It has more power
and consequently better
straight-line performance, but
a thorough comparison test with its
predecessor showed the new Commodore II has
little else in the way of improvements. Barry Lake and
Peter McKay drove the two cars and arrived at the decision that the new VC is a...
MODERN MOTOR, June 1980
The slalom tests, below, resulted in consistent wins for the older Commodore despite the power advantage of the new car.
Subtle cosmetic changes like badgework, grille
and tail-lights make up the external differences
on the new VC Commodore. But the dyno-test
revealed that engine power increase was the
only really worthwhile mecanical
MODERN Motor, June 1980
MODERN MOTOR, June 1980
EXACTLY how good is the new VC Commodore, or Commodore II? To find out, we tested it directly against a VB of the same specifications — 3.3-litre, six-cylinder au-tomatic.
The new car, little different from the former model in appearance, has undergone extensive changes to the engine and to the Suspension. Holden Claims big improvements in engine power, fuel economy and in the quality of ride comfort.
Few will argue that the engine was due for attention. It was the weak link in an otherwise very strong design when the first Commodore was released. After all, it's been pushing Holdens around this vast country since it was introduced with the EH model way back in 1963 and hasn't had too much development work since, apart from that necessary to make it meet emissions requirements.
An entirely new engine design would have been the ideal answer but economics pre-vented such a move. Instead, the existing engine underwent a massive surgery to improve its breathing ability, the quality of combustion of the fuel/air mixture, its smoothness, and even the strength and reliability of major components.
The Suspension has also been changed — shock absorbers, spring rates and the anti-roll bars have all been altered in a quest for better ride while maintaining roadholding.
But little has been done to alter the appearance or the inferior. The grille has been changed at the front to a
honeycomb or "eggcrate" design, a new section of side-protection moulding on the front doors now carries model identification and the tail-light lenses have had very minor changes.
Inside, most of the models are virtually unchanged, although the SL/E has a single-spoke steering wheel, a centre front arm rest/ console (also on the SL), an improved radio/cassette player, and an "economy gauge" rather than a tachometer. For models fitted with air-conditioning, a new, lighter system is now supplied.
We were supplied a regular VC test car by Holden, but the General was unable to provide a VB for comparison purposes. Instead, we tracked down a privately-owned car with identical specifications. The VB had the optional wider alloy wheels so we organised a set of steel wheels and radials like these on the VC; we wanted no disparities which might affect the handling, performance or fuel economy.
Neither car was specially tuned by us for the test, the VC presumably had the normal pre-road test service (although the finish was a little scruffy in some areas — file marks and overspray for instance) and the VB had been regularly serviced under warranty. We did check that the ignition timing was correctly set on both cars, this usually being the most likely variation from correct tune.
THERE IS no doubt that the engine in the VC is smoother and more power-ful than it was in the VB. The engineers have done themselves proud on this count. Gone is any trace of harshness and there is a smooth, usable power right through the range.
This shows up noticeably in our per-formance figures where the VC was considerably faster and continued to increase its advantage as the speeds rose. The Vane dynamometer testing demonstrated why. The power available at the rear wheels was 12.9 percent better on the VC at 2500 rpm, at 3000 rpm the advantage to the new car was 22.2 percent and, despite Holden's claim of an increase of only 17 percent, at 3500 rpm the advan-tage in favour of the VC in our dyno test was 41.7 percent. The VB peaked out there and began to fall off rapidly, but the VC held its power to 4000 rpm and had fallen off only slightly at 4500 rpm — at which point the VB had already died.
In the VB range, the manuals and automatics had engines of differing power, the manual developing its peak of 66 kW at 3600 rpm, while the engine in the automatics devel-loped 71 kW at 3800 rpm. For the VC range, only one form of engine is used, which tops out at 83 kW at 4000 rpm. These are figures provided by Holden and are measured at the fly-wheel. This power increase is achieved by a number of detail improvements to the engine.
Separate ports for each of the 12
While running on the dynamometer, the new VC Commodore showed higher than normal CO readings (a rich mixture) at 3000 rpm (above), but a very lean mixture at idle (below).
valves (six inlet and six exhaust) plus a re-designed combustion chamber make much of the difference but there is also a new dual-throat Varajet carburettor and new inlet manifold to assist with the breathing.
The exhaust manifold now has two outlets and the camshaft profiles have been reshaped. The redesigned head has led to the use of long-reach spark plugs and a high-energy point-less ignition system adds to the power boost.
Added reliability comes from exhaust valve rotators (actually a result of long-term emission control requirements), strengthened pistons, stronger connecting rods, improved quality bearings, increased oil flow for the hydraulic valve filters and improved ignition leads.
The compression ratio has been lowered for improved emissions.
On the 3.3-litre six-cylinder, a new 12 counterweight crankshaft with torsional damper has been added to aid smoothness of the engine.
THE VC comes out way ahead in straight-line performance. The 0-60 km/h time has it nosing ahead of the older car, by 80 km/h it is noticeably in front and, from there on, it just sprints away. It gets to 120 km/h some seven seconds quicker than the VB and it's 1.4 seconds better over the standing 400 metres.
MODERN MOTOR, June 1980
The advantage is there, also, in the all-important overtaking acceleration figures. The less time you spend overtaking other cars, in certain situations, the better off you are, and the VC is markedly faster in both the 50-80 km/h and 60-100 km/h brackets.
BUT WHERE is this magical increase in fuel economy? We couldn't find it. We took the two cars for an extended city/country drive to check them back-to-back. Using experience gained in the Total Oil Economy Run we were able to conduct what we consider to be a very fair comparison. Both cars were carefully fil-led both before and after the run; we drove them in as near as possible to identical manner all the way; we started them at the same times, stopped them at the same times, and when one moved — even just a few metres — the other moved with it. On top of that drivers were changed every 50 kilometres, just in case there was a Variation in driving styles although, after having driven together in the economy run, we were familar with each othe-r's styles and were quite sure we drove in similar fashion at all times.
