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2018 Honda Civic Si Project Car Gains 130 Horsepower and Over 120 lb.-ft. of Torque!

SPEC Clutch, Powermetric.net and E85 make a world of difference in Part 8 of our long-term 10th gen. project car series.

Rodrez
Apr 6, 2020

Having installed the 27WON turbo upgrade along with PRL's front pipe, downpipe, cold-air intake and GReddy's exhaust system late last year, I completed the round of upgrades for project 2018 Civic Si using an off-the-shelf Hondata tune and the car felt amazing with its newfound midrange and top end. Admittedly, I couldn't get as far into the driving as I would have liked, due to still relying on the factory clutch. Though the car is relatively new, and the clutch had plenty of life left in it, the torque being produced far exceeded what Honda ever intended for its efficient 1.5L. Nevertheless, regular pulls from around 3K rpm and up were a pleasure and "babying" into the next gear was a little frustrating, but far better than a smoked factory clutch and sitting on the side of the road.

2018 Honda Civic Si Engine Bay Photo 50/50   |   2018 Honda Civic Si Project Car Gains 130 Horsepower and Over 120 lb.-ft. of Torque!

When the 2019 SEMA Show rolled around and the time crunch was on (always the case with a SEMA deadline), I installed PRL's Big Turbo Kit. Based around a Garrett gtX2860R Gen II in my case, the kit included a new downpipe and would be making more power than ever before. Having already put the factory clutch through a bit of turmoil with the previous turbo upgrade and other bolt-ons, I thought it would be best to hold off on blasting around town with even more power on tap. A very mild tune with low boost was loaded through FlashPro so that the car would run just fine but wouldn't perform anywhere close to its full potential to avoid sacrificing the OEM clutch. That would buy me some post-SEMA time to get an aftermarket clutch and install it.

SPEC CLUTCH - specclutch.com @specclutch

2018 Honda Civic Si spec stage3 clutch 01 Photo 50/50   |   2018 Honda Civic Si Project Car Gains 130 Horsepower and Over 120 lb.-ft. of Torque!

Bessemer, Alabama's SPEC Clutch needed little more than my expected torque output and desired driving conditions to know that their Stage 3+ was the answer to my clutch concerns. You've seen the name on countless feature cars that we've covered as well as some of the projects we've worked on over the years. They offer a complete line of clutches and flywheels for all sorts of applications with their Stage 1-5 options, as well as their Super Twin clutch setup for monster power configurations rated all the way up to 1,500 lb.-ft. of torque! Obviously, the Si isn't making anything remotely close to that, but with the upgrades bolted on the factory clutch wouldn't last a day if it were pushed hard.

Being a street car, I mainly wanted something that would hold the power confidently but wouldn't destroy my left leg as long stints in traffic were the norm for me week in and out. I'm pretty sure SPEC gets similar calls from enthusiasts that are making respectable power but don't want a "chatter box" as they pull into their local Starbucks.

2018 Honda Civic Si spec clutch cover Photo 50/50   |   2018 Honda Civic Si Project Car Gains 130 Horsepower and Over 120 lb.-ft. of Torque!

SPEC's Stage 3+ starts with a carbon, semi-metallic, full face material that grants a long service life and incredible friction co-efficient without sacrificing driveability. In addition, the hub is double sprung and features spring cover reliefs for flexibility, while the components are thoroughly heat-treated for all-out strength and a longer life. The stage 3+ for this application is rated to hold up to 371 lb.-ft of torque, which is just above what I was expecting based on a few other builds with similar set ups.

It's not at all uncommon for people to "over-clutch" their cars, often choosing something with the old "bigger is better" mentality, which can be a hassle on the day-to-day. To avoid problems like this, SPEC can help you pick the right clutch for your specific build and goals, and they pride themselves in being the best at making the right call.

2018 Honda Civic Si spec billet flywheel Photo 50/50   |   2018 Honda Civic Si Project Car Gains 130 Horsepower and Over 120 lb.-ft. of Torque!

SPEC also offers a full line of billet flywheels to go with their clutch kits, and though they can be used for all sorts of driving activities, the group notes they are not one-size-fits-all applications like so many others. Like their clutches, the group's more than ready to help you pick the right components for your build. The flywheel they recommended for this setup is only 10.9lbs. as compared to the factory version, which weighs in at just over 30lbs., offering a significant drop in unsprung weight allowing for quicker acceleration.

Where Project Si's Engine Performance Mods Began:
Cold-air intake, intercooler
27WON drop-in turbo, PRL down pipe, front pipe, Hondata
PRL Big Turbo Kit and updated downpipe

Pack a lunch, it's going to be a long day

2018 Honda Civic Si lift Photo 50/50   |   2018 Honda Civic Si Project Car Gains 130 Horsepower and Over 120 lb.-ft. of Torque!

