924 Carrera GTR at Le Mans - part 2

Canon Cameras / GTI Engineering

Richard Lloyd's GTI Engineering was one of the most active 924 GTR racers. Often pairing with Andy Rouse and occasionally with Jonathan Palmer, the team enjoyed some success in the GT classes. GTI Engineering later raced a Porsche 956 in Group C. Richard Lloyd's roadgoing 924 Carrera GTS Club Sport was sold by his family after his death in 2008.

Results
1981 1000km Monza, 8th, GT class, #22
1981 6hr Silverstone, 11th, GT class, #22
1981 1000km Nurburgring, 15th, GT class, #43
1981 1000km Brands Hatch, 9th, GT class, #41
1982 1000km Monza, DNF, GTX class, #97
1982 6hr Silverstone, DNF, GTO class, #84
1982 1000km Nurburgring, 5th, GTO class, #58
1982 24hr Le Mans, DNF, GTO class, #84
1982 1000km Spa, 15th, GTO class, #84
1982 6hr Mugello, DNF, GTO class, #22
1982 1000km Brands Hatch, 17th, GTO class, #34

Thanks to Alain Jourdainne and Paul Kooyman for the photos. This car was for sale at John Starkey Cars in 2008.

Herman/Miller

The Herman/Miller car was entered into the 1982 24hrs of Le Mans under the BF Goodrich team name.

Results
1981 24hr Daytona, placed 22nd, #36
1981 12hr Sebring, DNS, #36
1981 6hr Watkins Glen, DNF, #36

These photos are from IMSA GT races in the US, which are yet to be listed. Many thanks to Mark Windecker. This is believed to be the car sold by Auto Collection at the Imperial Palace in Las Vegas in 2008.

Whitehall Promotions

Drivers Winters, Bergstrom

Results
1981 1000km Monza, 8th, GT class, #22
1981 6hr Watkins Glen, DNF, GT class, #79
1981 6hr Mosport, 13th, GTO class, #79
1981 500 miles Road America, 23rd, GTO class, #79

924 Carrera GTR at Le Mans

There were no works 911 variants at Le Mans in 1980. In keeping with the company's move away from the 911*, Porsche entered three works 924 Carrera GTRs into the GTP class, as the first move to make the 924 the Le Mans winning successor to the 934/935 within three or four years. Although down on power (320bhp) against other entrants, the three 924 Carrera GTs acquitted themselves well, finishing 6th, 12th, and 13th due to reliability, and excellent handling at a wet Le Mans.

In 1981 Porsche entered a 924 Carrera GTP and a 944 LM, which used the new 2.5l engine later used in the 924S and 944. In 1982 924s were entered only by privateers, including two cars entered by BF Goodrich using road tyres. The 924 won the IMSA GTO class in 1981 and the IMSA GT class in 1982, but overall never bettered the Porsche works results, despite the customer cars having more power than the original works cars. After 1980 Porsche focused on mid-engined cars for the new Group C regulations for 1982, dominating the class and ending factory development of the 924 Carrera GTR.

The 924 Carrera GTRs used the standard 924 block, (931) cylinder head, crankshaft, and con-rods. The turbo and intercooler were much larger and moved to the inlet side and front of the engine bay respectively. An aluminium torque tube and titanium drive shafts lightened the drive train components. A 935-based gearbox was used.

*Paraphrased from Paul Frere's excellent book, "Porsche 911 Story"

At the end of 1980, Professor Ernst Fuhrmann (who had been in charge of Porsche's activities since the end of 1972) resigned from his office one year before his contract expired...Fuhrmann, under whose leadership the Porsche 924, 944, and 928 had been developed, was much more inclined to push these cars than the 911...But Dr Ferry Porsche, who had been the real "father" of the 911, had different views...Professor Fuhrmann's policy had led to a considerable reduction of the 911 development programme, but as soon as Peter Schutz took office [to Managing Director], in January 1981, the decision was taken to reactivate the development of the model".

