1987 Technical Highlights
A look at what’s new
By Greg Raven
Auto Pacific magazine
June 1987, page 71
If you have attended an auto show lately, you know that many of the Japanese manufacturers are working on “concept” cars, cars that incorporate advanced technology to push forward the current state-of-the-art. The whole idea behind concept cars is that they must explore technology of the future in order to determine whether or not the designs are appropriate for production vehicles.
Eventually, the results of all this research and development trickle down to us tire-kickers. Here, then, is a sampling of the latest in what’s available from each of the manufacturers.
The Integra and Legend hardly seem to have been manufacturered by the same company. Where the Integra gets a DOHC 4-cylinder engine, the Legend gets a SOHC V6 (see below). The Integra has torsion bar strut front suspension, while the Legend gets a double wishbone front end. In the rear, the Integra has a three-link beam; the Legend has Honda’s new reduced friction strut (RFS) suspension.
Both cars have 5-speed manual or optional 4-speed automatic transmissions (the automatic has a lock-up torque converter), and both have power-assisted 4-wheel disc brakes. However, instead of power-assisted rack-and-pinion steering found on the Integra, the Legend is fitted with speed-sensitive power steering that can be a bit disconcerting at times.
The 2.5 liter SOHC 90 degree V6 engine found in the Legend is a curious admixture of the good and the latent. Its 151 hp don’t make it the most powerful 2.5 liter 4-valve currently available, possibly because not all hands seem to be pulling at the oars: the compression ratio, at 9.0:1, is lower than it could be; the ignition system is transistorized but not computerized; and, while “4-valve engine” might be the buzzword that sells cars, the monkey-motion actuators for the exhaust bank must be a concession to space limitations in the engine compartment, if not to cost of manufacturing.
We would expect that Honda will address at least some of these issues in future versions of this engine. Compression could be raised to well over 10.0:1 and digital ignition management could join their already computer-controlled fuel injection to help overcome the additional internal friction of the six-cylinder design (as opposed to a 2.5 liter 4-cylinder engine).
One thing they may have a problem with, however, is lessening the peakiness of the torque curve. Motors with big fat torque curves are usually much more pleasant to drive than those with high, narrow torque peaks. The Legend V6 falls into the latter category, with 154 lb/ft of torque at 4500 rpm.
The three-cylinder Suzuki-built Chevrolet Sprint can now be had with an intercooled turbocharger, boosting the horsepower from 47 to 70, a 46 percent increase. Torque goes up from 58 lb/ft to 80 lb/ft. The IHI turbocharger is water-cooled for to help reduce oil coking and premature turbo bearing failure, even with the 230,000 rpm “redline” for the turbo.
The Turbo Sprint still runs on 87 octane fuel, necessitating the use of a multi-port L-Jetronic fuel injection and electronic ignition with knock sensor. Internally, the Turbo Sprint uses hollow design camshaft and crankshaft for reduced weight and forged connecting rods for strength.
All this adds up to 0-60 times of less than 10 seconds (as compared to the base Sprint’s 13.5 second 0-60). The penalty is that the Turbo Sprint gets 37 mpg city and 41 mpg highway, still good, but not quite the Sprint’s outstanding 44 mpg city and 50 mpg highway.
Ford’s contributions to the rapidly heating up B-Class vehicle category are the Festiva and Festiva LX. The Festiva makes use of a lot of tried-and-true technology, concentrating more on execution than originality to score points with car buyers. In this category, front-wheel drive is a given, as is the MacPherson strut front suspension. The front sway bar on the Festiva doubles as a locator for the lower suspension arm. Like others, the Festiva also has manual rack-and-pinion steering and torsion beam rear suspension. Stopping power is supplied through power assisted front discs and rear drums, which, in our opinion, could use abit more swept area.
The Mazda-built engine in the Festiva is a carbureted, overhead cam, two-valve, 1.3 liter four-cylinder with a cast iron block and aluminum alloy head. Maximum output is 73 lb/ft of torque at 3500 rpm, good for 58 hp at 5000 rpm.
The base Festiva comes with a 4-speed transmission, while the Festiva LX sports a 5-speed. In both cases, top gear provides an overdrive for better mileage. The Festive LX also gets wider wheels and tires than the Festiva. Tires for the Festiva are size 145/SR12 on 12 x 4-inch wheels, while the Festiva LX gets slightly larger (but still undersized) 165/70SR12 tires on 12 x 4.5-inch wheels.
To help push up the fuel mileage, Ford has invested in some aerodynamic aids for the Festiva, including frameless and flush headlamps, flush door handles, low profile glass moldings, and a drag coefficient of 0.36.
Although most of the news from Nissan comes from the styling department, there are some new technical highlights for both the Pulsar NX and the 300ZX.
The Pulsar NX, for example, has two engines available. The standard engine puts out 70 hp (94 lb/ft of torque) from a SOHC 1.6 liter with SPI fuel injection, running at 9.4:1 compression. Those who want some go to match their show will opt for the 113 hp (99 lb/ft of torque) DOHC version, which runs at 10.0:1 compression using MPI injection. The gear ratios are different for each motor, and the DOHC comes only with a 5-speed manual transmission, whereas the SOHC is available with either a 5-speed manual or a 3-speed automatic.