Installation of any clutch on the 10th gen. Civic family, OEM or aftermarket, isn't at all fun. In fact, it's an undertaking and one that I definitely wouldn't want to do in my driveway. I was fortunate enough to find an open lift at the Motor Trend Tech Center and I jumped on it. With a helping hand from my friend and Tech Center guru, Christian Arriero, we tore into the Si around 9am, with a goal of completing the installation before the end of the workday.

2018 Honda Civic Si prl chargepipe removal Photo 50/50   |   2018 Honda Civic Si Project Car Gains 130 Horsepower and Over 120 lb.-ft. of Torque!
2018 Honda Civic Si acuity instruments bushing removal Photo 50/50   |   2018 Honda Civic Si Project Car Gains 130 Horsepower and Over 120 lb.-ft. of Torque!

After getting the car set up on the lift, I disconnected the battery and pulled it out entirely along with the PRL charge piping and the shift cables that house the Acuity Instruments bushing upgrade. Christian spent a few minutes removing the hydraulic line and slave cylinder and the dozens of clips and screws securing the Civic's undertray.

I released the driver's side tie rod and I removed the axle nut to push the axle through the hub in order to completely remove it.

2018 Honda Civic Si steering joint Photo 50/50   |   2018 Honda Civic Si Project Car Gains 130 Horsepower and Over 120 lb.-ft. of Torque!

Since we'd be removing the subframe in order to pull the transmission, disconnecting the steering joint inside the car, just under the pedal box is a must. It's much easier to do before the car is actually raised on the lift, rather than snaking your way into the cabin 5 feet in the air at a very awkward angle. Ask me how I know ...

2018 Honda Civic Si subframe removed Photo 50/50   |   2018 Honda Civic Si Project Car Gains 130 Horsepower and Over 120 lb.-ft. of Torque!
2018 Honda Civic Si intermediate shaft removal Photo 50/50   |   2018 Honda Civic Si Project Car Gains 130 Horsepower and Over 120 lb.-ft. of Torque!

With an array of large bolts removed from under the car as well as the rear engine mount, we pulled the subframe out along with the intermediate shaft.

2018 Honda Civic Si spec throwout bearing Photo 50/50   |   2018 Honda Civic Si Project Car Gains 130 Horsepower and Over 120 lb.-ft. of Torque!
2018 Honda Civic Si spec throwout bearing installed Photo 50/50   |   2018 Honda Civic Si Project Car Gains 130 Horsepower and Over 120 lb.-ft. of Torque!

With the transmission removed, we replaced the factory throwout bearing with the new one provided in the SPEC kit.

2018 Honda Civic Si oem clutch removal Photo 50/50   |   2018 Honda Civic Si Project Car Gains 130 Horsepower and Over 120 lb.-ft. of Torque!
2018 Honda Civic Si clutch removal Photo 50/50   |   2018 Honda Civic Si Project Car Gains 130 Horsepower and Over 120 lb.-ft. of Torque!

Off came the stock clutch and 30-plus pound flywheel ...

2018 Honda Civic Si spec billet flywheel install Photo 50/50   |   2018 Honda Civic Si Project Car Gains 130 Horsepower and Over 120 lb.-ft. of Torque!
2018 Honda Civic Si spec stage3 clutch 02 Photo 50/50   |   2018 Honda Civic Si Project Car Gains 130 Horsepower and Over 120 lb.-ft. of Torque!

... and on went SPEC's 10.9-pound billet flywheel and Stage 3+ clutch kit, along with the included alignment tool.

2018 Honda Civic Si spec clutch Photo 50/50   |   2018 Honda Civic Si Project Car Gains 130 Horsepower and Over 120 lb.-ft. of Torque!

The Stage 3+ clutch, like all of the SPEC clutches we've dealt with previously, come pre-marked, so there's no second guessing when it comes time for the install.

2018 Honda Civic Si spec clutch alignment tool Photo 50/50   |   2018 Honda Civic Si Project Car Gains 130 Horsepower and Over 120 lb.-ft. of Torque!
2018 Honda Civic Si spec clutch torquing Photo 50/50   |   2018 Honda Civic Si Project Car Gains 130 Horsepower and Over 120 lb.-ft. of Torque!

Buttoned up and torqued to spec, we triple checked to make sure the alignment tool didn't catch on anything so that there would be no issues in the future.

2018 Honda Civic Si transmission installation Photo 50/50   |   2018 Honda Civic Si Project Car Gains 130 Horsepower and Over 120 lb.-ft. of Torque!

Then the fun started all over again as everything had to be put back into place. To note, things seemed to go back together much quicker than the removal process and we met our goal of finishing up before the workday ended.

Yeah, But What About Pedal Feel?

