New Data Suggests Subaru BRZ and Toyota GR86 Lose Oil Pressure In Right Turns on Track
Since the arrival of the second-generation Subaru BRZ and Toyota GR86 in 2021, there have been reports of engine failures occurring during or after track driving. Initially it seemed this was a result of excessive gasket sealant—room temperature vulcanizing (RTV) silicone—blocking the oil pickup tube. Now however, new data indicates that the BRZ/GR86 may be experiencing significant oil-pressure as a result of something else, or possibly in addition to the excess RTV found in some cars.
Brian Armstrong, a Bay Area software engineer who documents his track-day adventures on social media as @900BRZ, published a video highlighting data indicating the new BRZ and GR86 experience oil-pressure drops in high-speed right-hand corners on track. Armstrong and friends devised a test using his 2022 BRZ, a 2022 Toyota GR86, plus a 2017 BRZ as a sort of control. For the 2022 model year, the BRZ and GR86 got a new 2.4-liter Subaru-built flat-four, the FA24. The first-gen BRZ and Toyota GT86 use the older 2.0-liter FA20 engine. All cars were fitted with oil-pressure sensors, and their data, along with CAN-BUS data from the car itself were recorded with an AiM Solo2, a popular motorsports data logger.
Both the 2022 cars are fit with Jackson Racing oil coolers, and both run slightly more negative camber at the front than stock, plus 260-treadwear GT Radial SX2 tires. The 2017 BRZ sports the same oil cooler and wears the same tires, but it has a more aggressive alignment, coilover suspension, and some light aero tweaks. So theoretically, the older car is capable of generating more grip than the two newer models. The GR86 had its oil pan cleaned of excess RTV, and while for the test the BRZ's oil pan hadn't been dropped, Armstrong tells Road & Track that he has since had it examined and found that there wasn't much excess RTV.
"In our testing, we found FA24 provides robust oil pressures in most circumstances on straights and left-hand turns," Armstrong said in a statement to Road & Track. "However, in some right-hand turns (particularly those with sustained lateral G, rapid lateral direction change, or elevation change) we can observe and reproduce severe oil-pressure drops."
Where at high revs, the FA24 usually maintains somewhere between 50 to 60 PSI of oil pressure, in fast right-hand corners, the pressure frequently drops into the 20s. Armstrong and friends saw as low as 20 PSI in the GR86 coming over the crest of Thunderhill West's turn 8.
"We believe these pressure drops are significant enough to cause bearing damage, even if not an immediate failure," Armstrong said. "We also believe these pressure drops are independent from the RTV problems that have been well documented, where engine sealant can potentially block the oil pickup. We've been able to reproduce this across multiple cars, including one with the RTV cleaned. (We do believe that the RTV is still cause for concern, but it's a separate problem.)"
Thunderhill West runs counterclockwise, so it's mainly left-hand turns, but turns 5 and 8 are fast right-handers, each with a bit of elevation. This is where the oil-pressure drops presented themselves. The 2017 BRZ had momentary pressure drops on turn-in at these spots, but oil pressure quickly returned to a seemingly normal state. Also notable, in Thunderhill West's slower turn 1, there's no major dip in oil-pressure levels for any of the cars.
A Subaru spokesperson tells R&T that "Subaru of America stands behind the design integrity of the FA24 engine which is used reliably in thousands of vehicles. Oil pressure varies in all engines based on RPM, temperature, cornering loads and numerous other external and internal factors. This is normal in an engine duty cycle. The FA24 engine is designed to perform within a wide set of tolerances for road use, and the Subaru BRZ is designed as a road car. Race cars are specially modified to be used for race conditions."
Toyota has yet to respond to our request for comment.
Since its launch, there have been two high-profile cases of Toyota GR86 engine failure where the automaker initially denied warranty claims because the cars were used in autocross and on track. Toyota then decided to warranty those engines. The first failure, involving owner Blake Alvarado, was confirmed to be the result of a spun bearing. The second, involving someone who posts on YouTube as LUNK, sounds to us like a spun bearing, based on the video of the failure, though the exact cause is unconfirmed.
Both Subaru and Toyota have highlighted the track capabilities of these cars. Subaru presented the BRZ to media at Lime Rock Park—incidentally, a track with mostly fast right-hand corners—and Toyota did the same at Monticello Motor Club. Toyota also offers a free one-year NASA membership and track day with any GR86 purchase.
We've driven these cars at a number of tracks, including both BRZ and GR86 at Monticello during our Performance Car of the Year 2022 testing, and while our test cars have suffered no failures, we weren't logging oil-pressure data. In the beginning of his video, Armstrong says that he knows of three FA24 failures with owners he describes as "meticulous." He also says all those cars ran aftermarket oil coolers. Nick Ruston, vice president of Subaru specialist Killer B Motorsports, said he's noticed a number of forum posts with concerns about oiling issues with BRZs on track. While he's not sure exactly why Armstrong's data showed drops only in right-hand turns, he tells R&T he thinks the issue might have something to do with the FA24 timing cover, which is larger than the FA20's. Ruston and Killer B are developing a baffled oil pan for the FA24, which Armstrong plans to test in the coming days.
It's hard to say why exactly this is occurring without resorting to conjecture.
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