Holden Commodore VL Turbo

Introduction

One of the hottest Holden’s ever to roll off the production line at Fishermens Bend was not a V8. And the engine was not American or Australian. But it was every bit as quick as a 350 Monaro GTS; as fast as a Torana A9X. And in stock form it was right up there with all but the best from Peter Brock’s HDT Vehicles Division.

To understand just how brilliant the VL Turbo was, you needed to turn back the clock to 1969 – a time when the 350 Monaro would thunder down the standing 400 metres in about 15.5 seconds, running out to a top speed of around 205 km/h. The 161 kW A9X hatch, with its moonshot 2.6:1 diff, would pull 210 km/h, but was three tenths slower over 400 metres. The stock Commodore Turbo put in a time of 15.28 seconds for the standing 400 metres, running out to a top speed of 206 km/h.

Despite the figures, the Commodore Turbo was a very different sort of musclecar from the previous decades Monaro’s and Torana’s. Back then of course it was important for a car to “look” as fast as it was – but with the VL Turbo subtlety was taken to a whole new level – all you got was a small 140mm badge on the boot-lid. But the differences were more than skin deep.

Forced Induction Across The Range

The Commodore Turbo was in many ways a remarkable car - and not the least because of its high stepping performance, low key packaging and Japanese engine. The Turbo was proof positive that performance was alive and well at Fishermens Bend. On the VL Commodore Holden were offering forced induction across the range, starting with the $18,381 SL and stretching to the $27,317 Calais, with Executives and Berlinas, in sedan and wagon form, in between.

But the turbo invasion didn’t signal the end of the Holden V8, with the 4.9 litre VLs remaining in production and ideally suited to towing applications, while the hot Brock-modified VL Group A SS was a true beast. But in a bang-for-buck scenario you couldn’t better the RB30ET engine, designed and built by Nissan to GM's specification, in turbo form. This engine was a turbo version of the 114 kW RB30 unit introduced with the VL range, not a turbo conversion.

GM's initial design brief to Nissan for the RB30 included provision for a turbo, so the development work on both engines occurred simultaneously. As such, upgraded components developed for the turbo were common to both engines. The essential differences between the two engines, therefore, were minimal. The turbo engine had a special camshaft, with reduced overlap and increased lift, and the compression ratio was dropped from 9.0:1 to 7.8:1. Other changes included the adoption of a larger oil pump to cope with the extra lubrication needed at the turbocharger main bearing and a heavier flywheel, while the engine's electronic management system incorporated a knock sensor and a two mode fuel injection system to handle the difference in fuel flow rates at idle and full throttle.

Behind the Wheel

The turbocharger was a water cooled Garrett AiResearch T3 which delivered maximum boost of between .42 and .50 bar from as low as 2400 rpm. Maximum power was 150 kW at 5600 rpm, with 296 Nm of torque at a usable 3200 rpm. The power delivery was smooth and progressive, almost linear in feel down low, although a strong surge at about 2500 to 3000 rpm and the chuffing of the waste-gate on the gear-changes left you in no doubt the Garrett had come on stream. Throttle response was good from as low as 1500 rpm. The turbo felt almost as responsive as the normally aspirated engine at the bottom end of the torque curve - which made it very pleasant to live with around town.

On the open road the engine was a delight, offering power aplenty for passing manoeuvres with simply a squeeze of the throttle - although the tall 0.76:1 fifth gear often demanded a downshift to fourth. The Commodore was explosive in the lower gears, taking just 5.4 seconds to accelerate from 60 to 100 km/h and 80 to 120 km/h in third, and 7.8 and 7.6 seconds respectively in fourth. Leave it in fifth, however, and it took 12.9 seconds for the 60 to 100 km/h increment and 13.0 seconds to reach 120 km/h from 80 km/h. Pushed hard to 5000 rpm and beyond through the gears, the engine would sound a little busy, but the problem was probably due to inadequate noise suppression rather than harshness.

As with all turbos, you didn’t get something for nothing. Use all that performance all the time and you could expect to pay at the petrol pump, with fuel consumption of 16.7 litres/ 100 kms not ideal. Turbo-charging the Commodore meant more than simply a revised engine. Changes were made to the suspension, steering, wheels and brakes to allow for the 32 percent power boost over the normally aspirated engine. Power steering was standard and all sedans were fitted with what GM-H called a FE2 pack suspension. Derived from the police pack suspension offered on the VK Commodore, the FE2 pack featured linear rate front coils in place of the variable rate springs, revised damper valving front and rear and slightly softer stabiliser bars.

