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April 1989 - Honda unleased the
irresistable seduction of a race-tuned high-revving street car upon an
unsuspecting public. This is the DA-generation Honda Integra, the first
VTEC Honda. Fitted with the legendary B16A, the Integra came as both DA6
2-door Coupe and DA8 4-door Sedan and in two trims, the basic
no-frills RSi and the high-end XSi which comes with
options of climate control, sunroof, and a 4-channel
anti-lock braking system. The 1st generation B16A in the Integra XSi/RSi
has a 16V DOHC design and uses VTEC to enable the heavy use of racing
technologies in a street engine. This enables the little B16A to generate an
incredible 160ps from only 1.6litres, and the ability to rev to a then unheard
of 8000rpm red-line ! The rest as we know well is now history.....
The JDM DC2 Integra Si-VTECThe JDM Honda Integra changed generation in early 1993. The new model, coded DB for 4-door and DC for 3-door received a body revision and quad-projector headlights. The most significant change however was the engine upgrade, from the 1.6l B16A to a longer stroke 1.8l DOHC VTEC B18C with a new intake manifold. The B18C engine red-lines at 8000rpm and generates 180ps at 7600rpm. Although only 10ps higher than the current B16A, its bigger displacement and the special intake manifold gave much better low-end and mid-range making it more driveable over the B16A especially with kerb-weight being only moderately increased. 
The new B18C intake manifold uses two sets of intake runners. The cut-away diagram of this intake manifold on the right shows how the runners are arranged. A marks the plenum (which the throttle body attaches to). B is where the intake runners attaches to the cylinder head. C is used to give readers a sense of perspective, it marks the fuel injectors. The top set of runners are curved around the lower set making it longer. The lower set of runners have butterfly valves built into them (marked by D). During low and mid-rpm operations, the valves are closed and only the top set of runners are feeding air into the cylinders. After 4400rpm, the butterfly valves open and air will now be fed into the cylinders via both sets of intake runners. This new intake system works in conjunction with VTEC, which now switches at 5800rpm, to optimize air-flow into the cylinders at all rpms making the power/torque curve of the B18C extremely wide and flat. Peak torque of the B18C is 17.8kgm at 6200rpm but torque output of the B18C is already near or at 17.0kgm all the way from approx 2500rpm right until the 8000rpm, a smaller than 5% spread for practically all operating rpms !!
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