How can you not love an over-achieving motor like the Integra Type Rs B18C5? To squeeze 195 hp from just 1.8 liters is quite a feat. Far more than just a red cam cover, the Type R motor gets its own unique higher compression pistons, more aggressive cams, among other tasty mechanical bits that let it howl as few passenger car motors ever have. The B18C5s ability to produce power is predicated on its ability that it can rev to heights that would annihilate lesser motors to gulp in the volumes of air necessary for such a high-per-liter specific output.
The Meguiars/HKS approach toward maximizing the power of the B18C5 under the hood involves forcing more air into the combustion chambers, using turbocharging and supercharging. The quest to do something completely different in a show car led to this Twin Charger solution after twin-turbocharging had been abandoned due to packaging constraints. Borrowing a page from the Lancia Group B rally program, HKS opted to use the Meguiars Type R as the test bed for this Twin Charger system.
The goal was to squeeze the fattest power curve from the 1.8L mill from idle to redline. In concept, the lag-free supercharging would boost torque under 4,000 rpm and low speed response, while the turbocharger would enhance the B18Cs penchant for top end power.
The primary requirement for this system was that it be a bolt-on affair. As such, there would be no use of lower compression aluminum piston forgings, a steel or reinforced head gasket, or any other trick done to the stock bottom end. The dual compressor system has been bolted to the Type R motor with a high 10.6:1 compression ratio, stock cast (though coated) pistons, and a stock head gasket, in much the same way that most enthusiasts would. This exercise sought to explore how far the term bolt-on could go toward improving performance.
The pressure-inducing components of this system are the self-lubricating Eaton blower and the HKS 2835 ball-bearing turbo. The air charge, which is force-fed to the blower by the turbo, is intercooled. As a result, the air gulped by the roots-blower is at or near ambient air temperature. The turbo is responsible for the majority of the boost, about .6.8 bar while the belt-driven blower accounts for about .3.4 bar, and given the roots-blowers design, has a tendency of heating the air charge a bit. Getting this sort of combination to survive without succumbing to the death-knock of detonation on the stock motor would be the challenge facing HKS engine guru Jon Kuroyama. The only way that double boost, high compression, and pump gas can co- exist without grenading the motor is the HKS F-CON S fuel/spark computer. The F-CON S is a piggyback system that connects to the stock Acura ECU and permits the fine-tuning of the spark and fuel parameters required by this unique pressurized combination.
The F-CON S system allows the injector duty cycle to be increased, providing more fuel to create power and cool the chamber. Additional fuel is necessary to make power, but also to avoid the lean fuel type condition that can lead to detonation and damage. with the F-CON system. The duty cycle can be tuned in 250 rpm (increments) for optimum fuel delivery across the powerband. In this case, the injector duty cycle is manipulated for operation between 60 and 90 percent of its capacity.
Meeting such fuel demands requires the use of an adjustable fuel pressure regulator and an electric Bosch racing pump that provides between 42 and 45 psi static pressure and about 60 psi under load. The F-CON Ss tweaks to the stock timing map shows between 3 and 6 degrees of timing retard after the VTEC kicks in with about 26 degrees of total timing. The F-CON S also allowed the timing to be backed down just before the VTEC point (5,800 rpm) to help prevent detonation as the power dipped momentarily while the VTEC cam profiles engaged.
Achieving a banzai dyno run required that the injector duty cycle be maxed-out and set the timing on the ragged edge of detonation inducing cylinder events, and with the total boost cranked to 1.5 bar (22.5 psi), 442 hp was attained on the DynoJet. This is dyno horsepower (with special sauce in the tank) with parameters for fuel and spark governed as the car rides on rollers. On the street, this combination could survive comfortably at a playful and reliable 325 hp, but its ability to create power makes a convincing argument for the F-CON S as a tuning aid.
This streetable compressor combination succeeds at fattening the torque of the engine at lower rpm, while the belt-driven compressor additional power builds more exhaust energy to help spool the turbo faster, and build top end power after the VTEC point. With some more fine-tuning, HKS hopes to soon offer this system as the ultimate bolt-on kit for the enthusiast who just cant seem to leave well enough alonewhich is all of us, really.