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  GTR-X Prototype Coupe

GTR-X (April 1970)
Back in the sixties Holden had been busy experimenting with quite a number of concepts such as fuel injection, over head cam-shafts and it was decided to design a Holden sports coupe on July 14th 1969. By December 15th the first body had been built which shows the effort and the outright determination of building a production lightweight sports coupe. After this the engineers started on the mechanicals which really had already been developed in the Torana which was developed on the track by Harry Firth and the boys.  The Torana running gear seemed a perfect option and helped of course to drop the production costs which is why Holden developed the six cylinder race engine in the first place instead of continueing with the Chevrolet V8's and Monaro. There were certain criteria that this coupe had to meet if it was to become a production model and the most important was price!  The Torana had the right ingredients in the suspension, transmission and engine departments. What Holden did with these restrictions was nothing short of brilliant and it was a great shame it never made it to the production line. The GTR-X was loaded with features like 4-wheel vacuum assisted disc brakes, retractable seat belts, foam filled fuel tank and electric windows to name a few. 
The GTR-X had to be sold for approximately 8 years to show a reasonable profit margin however to cover the tooling, production and design costs. The GTR-X came very close to going into production and the decision not to was most probably because of the release of the Datsun (Nissan) 240Z.  The Datsun won the world over and the price was super competitive which showed in its sales, the 240Z became the biggest selling coupe in the world! Colour sales/info brochures on the GTR-X were even printed and handed out at various motor shows at the time. Opel may have had a contributing factor in the demise of the GTR-X as well because it was already selling it's own coupe and the parent company GMC were not sure the market could handle two low cost coupes as both Opel and Holden exported to the same countries then and still do today.  The Opel was a very modest performer and the GTR-X would have been much closer in performance to the Corvette but it is now history and Holden was only allowed to build one coupe which was the Monaro as you couldn't really consider calling the two-door Torana a sports coupe.
Opel GT coupe 1968-1973
103,463 units made 
3,573 units had 1078cc engine 
99,890 units had 1897cc engine 
1897cc = 90bhp
GTR-X = 190bhp (202 XU-1)
Not exactly mind blowing power figures from the Opel
Datsun 240 Z 1970
The real threat to the GTR-X which was exported all over the world!
151 hp @ 5600 rpm
0-60mph(96km/h) = 8.0 seconds
Top speed = 125 mph(200 km/h)
A fact I stumbeld on was the GTR-X was driven around Mount Panarama at the 1970 Bathurst 500 meeting! I wonder who the lucky person was to drive this little gem. Also this was where a large amount of brochures were given out to the public.  If anyone has one of these I would be interested in seeing it.

There is no doubt that this coupe if it entered production would have been powered by the high performance triple carburetor 202ci XU-1 engine which gave the bathurst tuned cars a 13.5 second quarter-mile time.  Even with the detuned street version it may have made this model the quickest mass production car in the world which went to another General Motors car, the Corvette twin turbo.

186 cid - 6 cylinder inline (3050 cc) 
Bore and stroke: 
3.625" (92.1 mm) x 3.00" (76.2 mm) 
OHV with hydraulic lifters 
single camshaft 
9 port head 
Triple 150CD carburettors 

Four speed manual all synchro 

Fuel Tank: 
55 litres (12 gallon)
Polyurethane foam filled to prevent surge (fuel cell) 

13" x 5.5 JJ and C70-13 4 P/R

Reciculating ball with parallel linkage. Energy absorbing steering column with tilt mechanism. Steering wheel 14" diameter with fully padded rim.

Front: 10" (254mm) vacuam assisted discs 
Rear: 9.75" (248mm) vacuam assisted discs 
Handbrake: Self adjusting
Master Cylinder: Tandem with pressure differential and electrical warning system.

Front: Independent type short and long arm, coil spring.
Rear: Four link type, consisting of two longitudinal lower outer links incorporating mounts for coils springs and two diagonal inner upper links located for maximum lateral control. Rear shocks are mounted close to the wheels and forward of axle with increased stroke and modified valving.


Fibreglass "form-fitting" seat base. Adjuster handle pivoted on seat base. Molded foam pad fitted into seat base and trimmed with Sadlon material.

Lap and shoulder seat belts with self-adjusting locking retraction and fitted to roll bar

Rear Axle:
Ratio 3.36:1 with limited slip differential. Conventional propellor shaft of 2.75" diameter.

119kW @  5200rpm (160bhp) 
257Nm @  3600rpm 

Standing 400m: 
16.2 seconds 

0-100 km/h: 
8.5 seconds 

Top speed

These figures were for the 160bhp motor but the intended engine was to be the 202ci which was still under developement. It is therefore an estimate that the 190bhp and 200 ft/lb torque larger engine and very light weight would have propelled the GTR-X to well over 140mph and would have quarter miled  in the low 15's to high 14's. What about the 230bhp Bathurst engine? 

Camshaft specifications: 
Inlet (No ramp) 
 Open  29° 
 Close  57° 
 Duration  266° 
 Lift  .345" (8.76mm) 
 Open  64° 
 Close  24° 
 Duration  266° 
 Lift  .345" (8.76mm) 
 Overlap  53°

Here is some original material from Holden about the GTR-X:

The interior is safety padded in all critical areas - instrument panel, centre console, roof, and doors. The vehicle is carpeted throughout including luggage compartment and spare wheel stowage. Instrumentation and controls: all instruments, radio and controls are mounted on a steel plate carrier to which is bonded an aluminium facia. The whole carrier assembly can be removed readily for service.
Instrumentation includes:
Speedometer, Tachometer, Radio, Electric Clock, Ammeter, Oil Pressure Gauge, Fuel Gauge, Temperature Gauge, Vacuum Gauge. 
Warning lights for:
Turn Signals, High Beam, Ignition, Handbrake and Brake Failure, Front and Rear Lamp Failure.

This shows the actual original chassis.
The chassis frame is a welded box section (5" high and 3" mean width) full perimeter type with welded-in central and rear box section cross-members.

This was like no other Holden ever made!

Even the air intake was placed under the bumper to give the lowest possible bonnet.


Gauges from left are:- clock, vacuum, fuel, oil, temp, tacho, speedo, amp. The name on the console reads Torana!