Tim Esterdahl | Mar 25, 2014 | Comments 16

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UPDATE: Looks like our source for this information, Motor Trend, got it wrong. The RC F won’t have cylinder deactivation. Instead it will use the Atkinson Cycle at lower loads.

This innovation is essentially variable valve timing, as the intake valves are left open a little longer at lower loads. The fuel savings is equivalent to reducing displacement 15%, yet power is unaffected.

Seems like this tech could work on any V8 if the engine was designed for it…

Next month at the North American International Auto Show in Detroit, Lexus is supposed to reveal its new Lexus RC and RC F coupe. While the news isn’t that exciting for truck fans, one nugget stood out. The RC F coupe will offer a Lexus and Toyota first of cylinder deactivation. Yep, Lexus is going to offer it. Here’s why and what it could mean for future Toyota products.

The Lexus RC F coupe is a track-ready sports car that will compete with the many of the other top production sports cars in the world. It will have a 5.0L V-8 capable of generating 455-hp at 6800 rpm and 401 lb-ft of torque at 5200 rpm. In other words, it will go fast, very fast! It is expected to reach top speeds of more than 186 mph according to MotorTrend.com.

While that is cool and all, the RC F is expected to have some tweaks to meet the very strict Euro-6 emissions regulations. Apparently that is where cylinder deactivation comes in. MotorTrend says; “To achieve that, the RC F will incorporate Lexus’ (and Toyota’s) first-ever cylinder deactivation technology in which four cylinders will be shut down during high-speed cruising.”

This is the same technology that other makers have notably used with mixed or bad results (like GM’s oil sucking issue.)

We reached out to several sources to question why they would use cylinder deactivation at all. Seems a bit odd to us that cylinder deactivation could be tied to emissions control. Here is the best response we got:

Chevrolet has been doing this for quite a while. It’s also becoming common in diesel engines in Europe. Most of the Euro-6 requirements are in regards to CO2 and NOx emissions, both of which are higher at higher RPM (which are often sustained at highway driving). The choice is to either add more gearing to reduce RPM, add more EGR/scrubbing, or use cylinder deactivation to reduce fuel use. Gearing adds weight and complexity, EGR and scrubbing causes efficiency losses, and deactivation hits somewhere in the middle. So it’s a choice of what you want to accomplish and then finding the cheapest solution to that problem.

While it makes sense to emit fewer CO2 and NOx emission particles at higher speeds, we wonder wouldn’t a multi-speed transmission get the same net effect (see: Ram’s 8-speed transmission).

It remains to be seen if Lexus will really offer this plan. If they do, we will be right there in Detroit with our questions on emissions and cylinder deactivation.

All of this brings us around to the BIG question, with Lexus planning to develop this system, will it get passed down throughout the lineup. Point blank, will a next-gen Toyota Tundra offer cylinder deactivation in an effort to curb fuel economy? That is the big question.

What do you think? Is this a sign of things to come or a one time deal?

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