Lexus will be demonstrating the Lexus RC F at the Goodwood Festival of Speed happening later this week, which would be the first time the public will be seeing the RC F in action. It will both be doing demo runs on the Goodwood hill climb as well as compete in the climb.
Powering the RC F will be a revised 5.0 litre V8, upgraded with new features from the one found in the previous IS F. Output is 450 horsepower and 520 Nm of torque, driving the rear wheels through an eight-speed Sports Direct Shift gearbox. The RC F is also equipped with a torque vectoring differential, which allows shifting drive between the rear left and right wheels as needed.
Now you might be thinking that Lexus is lagging behind the competition, still using a large normally aspirated engine compared to competitors who have all gone with reduced displacement V8 engines. The BMW M3 uses a turbocharged 3.0 litre straight-six while the upcoming C 63 AMG is expected to use a turbocharged 4.0 litre V8.
But the RC F’s V8 has a bag of tricks of its own, which includes something we’ve never heard of before – the ability to switch between the Otto cycle and Atkinson cycle.
Most car engines use the Otto cycle. The Atkinson cycle is usually more efficient because of its greater thermal efficiency, but comes at the expense of power to displacement ratio, so they’re normally only used in hybrid engines. The only car to use an non-hybrid Atkinson cycle engine that we know of at the moment is Mazda’s SkyActiv engine.
Basically the ability to run on both Otto and Atkinson cycles give the Lexus engine the ability to produce lots of power when the driver demands it, but run fuel efficiently while the owner isn’t chasing M3s as well.
How does the engine achieve this? Lexus has used electric cam phasing which allows for far greater flexibility compared to traditionally hydraulic-powered variable cam timing devices. The electric cam phasing solenoids hold the intake valves open longer to lengthen the power stroke to achieve an Atkinson cycle during light loads, and revert back to normal valve timing during heavy load.
We look forward to seeing what the RC F can do at Goodwood. Hopefully Lexus will be producing a video.
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My dream car! Will it appear in Malaysia? Hopefully price can compete with M5 or Porsche and not higher
Your dream car look nice but wth with Nike DRL…?
Who said Toyota don’t have muscular car?
It is only the matter you can afford or not.
Why you can’t afford, because there is a thing called “protection” for the almighty Proton.
The car’s atkinson cycle switchover effectively reduces the static displacement of the engine, making it “smaller” and reducing pumping losses.
However, its not ideal. You are still using “a big engine” to run lower effective displacement (ie. by reducing stroke”.
It should have taken a page out of Mazda’s book and slapping on a variable boost supercharger like Mazda’s own Miller Cycle engines (which also runs similar to an atkinson cycle)….or keeping it simple and slapping on a few variable geometry turbo chargers to a smaller engine like everyone else is doing.
Mate, If they did that “like everyone else”, then Lexus will just be another “Me-too” product. Can’t have that!
The whole point of NA engine, aside from fuel saving tech, is to make the car more engaging and responsive, not to mention a damn awesome exhaust note.
What you fail to point out is that Mazda’s Skyactiv is only able to produce decent power and be extremely frugal at the same time is due to it running on extremely high combustion ratio to maximize the combustion of fuel. As everyone knows, forced induction like superchargers and turbochargers don’t work well with high combustion ratio. This is also why Mazda has stated that they would not forced induced their Skyactiv.
I’m not that well versed in Mazda’s Skyactive. But if its running on the atkinson cycle as the article claims, then it sounds like an oxymoron. The nature of Atkinson engines by design isn’t known for being high compression. That said, perhaps there is a little confusion between the compression ratio and the expansion ratio of the engine, in case of the Atkinson/Miller, both can be different and varied depending on the electronics that govern the valve opening timings of the power stroke. For example, the Pruis’ Atkinson has compression ratio of about 9:1 and expansion ratio of 13:1 but official documentation only claims 13:1. Perhaps the same applies to the Skyactive as well. 14:1 is unnaturally high, and being so high, would adversely affect torque production (knocking will result to retarded timing). It may be likely that the Skyactive G has a MAXIMUM possible compression ratio of 14:1 but may not always run that high (maybe only light throttle and coasting)
Any other Atkinson engine specialist wants to chime in?
I’ve worked on the Supercharged Miller cycle before so I am more familiar with that but I don’t know what has changed with the Skyactive. If I remembered correctly, the Milly cycle only had static compression of 8:1. Very low for a modern engine, which is why it needed the positive displacement supercharger to “gain” back some of that compression. I think the Intake valves stay open to something like 45 degrees BTC.
If anything, with the lower compression ratio with atkinson engines and cooling and more focused intake charge of Direct injection, it would be a waste not to somehow forcefeed it.
Anyway, I do not consider the Skyactive G being a powerful engine. Frugal yes, Powerful no.
I tend to favour slightly lower compression motors and more robust setups and slightly more aggressive timing advance as you actually get better low RPM throttle response and higher torque. But thats just personal preference (perhaps the feel of big lazy V8s and turbo 4 have dulled my senses).
I would think the Lexus will also benefit from a supercharger. It retains the aural symphony of the V8 without muffling it with turbo chargers. and the positive displacement supercharger will give it instant torque. They could very easily given it a 2 stage, one when it runs on atkinson, another when it switches to Otto.
Waiting for kzm to come here to tell everyone this engine was designed in Malaysia and produced fully by Malaysians eventhough Lexus is taking credit for it.
Kzm where are you?
With this Otto & Atkinson cycle switchability, there’s still some life at big cubic inch engines.Can’t wait to see the comparison test between the Lexus RC-F & BMW M4!
An eight-speed Sports Direct Shift gearbox?! Oh Noooo~~!!!!
revert back? What do you mean?
UMW version….2 airbag, stereo system from Brothers…triple the price
Can anybody tell me, this car can beat my golf or not?
It will not only beat ur golf, it will also whack ur “golf BALLS”..
BMW calls it Valvetronic system, 1st introduced in 2001. The motor is a high precision electric motor that is very sensitive and famous for failure. If Toyota choose to use this, engine reliability will be compromised.