2006 Honda Civic Si, Part 1

The eighth generation Honda Civic represents a legacy that dates back to the early 70’s. What started as an economy car evolved into the leader of the import tuning revolution of the early 90’s. Even though Subaru’s STI, Mitsubishi’s Evolution and Nissan’s Z have become exceptionally popular in the sport compact segment, an army of Honda loyalists continue to support the Civic banner, and Honda continues to answer with the Si.

Text by Richard Fong // Photos by Jeren Walker, Vinh Nguyen and Richard Fong // Wrenching by Jeren Walker

DSPORT Issue #102


K20Z3 Engine

The FG2 Civic Si coupe and the FA5 Civic Si sedan share the same naturally-aspirated (N/A) K20Z3 engine that boasts nearly 100 horsepower-per-liter. The two-liter mill features Honda’s revised variable-valve timing and lift technology, intelligent-VTEC (iVTEC). The new system permits active phasing of the intake camshaft for improved low and midrange power. As the successor to Honda’s venerable and still widely popular B-series engine, the K-series is gaining popularity as a swap-in engine into multiple platforms, garnering further support from aftermarket manufacturers.

The Parts

test-tune-civic-si-102-005For this first Test and Tune session with the Si, we wanted to evaluate the efficiency of standard mineral engine oil compared to synthetic racing oil. Torco SR-5 Synthetic Racing Oil features a combination of synthetic base oils along with additives designed to withstand grueling racing conditions while still effectively lubricating the rotating assembly. According to the manufacturer, the SR-5 formula should also reduce friction loss, effectively freeing up horsepower. test-tune-civic-si-102-007The next easiest horsepower improvement should come from replacing the restrictive factory air intake system. Most factory intakes consist of a rubber hose that draws air through a filtered air box en route to the intake manifold. Factory intakes usually use a paper-based filtration media and the intake system is generally designed with low cost and the reduction of intake noise as a priorities. The Injen Technology Short Ram intake employs an aluminum pipe that features its proprietary MR (Mega Ram) Technology. MR Technology combined with Injen’s proprietary cone filter design should facilitate improved airflow which the manufacturer states has been tuned to deliver horsepower gains without creating a lean air/fuel mixture. test-tune-civic-si-102-009After an intake system replacement, the next most common performance improvement requires replacing the exhaust system. While allowing an engine to breathe more easily helps to free up horsepower, a larger exhaust pipe diameter helps to reduce power-robbing pumping loss. We turned to Skunk2 for its Racing Mega Power exhaust. Constructed from T-304 stainless-steel, each exhaust features application specific pipe diameters for optimal performance. The 70mm exhaust for the Civic Si includes all pipes, gaskets and hardware for a complete catalytic-back system, finished with an N1-style muffler and removable silencer.