Project Car Diaries: Making My Civic Type R Faster With Downforce

The truth of where you should spend your money (seat time versus parts) is a bit of a mix. Don’t go crazy changing parts for the sake of changing them, but also develop your car to suit you and your style. The trouble is that my CTR is already extremely well-optimized in terms of handling. The stock adaptive suspension works so well that I don’t want to touch it unless it’s for a proper three-way motorsport damper, and the car does a lot of brake vectoring trickery that aids this handling at low speeds. Still, during my last track sessions at Buttonwillow Raceway Park, I felt that the CTR left something to be desired in terms of high-speed balance.

I could go crazy with suspension and ratcheting up rear stiffness until the car rotated how I wanted it to, but there’s one more thing besides cost and the fact that the suspension is good as-is; I want to compete with this car in grassroots time attack. Reading through the rulebooks of local time attack series and more serious ones like Global Time Attack (GTA), aero is a much more open avenue of development than suspension, with prescribed rules on the kind of suspension hardware you can run. There is lap time in good suspension, but for the money, I think subtle aero nets a bigger benefit.

So I started looking into aero. Frankly, I was skeptical of adding a big GT wing and calling it a day, knowing that I would likely add a lot of drag and a dose of understeer to the car. Nerds who watch F1 will be aware that having balanced downforce front-to-back on a car is much more beneficial than having the biggest wing and splitter possible. 

What I wanted was a complete, off-the-shelf solution that could be a starting point but that didn’t get too aggressive. After some light research, Verus Engineering and APR Performance were my two options, but I preferred the lower cost and aesthetics of Verus, as well as the neat aero plots they posted on its site that demonstrate what the kit does in CFD.

The FK8 CTR comes from the factory with considerations for aerodynamics. It has a mostly flat underbody, a functional rear wing, as well as fender slits that vent hot air from the engine bay through the hood scoop. Honda says the hood scoop/fender vent combo also contributes to downforce, though I’m personally skeptical of that. Either way, the CTR works out to be a zero-lift car rather than a downforce car from the factory, has no real aero on the front, and the rear wing profile is extremely tame and designed for minimal drag rather than downforce generation.

Verus Engineering took a 3D scan of a stock FK8 and put it into CFD software to develop its Ventus 2 aero kit, which includes a composite front splitter, carbon fiber canards, a more aggressively profiled carbon fiber wing, and an axle-back aluminum rear diffuser. It wasn’t developed in a wind tunnel (very few companies have access to such a thing) but was track tested to verify the CFD numbers. Also, it cleanly matched the factory aesthetics of the car, something I wanted to retain for this stage of my time with the car.

The company’s graph of this kit shows a decent increase in downforce without much drag penalty, with most of the downforce coming from the P10 wing and splitter. The wing is much more aggressively cambered than the stock wing, and about two pounds lighter. It has a three-dimensional profile and a much more aggressive aerofoil that will for sure generate more downforce. The splitter is relatively small but contributes to decent, efficient front-end downforce by causing suction underneath and also using the high-energy air at the nose of the car to also push down on the splitter where it meets the bumper, though that effect is smaller than the under-splitter suction.

Verus’ aero plots show some flow separation at the leading edge of the splitter, which is likely caused by the fully square profile of the splitter’s leading edge. If you look at downforce cars, splitters are often shaped like the leading edge of a wing, which is rounded. The reasons why are simple: cost. Doing a nice rounded edge out of a cheap material is difficult, but more on that later.

The canards also don’t contribute to downforce per se but rather provide a vortice that extracts air from the wheel well. Meanwhile, the diffuser is the largest and most involved piece, including flat shrouds that sit close to the rear control arms and seal off the most turbulent part of the underbody where the exhaust normally lives. Again, this isn’t a huge downforce gain according to Verus, but is a definite decrease in drag. It looks quite cool too.

Installing the kit was shockingly straightforward, only taking some minor finagling to install the rear diffuser. First, the rear diffuser brackets had to get loosely bolted in, then the three-part diffuser and diffuser blades had to get loosely pre-assembled before offering the whole lot up to the car. I threaded the bolts closest to the center of the car first, then pivoted the diffuser up and threaded the bolts closest to the rear. From there, I could reach everything and tighten it into place while making sure the diffuser was adjusted properly to clear my aftermarket Fujitsubo exhaust.