In the 300ZX camp, the entire suspension has been recalibrated. The front springs, bushings, power steering pump, and stabilizer bars have been upgraded for firmer cornering and improved steering response. In the rear, a 24mm solid stabilizer bar has been added to help flatten corners. The shock absorbers are now cockpit adjustable with three settings. Stopping distances have been shortened with 4-wheel ventilated disc brakes and larger calipers.
Under the hood, the biggest change is that the fuel injectors are now are designed for bottom flow for smoother idling.
Subaru’s new Justy offers several interesting features, not the least of which is the performance. The Justy’s 1.2 liter 3-cylinder engine utilizes three valves-per-cylinder and a balance shaft (normally found only on engines larger than two liters) to pump out 66 hp and 70 lb/ft of torque. Even with the 0.38 coefficient of drag, it manages to push the Justy to 60 mph in 11.6 seconds and through the quarter mile in 18.4 seconds.
The balance shaft helps smooth out the pitching and yawing caused by the piston and crankshaft counterweight couples that are inherent in a 3-cylinder engine. The difference between the balance shaft in the Justy and others is that 1) there is only one of them, and 2) it rotates at crankshaft speed.
Underneath, the Justy is suspended on MacPherson struts fore and aft. Steering is accomplished with a non-powered rack-and-pinion, while braking is handled by power-assisted front discs and rear drums.
Elsewhere from Subaru, full-time 4-wheel drive is now available in the Sedan and 3-door coupe, the Sedan, Wagon, and XT can be ordered with a pneumatic suspension system, and the Subaru Turbo now comes with computer engine management.
Fitting four valves per cylinder instead of the normal two aids air flow into the motor at high rpm. Turbocharging does the same thing. It would seem to make sense, then, that turbocharging a 4-valve engine would result in power that would all come in on the big end.
In the Supra Turbo this isn’t the case. In fact, the torque “curve” is relatively flat from just under 2,000 rpm to the 4,000 rpm torque peak. That’s “flat,” as in “foot flat to the floor,” when the car “flat out accelerates.”
What’s the secret? The 7M-GTE motor is built for torque. The comparitively long stroke (91 mm/3.58 inch) and small bore (83 mm/3.27 inch) may limit how tight the 3.0 liter can be twisted, but down low where most driving is done the power is there on demand.
In the Supra Turbo, this actually turns out to be less of a convenience than it is a necessity. By the time the turbo has pumped pressurized air up the side of the engine, through the intercooler, and into the engine intake, several feet of plumbing have been taken into consideration. With this designed-in turbo lag, the naturally strong low rpm performance of the 7M-GTE motor helps smooth throttle response. In other words, although adding the turbo provides the frosting on the cake, the cake itself is not too bad all by itself.
The 7M-GTE turbo engine also inherits dual overhead camshafts from the 7M-GE motor, but where the normally-aspirated motor is set up with 9.2:1 compression, the turbo motor at 8.4:1 gives away a few points to make room for the turbo to work.
Lowering the compression ratio to accommodate the turbocharger is fairly common practice. Using your own turbocharger isn’t, but that is what Toyota does. Like the turbos sold by the “big name” turbo manufacturers, Toyota turbo housing is water-cooled to encourage turbo bearing longevity. To encourage motor longevity, the Supra Turbo runs the engine oil through an auxiliary oil cooler.
With the mechanical aspect of the Supra Turbo motor so well handled, it is nice to see that Toyota also spent some time on the fuel and spark delivery systems. Their solution is the Toyota Computer Controlled System (TCCS). The TCCS is a “closed-loop” system, meaning that it constantly monitors its own performance and modifies fuel delivery, spark timing, or both to meet emissions requirements. In addition to an oxygen sensor, the TCCS checks twelve other sensors, including knock, intake air temperature, coolant temperature, altitude, throttle position, vehicle speed, rpm, and (of course) boost.
Although most of the hardware and firmware in the Supra Turbo is most accurately classed as “medium tech,” it works just fine and it leaves Toyota in the enviable position of having plenty of room to improve performance without having to boldly go where no auto manufacturer has gone before.
71A) The Integra’s torsion bar MacPherson strut front end (right) are similar to that in the Porsche 911. The rear suspension features progressive rate springs and gas shocks.
71B) The Legend V6 is smooth and quiet, but could benefit from more low-end torque.
72A) The Festive motor has a single overhead cam, cross-flow head, and direct-drive distributor.
72B) MacPherson struts and unequal length driveshafts provide the front underpinnings for the Festiva.
72C) The Festiva rear torsion beam also acts as an anti-sway bar.
72D) Subaru offers high-tech 4-wheel drive using reliable low-tech ring-and-pinions.
72E) Ignition in the Turbo Supra is computer controlled, using three coils (two plugs per coil) and no traditional distributor. Also note the oil nozzles for piston cooling.