Ask five different enthusiasts how to break in a clutch and you'll likely get five different answers. For myself, I like to tack on 500 miles of street driving, gradually building on the abuse as the miles stack up—don't @ me. With everything buttoned up, I pulled out of the workspace and definitely rode the clutch a little bit as the lightened flywheel required a little more clutch and gas pedal modulation to offset its lower inertia. Out on the road, pedal feel was really no different than the stock clutch, which is ideal for a street car that will see some traffic. Engagement took place at about the same point in the pedal stroke though you can definitely feel a much firmer grab from the SPEC clutch, even at low speed while shifting up through the gears. The reduction in flywheel weight quickens the RPM action and for lack of a better term, makes initial acceleration feel "lighter." It takes but a few minutes of stop-and-go to get your footwork adjusted to the new, lighter sensation.

Those Performance Parts Aren't Worth Much Without a Tune

Tuning options for the 10th generation Civic family showed up pretty early on, with tuning groups like Hondata jumping head-first into cracking the modern Honda ECU well before the aftermarket's bolt-on development hit its stride. Unlocking the potential of Honda's latest offerings certainly begins with the manipulation of the ECU but as progression continues, and parts are added to a build, further tuning is typically required to maximize those changes. Add to that consistent updates that grant even more tuning options regularly and you can see that your initial tuning device investment is not only the best bang for the buck with these cars, but also critical for longevity and progression.

2018 Honda Civic Si hondata flashpro Photo 50/50   |   2018 Honda Civic Si Project Car Gains 130 Horsepower and Over 120 lb.-ft. of Torque!

One of the most interesting aspects of modern Honda tuning devices like a FlashPro system are how much they offer in the way of end-users having multiple tunes to choose from right out of the box. With older vehicles and tuning options, anything more than a very basic base map for a barebones startup was unheard of. Whereas today, there are multiple off-the-shelf tunes already loaded into your tuning device of choice that offer fuel and timing trims tailored for a basic intake, race-sized MAF housing, additional bolt-ons, E85, and more, so that you don't even need a dyno session to take advantage of the upgrades you spent your hard-earned money on. The repeatability and basic tuning parameters of the 10th gen. Civics are tighter than any other Civic generation we've encountered. Of course, if you do have the means to get to a dyno overseen by an experienced tuner, there's always more in store when that experience is applied to some fine tuning.

Power Metric - powermetric.net @powermetric_

2018 Honda Civic Si power metric site Photo 50/50   |   2018 Honda Civic Si Project Car Gains 130 Horsepower and Over 120 lb.-ft. of Torque!

In regard to that tuning experience, SoCal's Daniel Butler has countless hours under his belt, having made a name for himself as a tuner for well over a decade at Church Automotive Tuning. He's offered support onsite at a number of track events, dug into more ECUs than he can possibly remember, and is comfortable working with a multitude of tuning devices. Butler worked extensively with Nick Zambrano of Ososik Media as the pair were glued to the dyno for quite some time in an effort to squeeze every ounce of power from the factory engine—a quest that eventually landed Zambrano's 2017 Si in 11-second territory and, just to note, was the very first to record such a time with the youngest Civic Si chassis.

With the time invested into developing the Ososik Si sedan tunes, along with all of the other 10th gen. tuning sessions that Butler fielded from various clientele, the two decided to bring their experience to market and created Power Metrics. Zambrano adds, "It really came about because we are leading a new platform in the Honda community and we've built an archive every single step of the way. As new bolt-ons were developed, we went to the dyno and tuned with them. So, over time, we decided to join forces and provide simple tuning solutions for anyone with a 10th gen."

2018 Honda Civic Si tuning laptop Photo 50/50   |   2018 Honda Civic Si Project Car Gains 130 Horsepower and Over 120 lb.-ft. of Torque!

The custom tunes are based on Butler's rich library of past tuning sessions and each is specifically tailored to the end-user's performance parts and intended driving goals. "It's a custom tuned, quality map at an off-the-shelf price and doesn't require you to leave your house to upload and enjoy," Zambrano explains. "We currently support all 10th gen. Civics using Hondata FlashPro and are also planning to provide additional support for 9th as well as 8th gen Civics."

Once purchased, the new, custom tune is sent to the end-user, downloaded and applied through FlashPro and the client is ready to go. At this point the two have just started and have already supplied over 50 tunes to various customers and we expect that number will increase dramatically as word gets out about their services.

2018 Honda Civic Si rear bumper Photo 50/50   |   2018 Honda Civic Si Project Car Gains 130 Horsepower and Over 120 lb.-ft. of Torque!
2018 Honda Civic Si e85 station Photo 50/50   |   2018 Honda Civic Si Project Car Gains 130 Horsepower and Over 120 lb.-ft. of Torque!

