It didn’t take long for the FL5 Civic Type R to start hitting the track and being involved in a variety of racing series in large numbers. The car comes from the factory tuned for incredible handling and ample power to keep up with plenty of production sports cars. However, there is one area the Honda engineering team came up short, and that was the oil cooling system.

Drivers regularly see high oil temperatures completely stock and even higher on modified examples. In testing, CSF observed temperatures over 275°F (135°C) on the track, and it was clear the FL5 needed a solution. The engineering team set out to develop CSF’s first ever complete engine oil cooler kit, and the results speak for themselves. CSF’s new engine oil cooler kit is the “Real Deal” with stunning performance and an aggressive look to match.

Design & Engineering

The initial challenge when designing this engine oil cooler kit was two fold. Firstly, the K20C1 did not come with any type of external engine oil cooler provision. The second challenge was space in which to mount an external engine oil cooler(s). The front bumper opening already has the Intercooler, A/C Condenser, and Radiator stacked there and using most of the available air.

While mounting an additional cooler behind the grill is the simple option, that just adds more heat to the full system and takes away from the cooling capacity of the radiator. On top of that, most owners who track their cars will have an upgraded/larger intercooler which further compounds the issue. That means the sides of the bumper are the obvious and optimal placement. However, the FL5 does not have great airflow in that area. To improve airflow, CSF needed to design a ducting/inlet system that would allow proper airflow for optimal performance.

With proper airflow handled, CSF built the kit around our compact universal oil coolers (CSF #8119), using two of them to offer the greatest cooling capacity possible. Paired with Superstrasse CPE lined stainless steel braided lines and DYME Pro/Spec Quick Release Fittings, this kit is the most serviceable kit on the market.

Key Features:

• Two Dual Pass High-Performance Oil Coolers
• CPE lined stainless steel braided lines
• DYME Pro/Spec Quick Release Fittings
• Billet Sandwich Plate with 175-195°F (80-90°C) Thermostat
• Oil Temperature reduction of up to ~15°F (~8°C)
• Carbon Fiber Bumper Vents
• Laser cut mounting brackets
• Approximately 7 Quarts (6.6L) overall oil capacity
• Pair with the CSF #7221 FL5 Performance Radiator for maximum cooling performance

Oil Coolers

The CSF kit is built around two 13” x 4.5” (33cm x 11.5cm) Dual-Pass Oil Coolers (CSF #8119) run in series. These High-Performance Coolers offer maximum heat dissipation with uncompromising durability. The Bar/Plate cores feature CSF’s “Aero-Flow” Bar Design which reduces weight while offering impressive strength and flow. The rugged design of these cores means you won’t need to worry about debris from the track puncturing the coolers like with tube and fin cores.

The 100% TIG welded construction with cast end tanks further increases the overall strength of the coolers. Every cooler is pressure tested to 120 PSI before leaving the factory so you can be confident you will never have one burst on you like some weaker designs used in other kits. The end tanks also feature specially designed 40-degree angle feed/return fittings for optimal flow and lower pressure drop.

Oil Cooler Key Features:

• Bar/Plate Core offers strength and durability
• 100% TIG Welded Construction tested to 120 PSI
• Smooth 40-degree feed/return fitting design
• Dual Pass flow for additional cooling
• Oil Capacity increased by over 2 Quarts (2 Liters)

The are the same coolers Honda Racing Corporation (HRC formerly HPD) uses on Honda’s factory FK8 TCR Touring Car. Honda and many racing teams/drivers saw a lot of success with the FK8 Type R TC. CSF is already working with teams like Precision Racing LA for their FL5 Touring Race Car and in talks with other SRO teams and HRC themselves.

Pressure Drop

When adding an engine oil cooler to a car that did not come with one from the factory, there is always a concern with pressure drop. This is due to the back pressure imposed on the system from running the oil through lines and cooling channels of an oil cooler.

In testing, CSF observed a small drop in oil pressure after installing the kit. While not a concern for casual driving, it was enough of an issue to address for those tracking their FL5s. To resolve this issue, CSF and test vehicles switched to a higher weight oil (from OE Spec 0W-20 to 0/5W-30) and this relieved the potential pressure issues.

CSF recommends the following oil weights depending on application:

• Light Track Duty and/or High Performance Street: 0/5W-30
• Heavy Track Duty and/or Dedicated Race Builds: 0/5W-40

Ducting & Vents

The challenge of getting proper air flow to the oil coolers was straightforward but far from simple. While mounting an additional cooler behind the grill would be the easy choice, that just adds more heat to the rest of the cooling system. The optimal placement for the coolers was in the sides of the bumper outside of having no direct airflow. While technically some air does flow to this area as it leaks around the intercooler, it is not enough for significant cooling performance. While utilizing the brake cooling ducts is a potential option, that could negatively impact braking performance.

CSF designed and modeled vents for the bumper to provide the two oil coolers with ample airflow to keep engine oil temperatures in check. These vents were carefully designed with CFD software for airflow and aero dynamics. Made from pre-preg carbon fiber, these vents match the lines and style of the FL5 and give a very OEM+ look to the front bumper. To further improve airflow and cooling, the kit also includes louvered vents that allow airflow out of the bumper area and into the fender wells.