Completing the whole performance package

The owner also wisely upgraded other crucial parts of the car. Eibach Sport-Line performance springs were installed to complement the GAB adjustable shocks that he already had. The Sport-Line drops the car by more than 2" and are tuned purely for performance so handling was improved by a large margin. Rather surprisingly however was the relatively good ride while the large amount of lowering did not cause a lot problems with undercarriage scraping.

The brake rotors were replaced by Powerslot slotted discs and the pads were later replaced with Endless brake pads, sourced from a third shop. The replacement of the pads were necessary because the upgrades allowed him to push the car so much harder that he experienced brake fade during spirited street driving. To improve the braking to the highest possible street level, the standard rubber-based brake hoses were replaced by steel-braided TEFLON hoses and HKS Super-DOT4 Racing brake fluid were used.

Earlier this year, a camber correction kit was installed for the front suspension because the owner didn't like the amount of camber change introduced by the Eibach Sport-Line's more than 2" drop (though apparently the absolute amount of deviation from factory recommended specs was really not a lot). Finally when the clutch was replaced, it was decided that the synchros in the gearbox were starting to fail so the transmission was replaced by a used-import unit from a specialist 'used-parts' shop. Rather fortunately for the owner, the replacement unit had the optional Honda viscous-coupling LSD fitted. The LSD made a significant improvement not only to handling but also to road-holding of the car. Dumping the clutch even on a wet road produced very little wheelspin which allowed the tyres to hook up very quickly enabling extremely rapid take-off. These final items completed the upgrade package to the car.

Quantifying the Power Upgrade

The owner did not do a benchmark dyno-test of his car prior to the project so we do not have a reference starting point for engine power.

However stock output of the B18C was rated at 180ps. With FWD, typical transmission loss was 11% to 15%. While 11% would be applicable to brand new engines/transmissions, a 15% loss would be more typical for a 1993 vintage engine/transmission. Using a 15% loss will give a power rating of around 150 - 153 PS at the wheels. This level would have been easily achievable since the owner maintained his car very carefully. This is supported by a 148ps dyno-run of a fully stock 1996 DC2 and a listing of 149ps for a 1995 DC2 Integra SiR-G on the Internet. Both these cars uses essentially the same engine. Therefore for this study, we should be able to safely use 148ps as the baseline power for this 1993 DC2.

The dyno-tune for the car actually started with a base of B18C with only the Tanabe header and exhaust system installed. This dynoed at 152.4ps at the wheels on a Dynojet. Peak power was generated around 7500 to 7600rpm, as per the spec, so this run also showed that the engine was in a good state of tune.

Next the HKS Super-Power-Flow air-filter system was installed. The stock air-filter box system was discarded since the HKS SPF is an open-element design. Addition of the SPF now allowed the engine to dyno at 155ps, again with essentially the same power curve profile. However a more important gain from the HKS Super-Power-Flow was the big increase in mid-range power, from 2500rpm to 6000rpm. Max power gain was close to 5ps at two points, below 4000rpm and again around 5000rpm. Thus the 2.5ps gain in peak power did not show the benefit of the open-element design of the HKS in full light - the gains in mid-range would have more impact to driveability than the peak power gain.

While the stock Honda ECU is more than capable of compensating for the increased air-flow from the filter-header-exhaust system, it is still tuned based on Japan's atmospheric conditions (the car being a JDM used-import). Thus the potential for fine-tuning the air-fuel ratio by the HKS AFR. This is the last item to be installed. Tuning of the AFR is relatively straight-forward but necessary, in order to realize the max power gains from mods. In this case, after properly setting it via a Dynojet tuning session, the AFR managed to up the power further to almost 158ps at the wheels, increasing the power by almost as much as what the Tanabe headers/cat-back system gave ! The AFR gave more increase at high RPMs, from about 5500rpm till the 8000rpm red-line.

Conclusion

There are two basic methods to convert the 158ps at the wheels rating back to engine power. Using the 15% transmission loss will give us an engine flywheel rating of about 186ps, 6ps increase from stock. However, an alternate assessment would be to base it on our assumed stock wheels-power of 148ps. If we use this as the base, then 158ps will mean a 10ps increase on wheel power and will work backwards to about 192ps engine flywheel power. So we should be able to say that the whole engine tuning package gave it more than 10ps increase in engine flywheel power. It should also be noted that the Super-Power-Flow/AFR combination alone gave almost 6ps power increase to the wheels. The more than 10ps engine power increase represents an impressive increase which speaks well for the high spec nature of the B18C.

Equally important too is the balanced approach taken by the owner. When engine power is upgraded the other areas such as handling and braking should be upgraded in conjunction. After being able to go very fast, one should be able to stop very fast (and safe) as well ! It doesn't really matter which part is worked on first as long as one exercises sensibility during the whole implementation. This is the basic principle which the owner followed with this upgrade exercise.

September 2000
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