Tag: Engineering Explained

  • Why the 2022 Subaru BRZ doesn’t need a turbocharger

    Since the original version launched, fans have been clamoring for a more powerful version of the Subaru BRZ, i.e. one fitted with a turbocharger, a la the WRX. But Engineering Explained host Jason Fenske is glad the redesigned 2022 Subaru BRZ doesn’t have a turbocharger. Here’s why.

    The second-generation BRZ gets a 2.4-liter flat-4 engine, replacing the previous generation’s 2.0-liter unit. That displacement increase did yield more power. The 2022 model produces 228 horsepower and 184 pound-feet of torque, compared to 205 hp and 156 lb-ft for the old model.

    Subaru does have a turbocharged 2.4-liter engine good for 260 hp and 277 lb-ft, which is currently used in the Ascent, Legacy, and Outback. So why isn’t the BRZ engine turbocharged as well?

    2022 Subaru BRZ

    2022 Subaru BRZ

    One reason why the BRZ is better off without a turbocharger, according to Fenske, is gearing. The naturally aspirated engine has a higher redline (7,500 rpm) than the turbocharged engine (6,000 rpm), allowing for more aggressive gearing. Those factors should lead to a more robust seat-of-the-pants feeling of acceleration, Fenske said, despite the BRZ engine’s lower output.

    Adding a turbocharger to the BRZ might also be difficult. The Ascent has a bottom-mounted turbo, Fenske noted, a configuration that would be challenging in the BRZ, where the engine is mounted very low in the chassis. That keeps the center of gravity low as well, improving handling. The turbo engine is also heavier, negating some of its power advantage, Fenske said.

    Finally, a naturally aspirated engine delivers better throttle response and throttle control. Modern turbo engines don’t suffer from the dreaded “turbo lag” of old, but they will never be as responsive as naturally aspirated engines. Plus, if you really want a turbocharged 2022 BRZ, the aftermarket will likely be eager to help.

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  • The Maserati MC20 has F1 tech

    Maserati hasn’t raced in Formula One in decades, but the automaker’s recently unveiled MC20 supercar boasts some F1-derived engine tech, according to Jason Fenske of Engineering Explained.

    Specifically, the car’s 3.0-liter twin-turbocharged V-6 uses pre-chamber combustion. That means each cylinder has dual combustion chambers, each with its own spark plug. Pre-chamber combustion isn’t new; Honda was using it in the 1970s, Fenske noted. But Maserati is doing something different with the technology.

    Maserati is likely the only automaker using a so-called passive pre-chamber system in a production car. As the name implies, air and fuel aren’t actively injected into the pre-chamber, which is smaller than the main combustion chamber and located directly above it. Instead, the air-fuel mixture is drawn into the main combustion chamber, and then pushed up into the pre-chamber, by the motion of the piston.

    Maserati Nettuno 3.0-liter twin-turbocharged V-6

    Maserati Nettuno 3.0-liter twin-turbocharged V-6

    This setup is designed to speed up combustion, which in turn reduces knock, Fenske said. Knock is a major potential issue due to the lean air-fuel ratios used in the engine and other modern engines to pass emissions tests. Maserati’s patent on the design also claims it can reduce fuel consumption by 30%, or allow for an engine to be downsized by 25% while producing the same power as a larger one.

    Both the pre-chamber and the main combustion chamber have their own spark plugs. At high rpm and high load, only the pre-chamber spark plug is used, while both are used in other conditions, Fenske said. The amount of time between firing each spark plug can also be adjusted, changing the duration of combustion to warm up the catalytic converter, or even make the engine quieter, Fenske said.

    In the MC20, the Nettuno engine produces 621 horsepower and 538 pound-feet of torque. That allows for 0-60 mph in 2.9 seconds and a top speed of 202 mph, according to Maserati. The automaker hasn’t provided pricing information or a production timeline for the MC20, its first supercar since the MC12 ended production in 2005.

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  • Here’s how Gordon Murray’s track-focused T50s can drive upside down

    Many automakers have claimed that their supercars produce enough downforce to drive upside down, but in a new video Engineering Explained’s Jason Fenske shows how Gordon Murray’s T50s might be the first car actually capable of pulling the stunt off.

    The T50s is the track-only version of the recently-unveiled T50 supercar. Like the road-going version, the T50s has a rear-mounted fan inspired by Murray’s Brabham BT46B “Fan Car” Formula One racer. But while the T50 has six modes for this fan, the T50s only has one—high downforce.

    In the T50s, the fan spins at a constant 7,000 rpm to continuously generate that downforce. The car gets a number of other aerodynamic add-ons as well, including a roof scoop that works as a ram-air intake for the engine, a stabilizing fin like the ones used on Le Mans prototypes, and a large rear spoiler.

    Gordon Murray T.50s

    Gordon Murray T.50s

    How does that allow the T50s to drive upside down? In order for that to happen, the downforce needs to cancel out the force of gravity, preventing the car from falling. The T50s might have enough downforce for that, and it can run at the sustained high speeds needed to continue generating that downforce, Fenske said, adding that Car and Driver estimated a top speed of 210 mph would be required.

    At 210 mph, the T50s should behave like a regular car driven at average speeds, but only as long as it’s driven at a steady speed in a straight line, Fenske said. Any braking or steering would upset the balance needed to keep the car upside down. Driving upside down would also require changes to the oil and fuel systems, which aren’t designed to work inverted, Fenske noted.

    Watch the full video for more details on the T50s and its downforce-generating abilities. In addition to more aero aids, the T50s gets a more powerful version of the T50 road car’s 3.9-liter Cosworth V-12, with 690 horsepower (or 720 hp with ram air). However, it also swaps the road car’s manual transmission for a paddle-shifted gearbox. Just 25 cars will be built, priced at $3.6 million each. Production is scheduled to start in 2023, or a year after the road car.

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