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Discussion Starter #1
So I'm reading up on the new Rav4 Hybrid, and some things are kind of hazy. :serious

For example Motortrend.com lists the following motor outputs:
2.5L/112-hp/206-lb-ft Atkinson cycle DOHC 16-valve I-4 plus 141-hp/199-lb-ft front, 67-hp/103-lb-ft rear electric motors; 194 hp combined
112hp + 141hp + 67hp = 320hp
206lb/ft + 199lb/ft + 103lb/ft = 508lb/ft

Based on the acceleration performance, it's obvious not all 3 motors are running at 100% for the 0-60mph test. Anybody know a reason for this? Not that it matters for most Rav4 buyers, but it seems like all the hardware is there to go 0-60mph in low 5 seconds. Why would Toyota not make this a selling point? It sure has worked for Tesla! :D

I also noticed that power output figures are all over the place. For example this press release lists the gas engine at 150hp/152lb-ft.

https://pressroom.toyota.com/releases/2016+rav4+hybrid+product+specs.download

Then other places say that the engine in the hybrid is the same as in the normal Rav4, which should be 176hp/172lb-ft.

Is there a final and definitive source about what powers the new hybrid?:confused:
 

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From wiki on the 2.5L 2AR-FXE Atkinson cycle engine.




https://en.wikipedia.org/wiki/Toyota_AR_engine




The 2AR-FXE [8] is an Atkinson cycle variant of the 2AR-FE. It has the same bore and stroke, but the cams and pistons are unique. Geometrical compression ratio is 12.5:1
The large valve overlap leads to a reduction in cylinder charge and reduced torque and power output, but efficiency is increased. This combination makes the 2AR-FXE suitable for use in hybrid vehicles, where peak torque and power demands can be met by the electric motor and battery.
Maximum output when used in the Camry hybrid is 154 hp with 153 lb·ft of torque which doesn't include the additional power of the electric motor that is used in the Camry Hybrid.
Applications:

 

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194 net horsepower is all you really need to know. The hybrid system never uses all the power at its disposal at any one time. To do so would be very inefficient. Its also true that output to the traction motors varies depending on available battery level. So the actual available HP is a variable number. And the hybrid synergy drive varies the blend of electric and gas power being delivered to the trans-axle.

The rear electric motor is used only intermittently, also variably.

The only thing the engine has in common with the gas Rav4 engine is the block.
In order to understand any of this you need to be acquainted with the hybrid system and how it works on the street.

For example, a traction motor may have a HP rating or KV rating of "xx", but that doesn't mean the system is able to deliver that much power to it, (or take that much power from it), at any one time due to constraints of the electrical system. The inverter/converter is already water cooled as it is.
 

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The hybrid system never uses all the power at its disposal at any one time. To do so would be very inefficient.
Undoubtedly. As is the case also when a Tesla goes to 60mph in under 3 seconds. But then again, this "inefficient" mode is only enabled when the pedal is to the metal. Maybe someone will release a "hack" for the Rav4. :D

In order to understand any of this you need to be acquainted with the hybrid system and how it works on the street.
Are there any detailed papers on this? Not something like a Wikipedia page. But something much more in depth, something that's way too complex for the general public, but someone with an engineering background might enjoy?
 

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Are there any detailed papers on this? Not something like a Wikipedia page. But something much more in depth, something that's way too complex for the general public, but someone with an engineering background might enjoy?
The Rav4, Highlander and Lexus models use a more complex system due to the electric rear drive. But the basics still apply. You can find a wealth of info as well as synergy drive break-downs if you search for Prius.

The Rav4 is using a Gen-3 hybrid system. The 2016 Prius is the only model currently using Gen-4, everything else currently uses Gen-3. Short version: the synergy drive is just a very large planetary gear set. Its a "power divider" device where the system uses a bit of electric and a bit of gas most of the time. Sometimes it uses all electric and sometimes all gas. The rear drive adds some HP some of the time for brief periods.
 

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Undoubtedly. As is the case also when a Tesla goes to 60mph in under 3 seconds. But then again, this "inefficient" mode is only enabled when the pedal is to the metal. Maybe someone will release a "hack" for the Rav4. :D

Are there any detailed papers on this? Not something like a Wikipedia page. But something much more in depth, something that's way too complex for the general public, but someone with an engineering background might enjoy?
With an engineering background, as have I, you certainly know that just a peak HP number by itself is pretty useless info. It's the RPM it occurs at and the shape of the curve, and the torque curve that translates to actual performance. I see it all the time on my dyno. One guy who has 90HP with the peak at a 6500RPM rev limiter with the curve still headed up can't understand how an 80HP @ 5000RPM bike could be faster.

For the peak HP numbers (or torque numbers) to be additive they have to be at the same rpm and that would have to take into account gearing to the wheels. Electric motors generate lots of low rpm torque but comparatively low horsepower at high rpm whereas gasoline engines tend to do the opposite. So they complement each other well.

My Accord hybrid is an easy to understand example since the electric motor is mounted on the torque converter and, with the TC locked, spins at engine rpm. It produces 100PF of torque but only 15HP. But since it's torque comes on before the gas engine has made much, and by the time it fades to the 15HP the V6 engine is making 240HP, the overall combination makes for a very enjoyable "thrust" package.

To accurately compute the max HP you'd need the line up the individual graphs rpm-wise and fine the additive peak. If we had that information we'd probably get 194.
 
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