Hyundai's 1.6 DOHC Four delivers good power from an efficient design
Automotive engine designs used to change about once every couple of decades. The small-block Chevrolet, for example, remained essentially unchanged for over thirty years, as did Ford’s small V-8. And DaimlerChrysler’s 5.9L product can trace its lineage to the B-engines of the ’60’s. That sort of longevity simply isn’t possible in today’s market, and with emissions, fuel efficiency and power all in demand simultaneously, ten years is too long for most engine designs, especially high-revving four cylinders. Hyundai is no exception, and their 1.6L four, offered in the Accent GSi, is an example of a modern powerplant spun off a basic design that’s only five years old itself.
The 1.6 has its origins in the 1.5L “Alpha” engine used in the Accent since 1995, but although the design is similar, the newer engine produces significantly more power with reduced NVH (noise, vibration and harshness). The four-valve 1.6 generates 106 HP at 5800 RPM, and 107 ft./lbs. of torque at a useable 3000 RPM. Those numbers are up from 92 HP and 98 ft./lbs. of torque (at 4000 RPM). The extra 100cc of displacement comes from a change in bore and stroke from 75.5mm by 83.5mm to 76.5mm by 87mm. The block has been redesigned, and is deeply ribbed for rigidity, and the crankshaft features eight counterweights (four were previously used) for lower torsional vibration. On top, double overhead cams and a new 110-tooth timing belt, which is not interchangeable with pre-2000 Alpha engines, actuates sixteen valves. The compression ratio is 10-1, and that compression is contained by a cylinder head-block deck-mating surface that has been precision finished to a five-micron (peak to valley) roughness limit with a flatness of 0.03mm in the usual crossways check. The super smooth finish allows Hyundai to replace the multi-layer head gasket with a single layer type, requiring a switch in torquing procedure to the torque-angle method used in Hyundai’s Beta engines.
The engine is dressed with new ancillaries that improve reliability and simplify service. The intake manifold, for example, is now a single piece design, reducing the chance of a vacuum or air leak, and the exhaust manifold features the catalytic converter MIG welded directly to the exhaust “flange”. The design simplifies undercar exhaust piping and allows faster converter “light off” for a faster transition to closed loop operation. Note that there are two oxygen sensors, one before and one after the converter. The rear sensor is easily accessed from beneath the vehicle. On the intake side, the intake air system has been shortened and simplified, with the filter box now fastened with clips in place of bolts used previously. Ignition is by a dual-coil distributorless system that’s up front and high-mounted for easy service.
Several sensors are now clustered to reduce the number of vacuum lines and ease serviceability. The Idle Speed Control Actuator, for example, is now integral with the Throttle Position Sensor at the throttle body. Unlike the 1.5 12-valve-engine, the 1.6 has no Mass Air Flow sensor, (it uses a MAP only), with the Intake Air Temperature Sensor residing at the intake air box. A new, shorter intake air tubing run allows remote IATS sensor positioning with good fuel injection metering precision, and lower noise. On the injection side, the bypass fuel system has been replaced with a single-line (no return) 50psi design.
Hyundai’s 1.6 Alpha isn’t stuffed with variable valve timing, turbochargers or drive-by-wire electronics, but produces very good power and economy in a package that’s drastically simplified when compared to similar engines of a decade ago. Modular design, fewer vacuum hoses and neat packaging make this engine perform well, and still remain easy to service.
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