Finally home after 3 weeks.

There is one other thing I have learnt about the 918 that I forgot to mentioned. On the track with the power distribution graph showing, I gain a new understanding on how the car work.

While it is well known that the front e-motor disconnect at 265km/hr, the rear e-motor actually doesn't engage all the time. Outside of e-mode where the rear is always driven by the e-motor, in every other mode it only comes on part time.

At partial throttle only the gas engine is driving the rear wheels, it will engage when the pedal is fully depressed in Sports and Race mode. In Hot Lap mode there is an extra resistance point in the throttle travel, the rear motor only engages when the pedal is pressed past that point, i.e. flat to the floor. So in a way, the has multiple HP rating.

At light throttle in e-mode, it is a 154HP car, more throttle input means the front e-motor also engages and it becomes a 279HP car.

In Sports Hybrid mode, the car is primarily a 608HP gas powered one, with the front 125HP chips in on heavy throttle input and becomes a 733HP car. When the throttle is fully depressed, it then becomes a 887HP car. But after 265km/hr, it goes back to being a 762HP car.

In Race mode, the car is driven as a 733HP car, gas engine plus front motor. Full throttle and the car is a 887HP until 265km/hr. 

In Hot Lap mode, the car is also a 733HP car, but the throttle doesn't need to be fully depressed to make it a 887HP one, as there is some more travel between the resistance point and the actually full throttle position. 

Quite a revelation, and a bit different than what I had understand the car is when I read and hear about it from Porsche personal's presentation.

I believed the LaFerrari and P1 works the same way, their e-motor only kicks in at full throttle, and that explains a lot about why and how their cars performed during those head to head competition, especially track time. The P1 has the added disadvantage of keep driving the e-motor in generator mode in order to charge the battery, while the LaFerrari and the 918 can do regen braking.

The cars are so powerful that pretty much only during long straights are the throttle fully depressed, and hence the actual performance of the cars are a lot closer than we expect just from looking at paper spec. The 918 actually had the advantage most of the time with the higher torque figures through out the rev range. 

 


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