Gen 4 Staff Manual (In Japanese) =/ Specs/Design/Other Info

It needs to be considered that all these are at-the-shaft figures, and does not take into account transmission losses. It is entirely possible that the loss of the planetary reduction gearset can offset the at-the-shaft reductions to result in a net gain at-the-wheels, which is one of the things that matters.

We really do have to wait-and-see.

But no, the figures are not confidence-inspiring if one was hoping for a faster car.

 

I suppose Toyota design engineers know all these and more...
We don't have all the details to make a judgement.

 

Yeah, that's all we can do now, wait and see.

But transmission losses are not going to account for reduced horse power. As per Toyota statement, they reduced the transmission losses up to 20% by changing to straight. But remember that is 20% of 3%( which is the loss for Planetary), that 0.6% at best.

May be that is the reason Toyota is trying to avoid publishing official total power output. As far as I remember they published HP figures for Gen 3.

 

Electric motor torque doesn't matter, because it can be compensated with gearing. As for the power, it must take all the power from MG1 (half of ICE power 36 kW) and from battery (the rest 16 kW). On paper we than have max combined system power of 89 kW or 121 PS, this doesn't necessarily mean less power in real world compared to gen3, because I never saw more than 22 kW (26kW on paper) of electric boost and on a dyno gen3 Prius never shoved more than ~81 kW combined power.

I expect gen4 to be down on power only by around 4-5 kW on a dyno, (20% more efficient HSD and more torquy ICE)

 

The more efficient engine due to lower internal friction and better air intake suggests more ICE power. The higher charge rate also means more takeoff power. So I am leaning towards a better launch and 0-60 time.

Bob Wilson

 

Sorry, I have to disagree with you about the statement "Torque doesn't matter".
Yes, torque does matter, if torque is less, then you have to compensate with high RPM with gearing which will raise HP. In this case it is down on both.

I am not sure what you meant by "it must take all the power from MG1 (half of ICE power 36 kW) and from battery (the rest 16 kW)."

Battery supplies power to motors. Battery itself does not generate any torque or HP, it is motor which take power from battery and generate Torque and HP.

Please check the Gen 3 specs on Toyota website for those numbers ( see my previous post).

Despite all this, I hope Toyota pulls some kind of rabbit out of hat, and does it better. Basically it is all power to weight ratio.

 

ICE power is already given in the spec. It is lower than current Prius (not much difference though). All internal engine friction is accounted for when flywheel HP is quoted.

But reduced transmission losses does help, but it is miniscule, and at best it could account for 1HP wheel horse power. But it does help a lot for fuel economy, but not much for acceleration.

Charge rate helps esp in regeneration. I am guessing it can absorb more charge during rapid braking. Despite batteries current delivery capacity, power would not exceed the Motors max HP numbers.

I am hoping for some kind of magic here, and some how Toyota is able to use more combined power than Gen 3, which helps in acceleration.

But again if combined power is 122HP as quoted in by Ken, I do not have too much hope.

 

They were very careful in the wording of the press releases to not predict improvement in acceleration numbers while stating that acceleration "feel" is better:

"New updates to the Prius' hybrid system software improve the feel of acceleration, giving a smooth and direct response in a lower rpm range."

Maybe, just maybe, that, with improvements in handling, will seem better than the current generation. I would love some magic too but I'm keeping my expectations low.

 

A car like the Prius is never about how quantitatively powerful/fast it is, as its core value (fuel efficiency) defeats this end. Even if you make it more-powerful/faster (probably at the sacrifice of *something*), it will still be middling in the grand scale of things.

But making it feel nimble and eager is entirely possible, esp. when you have the aid of the instant torque of electric motors. Let's hope the direct-er drive and improved electronic efficiency improves this aspect despite the reduction in spec output.

The thing they should not do is to fake this with an aggressive E-throttle tip-in map. This is the unfortunate case with my IS300, and every time my girlfriend wants to drive it I have to warn her about the touchy gas pedal.

 

@chinna
I think you are jumping to conclusions too soon without having all data in front of you. I am sure Toyota has some more tools in their toolbox.
Example: What if, compared to Gen 3, they have changed the PSD 'gear ratio' so more than 72% of ICE torque is sent the mechanical path to the wheels and less than 28% to MG1 to produce electricity? This way lower currents are going through and motors plus PCU can be smaller (as they are reporting), lower current means also less absolute losses.
Example 2: What if they have succeeded to widen the 'sweet range' of ICE high efficiency toward lower RPM? this may give it similar performance with slightly lower peak power.
Even in 0-60 peak power is developed toward the end of the test. Average trip power is more important than peak power.

 

Yes, I agree. I looked thru all pdfs, and it indicates what you said.

Still.. you know I want it to perform better, so that merging on highway makes it less stressful (some between jammed up exit lanes to fast moving main lane, and some very short entry ramps)..

 

Yes, I am hoping for some tricks here. I am pretty sure torque curve of the ICE is broader than outgoing version, but generally improvements would be in very few percentile, not anywhere compensating for 25% deficiency of torque from motors and dropped HP.

But one thing I really like is the fact they addressed the NVH problem. That is one of biggest problem for me for long drives(or to avoid long drives in Prius), that why I take my 328i(which gives about 35 on Hwy) more often than Prius for long drives.

 

What is NVH?

 

Noise, Vibration, Harshness.

 

If MG2 spins faster and the reduction gear will make the same torque at the wheels. This was how it went from Gen2 to Gen3.

 

Forgetting all the conjecture about changes in ice and electric motor outputs and how it will affect 0 to 60 acceleration, I believe that the gen 4 will be more peppy. Toyota is spicing up this car in every way it can and I don't think that the same acceleration as gen3 would be acceptable to them. This new generation is very important to the company. Anyone test driving this car will be expecting it to do more than corner well and be quieter. It has to have a bit more oomph.

 

0-60 may be faster but slower for a quarter mile? That is, faster power delivery to reach the peak but the peak is lower.

 

Hello all,
As we know there was a latest update from Toyota officially.
Also, there are some articles from Japanese media including this good one (Japanese language only).

I would like to update the previous information with new ones.

The first one is a better image of the transaxle posted on #87.

Enjoy,
Ken@Japan