Infinity Design Toyota GR86 Carbon Intake

A Rewarding Challenge: The GR86 Intake

The GR86 is already a highly entertaining, back-to-basics sports car that is a joy to drive, with an engine that builds power progressively to the redline. However, it has been noted that the car lacks a genuine induction sound, which is mostly artificial and piped through the speakers. The stock system is also very small and uses Helmholtz resonators to quiet the sound. A distinct hesitation at lower RPMs, separate from the mild torque dip, was also identified.

The goal was to vastly improve the intake with a full redesign to deliver faster throttle response, enhanced torque under both partial and full load, and, most importantly, a more authentic induction sound. While the GR86 is the least powerful car the team has ever developed an intake system for, it has proven to be the most rewarding project.

The Development Process

During development, multiple prototypes were created. The initial prototype used a straight venturi tube feeding into a large airbox that drew air from the stock OEM area, with an additional small air feed on the opposite side. The idea was that this extra feed would increase available airflow. However, this design failed to yield the desired results, both on the dyno and on the road, showing no significant power difference. CFD analysis revealed significant turbulence in front of the air filter.

The OEM system bends toward the right side of the engine bay, with the air filter in line with the air feed, providing the most direct path for airflow. This insight led to a new design strategy that followed the same path but with three major changes:

1. Doubled the cross-sectional area of the front inlet feed, providing a more than adequate increase in available air for the FA24 engine.
2. Extended the snorkel toward the front and incorporated a bell mouth to smooth airflow.
3. Used a significantly larger air filter housing and the largest possible venturi inlet tube.

After several iterations, this method produced the best results in CFD analysis, showing less turbulence than the OEM system and vastly increased airflow. The results on both the dyno and during road driving were excellent, with vastly improved throttle response, enhanced low-end torque, and the elimination of the hesitation. Under spirited driving, the engine feels even more eager to accelerate in the 2000-4000 RPM range.

Air Intake Temperatures & Heat Soak

Intake temperatures were tested on the stock system by placing thermocouples before the air filter on both the OEM and Infinity systems. The OEM system was found to maintain ambient temperatures as low as 20 mph and immediately under full load, setting the benchmark for temperature control. With the Infinity intake fitted and the front snorkel in place, the system draws air from the exact same area as the OEM system, ensuring it matches the OEM’s efficiency in maintaining ambient air temperatures.

Air Filtration

Within the beautifully shaped carbon enclosures sits a bespoke, short-stack, high-surface-area filter. At a huge 170mm (6 3/4″), it is larger than any cone filter design currently on the market and is designed to take full advantage of the intake tubes by directing airflow toward the outer walls.

By placing the air filter in front of the inlet tube, the design achieves the largest velocity stack ever seen for the FA24 engine, which also provides the best laminar flow. The team painstakingly opted for the largest possible air filter for several reasons. A larger filter not only allows for more airflow and power but also remains efficient at its primary purpose—filtering harmful elements from the air—for a longer period without clogging.

Dyno Testing: Verified Gains

Dyno tests were performed under strict, controlled conditions on an independent Maha MSR500 dynamometer to show a true and realistic result.

The stock car made almost exactly what the manufacturer quotes: 228 BHP and 179 lb.-ft. of torque, with a perfect power curve. After fitting the intake system, peak power increased to 239 BHP and 184 lb.-ft. of torque, representing a significant gain of 11 BHP and 5 lb.-ft. of peak torque.

From 2000-3000 RPM, a substantial 10 lb.-ft. of torque was gained. From 6000 RPM onward, the FA24 engine saw significant gains in both horsepower and torque all the way to the redline. Rundown losses and ambient temperatures remained identical between both sets of tests, which were performed with identical starting oil and coolant temperatures.

Specifications

• 1 x Inlet Tube with integrated CNC MAF Boss
• 1 x Air Filter Housing / Inlet Duct
• 1 x Inlet Snorkel
• 1 x Bespoke Infinity Design Air Filter
• 1 x black metal clamp
• 1 x EPDM Flexi hoses with clamps
• 1 x Bracket
• 1 x Fitting Kit