Motor replacements? ICE and Electric

I am most familiar with the Gen II Prius but I think my answers apply to Gen III as well.

1. I believe MG2 already is more powerful than the max amperage of the HV Battery and MG1 combined. You would first have to upgrade one or both of them before running into the limits of the current MG2

2. Here are the cars running the same ICE as the Gen II Prius except in Otto cycle.
Toyota ZR engine - Wikipedia, the free encyclopedia
You may be able to swap in a 155 HP Otto engine in place of the 98 HP stock ICE.

4. Some Aussie has added both a supercharger and a turbocharger to his Gen I Prius, with mixed results. (Much of the power increase makes more electricity)

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5. The mods will not be mainstream for a Prius as sensible owners bought the Prius for fuel economy. I suspect it will always be custom for Prius, but pressurized induction parts may exist (I did not find any) for the Otto variants of the ICE.

I have no idea how much of that would be street legal in MD.

 

The land speed record Prius used a different differential gearing to achieve higher speeds. You could achieve the same thing by using larger tires.

The use of the otto cycle engine in the landspeed Prius probably only served to provide more horsepower at lower speeds. This would be important for 0-60 or quarter mile times, but not for top speed. The regular atkinson-cycle ICE is still constrained by the PSD at lower speeds to certain RPMs where it can not produce maximum power.

Methinks the inverter will be the limit of any performance gains at higher speeds via a different ICE.

Since no one has sufficiently decoded the Gen III Prius, I think you are out of luck.

 

Another potential problem are is that if you add ICE power, then you need more electric motor power to balance the ICE power at the torque splitter (planetary gear set). The data needed to calculate that is on the forum in other threads.

You might also run into motor thermal limits because of space constraints in the transnaxle.

Sounds like a good place to do a Systems Engineering exercise.

 

A caveat to my earlier statement:

There are certain configurations of the PSD that lets the extra power of the ICE go directly to the wheels without having to go through the electrical pathway.

The only thing is if the Prius ECU is smart enough to adapt to this and run the ICE/MG1 combination at the appropriate RPMs without having to spoof certain things.

 

How do you avoid having to provide enough electrical motor torque at the torque splitter to balance the ICE?

 

You have to set MG1 to spin at a lower RPM. Power is the product of torque and RPM.

Power Split is a misnomer. The reality is the ICE torque split is fixed at 72/28 to the wheels/MG1. The power split ratio is dependent on wheel speed, and mg1 speed. Even if 28% of the ICE's torque is going to MG1, it could be receiving 0% of the power if it is not spinning.

At 0 RPM, MG1 can provide a counter-torque to the ICE without providing any "real power". To provide this torque, it only consumes power to overcome its electrical resistance.

On the flip side, if the wheels are not spinning, 100% of the power goes to MG1, and then to the batteries. Still, only 28% of the torque is going to MG1.