was only available in red. The styling exercise and full race cars were white.

Engine

The 924 Carrera GT's engine is designated M31.50 with engine numbers beginning 3150. It generates 210 bhp at 6,000 rpm, or 105.8 bhp per litre, at a low 8.0:1 compression and was apparently the most fuel efficient engine in the 924 range.

The M31.50 uses the standard 1984cc cast-iron Porsche 924 block and uprated parts as used on the M31.30 Series II 931, such as the aluminium head, camshaft, and cooling system. There are few parts unique to the 924 Carrera GT, namely the lighter forged pistons made by Kolbenschmidt, a slightly larger version of the 931 KKK turbocharger running at 0.75 bar, and a unique - although still similar to the European Series II 924 Turbo unit - Digital Ignition Timing Computer (DITC). Total dry engine weight is 175kg including the turbo and intercooler.

	Manufacturer	Porsche #	Manf. ref	Figures
Pistons	(KS) Kolbenschmidt	931 103 042 01		86.50mm, 8:1 compression
DITC	Siemens	937 602 071 00
Turbocharger	KKK	931 123 002 10	K26-2660 GA 6.10	Compressor cover 5326 100 5104
				Compressor wheel 5326 100 6328
				Compressor exducer 66mm
				Compressor inducer 39.6mm
				Trim 36
Intercooler	Langerer & Reich	931 110 033 04	37091207, 68652

Transmission

Getrag produced the G31 gearbox for the 924 Turbo, and it is perhaps the strongest in the Porsche 924-944 range, much of which used an Audi-derived 016 transaxle. The G31 uses a number of parts from the 915 and 930 transmissions such as the baulk ring synchromesh and bearings.

The 924 Carrera GT gearbox is designated G31.03, serial numbers start 3103. It is similar to the 931 unit, with the same ratios, but has strengthened gear sets to handle the increased horsepower. A limited slip differential was an option on all G31 equipped cars. Like many racing gearboxes the G31 has a "dogleg" first gear; down and to the left, to reduce the risk of accidentally engaging first at speed. Second is where first would be on a normal H pattern box, third is where second is, etc, etc. Reverse is above first.

G31.03	1st	2nd	3rd	4th	5th	Final
Tooth count	10/36	16/34	24/35	28/31	37/27	9/35
Ratio	3.6000	2.1250	1.4583	1.1071	0.7297	3.8889
Max MPH*	32	54	79	104	157
RPM @ upshift		3,542	4,118	4,555	3,955

*Assuming 225/50/16 rear tyres and upshift at 6,000RPM.

Suspension

All Porsche 924s have MacPherson struts and coil springs at the front, trailing arms with torsion bars at the rear. The 924 Carrera GT has a lightly uprated version of the Series II Turbo suspension with strengthened rear trailing arms. Springs are from the pre-1980 924, which have a lowering effect on the 937. Porsche, Koni, and Bilstein dampers were specified as original equipment and are interchangeable with the 944. Koni and Bilstein dampers are widely available and are highly recommended as replacements. Double-check compatibility with front struts before buying. Either 21mm or 23mm front anti-roll bars could be specified, a 16mm anti-roll bar is fitted at the rear.

Damper brand	Front ref	Porsche #	Rear ref	Porsche #
Porsche		944 343 031 12		477 513 031 H
Koni	86-1980	944 343 031 11	80-2349	944 333 031 00
Koni adjustable	8641-1038 Sport		26-1209 Sport
Bilstein B6 Sport	P30-0040 (Boge struts)	477 412 059 A	B36-0161	477 513 031 A
Bilstein B6 Sport	P30-0104	944 343 059 00

Wheels, Brakes, Tyres

The 924 Carrera GT wore Fuchs alloys from the 911 Carrera:

	Size	Porsche #	Tyres	Shared with
Fuchs Front	7Jx15 ET23	911 361 020 41	215/60 VR15	911 SC
Fuchs Front (option)	7Jx16 ET23	911 362 115 00	205/55 VR16	911 SC
Fuchs Rear	8Jx16 ET23	911 362 117 00	225/50 VR16	930

All have ET23 offsets and five nuts with 130 PC diameter, the same specifications can be found on certain 911, 930, and 944 wheels. Spacers are employed on the rear wheels to further widen the track.

The 924 and 931 had 6x14-16 inch wide wheels with ET20 offsets, giving them a narrower track and therefore incompatible as a direct swap onto a 924 Carrera GT. Conversely, the 911 wheels used on the GT are unlikely to fit on an unmodified 924 or 924 Turbo; the wider front and rear wings are required to accomodate them.

The 924 Carrera GT uses the same floating calipers as the 924 Turbo and were carried forward to the 1982-5 944. The GT also has plastic vents that duct cool air from the front bumper to the discs.