2009 Honda Civic Si Sedan - Go Power Motorsports

The New Si Is Hiding More Power Than You Might Think...

(Jeff Giovino has over 18 years of experience in the automotive performance
industry. He played a leading role in championship-winning teams in NHRA, NHRA Sport Compact, and PSCA competition. As the Go Power R&D director, Giovino heads both the engine development and chassis fabrication departments.)

2009 Honda Civic Si Sedan Front Dyno
The test mule; a 2009 Civic...

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2009 Honda Civic Si Sedan Front Dyno
The test mule; a 2009 Civic Si sedan.
The Honda Civic Si has always been a popular tuner car because of the ease of modification and aftermarket support. From its earliest models, to the '88-'91 era that sparked a nation of loyal fans, the Si holds a special place in the hearts of every Honda enthusiast. In the past, tuners and aftermarket companies had no problems cracking the power safe, and stealing both horsepower and torque in order to improve on vehicles' performance. However, the latest offering ('06-'09) has proven thus far to be much more limited in the modifications department. The notorious drive-by-wire system, lack of engine management options, and overall aftermarket support have all been key components in turning many fans away from the newer chassis. However, as with anything Honda related, it's only a matter of time before Hondata figures out the ECU equation and offers something to cure the problem. FlashPro has recently hit the market and is making waves, as is the Cobb tuning Access Port system; both offering a way to dive into the factory ECU and make changes. Many may disagree, but in my opinion, with these new tools, we have by far the best Si to work with. You've got a car that comes with power steering, air conditioning, excellent comfort, great handling, two- and four-door options, and the best of all, it's K-powered. This means you have a great foundation to make a fun daily driver, aggressive track car, race car-whatever you're into. Currently, we've spent quite a bit of time focusing on the engine's output with the goal of making the most usable power while maintaining reliability and comfort. As with any VTEC engine, most of the power is going to be found on top, after the VTEC crossover lets loose.

The '09 Si is equipped with a close ratio 6-speed transmission, and is powered by a K20Z3 engine rated at 197hp @ 7,900 RPM, and 139tq @ 6,100 RPM. All runs on the dyno before and after modifications were done in 4th gear on our Dynapack dyno. The iVTEC system can adjust the intake cam up to 50 degrees, and the car is claimed to produce 21/29 mpg, though I've personally achieved slightly better mileage. Our K20Z3 is also equipped with the coveted RBC intake manifold, which many tuners have used to achieve 300whp and above with Frankenstein builds.

2009 Honda Civic Si Sedan Aem Intake Kit
Our test car had just over 200 miles on the clock, and netted peak numbers of 165wph at 7,980 RPM, and 127.2 at 6,325 RPM. To get started, we dug into the ECU. Hondata's new Flashpro system changes the VTEC crossover and raises the redline from 8,000 to 8,600 RPM. Though this change won't really increase power, it did a great job in smoothing out the graph, and simply makes for more fun behind the wheel. Our next upgrade was the Skunk2 header which features a 4-2-1 design, along with a custom Go Power Motorsports exhaust. Our system uses 2.5-inch piping, a resonator, and chambered muffler. The Hondata ECU upgrade and exhaust flow changes had an incredible impact on peak power output; over 20 hp at 8,500 RPM, and 16 ft-lbs of torque at 5,367 RPM, which is amazing for just a few minor changes. The sound is much louder than stock, but still quite bearable.