In view of the Turbo's performance potential, the FE2 pack tamed the VL Commodore's questionable handing. Simply put, the turbo inspired confidence and was a much better drive than the normally aspirated Commodore. There was less lurching weight transfer and more response to steering wheel inputs during cornering. The turbo tracked straight on rough surfaces, and the rear axle was noticeably less nervous under hard acceleration. The ride was firmer, but not overly so, and what any real driver would have wanted from their sports sedan.

But that’s not to say the VL Turbo was perfect - the rear axle still steered in rough corners and the roll bars needed to be stiffer - but the FE2 pack was a vast improvement over the standard VL set up. A lso a vast improvement were the Turbo's brakes. The rear end used standard Commodore discs, but up front the usual 271mm stoppers were replaced by hefty 289mm units, while the stock callipers were substituted by impressive alloy Girlock units originally developed for the Chev Corvette. The result was an excellent progressive feel through the brake pedal and the ability to cope with repeated stops from near terminal velocities.

Because of the larger front discs 15 inch wheels were used across the Turbo range. Calais versions retained their standard 15 inch alloys, but the Berlina and SL Models were given new larger diameter steel wheels complete with racier plastic trims. With 205/65 HR 15 tyres, the Turbos had a firmer grip on the ground than their normally aspirated cousins - with the exception of the Calais, of course.

Such was the sheer grunt on the RB30ET that traction was a real problem on anything other than a dry, smooth surfaces. On wet roads or loose surfaces the Turbo could be a handful, and was not a suitable car for a learner driver. Care was needed when accelerating away from the lights and through corners to avoid wheel-spin, particularly in the first three gears.

Stunning performance and improved handling aside, the Turbo was basically just a VL Commodore - with all the inherent good and bad that entailed. At launch it came with a sticker price of $2596. When you consider what you got, which included the turbo engine, bigger wheels and tyres, bigger brakes and a couple of badges, it was well worth the money. For those seeking performance in a family sedan, it was a downright bargain.

To ensure adequate stopping power for turbo fitted cars, each was fitted with larger brakes and Girlock finned alloy front callipers (as used on the Chevrolet Corvette), the 15 inch wheels being shod with 205/65 rubber. Fans of the 5.0 litre V8 had to wait a little while after the VL's s introduction to allow the GM engineers time to re-tune the motor to suit unleaded fuel. Finally released in October 1986, it still featured the familiar Rochester four-barrel carburettor, naturally enough many had been hoping the delay in its release was due to the fitment of EFI.

The Brock Turbo Calais

How good was the Turbo Calais? Peter Brock thought it was plenty good, and used it as his personal road car in 1986. And it was an automatic. The General's turbo six was ignored by HDT for a fair while, but production of a batch of special vehicles started in late 1986. HDT still made the ground thumping V8 models, but these were Group As and Calais Directors. Meanwhile, Brock's first foray into the world of forced induction produced a very adequate device. HDT had fiddled with six cylinders before, with the normally-aspirated LE Calais.

The LE Turbo started its life as a Calais, manual or automatic, so it had all the good gear fitted as standard, including cruise control, power windows, central locking, power steering, velour trim, and a reasonable stereo, as well as a heap of other convenience features. It was also fitted with a turbocharger with revised suspension and brakes before it left the General, but that's about it. HDT then started work on the suspension, and threw away most of the innards. The components were replaced with rerated coils, gas dampers, and different stabiliser bars. The Brock cars were also ordered with the factory optional limited slip differential.

The Calais was then treated to a set of 16" X 7JJ Momo wheels, and Bridgestone 205 section, 55 series tyres. The tyres were unidirectional. The suspension modifications were fairly simple on paper, but they did combine well enough to make full use of the turbo-motor's surging power. It was more a question of using the right suspension replacement parts, rather than going for radical changes. Brock did claim that modifications were made to the engine management system, but was never specific so we do not know what these changes were - perhaps a previous owner will be able to enlighten us. What we do know, however, was that the controversial polariser was included in the under-bonnet changes.