1980-1982 924 Carrera GTR Le Mans results:

Year	Team	No.	Result	Drivers	Class	Links
1980	Porsche System	4	6th	Manfred Schurti, Jurgen Barth	GTP
	Porsche System	2	12th	Tony Dron, Andy Rouse	GTP
	Porsche System	3	13th	Derek Bell, Al Holbert	GTP
1981	Porsche System	1	7th	Jurgen Barth, Walter Rohrl	GTP
	Porsche System	36	11th (class win)	Manfred Schurti, Andy Rouse	IMSA GTO
	Eminence Racing	73	51st (DNF)	Jean-Marie Almeras, Jacques Almeras	Group 4
	Porsche Australia	74	DNQ	Colin Bond, Peter Brock	Group 4
	Canon / GTI	75	DNQ	Richard Lloyd, Andy Rouse	Group 4
1982	BF Goodrich	86	16th (class win)	Jim Busby, Doc Bundy, Marcel Mignot	IMSA GT	Video
	BF Goodrich	87	DNF	Paul Miller, Pat Bedard, Manfred Schurti	IMSA GT	Video
	Canon / GTI	84	DNF	Richard Lloyd, Andy Rouse	IMSA GT	Wiki

Le Mans photo acknowledgements and thanks to: Paul Kooyman, Jean-Philippe Legrand, Alain Jourdainne and Francois-Rene Alexandre at photos24hlemans.free.fr

Privateer World Championship racing 1981-84

Privateers entered 924 Carrera GTRs in World Championship races in 1981-4. The late Richard Lloyd's Canon Cameras / GTI Engineering and the Formel Rennsport Club teams were the most prolific. Canon/GTI Engineering later had success with a Porsche 956 in Group C. Any photos of any of the cars below are much appreciated, please send them to CGT924@hotmail.com, with any requests for acknowledgements and cross-links.

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.

924 Carrera GT

The Porsche 924 was a design commission undertaken by Porsche for VW/Audi that was abandoned by the client and sold back to Porsche late in development, with Audi agreeing to build the car at its Neckarsulm plant. The Porsche 924 was a hit and brought in much needed cash after the company hit trouble following the 1970s oil crisis. About 125,000 Porsche 924s and 14,000 924 Turbos (officially designated Porsche 931) were sold between 1976 and 1985.

In 1979 Porsche submitted a styling exercise to the Frankfurt Motor Show to introduce ideas that shaped the look of the forthcoming 944. The following year, the company entered the 924 at Le Mans, and needed to homologate a race car to meet Group 4 racing regulations (although the racers were eventually entered in the GTP class). The homologation version was called the 924 Carrera GT and was a developed 924 Turbo incorporating wider front and rear wings similar to those seen on the well-received styling exercise.

Porsche made 406 924 Carrera GTs in 1981, including six prototypes. LHD cars are designated type 937, RHD are 938 (75 made). The 924 Carrera GT makes 210bhp from a developed 924 Turbo engine, weighs 1,180 kilos, has 49/51 weight distribution, handles well, is reliable, has racing pedigree, and is one of the cheapest Porsches to maintain.

A step up from the 924 Carrera GT is the GTS, of which 59 were made in the Stuttgart factory. These are more powerful than the 924 Carrera GT thanks largely to running increased boost and are easily distinguished by the perspex headlamp covers replacing the pop-up headlights on the GT, and an intercooler in front of the engine rather than on top of it. 15 of the 59 were Club Sport cars, which had a roll cage and were even more powerful and lighter than the GTS.

19 full race 924 Carrera GTRs were produced, of which nine either raced or qualified at Le Mans.

Variants

Variant	# Made	Power/torque	Boost	Weight	0-60, VMAX	Notes
924 Carrera GT	406 (75 RHD)	210bhp, 203lb/ft	0.75 bar	1,180kg	6.9s, 150mph	Red, silver, black
924 Carrera GTS	44	245bhp, 247lb/ft	1.0 bar	1,121kg	6.2s, 155mph	LHD red only
924 Carrera GTS CS	15	270bhp, 247lb/ft	1.1 bar	1,060kg	5.2s, 158mph	LHD red only
924 Carrera GTR	19	320bhp+	N/A	930kg	4.7s, 180mph+

924S

924S

Porsche 924S in Guards Red.

In 1984 VW decided to stop manufacturing the engine blocks used in the 2.0 924, leaving Porsche with a predicament. The 924 was considerably cheaper than its 944 stablemate, and dropping the model left Porsche without an affordable entry-level option. The decision was made to equip the narrower bodied 924 with a slightly detuned version of the 944's 163bhp 2.5 litre straight four, upgrading the suspension but retaining the 924's early interior. The result was 1986's 150bhp 924S. Porsche also decided to re-introduce the 924 to the American market with an initial price tag of under $20,000.

1987 saw Porsche release the limited edition 924S Le Mans. Available only in Alpine White or Black, it had uprated suspension and cosmetically upgraded interior and exterior. In Le Mans spec, the S' 2.5 litre engine produced an additional 10bhp, taking the total to 160. The Le Mans also came with an electric tilt and slide sunroof as standard (normally an option). A total of 980 924S Le Mans were manufactured during the 1987 model year; 813 in black (the only colour available for the US market) and 167 white cars.

