Import Tuner Magazine Homepage
Facebook Click here to find out more!

Power Pages: 2004 Honda Civic Si

Text By Jasper Chan, Photography by By the Author
2004 Honda Civic Si Front Left View

Owner: Anthony Yu
Dynamometer model: SPEngineering Dynoject Chassis Dnyo 248e
Testing: Jasper Chan

Dyno 1

Baseline

139.4 hp 126.4 tq

0411It Ppcivic 02 Z

Pros

I have been an avid Honda enthusiast for most of my life. My first ride was a baby blue 1984 Honda Civic DX with blue vinyl interior. It was modified with a 4-1 header from a Civic Si I found at the local Pick-a-Part and a muffler shop special exhaust system. It might not seem like much by today's standards, but it was my pride and joy. Since then I have owned the next three generations of Civics: the EF (1989-'91), EG (1992-'95) and EK (1996-'01). Each generation of Civic refines the chassis, engine and overall vehicle quality. When Honda decided to release the latest incarnation of Civic with a chassis code of EP, I couldn't wait to get my hands on one. But the question arose: "Would the EP Civic be better than the previous generation?" Well, we decided to borrow a brand-spanking-new Civic Si and see how well the Honda responded to bolt-on performance parts.

Cons

If you are used to having the shifter on the floor, it might take a while to get used to the dash-mounted shifter of the Civic Si. One thing you notice driving the Civic Si is its weight; it is definitely not like the Atkin's-conscious EK Civic.

Temp

air temp @ 81 Degrees Fahrenheit

Notes

The good thing about the EP Civic Si is the powerplant, which it shares with the standard Acura RSX. The 2.0-liter i-VTEC engine is by far the best normally aspirated four-cylinder production engine Honda has ever produced. The square engine (86mm x 86mm) was engineered to be revved. When compared to the previous generation B-series engines, the K20 engines have a shorter stroke yet have a much larger displacement.


Dyno 2

Comptech Exhaust

0411It Ppcivic 03 Z

141.8 hp 126.0 tq

Pros

The Comptech exhaust is beautifully manufactured and finished. The flanges are CNC machined and the tubing is constructed from T-304 stainless steel. All joints in the exhaust are TIG welded, and the canister is polished to a mirror finish. Besides being well constructed, the exhaust performed well on the dyno. Compared to the stock exhaust, the Comptech system gained throughout the entire powerband with peak gains of 4 hp. Peak power was increased to 141.8 hp and 126.0 lb-ft of torque.

Cons

0411It Ppcivic 04 Z

The muffler section of the Comptech system is not as visually appealing as some Japanese counterparts. So if you are looking for an N1-style system, the Comptech exhaust is not for you.

Notes

Even on our brand-new Civic Si some of the nuts and bolts were hard to remove. Let the vehicle cool down and spray liberal amounts of WD-40 on the fasteners to prevent stripping.

Parts

Polished stainless-steel canister, mandrel-bent stainless-steel B-pipe, gasket, fasteners, stickers and instructions

Tools

12-, 14- and 17mm socket, 17mm wrench, ratchet and 6-inch extension

Intallation time

45 min

2000 to 3500 HP range: 1-2 2000 to 3500 TQ range: 1-2

3500 to 5500 HP range: 1-3 3500 to 5500 TQ range: 1-2

5500 to redline HP range: 1-4 5500 to redline TQ range: 1-2

Peak HP 141.8 Peak TQ 126.0

Temp

Air temp @ 82 Degrees FahrenheitTemperature difference from previous run:+1 degree Fahrenheit


Dyno 3

comptech iceboxair intake system

144.9 hp 127.5 tq

Pros

0411It Ppcivic 05 Z

The Comptech Icebox air intake system is one serious intake system. Retaining much of the stock appearance, the Comptech system utilizes a high-flow foam filter and cold-air intake tube so the engine uses cooler, oxygen-rich air. The byproduct is more horsepower. On the dyno the Comptech intake increased power throughout the rpm band. Peak power rose to 144.9 hp and 127.5 lb-ft of torque.

Cons

Removing the stock airbox and installing the Comptech system is not easy. Be sure to read the instructions thoroughly.

Notes

The Comptech system requires some of the factory intake hardware.

0411It Ppcivic 06 Z

Parts

ABS plastic cold-air box, ABS plastic intake tube, high-flow foam filter, hose clamps, misc hardware, stickers and instructions.

Tools

10mm socket, ratchet and extensions; standard and Phillips screwdriver; needle nose pliers.

Intallation Time

25 to 40 min.

Temp

air temp @ 82 Degrees Fahrenheit

Temperature difference from previous run:+0 degree Fahrenheit

2000 to 3500 HP range: 1-2 2000 to 3500 TQ range: 1-2

3500 to 5500 HP range: 1-3 3500 to 5500 TQ range: 1-3

5500 to redline HP range: 2-3 5500 to redline TQ range: 1-2

Peak HP 144.9 Peak TQ 127.5


Dyno 4

comptech header

152.9.9 hp 127.6 tq

0411It Ppcivic 07 Z

Pros

The Comptech header performed exactly as we predicted. The larger piping and the 4-2 design increased power at the higher rpms but lost power at the lower. But the gains definitely out weigh the losses. At one point in the powerband we saw an increase of 8 hp.

Cons

Although we first cringed since the header sits next to the firewall-- unlike the D- and B-series engines, which sit up front--removing the system was much easier than anticipated.

Notes

0411It Ppcivic 08 Z

If you plan on reusing the steel metal exhaust gasket, we recommend coating it with copper spray. You don't want any leaks or to have to remove the system again.

Parts

Stainless-steel 4-2 header, instructions, stickers

Tools

10-, 12- and 14mm wrench, 12- and 14mm socket, ratchet, 6-inch extension, and pliers

Intallation Time

60 min.

2000 to 3500 HP range: 0-1 2000 to 3500 TQ range: 0-1

3500 to 5500 HP range: 1-2 3500 to 5500 TQ range: 0-1

5500 to redline HP range: 2-8 5500 to redline TQ range: 2-5

Peak HP 152.9 Peak TQ 127.6

Temp

air temp @ 82 Degrees FahrenheitTemperature difference from previous run:+0 degree Fahrenheit

Bankroll

1 Comptech Stainless Steel Exhaust $ 695.00

2 Comptech Icebox Air Intake System $ 289.00

3 Comptech Header $ 529.00

MSRP Total $ 1513.00

Conclusion

From the looks of our testing, the EP Civic is a worthy successor to the EK. The powerplant does well with bolt-ons, and the car is extremely solid all around. We just need to put the EP on the Atkin's diet, and it should be an all-out performer at the track.

Conclusion

HP Level HP+ TQ Level TQ+Baseline 138.4 126.4

1 Comptech Stainless Steel Exhaust 141.8 3.4 126.0 -0.4

2 Comptech Icebox Intake System 144.9 3.1 127.5 1.5

3 Comptech Header 152.6 7.7 127.6 0.1

Final 152.6 14.2 127.6 1.2

By Jasper Chan
Enjoyed this Post? Subscribe to our RSS Feed, or use your favorite social media to recommend us to friends and colleagues!

*Please enter your username

*Please enter your password

*Please enter your comments
Comments:
Not Registered?Signup Here
(1024 character limit)
Import Tuner