And we can't even offer the excuse for the VC that "if the extra power is there, you'll use it and push the fuel consumption figures up" because they both ran at the same speeds all of the time.
While on the dyno at Applied Power, the VC showed itself to be very lean at idle but quite rieh at 3000 rpm (eight percent CO compared to six percent for the VB) which probably helps provide the extra power, but does little for fuel economy.
The end result was an almost immeasurable difference in the fuel consumed. We had to take the resultant figures to two decimal places to show the variance in fuel consump-tion. The VC did come out ahead, but by so little it barely Warrants mentioning. The VC scored 12.15 litres per 100 km (23.25 mpg) and the VB 12.18 litres per 100 (23.19 mpg). As we've already said, it was always smooth and responsive throughout the test.
THIS IS THE other area where a lot of work has been done. Why, we're not sure. The ear-lier Commodore reeeived rave write-ups from almost every writer in the country on its great handling and we've heard no complaints from owners since.
For some reason, The General decided that the Commodore should have softer ride and, at the same time, improved handling while fully laden with passengers and luggage. This was the one area where, we are told, some complaints arose. Apparently the older car wasn't at its best with a füll load, though we'd never experienced such a Situation.
Our Editor-in-Chief tested the new car with a füll load at Lang Lang and agreed that it did seem to handle and ride well under these conditions, especially on rough or uneven ter-rain.
On the other hand, Barry Lake drove both VB and VC models at Lang Lang and found he was always happier and faster in the VB, with two or one up, than with the VC under the same conditions. On the high-speed undulations of the handling cireuit, the VC feit very unstable compared to the VB.
VC v VB
The only exception was on really rough roads, where the progressive rate Springs did their Job well. It is these progressive rate Springs which have improved the full-load handling also and this is definitely the way to go, but in all of the conditions under which we condueted our comparison test, the older car continually came out ahead.
All who drove the VC found it heavier in the steering, soft to the point of being "wallowy" (and even inclined to produce car-sickness Symptoms) and definitely slower through any given corner.
It did have traits which probably make it safer for less-experienced drivers. For Starters, the VC was more inclined to understeer — and when the tail did let go, it broke away more progressively and was easier to catch. The VB was inclined to be a little twitchy in the rearend and would, on occasions, poke its tail out quite suddenly — although it never wor-ried us.
THE SLALOM TEST
WE TESTED the handling of the two cars through the slalom rather than on the corners of a race cireuit because the added power of the VC would have distorted the results. The slalom almost offsets any power advantage, bringing the result back to a fairer comparison. We say almost because it is possible to accelerate through the last couple of cones because it doesn't matter if the car is unba-lanced after it passes the last cone and timing mark.
This is, in fact, what we were doing with the VC and it was gaining a noticeable advantage in that last burst. Yet it still came off second best to the VB.
The other surprising factor which showed up on the oscilloscope was that the breaker-less electronic ignition system(which is sup-posed to do away with loss of tune due to points wear and burning) showed a Variation of five degrees in timing from the "earliest" to the "tatest" cylinder. That's more than would be tolerated from a worn-out distributor and, by comparison, the VB showed a Variation of only two degrees.
The electronic ignition, while supposedly more trouble-free than the old type, doesn't lend itself to do-it-yourself-type roadside re-pairs either.
But, strangely, this timing Variation had no apparent effect on the Performance of the engine.
The VB (top left) looked and feit more stable through the slalom than the VC (top right) and was also faster. The interior (above) has changed very little.
MODERN MOTOR, June 1980
We checked the tyre pressures to make sure they were the same on both cars and we had two passen-gers in each car at all times. First Lake would have three consecutive runs in one car, then McKay would do likewise in the same car. The other car would then do the routine —three runs with one driver, three with the other. Then we repeated the excercise.
After the first set of runs the VB was best with an average of 72.6 km/h to the VC's 70.9 km/h. On the second runs, with both drivers improving with practice, the VB scored 74.4 km/h, the VC 72.6 km/h. The averages of all times worked out with about the same advantage to the VB.
At all times both drivers felt more at home in the VB and the figures bore this out.
THE CHANGES made to the suspension include teflon piston rings and re-valving in the front struts "to improve ride", similar modifications to the rear shock absorbers, progressive rate springs all round, and slightly stiffer front anti-roll bars with considerably softer rear anti-roll bars. While we
are prepared to concede that the car might handle better in some circumstances, it didn't handle better in the type of driving we and, we believe, most city-based Commodore buyers would use it for.
WE'RE NOT anti-Commodore. We like the car and we've liked the VB since it was first released. And we're not saying that the VC is a bad car. To most potential buyers doing a round-the-block test drive the car would feel great — there's plenty of power and a pleasant ride. Even owning it, one wouldn't be unhappy with it. But, up against its predecessor in a straight out comparison drive, we found it no better. What it has gained in power it has lost in handling. The rest is little changed. We can't look on it as any more than a giant step sideways.
We'd reckon the older car at end-of-model sellout prices is probably a good buy and, if you really want a good Commodore, try to track down the "special" built for the Total Oil Economy Run (but which didn't compete). It had the new engine in the old car. That would probably be the best six-cyl inder Commodore of them all!
The engine in the new VC Commo-dore (above) looks unchanged at first glance, being based on the 17-years-old power plant first introduced in the EH Ho/den, but detail improvements have boosted power considerably.
MODERN MOTOR, June 1980