In 1988, the 924S' final year of production, power increased to 160bhp matching that of the previous year's Le Mans spec cars and the base model 944 (itself detuned by 3bhp for 1988). This was achieved using different pistons which raised the S' compression ratio from 9.7:1 to 10.2:1, the knock-on effect being an increase in the octane rating, up from 91RON to 95. This made the 924S faster than the base 944 due to its lighter weight and more aerodynamic body.

With unfavourable exchange rates in the late 1980s, Porsche decided to focus its efforts on its more upmarket models, dropping the 924S for 1989 and the base 944 later that same year.

924 Turbo

Walter Röhrl's 1981 924 Carrera GTS driven during the 2008 Rallye Deutschland.

Porsche executives soon recognised the need for a higher-performance version of the 924 that could bridge the gap between the basic 924 and the 911s. Having already found the benefits of turbochargers on several race cars and the 1975 911 Turbo, Porsche chose to use this technology for the 924, eventually introducing the 924 Turbo as a 1978 model.

Porsche started with the same Audi-sourced 2.0 L I4, designed an all new cylinder head (which was hand assembled at Stuttgart), dropped the compression to 7.5:1 and engineered a KKK K-26 turbocharger for it. With 10 psi (70 kPa) boost, output increased to 170 hp (127 kW). The 924 Turbo engine assembly weighed about 65 lb (29 kg) more, so front spring rates and anti-roll bars were revised. Weight distribution was now 49/51 compared to the original 924 figure of 48/52 front to rear.

In order to help make the car more functional, as well as to distinguish it from the naturally-aspirated version, Porsche added a NACA duct in the hood and air intakes in the badge panel in the nose, 15-inch spoke-style alloy wheels, four-wheel disc brakes with 5 stud hubs and a five-speed transmission. Forged 16" flat wheels from the 928 were optional.

Internally, Porsche called it 931 (left hand drive) and 932 (right hand drive), much like the 911 Carrera Turbo, which had been "Type 930". These designations are commonly used by 924 aficionados.

The turbocharged engine allowed the 924's performance to come surprisingly close to that of the 911 SC (180 bhp), thanks in part to a lighter curb weight, but it also brought reliability problems.

Intense heat in the engine bay lead to short turbocharger life and turbo-related seal and seat problems. To fix the problems, Porsche released a revised 924 Turbo series 2 (although badging still read 924 Turbo) in 1981. By using a smaller turbocharger running at increased boost, slightly higher compression of 8:1 and an improved fuel injection system with DITC ignition triggered by the flywheel, reliability improved and power rose to 177 hp (132 kW).

After a successful sales run of both naturally-aspirated and turbo models, in 1981 Porsche decided to surprise everyone and a new 924 variant was unveiled at Le Mans 24 Hours.

By adding an intercooler, increasing compression to 8.5:1 as well as various other little changes, Porsche was able to develop the 924 Turbo into the race car they had wanted, dubbing it the 924 Carrera GT.

A 924 Carrera GTR campaigned by GTi Engineering in 1982 and 1982.

Visually it differed to the 931 in that it had polyurethane plastic front and rear flared guards, a polyurethane plastic front spoiler, a top mounted air scoop for the intercooler, a much larger rubber rear spoiler and a flush mounted front windscreen. It lost the 931's NACA duct in the hood but retained the air intakes in the badge panel. This more aggressive styling was later used for as motivation for the 944.

In order to comply with the homologation regulations, the 924 Carrera GT and later 924 Carrera GTS were offered as road cars as well, producing 210 and 245 hp (157 and 183 kW) respectively. Clubsport versions of the GTS were available with a factory included Matter rollcage and race seats. 924 Carrera GT variations were known by model numbers 937 (left hand drive) and 938 (right hand drive).

The ultimate development of the 924 in its race trim was the 924 Carrera GTR race car, which produced 375 hp (280 kW) from a highly modified version of the 2.0 L I4 used in all 924s except for the 944 Carrera GTP which used a highly modified as yet unreleased 944 2.5 litre DOHC 16v Porsche unit. This last model variant came 7th overall at Le Mans 24 Hours and spent the least time out of any other car in the pits.

Production of the 924 Turbo ceased in 1982 except for the Italian market which lasted until 1984. This is due to the restrictions on engines larger than 2 liters, putting the 2.5 liter 944 into a much higher tax category.