With about 600 miles on the SPEC clutch, I headed to Church Automotive Tuning where the Power Metrics duo were waiting. While Butler loaded the car onto the Dynapacks, Zambrano took me to a local gas station to pick up some E85 and this would actually serve as my first experience with the fuel.

2018 Honda Civic Si e85 02 Photo 50/50   |   2018 Honda Civic Si Project Car Gains 130 Horsepower and Over 120 lb.-ft. of Torque!
2018 Honda Civic Si e85 01 Photo 50/50   |   2018 Honda Civic Si Project Car Gains 130 Horsepower and Over 120 lb.-ft. of Torque!

Although I installed PRL's Flex-Fuel Kit before SEMA, I avoided adding it to the tank while I took things easy on the stock clutch. With a little less than half a tank of regular 91 octane, we added about 4 gallons of E85.

2018 Honda Civic Si dynapack 01 Photo 50/50   |   2018 Honda Civic Si Project Car Gains 130 Horsepower and Over 120 lb.-ft. of Torque!
2018 Honda Civic Si dynograph Photo 50/50   |   2018 Honda Civic Si Project Car Gains 130 Horsepower and Over 120 lb.-ft. of Torque!

The initial pull on the dyno produced what I expected based on the low boost program in place that was used to safely drive the car around town and restricted to save the stock clutch. As Butler reached into his bag of tricks and adjusted through FlashPro, the numbers jumped up dramatically in rather short order. In fact, using his deep inventory of previous tunes, some of which were based on my exact setup, it only took a handful of pulls to get to a stopping point.

2018 Honda Civic Si dynapack hub connector Photo 50/50   |   2018 Honda Civic Si Project Car Gains 130 Horsepower and Over 120 lb.-ft. of Torque!
2018 Honda Civic Si dynapack dynograph Photo 50/50   |   2018 Honda Civic Si Project Car Gains 130 Horsepower and Over 120 lb.-ft. of Torque!

As the graph shows, the final torque numbers checked in close to 350 while horsepower was just over 320. Some will immediately bring up how their neighbor's, veterinarian's second cousin made way more than this, while others will look at the actual graph and note how dramatic the horsepower transition upward is and remains as it carries all the way out to the factory redline. Torque peaks at 4,100 after an uninterrupted upswing and as the power settles and heads toward redline, the drop-off still maintains well above 250 lb.-ft. of torque.

2018 Honda Civic Si prl intake Photo 50/50   |   2018 Honda Civic Si Project Car Gains 130 Horsepower and Over 120 lb.-ft. of Torque!

Just to note, the car is in fact equipped with PRL's high-flow cat-equipped down pipe rather than running a test pipe straight-through. Could this setup have made more power through additional tuning? Absolutely. Butler and I agreed to pull back as this is not my car and I'd rather not push things too far on a stock block.

More Power on Tap

The roads surrounding the dyno are mostly traveled by 18-wheelers. Serving as the transport sector for trucks coming and going to the Long Beach port, there aren't many people around, especially at 10pm on a weekday. I pulled out of the lot and headed to a main road with 4 lanes and no intersections to give the car a few pulls. Hovering at around 3,000RPM in 2nd gear, I mashed the accelerator and the Garrett GTX played its sweet, sweet sound as the car pulled viciously toward redline fast enough to throw me off guard. Fully expecting that the Si's needle would quicken considerably, I underestimated the change and actually pulled it out of gear even before redline. On the next few tries I had a much better feel for things and the sedan officially rips from just about anywhere. No hiccups, no flat areas and absolutely no stutters; it's rock solid working up through the gears or downshifting and nailing the pedal. Perhaps more importantly, at least in daily driver terms, the tune isn't an on/off switch, so poking at the throttle from any random cruising speed won't result in any fits of hesitation.

The End of the Road

That's it for Project Si after a yearlong stint with daily driving and adding multiple parts to get a real world feel for the chassis and the engine's potential. For the little 1.5L to produce well over 300 lb.-ft of torque without any internal work is incredibly promising. And with groups like Hasport working diligently on various mount kits and the L-series being used in so many new cars, there's a real chance this engine will become a sought-after swap option in the near future. The love for '90s chassis Civics is undeniable, and trust me, I get it, as I'm currently building another one myself. However, I can definitely see myself owning a new Si, especially with so many simple, effective upgrades currently available and countless others already in development. The long-running Civic tuning addiction continues.

2018 Honda Civic Si laptop tuner Photo 50/50   |   2018 Honda Civic Si Project Car Gains 130 Horsepower and Over 120 lb.-ft. of Torque!
2018 Honda Civic Si dynamometer Photo 50/50   |   2018 Honda Civic Si Project Car Gains 130 Horsepower and Over 120 lb.-ft. of Torque!
By Rodrez
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