By Jonathon Ramsey, Autoblog
Two magazines put two 2020 Toyota Supras on two dynos in two parts of the country on two different days. Both magazines came to the same result: Toyota underrated the power figures of the particular Supras being tested. In May, Car and Driver strapped a Supra to an all-wheel drive Dynojet dynamometer in Livernois, Michigan. CD's figures came to 339 horsepower and 427 lb-ft of torque at the wheels. After that, Motor Trend strapped a Supra to a Mustang eddy-current chassis dynamometer in Torrance, California. MT's weather-corrected numbers came to 332 hp and 387 lb-ft.
Toyota's official numbers for the 3.0-liter turbocharged inline-six cylinder sourced from BMW are 335
hp and 365 lb-ft, measured at the crank. Using the hoary conventional
wisdom of driveline and hydraulic losses causing 15 percent of power to
evaporate before reaching the wheels, we'd expect the Supra's power at
the contact patch to be around 285 hp and 310 lb-ft. Even updating that
parasitic loss figure to 10 percent for a modern drivetrain, we're still
at around 300 hp and 328 lb-ft.
Using MT's tallies and parasitic losses of 10 percent,
the Supra in question was putting out more like 364 hp and 426 lb-ft at
the crank. At 15 percent loss, the numbers suggest 390 hp and 445
lb-ft. Those numbers don't line up with the higher-powered incarnation
of the B58 engine in the Z4 M40i, either, officially classified at 380 hp and 369 lb-ft.
The C/D
torque figure can be rule an anomaly, the mag measuring torque in fifth
gear at a 1.32:1 ratio instead of the 1.00:1 ratio in sixth gear
because they couldn't hit redline in sixth. The mag avowed "there's a
chance the peak torque output may be slightly inflated." On the other
hand, Mustang dynos like the kind used by MT have earned the nickname "heartbreaker" from a habit of returning disappointing power totals.
Between car, region, weather, tester, and dyno variations, it's useless to directly compare numbers worked up by C/D and MT.
The point is that two data points arrived at independently found
noteworthy power surpluses compared to Supra brochure numbers.
Neither story tries to assign a reason for the difference. C/D, and the Internet, say BMW is known for understating outputs. When C/D put the current M5 Competition
on the same Dynojet used to test the Supra, the readout showed 617 hp
and 606 lb-ft at the wheels for a sedan officially rated at 617 hp and
553 lb-ft. MT said its press loaner was like an "early build
preproduction car," perhaps with a "partially hand-built engine" and
without the latest calibration.
Check out both articles for more
details on the testing, and videos. Not that it matters for the moment,
though; the real test will be to see whether customer cars get extra
oomph, too.
