Japanese Car Spotters Guide - 1983

Also see: 1983 Australian Car Spotters Guide | 1983 European Car Spotters Guide | 1983 American Car Spotters Guide

Despite the strenuous efforts being made to reduce fuel consumption, the basic design of the petrol engine, which of course powered the vast majority of cars in 1983, changed relatively little. There were a few innovations, however - several of them Japanese. On the engine fitted to the front-wheel drive Toyota Corolla introduced in May, for example, each intake port splits into two passages of unequal size. The smaller of the two is curved to promote swirl during low-speed running. The larger offers less obstruction to the incoming mixture but is sealed by a swirl control valve (SCV) which opens under the innfluence of manifold pressure only when more power is needed. In this way parttthrottle economy is improved but fulllthrottle power remains unimpaired. Similar reasoning led to a rather different physical arrangement in the four-cylinder l2-valve Honda engine introduced with the new Prelude and now used throughout the range. In this engine each combustion chamber is provided with two inlet valves, the opening and closing of the first being timed so that there is no overlap between it
 
and the single exhaust valve which lies directly opposite. The second valve is laterally displaced from the first to create an L-shaped configuration and its timing does incorporate overlap. At low speeds and throttle openings, however, the lag imposed by the longer gas path associated with the lateral displacement cancels the overlap effect so that very little unburnt mixture passes through the combustion chamber to be wasted in the exhaust system. But at the increased gas velocities associated with higher speeds and larger throttle openings, the longer induction path represents no significant obstacle, and the benefits of valve overlap for top-end power are retained.
 
The advantage of using more than two valves for each combustion chamber of a spark-ignition engine have been known at least since Ernest Henri designed the fourrvalve engine of the 1913 Grand Prix Peugeot. The reasoning is simple: the total area of the four largest valves that can just be squeezed into a surface of a given size is considerably greater than the area of the two largest valves that can be squeezed in. For it is always possible to cover a given area (or fill a given volume) more completeely with a large number of small objects than with a small number of large objects: the boot of a car, for example, will accommmodate a greater volume of table tennis balls, which fill every corner, than of suitcases. And with more area more mixture can be drawn in on every stroke and more power developed. In a four-valve configuration, too, more area also becomes available to cool the valves, while their lower individual inertias makes it possible to reduce valve mechanism stresses.
 
This configuration, virtually a standard design feature of racing engines, has long been used for high-performance roaddgoing power units also, and was recently adopted by Daimler-Benz for a sporting version of the 190. The special twin-cam 166valve cylinder head was developed with the help of Cosworth Engineering in Britain, who will be supplying the basic castings, and is mated to the bottom end of a standard Mercedes 2.3,liter engine. The result is a 185 bhp road-burner capable of 235 km/h, with acceleration to match, which has already broken a string of records at Nardo and must be making BMW very nervous, even though it won't be available until next July. Just recently, though, a number of manuufacturers have begun to realize that the four-valve combustion chamber has other advantages. Perhaps partly because of its tolerance of high compression ratios owing to excellent exhaust valve cooling, perhaps partly because of the high turbulence associated with two separate jets of inncoming mixture, it is also known for the outstandingly good specific fuel consumpption that can be extracted from it. Both Saab and BL Technology have acknowlledged their interest in this potential and their intention of developing engines designed to exploit it.
 
For the most part, though, petrol engines changed relatively little in mechanical design during the last twelve months. Compression ratios were raised a little and mixtures made a little leaner, but no radical combustion systems were introduced or new mechanical arrangements put into production. But those lean burn/high compression combinations are very often only made possible by the microchip and the sophissticated electronic engine management systems it makes possible. Systems of this sort, such as the Bosch Motronic, are no longer to be found merely on up-market fuel-injected cars of the BMW class, but are very rapidly being fitted to low-cost highhvolume models with carburetters, while breakerless transistorized ignition systems are swiftly becoming the norm. Thus the ignition timing of the engine fitted to the new Fiat Uno ES model is no longer controlled by the usual centrifugal and vacuum arrangements, but by the Marelli Digiplex system. The new Austin Maestro retains a conventional ignition timing system, but has quite an elaborate elecctronic engine management system, conntrolling an overrun fuel cut-off, cold starting and warm-up.

Advances in diesel engine design were gradual in 1983. Ford were claiming high efficiency for their new lightweight four-cylinder unit availlable on the Fiesta, but it was essentially of the conventional indirect-injection type. A number of manufacturers talked about introducing the fundamentally more efficient direct-injection engine in a form suitable for automotive applications but none had managed to do so for their 1983 models. Perhaps the boldest step was taken by Daihatsu who introduced a tiny three-cylinder diesel for their revamped Charade model - thus creating what must surely be the most potentially vibratory power unit for transport purpose to be seen outside a boat. Early reports, however, suggest that it is a good deal less rough than might perhaps be expected. Another important innovation, but of a different sort, was introduced by Honda in the form of the four-wheel anti-lock brake (4W-ALB) system fitted to the new Prelude.

The control logic of this differs from that of existing systems such as the Bosch ABS design. In the Honda system the rear wheels are controlled as a pair with "select low" logic determined by the conditions necessary to prevent the wheel with the lowest grip from locking up, while the front wheels are controlled as a pair with "select high" logic - which means that the low-grip front wheel is allowed to lock up as long as the high-grip one does not. Honda claim advantages for this system, but tests suggest that while it works well enough, it does so in a crude and unrefined way compared to the ABS system. But its significance lies far less in the details of its performance than in the fact that Honda have brought anti-lock braking within the reach of the ordinary motorist by developping a relatively inexpensive system.

 

	Toyota Corolla Sedan and Wagon
	Also see: Toyota Car Reviews
	An important new Japanese car for 1983, from the point of view of world markets, was the front wheel drive Toyota Corolla. The Corolla name covered both sedans and coupes, and although the entire range was updated, only the sedans were equipped with the newly developed front wheel drive package. Toyota's action was more understandable when considered in the light of their marketing organization in Japan, where different models were sold through different dealer networks; it was only in export markets that one dealer would handle the entire range. The sedan and hatchback versions of the Corolla were fairly typical of large-production Japanese cars of their generation, efficient without being outstanding, and their styling was somewhat bland. The range of power units was wide, covering 1.3, 1.5, and 1.6 liter petrol engines and a 1.8 liter diesel. The engines were mounted transversely, unlike the smaller Tercel, which had a north-south layout, but there was still quite a lot of Tercel in the mechanical make-up of the cars. The coupe made up for its lack of a new drive set-up with the availability of a sophisticated four valves per cylinder 1600 cc twin cam engine utilizing an unusual induction system developed in collaboration with Yamaha, who built many of Toyota's high performance engines. The system involved a butterfly valve in the inlet tract for each cylinder which opened and closed in relation to engine speed. Toyota claimed that it improved drive ability and torque at low speeds.