The Calais used big four wheel power disc brakes with Girlock callipers. The car also retained the 63 litre fuel tank as standard. Externally the Brock body package for the Calais was one of HDT's best efforts. There was a rear deck spoiler, and a deep front spoiler. Bumpers were colour coded, there were deep section side mouldings, a special grille, and a few HDT identification badges. Inside the LE was treated to a Momo steering wheel, and extra under-thigh padding in the driver's seat. Low contoured sports seats were optional, or you could specify the full house HDT pack which included the rear seats, seat belts and head rests.

Like all Brock cars, the LE Calais is tested and recalibrated, and fitted with a firewall authenticity plaque with the car's build number. As a package the car looked subtle enough for most, without extravagant bits of fibreglass hanging off each corner, but it also never failed to draw attention. Especially from those in the know. Basically, the car managed to appeal to the type of person who would have normally bought a standard Calais. This one just happened to be quicker and easier to muscle through the twisty bits.

On the Road

Even though it was a six cylinder - any thoughts that the car was underpowered were dispelled the minute you got behind the wheel. The turbo provided a seemingly endless explosion of readily usable power. As the rest of the car was very quiet, the turbo could easily be heard puffing up its chest with a satisfying whistle. Then there was a slight whoosh that told you the wastegate had just come into the equation. And the whole time there was the best exhaust note on a six cylinder this side of a GTV6. The big bore exhaust system emitted a deep menacing rumble.

It was only at high cruising speeds that the somewhat dated bodyshell design began to show its age. Wind noise in the car was apparent at blatantly illegal speeds and, as with every GMH product from the 1980s, there was a chorus of annoying rattles. The windows lacked a locked mode for either up or down operation which was a shame as they were very slow. The windows would protest loudly against the sealing rubber every time they were asked to move - a fualt common to all VL Commodores. The power locking, too, was a little less than perfect - and longer term owners would often complain of the systems unreliability.

The shift on the manual five speed gearbox was stiff and slow - and this was worse when cold. Combined with the long throw clutch, and you had a recipe for clumsy changes. The LE Calais really should have been fitted with a super short throw gearchange with narrow gates, which would bring out its best. The ratios combined with the high diff endow the car with a high top end speed, and majestic loping ability. At an indicated 100 km/h, the Calais' engine was spinning at less than 2,100 rpm. Fourth gear was basically useless at anything under 70 km/h, and most wouldn't have bothered using fifth at less than 100 km/h.

Brilliant Handling

The reason was not that the engine would not pull away at low revs, because it would. Rather, there was a terrible grating resonance from the exhaust system that forced you to change down. The clean, crisp exhaust note was replaced by a humming grunt that was not exactly music to the ears - something akin to pulling away at top from 20 km/h in a four cylinder. Performance cars were often a compromise, but not in this case. The ride/handling compromise was almost non existent. The suspension could not be described as anything but firm, yet small, high frequency bumps were never a problem as they sometimes were in stiffly sprung cars. Even mid-corner bumps, a traditional area to steer clear of in a Commodore, were no problem. The Brock modified rear end tracked true, and only irresponsible squirts of power in the lower gears could ever hope to bring the back end undone.

The flat handling characteristics of the car and the big rubber virtually eliminated understeer. It was only when pushed extremely hard that the front end would stop tracking true and begin to push a little wide, although it was always gradual and predictable. The car pointed so well, that you often arrived at an apex with a Iittle too much lock on; Even then you had a choice. Either unwind an inch of lock on the fat, contoured steering wheel, or blip the throttle. Either method will place the machine exactly where you want it to go.

Performance and economy was another likely area for a compromise to crop up. But again the LE Turbo had all its bases covered. Cruising at legal highway speeds could return a fuel consumption figure close to 12 litres per 100 km, although economy would suffer a little if the most was made of the available boost. But it was the power that this car was all about. The Calais had more than enough grunt to wind the needle off the 200 km/h speedo, and almost back around to the stop. It also had enough surge off the line to see off just about any locally produced V8.

Brock estimated his turbo engines were putting out about 10 percent more horsepower a ttheflywheel than the General's offerings. But few road testers were able to show up any tangible evidence of increased performance. It was certainly no slower though. A standing 400m time of low 15 seconds was attainable in any run-in car. For a late 1980s Commodore, in Calais trim, with all the extras on board, was remarkable.