"This is it folks - one of the hottest Holdens ever to roll off the production line at Fishermans Bend." (Car Australia, October 1986)
About six months after the introduction of the VL Commodore, the VL Turbo hit the scene like a thunderbolt. In the absence of the V8 (still being re-engineered for unleaded and nothing special when it finally did arrive - it's covered next week) the Turbo was the gun Commodore engine. And what an engine! Available as an option across the whole range (including wagons), the RB30ET dramatically changed the traditional Aussie view of six-cylinder performance. Previously - with very few exceptions like the XU1 Torana and E49 Charger - Australian performance meant a V8. And those six-packs that did go hard had been homologation racing specials - now here was an engine that remained as smooth as silk while it kicked performance goals. The author traded-in his injected 3 litre BMW 3.0si on a turbo Commodore Berlina sedan ....and he wasn't unusual.
Wheels magazine ran a VL Turbo on the cover, close-up pic of the speedo showing 217 km/h. Modern Motor did even better, quoting a top speed of 223 km/h, while Car Australia punched out a 15.3 second standing 400 metres time. The praise just didn't stop.
The turbo version of the RB30E was designated the RB30ET. It was a straightforward Nissan turbo upgrade, running a water-cooled Garret/Nissan T03. Maximum boost pressure of 6.1 - 7.2 psi was developed by 2400 rpm and was then limited by an internal wastegate. The wastegate was not controlled electronically. A larger oil pump (increased over the 10.8mm standard width by 2.6mm) was fitted to cater for the required turbo supply, and the flywheel was increased in mass. A finned crossover pipe connected the turbo compressor to the throttle body - no intercooler was fitted. An emergency pressure relief valve was screwed to the rectangular plenum chamber. A common fitting on Nissan engines of the era, it vented turbo pressure if it rose above 7.6 - 8.3 psi (measured at the compressor housing).
The compression ratio was decreased to 7.8:1, achieved by the use of new pistons with lower crowns. In addition, the piston rings were specific to the turbo engine. A new camshaft with decreased valve overlap and increased lift was fitted - it was housed inside a red-painted cam cover. The intake manifold was altered - shorter runners were used - and a new cast iron exhaust manifold flowed exhaust gases to the turbo. A larger (1.7 litre) cat converter was fitted and the pipe leading to the cat was 64mm in diameter.
The engine management system was upgraded, with a knock sensor and multi-mode injector operation added. The latter was designed to cope with the required wide variation in fuel flow and consisted of group injection at light loads (injectors fired in two groups once per cycle) and simultaneous injection (where the injectors were fired once, twice per cycle). The over-run injector shut-off calibration was revised, and the system that increased fuel pressure during hot starts was also altered. The injectors were new, with the injector stroke increased for the turbo engine.
The power output of the RB30ET was 150kW at 5600 rpm and peak torque was 296Nm at 3200 rpm. These figures represented gains of 32 per cent for power and 20 per cent for torque over the standard engine.
All turbo Commodores were supposed to be fitted with the FE2 sports pack suspension. However, official Holden literature shows that in fact some cars may have been equipped with Country Pack suspension or in some cases, even standard suspension. The braking system was upgraded on all turbo Commodores equipped. The 'Corvette' front discs were 18mm larger in diameter and were fitted with new finned calipers that used semi-metallic pads. The master cylinder size was increased from 23.8mm to 25.4mm and a Master-Vac tandem brake booster was used. All turbo cars were equipped with four-wheel discs. The larger front brakes necessitated the use of 15 inch wheels (up an inch over standard VL wheels) and these were available in steel or alloy. The 15-inch steel rims became known as 'police rims' because they were also used on all police cars.
Power steering was fitted to all turbo cars, and specific transmissions were used. The automatic transmission had its torque converter clutch deleted and was upgraded in its torque handling capacity. For example, the internal clutch plates were increased in number from seven to eight in the low and reverse brake, and the second gear brake band piston size was increased from 72 to 80mm. The manual transmission was strengthened and had lower ratios (higher numerically) for the first three gears. The clutch was increased in diameter by 10mm, to 250mm. The differential was a stronger 4-pinion design and used 28 spline large-diameter axles. A mechanical LSD was an option, with in all cases the 3.45 diff ratio of the naturally aspirated cars retained.
When equipped with the automatic transmission, the Turbo slowed a noticeable amount in its standing-start performance times - tests found the auto got to 100 km/h in 8.4 seconds, more than half a second slower than the manual transmission cars. However, the kickdown in-gear times for the automatic were excellent, being in fact faster than the 5-speed cars in every low speed increment, and only a fraction slower at higher speeds. This made the automatic car an excellent country car, with blistering passing acceleration and - with the very tall gearing - relaxed revs when cruising. The cruise control, automatic trans and turbo worked extremely well as a combination.
Inside the cabin a few 'turbo' badges were dotted around (their location depended on when the car was built) and the optional cruise control buttons interfaced with electronics that were re-calibrated for the turbo engine. On the dashboard there wasn't a boost gauge, or even a boost light. Externally the turbo models were also subtle - they could be picked only by their bootlid badging, 15-inch steel wheels with their unique hubcaps (all Calais models had this diameter of alloy wheel anyway), and 'erect' exhaust tip (it poked upwards at an angle, whereas standard Commodores had a tip parallel to the ground!). On a Calais you could simply remove the bootlid turbo badge - and then picking the type of engine under the bonnet became very difficult indeed.
And it was the Calais that dominated the sales of turbo Commodores. While Holden had originally expected 17 per cent of turbo sales to be of the Calais and 11 per cent to be the (next trim level down) Berlina, most people who could afford insurance on the turbo cars were happy to have the top-of-the-line Calais. At the other extreme, most buying the SL in turbo form wore peaked caps and used the cars to chase criminals. Holden had involved the police in assessing the worth of the turbo VL well before it was released; as a result most state police departments added Commodore Turbos to their open-road 'pursuit' squads. They were very popular with the police, although by the time lights and sirens were added to the roof, the top speed was down to only about 180 km/h.
For the police and public alike, the turbo option was incredibly cheap. For a 14 per cent premium over the price of a standard Berlina you got the better brakes, better suspension, stronger diff - and 30 per cent more power! No wonder they sold like hot cakes....
But the Nissan six was available in Commodores only for the life of the VL; the next model VN came with a V6 that had no relationship to the VL - or even Nissan for that matter. But the Nissan-engined Commodore had proved to be so popular (151,801 VL's were produced) that Holden actually delayed the introduction of the new-generation VN to allow more time to sort out its teething problems. So, why drop the engine that had been so successful? It came down to two main points - dollars and marketing.
Even when the VL was first released, devaluation of the Australian dollar against the Japanese Yen had already increased the engine price by 30 per cent over the cost prevailing when the letter of intent was signed. More than any other factor, it was these currency fluctuation price rises that limited the use of the Nissan six to just the VL model. However, there was also the Aussie love affair with big engines. The arch-rival Ford Falcon had larger engines - and it was easy for a Ford salesman to talk about the 3.3 and 4.1 litre sixes available in the blue-oval product. The RB30 could not be increased in size, and along with the runaway cost increases, that made the Buick 3.8 litre V6 from the US look very attractive. Even if, in comparison, that engine was a coarse and low-tech lump....
Next week - the other performance VLs.
The VL Commodore Six - Part 1
The VL Commodore Six - Part 2
The VL Commodore Six - Part 4
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