Featured SkyActiv-3 and Project One. The future of efficient hybrid engines

No, I clearly spelled out for some turbo charging and reworking the camry hsd system would be one way to get rid of some of the problems with the V6 hybrid system. I was wrong about gm's 2-mode being dead, but I still think it should be. I'll change my mind if I ever see gm make a desirable 2-mode vehicle. Interesting that this one is mainly for the chinese market and made in china and imported to the US in small numbers for those that want it. Who knows maybe the range is good enough and that it won't use much gas. It certainly is less expensive in the US than the model S or 740e (another poor plug-in). I guess I haven't been clear enough on these points.

I don't know why it is this bad. If we look at the rwd tesla models it can't just be regen braking. We also can't blame the bad efficiency on 2-mode because something else is going on here, but maybe. It is a worse hit than normal for a rwd.

No, I understand what is going on fine. I just think the numbers don't look that good without a bigger battery or different hybrid system. When we look at the camry le 2.5L hybrid system it weighs less than the V6 + transmission. The Highlander hybrid system adds 290 lbs to the weight of a highlander awd, but the awd is not as good. Highlander hybrid can supply 45 kw from the battery and toyota doesn't seem to be reporting how many kw mg can supply. Mg2 is 123 kw, mg3 is 50 kw, and the system is heavy. The battery in the camry is 20% lower energy if its nimh, which means I guess it can supply 36 kw, but its not additive because torque curves don't match adding 24 kw to the peak which is not bad when you need it. mg2 on the camry hybrid is 88 kw or 51% of mg2 + mg3 of the highlander. The extra weight could just be because they have not used their best motor/inverter technology or sized it right for the engine. But ... 123 kw would all be used in a phev. It could simply be they need to redesign the system, but if doing that why not base it on a 2.5L turbo that could be used in the rav4 and camry as well?

I know I know, you don't believe me a turbo could be more efficient. I don't want to argue with you. I showed a chart. The 2.5L prius has done all the work to make a turbo efficient, and toyota can make a turbo for efficiency, they know how in the lab, and have some experience with the 3.5 L in the new lexus, and the 2 L that needs some help in the lexus nxt.

Just to respond to the stuff on manifolds, that mazda marketing mixed up turbo with skyactiv-g normally aspirated exhaust. The correct way to plumb a turbo for a 4 cylinder in line is a twin scroll with opposite banks and equal lengths. Toyota is doing this with its turbos, and a turbo designed right will use the power of the exhaust of other cylinders to scavenge the last bit of a cylinder about to close its exhaust valves. In a hybrid application turbo lag can be countered with battery power, while inefficient areas of the bsfc curve can be eliminated with an eco button, but full power made available in other modes. The reason few companies use cooled egr in a gasoline turbo, is it is not needed for emissions, and only increases mpg in the real world, not on the government tests. The engine also has port injection which toyota can use to go deeper into miller cycle at higher rpms.

 

I think I was being perfectly fair, this being the internet. We have the weight penalty, and worse awd, and worse handling, and from reviews, if you use the hp, it won't give you much of an advantage versus the non-hybrid.

On the other hand sales for the rav4 hybrid have been going really well. Reviews have said because of its lower weight the hybrid system does much better in this car than the Lexus NX hybrid, and it is at a really good price point. But yes this is a new technology thread, and the rav4 hybrid system is heavier and less efficient than it should be. I didn't mention it because we all know it is being redesigned now. This is doesn't give the benefit of the doubt to the highlander and Lexus RX V6 hybrids as who knows if their hybrid systems will be revamped, but these cars already have Toyota's excellent Atkinson D4S system, which will lead to an improvement in the Rav4.

3 key technologies should improve the Rav4 hybrid. First the D4S improvements in the engine boost peak efficiency from 38% to 41%, but also make the system more responsive and need less battery buffering for power demand. That should provide at least a 10% improvement in efficiency. The next is lithium battery technology, its what made the the 33 lb difference between the le hybrid system and the xle/xse that uses nimh, but it is responsible for a greater efficiency improvement as the battery can handle power better. The third would be improved e-four system that should improve awd performance.

How much the Rav4 hybrid improves is unknown at this time. Toyota seems to still be pushing nimh. A rav4 hybrid all wheel drive probably should have a 1.5 kwh lithium battery (0.9 kwh usable) versus the 1 kwh lithium or 1.6kwh nimh (0.6 kwh usable) in the camry hybrid le and xle respectively. The crossover will need more battery power to efficiently use better awd. We still don't know the specifics of the new e four system.

Sure but if the reason you are selling the hybrid instead of a phev (bmw X5, pacifica hybrid) is the batteries weigh too much, then that v6 system uses its weight poorly. The AWD system doesn't work very well in the real world. Toyota could fix all these things with a redesign that works, but I'm sceptical. The bmw system seems like it doesn't work as well as that in the pacifica, perhaps it simply needs a bigger battery of a different type and better software. Chrysler is using the inexpensive LG chem batteries that chevy is using in the bolt and volt. To get the power levels from the battery bmw is using more expensive lithium. The i8 is increasing the battery size. A different approach would be to use some of the high powered lithium tech that toyota and ford are using in the camry and fusion hybrids, with some less expensive bev type batteries.