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2008 Honda Civic SI - Dyno 1: Baseline - Power Pages

Peak HP 172.1 / Peak TQ 121.7

Luke Munnell
May 1, 2008
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If we had to choose one defining "halo car" of the tuner movement it would have to be the Civic. Love it or hate it, the car's positive response to modification has made it popular with gearheads since its debut over 30 years ago. The Si hatchback of the late '80s really started to get things moving and by the time the '00 Si Coupe rolled into showrooms, the tuner movement was in full swing. Honda may have missed the mark with the EM Civic-which the States got stuck with in 2001-but quickly redeemed itself with the release of the EP Si Hatch in later years and the Si Coupe that followed. This month we test Honda's newest Si Sedan offering and find the platform has only improved with age; its K20 banged out just over 172 whp at baseline-12 horses more than could be generated at the flywheel of the stock B16A-powered Si we all lusted after just years ago.

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The si's K20 is a double-edged sword: mechanical improvements over its venerable B-series predecessors increase its efficiency and pave the way for power, but emissions requirements mandated in '08 vehicles keep it from reaching its full potential in factory trim-and create headaches for those trying to coax more power from it through the use of basic aftermarket parts, while maintaining street legality.

2019 Honda Civic
$21,450 Base Model (MSRP) MPG Fuel Economy
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In tinkering with Honda's latest Civic, we thought it only logical to call upon the assistance of a man who has been in the game long enough to have modi- fied the company's earliest Civics. Oscar Jackson oversaw this month's installs and testing, from within the accommodating confines of the Skunk2 Racing/ Kraftwerks Performance headquarters in Norco, Calif. Once again proving that if there's anything he knows better than most-it's how to wrench!

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Dyno 2
Skunk2 Mega Power R Cat-Back ExhaustPeakHP 174.5 / PeaKTq 126.1

Horsepower Gain
* 2,000 to 3,500 hP range: -2.1 to -1.0
* 3,500 to 5,500 hP range: -1.0 to 1.2
* 5,500 to redline hP range: 1.2 to 6.0

Torque Gain
* 2,000 to 3,500 tQ range: -4.0 to -2.1
* 3,500 to 5,500 tQ range: -2.1 to 0.9
* 5,500 to redline tQ range: 0.9 to 5.1

0805_impp_07_z+2008_honda_civic_si+exhaust Photo 5/12   |   2008 Honda Civic SI - Dyno 1: Baseline - Power Pages

The Skunk2 exhaust's larger 70mm piping and straightthrough muffler design offer improved flow over the stocker; power and torque output after the VTEC crossover point jumped considerably. unlike other exhausts that are simply adopted coupe systems, Skunk2 actually designed their Si sedan unit from the ground up-you won't find a better-fitting system out there. Full stainless steel construction ensures you'll get a lifetime of use from it.

Low-end power suffered a little on the dyno and power production took a strange dive near redline as well- neither significant of a defect in the exhaust, but more a product of the K20's ECu adjusting for the change in air flow. The exhaust's aggressive design makes it a little on the loud side (but not at all raspy), which we were okay with, but if getting hassled by the cops is a problem where you drive, you'll probably want to make use of the muffler's removable silencer.

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Three-piece exhaust system with muffler, hardware and gaskets

14mm socket and wrench, wD-40

Installation Time
20 minutes

Use plenty of wD-40 on the rubber hangers to help with their removal and reinstallation. The Skunk2 system bolts up to the OE catalytic converter studs so don't lose the nuts. Lastly, make sure to re-use the OE ring gasket at the catalytic converter and the included Skunk2 gaskets where applicable.

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Dyno 3
Fujita Short Ram Intake System
Peak HP 178.5 / Peak TQ 126.3

Horsepower Gain
* 2,000 to 3,500 hP range: 6.0 to 2.1
* 3,500 to 5,500 hP range: 2.1 to -0.5
* 5,500 to redline hP range: -1.0 to 5

Torque Gain
* 2,000 to 3,500 tQ range: 6.1 to -1.5
* 3,500 to 5,500 tQ range: -1.5 to 1.0
* 5,500 to redline tQ range: 1.0 to 3.1

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Fujita's kit comes complete with everything needed for the install and then some. Fitment was perfect, replacement vacuum lines were cut to just the right lengths and the filter fits in the engine bay with room to spare. Initial throttle power levels jumped, as did power after the VTEC switch over point. The louder, deeper intake growl under wide-open throttle was a welcome improvement over stock, as was the tubing's bronze wrinkle-paint finish.

