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

Lines, Fittings, and Thermostat

CSF partnered with DYME PSI again for their exceptional quality and innovative quick-release hose and fitting solutions. The DYME Pro/Spec Quick Release Fittings offer race-proven performance with the convenience of tool-free clamshell removal and capable of withstanding up to 10,000 PSI. Quick Release fittings make the installation of the CSF kit much faster than traditional threaded fittings. In addition, they make maintenance like fluid changes much less of a headache.

The DYME PSI fittings are hydraulically crimped to their motorsport quality Superstrasse CPE lined 304 stainless steel braided lines. DYME PSI manufactures these lines and fittings in house to CSF exact specifications with the highest level of quality and precision. These lines offer the best flexibility, flow, and chemical resistance possible.

Oil flow is managed by a Billet Aluminum thermostatic sandwich plate. This plate bolts in the factory oil filter location with a M20x1.5 adapter. The sandwich plate was designed to reuse the OE oil filter but can be fitted with a larger filter up to 70mm in diameter with a M20x1.5 thread (check height clearance when looking at filter options).

The thermostat is designed to start opening at 175°F (80°C) and be fully open at 195°F (90°C), great for motorsports and high-performance street applications. The sandwich plate also includes a pre-plugged 1/8 NPT port for aftermarket oil temperature sensors. This is a great addition for drivers looking for more accurate data/metrics.

Key Features:

• Fittings:
  • Forged 6061-T6 Aluminum Body
  • 180° Swivel Adjustment
  • Dual FLUOROK™ FKM Seals
  • Chemical & Heat Resistance up to 401°F (205°C) continuous operation temperature
  • Secure & Permanent Crimp-On connection for high-pressure systems
• Lines:
  • 304 Stainless Steel reinforcing braid and Polyethylene top braid
  • Burst pressure of over 2000 PSI
  • Suitable for up to 302°F (150°C) continuous operation temperature
• Sandwich Plate:
  • Billet Aluminum Construction
  • 175-195°F (80-90°C) Thermostat
  • Accommodates OE Filter or others up to 70mm in diameter with a M20x1.5 thread
  • 1/8 NPT Pre-plugged Port for Temperature Sensor

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.

OE Fit and Finish

CSF leveraged many industry connections to find the best possible source for motorsport grade carbon fiber. The quality, fit, and finish of these parts are of the highest caliber and have been extensively track tested. Each vent bolts on without the use of double sided tape so they are very secure.

Cut out templates are included with the kit instructions to allow for easy installation and ensure proper alignment. CSF also designed templates for the international market with FL5s that come equipped with PDC sensors. The factory PDC sensors will still function perfectly and retain the OE look and feel.

While there may be kits available that do not require cutting the bumper, they cannot match the airflow and cooling performance of the CSF kit.

Air Duct Key Features:

• Motorsport Grade Pre-Preg 2×2 Carbon Fiber Construction
• OE level fitment and finish*
• Provides optimal airflow to the Oil Coolers vs kits with air deflectors from the center opening
• Instruction include cut out templates for easy install with motorsport grade hardware (no tape)
• Laser Cut Louvered Vents for airflow into the wheel wells

*Note: Carbon fiber vents can be refinished as in matte clear or painted. CSF recommends using a qualified paint or body shop for best results.

Duct Development and Testing with Dustin Williams

CSF was fortunate enough to have Dustin Williams (@dustiinw) loan out his car to the engineering team for final testing and refinement on the bumper vents. CSF owner Ravi Dolwani delivered the final prototype kit with the final design of the vents in person and Dustin’s reaction was great. He thought the vents match the style of the car so well that they should have come from the factory like that.

Replacement Windshield Washer Reservoir

To make room inside of the right hand side bumper for both the oil cooler and proper airflow, CSF designed a replacement windshield washer fluid reservoir. This low clearance reservoir/bottle works with the factory pump and filler neck. The engine bay retains a clean factory look while freeing up space in the bumper for the cooler.

Testing and Results

CSF spent over a year in testing and development of this kit working with R&D Partners and multiple drivers competing in Global Time Attack (GTA) and GridLife. Initial testing was performed in the controlled environment of a dyno. CSF then moved into aggressive real world testing and development on the track where most customers would be using these kits.

Dyno Testing

For initial testing, CSF turned to the automotive authorities and industry experts at MotoIQ for third party verified data collection. Mike and the team there developed the testing procedures for the prototype baseline data.

Temperature readings were taken with two temperature sensors installed at the oil filter housing/sandwich plate for the most accurate readings. The FL5 was first run for 9 consecutive pulls on the dyno at World Motorsport to simulate hard driving and engine oil heat soak. The prototype CSF Oil Cooler Kit was then installed and the same test was conducted again. Average ambient temperature was only 0.5°F (0.3°C) higher on the test with the CSF kit.

You can see from the results the CSF prototype kit offered consistently cooler engine oil temperatures throughout the test. On average the engine oil temperatures were about 9°F (5°C) cooler with the CSF kit installed. While the max temperature seen was only 222°F (105.5°C), this gave the engineering team a great comparison data point. This test was performed before the addition of the fender liner vents.

While the dyno is a great place to begin testing, the track test results reveal dramatic reductions in engine oil cooler temperatures under extreme conditions.