Then I had to remove a plastic panel underneath the car and install threaded inserts into the panel for the splitter. Verus also provides splitter supports that are meant to extend out of the lower front grill, but I modified the installation slightly and moved the supports to behind the grill in the name of aesthetics. Instead of installing two threaded inserts, I used the holes to bolt the supports onto one of the inner bolt holes of the splitter. It is a little weaker on the leading edge of the splitter, but most of the downforce is generated at the center of the splitter. Thus, the supports actually support a more critical area while looking better than having the exposed stays. From there, the splitter simply bolts onto the bottom of the car.

The canards have the option of using bolts, but I opted to just use the 3M double-sided adhesive provided in the kit in the name of reversibility. Then the wing was similarly simple, just requiring unbolting the old rear wing and removing it, and placing the Verus P10 wing in the same spot. Overall, the install took me an afternoon and was pretty painless. The result is a much sicker-looking FK8 and a claimed 150 lbs of downforce at 100 mph.

I trucked my way to Buttonwillow once more to test the car in its current state. Now it had a scrubbed set of 265mm wide Bridgestone RE-71RS tires, better Counterspace Garage brakes, and the Verus aero kit. Over two weekends, both where I was struggling with other issues, the Verus aero kit was a serious highlight; a genuine light bulb moment. 

The difference was immediate. Through the high-speed 100-plus sweepers of CW13, there was stability and grip that didn’t exist before. Turn-in at high speed became noticeably more responsive, while direction changes at 100 mph felt like child’s play compared to the gentle sliding that would happen before. 

There were three places on the track where I was flat where I used to lift, and on the fastest corner of the track GPS data showed that I went 10 mph faster before Phil Hill because I could carry more speed through the torturous Riverside. And this was on a day that was 25 degrees hotter than my previous benchmark at 84 degrees Fahrenheit, with the car pulling power severely due to overheating. Over one lap, the kit did its job. But I still wished for more front downforce to make the car a bit more nosey, and to help save the already overstressed front tires from more sliding. My CTR had a lot of speed in it, but would cook the front tires in a single lap.

Where the downforce would make itself known was over crests, where the CTR would hunker down where it used to get much lighter. The rest of the time, it just felt like miraculous extra grip and didn’t change the driving style of the car. The Ventus 2 kit is not aggressive by any means, being a modest aero kit in the grand scheme of track driving.

Still, it represented a huge decrease in lap time. Compared to my previous personal best in better weather (a 1:59.091 at around 60 degrees Fahrenheit ambient), my CTR clocked in a 1:58.145 at 84 degrees Fahrenheit ambient temperature. With apples-to-apples weather, I estimate that the aero is worth 0.5 to 0.7 seconds. Compared to my previous personal best, the other big change is tires, where the old lap was done on Bridgestone RE-71R, and the 58.145 on Bridgestone RE-71RS. More on the tires in another post, but they are another big step forward. It’s competitive with other near-stock FK8 lap times that have GT wings and other basic aero parts. With cold weather, there is a lot more in the tank.

For the $2,314 that the kit costs, the reduction in lap time is a bargain. It’s the same price as getting full bolt-ons for an FK8 but easily contributes to much more speed than raw power, and it works well with the stock suspension. Not to mention, the whole kit costs about the same as a J’s Racing GT wing or an APR wing, and less than a Voltex wing. For your money, you get a more complete aero package over just a big rear wing.

But some improvements can be made on the kit, specifically the splitter. It is a decent-sized splitter but doesn’t extend very far back under the engine. Another issue is that the leading edge profile of the splitter is a square cut instead of a rounded aerodynamic edge. Verus says that it’s a cost and material deficiency; the plastic they use isn’t rigid enough to support the cut required for a rounded profile and moving to a stronger material like carbon fiber would make the cost exorbitant for casual track folks. In all fairness, it’s a fairly inexpensive splitter solution, and it works well and has decent surface area even with the blade shape.

Verus recently acquired an FK8 to do more engineering on, so updates are possible, and more aggressive parts are incoming. But even if I had all of the downforce in the world, there is one major issue holding my car back: overheating.

Yes, my car overheated. Badly. Three times. I pinned the coolant gauge to maximum every session I went out and just could not find a way to keep the car cool while running at any sort of fun pace. When I logged temperature, I found that my car would peak at 250 degrees coolant temperature at the end of a single hot lap, even with an upgraded radiator. It’s a huge issue that I’ve just begun to tackle and I’m determined to figure out a solution, brute force or otherwise.

So while the aero kit worked beautifully and dropped my lap time by one whole second, I could find another second in just keeping the car cool. The FK8 pulls power as coolant temperature rises, meaning that by the end of the lap, I was running 15 mph slower at the end of some long straightaways. 

But that is for another Project Car Diary. Rest assured FK8 owners, I have a plan.