The new Civic's OE intake design is a complete maze compared to those of older years. we had to temporarily remove the battery, windshield fluid reservoir and several hard-to-reach clips just to pull out the airbox and upper tubing. The Civic's cramped engine bay requires short ram intake systems to position their filters toward the back of the engine bay near the header-taking in a warmerthan- desired supply of air; even worse, any cold air intake would have to position its filter element underneath the frame rail, possibly exposing it to water, dirt and other road contaminates.

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Intake tube, filter element, silicone coupler, silicone tubing, clamps, all the necessary hardware, license plate frame, stickers, NOS beverage

Phillips and flat-head screwdrivers, 10mm deep socket wrench, extension, pliers

Installation Time
30 minutes

By this point, installation of the Fujita intake leveled out the powerband a little, eliminating the strange fall-off of power at the low and high extremes. Power production actually rose (to a point) over the course of several dyno pulls, just as it had after the addition of the Skunk2 exhaust-the ECu gradually adjusted to the increased airflow.

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Dyno 4
Vibrant Performance SI Header With High Flow Cat
Peak HP 184.4 / Peak TQ 129.4

Horsepower Gain
* 2,000 to 3,500 hP range: -2.1 to 0
* 3,500 to 5,500 hP range: 0 to 2.1
* 5,500 to redline hP range: 0 to 9.2

Torque Gain
* 2,000 to 3,500 tQ range: -2.1 to 5.9
* 3,500 to 5,500 tQ range: -2.1 to 1.6
* 5,500 to redline tQ range: 0.1 to 6.9

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Vibrant Performance adds a high-flow catalytic converter to their Race Header with this unit. Since the '06 and later OE Civic Si header has its catalyst welded-in, replacing the header means removing the cat as well. Most aftermarket manufacturers simply design headers around that fact-with no replacement cat. Vibrant offers one of the only solutions for Civic Si owners to modify their cars while maintaining some semblance of street legality. The Vibrant header/cat combo accommodates the OE O2 sensors, features longer, wider runners and full stainless steel construction. Oh, and it brought monster gains in top-end power.

Removal of the OE header set-up was a royal pain in the ass! Aside from that, nothing.

Header and cat combo

17-, 14-, 10- and 12mm sockets, swivel, wrench and extensions; breaker bar or impact wrench; 14mm open-end, 17mm brake line wrench or socket, pocket knife or razor blade, wD-40

Installation Time
One hour

Set aside plenty of time for installation. The heat shield and top row of bolts holding the header flanges onto the cylinder head have to be accessed from above the engine, meaning the windshield wipers, lower windshield "plastics" and metal gutter all have to be removed first. The lower row of flange-section bolts can be removed from below (with a swivel socked and no less than 2-feet of extension), but the section of piping housing the catalyst and connecting to the exhaust has to be removed first. Once you've detached the flange section from the head, six bolts holding the car's front cross-member to its unibody need to be loosened to give enough room for the flange section to be pulled out. Afterward, the aftermarket replacement can slide in its place-but only at a very particular angle. Then you get to do it all in reverse!

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Testing to our '08 Civic Si reinforced the inescapable truth that increasing power in newer cars is becoming increasingly more difficult with simple bolt-on parts. The mechanical advantages of all the parts we installed were visually apparent, yet the power gains weren't as large as some we've seen on engines with far less potential than the K20. while every part we added made power, seeing the Ecu adjust to compensate for each change all but proved to us that more power could be made. Does this mean you shouldn't waste time modifying the newer platforms? No, it simply means there's more to be discovered through tuning. Look for a future installment of Power Pages, in which we'll be testing an engine management product that claims to offer as much power in one step as we've made here in three-proving the new Si isn't a platform to be overlooked.

Skunk2 Mega Power R cat-back exhaust $538.65
Fujita Short Ram air intake $1,258.00
Vibrant Performance Si Header with High Flow Cat $899.95
TOTAL $1,696.60
  HP Level +HP TQ Level +TQ
BASELINE 172.1   121.7  
SKUNK2 MEGA POWER R EXHAUST 174.5 2.4 126.1 4.4
FUJITA SHORT RAM INTAKE 178.5 4.0 126.3 0.2
VIBRANT HEADER W/ HIGH FLOW CAT 184.4 5.9 129.4 3.1
FINAL 184.4 12.3 129.4 7.7


Skunk2 Racing
Norco, CA 92860
Vibrant Performance
By Luke Munnell
304 Articles



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