S-plus - Is it really 'fake'

[GoZoner]

My contention is that S+ is about performance and, as Honda says, engagement but S+ is definitely not about 'fake' shifts. Every single YouTube personality (and I've seen them all in every language) claims 'shifts are fake'. Honda focuses on engagement and has not mentioned performance, that I've seen. This Honda position might suggest I'm wrong; but I'll explain.

The singular reason for a transmission in non-hybrid, IC engines is to keep the engine in its power band. To achieve that, manufacturers adjust gear ratios (and the spacing between gears) so that shifting, whether by a manual or automatic, keeps the engine revving in the desired RPM range. Sometimes to maximize torque; other times to maximize power (top speed). Doesn't the same apply to Honda's hybrid system?

The Honda e:HEV system connects the ICE output to a generator motor that produces electricity. That electricity is used to 1) charge the battery, 2) power the wheel drive motor, or 3) both. The faster the generator turns the more electricity that is generated (think windmills); if directed to the wheels, more electricity means more acceleration (or power overcoming aero-drag at higher speeds). We know this to be true because when 'brake torquing' Honda e:HEV cars, Honda sets the engine RPMs to the max, and keeps them there, in order to produce the fastest acceleration. So, what is S+ about?

S+ allows the driver to keep the engine rpms high, if desired, thereby generating more electricity which can be used for acceleration. (Or used for recharging the battery if the pedal is not demanding acceleration). Just like a traditional manual or automatic transmission, S+ allows the engine to spin at the optimal RPMs to generate electricity. As a side benefit, the higher reving engine generates sound and the action of shifting with the paddles increase engagement.

But, it is all about generating electricity at higher RPMs.

Makes sense?

 

[qlaval]

Using the S+ Shift function doesn’t add real gears, as the Prelude electric motor only have a single direct-drive gear. No transmission in the Prelude, none. At highway speed, a clutch may engage the ICE to drive the wheels directly, because it more economical to do so and/or because it can act as power booster. For car enthusiasts, part of the joy of driving is choosing gears yourself. The act of shifting is an experience many aren’t ready to give up. So, to fulfill that wish with hybrid cars Honda invented the S+ shift function.

So yes, the feeling of sensing/hearing a gear shift is simulate, as there are no gears in the Prelude hybrid setup.

There are 2 electric motors, one to move the wheels and one to generate power to the battery.

The S+ function is able to make the sensation of shifting more "real", by making the generator motor (ICE) modulate its RPM to fit the one made by a regular motor who is shifting real gears. It's just modulating the RPM of the ICE to enhance the illusion of a real gear shifting. The ICE revs, blips for downshifts, “holds gears” on command, and more. Doing so hurt efficiency, that's why when using S+ you will burn more gas than if you don't use the S+. More using S+ mode will add to the 0-60mph time by about 1.5 sec, because instead of a seamless power delivery for maximum performance you will have a system that goes up and down. The only advantage of S+, at high RPM the ICE generates more electricity for the battery but at an added cost has this is not done at the economical sweet spot. More that surplus of electricity doesn't push the electric motor to give more torque, it just fills the battery faster...

 

[GoZoner]

I think you've described the standard view of S+; I'm suggesting something different.

In a traditional transmission, gears exist for one-and-only-one reason - to keep the ICE in its optimal torque/power band. In addition to what you describe, the S+ button exists to keep the e:HEV ICE at its optimal electricity output band - which is high-rpms.

So, for spirited driving, where you want acceleration, use the S+ button to keep the revs elevated, thus providing more power to the front-wheel drive motors.

You said "It's just modulating the RPM of the ICE to enhance the illusion of a real gear shifting"; I'd say "It is allowing you to modulate the RPM of the ICE engine to enhance electricity generation and thus acceleration"

 

[qlaval]

Where I differ a little bit, is where the enhance electricity generation from high RPM is only charging the battery faster, the acceleration is not impacted as it received the same amount of power from the battery. Changing the recharge rate of the battery doesn't change the output power of the battery, only the depression of the accelerator does, and it does that in the same manner for either a low or a full battery. A 1/4 full battery give the same output as a full battery, only the duration of the output is changed before the generator goes on again. If it was like you've said, the 0-60 would be faster with the S+ on, but in reality the 0-60 is faster by 1.5 sec when it is off.

 

[GoZoner]

Like you said, the 0-60 time is not faster w/ S+ but that is because the engine RPMs can't be held a the maximum with S+. The fastest time is with 'brake torque' which holds the RPMs at the limit. But that brake torque just proves the point - Honda produces the best 0-60 at maximum RPMs; we get to use S+ to produce more power at higher RPMs - if is not 'fake' it is real power at higher RPMs.

Honda could replace S+ with a 'B' ('boost') button - hit the 'B' button and the engine stays at max rpms until the 'B' button is pressed again. That is, the 'B' button lets the driver enter a 'brake torque' like mode on demand. (The car would drone, and not be engaging, but it would produce maximum power.)

 

[qlaval]