Porsche 924 - History

History

The 924 was originally intended to be Volkswagen's flagship coupé sports car. Volkswagen commissioned Porsche to design the car (VW project number 425), who developed a fresh chassis and transmission that would work with an existing Audi I4 engine. They also handled the suspension, and the interior and exterior design. Porsche decided on a rear wheel drive layout, and chose a rear transaxle to help provide 48/52 front/rear weight distribution. This slight rear weight bias, despite the front mounted engine, aided both traction and brake balance.

Due to growing concern over the 1973 oil crisis and a change of directors at Volkswagen, they put the 425 project on hold, eventually dumping it entirely after their decision to move forward with the Volkswagen Scirocco model instead. Porsche, who needed a model to replace the 914, made a deal with Volkswagen leadership, agreeing to buy the design for an undisclosed figure—some suggest 100 million DM, others say 160 million—but most agree it was less than the amount Volkswagen paid Porsche to design it.

The deal specified that the car would be built at the ex-NSU factory in Neckarsulm located north of the Porsche headquarters in Stuttgart, the Volkswagen employees would do the actual production line work and that Porsche would own the design. It became one of Porsche's best-selling models to date, and the relative cheapness of building the car made it both profitable and fairly easy for Porsche to finance.

The original design used an Audi-sourced four-speed manual transmission for the 924 mated to VW's EA831 2.0 L I4 engine, previously used in the Audi 100 and Volkswagen LT van and producing 95 hp (71 kW) in North American trim. This was brought up to 110 hp (87 kW) in mid-1977 with the introduction of a catalytic converter, which reduced the need for power-robbing smog equipment. The four-speed manual was the only transmission available for the initial 1976 model. An Audi three speed automatic was offered starting with the 1977.5 model.

European models, which didn't require any emissions equipment, made 125 hp (93 kW). They also differed visually from the US spec model by not having the US cars' low-speed impact bumpers and the round reflectors on each end of the body.

A 5-speed transmission, available starting in 1979, was a "dogleg" Porsche unit, with first gear below reverse on the left side. This was troublesome and was quickly replaced for 1980 with a normal H-pattern Audi five speed. The brakes were solid discs at the front and drums at the rear. The car was criticised in Car and Driver magazine for this braking arrangement, which was viewed as a step backward from the 914's standard four-wheel disc brakes. However, four wheel disc brakes, five stud hubs and alloys from the 924 Turbo were available on the base 924 as an "S" package starting with the 1980 model year.

The overall styling was penned by Dutchman Harm Lagaay, a member of the Porsche styling team, with the hidden headlights, sloping bonnet line and grille-less nose giving the car its popular wedge shape. The car went on sale in the USA in July 1976 as a 1977 model with a base price of $9,395. Porsche made small improvements to the 924 each model year between 1977 and 1985, but nothing major was changed.

J. Pasha, writing in Excellence magazine, at the time, described the 924 as "the best handling Porsche in stock form".

Porsche 924

Porsche 924

Manufacturer	Volkswagen AG
Production	1976–1988
Predecessor	Porsche 914
Successor	Porsche 944
Class	Sports car
Body style(s)	2+2 coupé
Layout	FR layout
Engine(s)	2 L, 2.5 L water cooled I4
Length	924 4200 mm (165.4 in)
Width	924 1685 mm (66.3 in)
Height	924 1270 mm (50 in)
Curb weight	924 1080 kg (2381 lb)
Designer	Porsche AG

The Porsche 924 is an automobile produced by Porsche AG of Germany from 1976 to 1988. A two-door, 2+2 coupé, the 924 replaced the 914 as the company's entry-level model, and was the model that finally retired the 912. It was the first Porsche model powered by a water-cooled, front-mounted engine to make production, although the similarly-configured 928 was designed before the 924. The front-engine, rear wheel drive arrangement was normal for most other manufacturers, but it was unusual for Porsche, who had previously only used mid or rear-mounted engines of a boxer configuration, all of which had been air-cooled.

The first official appearance of the 924 took place in November 1975 (as a press launch rather than a motorshow appearance) at the harbour at La Grande Motte, Camargue in the south of France. The model was a success and not only helped to take Porsche out of financial ruin, but created the revenue stream needed to continue building and developing the 911. The 924 was replaced by the 944 in 1983 in the US market, but continued to be produced until 1985 for other markets.

For the 1986 to 1988 model years the car acquired the powerplant from the 944 model and became the Porsche 924S.