Toyota new engines gain 10% fuel efficiency; up to 38% thermal

Great readings, I suppose...

 

And it's this kind of thing that's going to give Gen IV Priuses 60+ MPG. If not more.

KBeck

 

this is very interesting, as it is two small engine series going into cheapo cars. It is KR and NR series that are already competitive in their class when it comes to consumption, so to NR to get 15% improvement and KR to get 30%, thats a lot. Toyota estimated "only" 7-8% when they introduced brand new ZR series with Valvematic.

I guess this VVT-IE with atkinson cycle "on demand" will go into every future engine. They said 14 new engines coming in 2015 with this tech, and they announced RC-F V8 to have it as well.

 

I hope and expect them to do better than that in the next gen prius. The Gen III is already 38% peak thermal efficiency, and the 2.5L DI atkinson sold in some models outside the US is 38.5% efficient.

 

It sounds like both the Yaris and Prius c will be getting a boost in their EPA ratings soon .

 

I can see how the future Prius engine would benefit from this.
Today we have 10:1 compression ratio in normal engine and 13:1 expansion ratio in Prius engine, compression ratio is probably the same 10:1 to avoid knock.
Tomorrow we will have 13.5:1 compression ratio in normal engine and something like 18:1 expansion ratio in Prius engine (compression ratio 13.5:1 knock solved).

Does this makes sense or it doesn't work like that?

 

Yes, this increasing trend of CR may be also shifted to the Prius ICE, within limits.
I would not bet on 15+, though.

 

I knew the concept, but only 8:1 effective compression ratio and huge 13:1 expansion? I didn't know the difference was so huge.

Still I would think there would be benefit from raising both this values to something like 10:1 and 16:1, with the tricks in that article, boosting efficiency over 40%.

 

The article doesn't mention direct injection, but that would allow higher compression with regular octane. Mazda's SkyActiv-G is 13:1 with US regular(14:1 elsewhere).

 

It strikes me that these sorts of developments threaten increased hybrid adoption, in that the fuel consumption difference between comparable hybrid <-> non-hybrid cars is likely to get smaller rather than larger. Of course the technology will benefit hybrids, but it will benefit non-hybrids more.

 

It's always a moving target.

Traditional vehicles are the true competition.

Don't let the rhetoric convenience you otherwise.

 

Toyota gas cars get efficient engine from hybrids - Businessweek

OK what is the main thrust of this new tech? Its valve control that lets them shift from otto valve timing to the timing we have in our prius, plus the very low friction coatings that are in our gen III prius may have slightly advanced and are being used on these less expensive engines.

What do we get Gen II prius 37%, Gen III 38%, 2.5 L atkinsion with di+pi 38.5% (lexus ISh) is moving to small non-hybrid engines 1.3L up to 38%, 1L up to 37%.

The advances mentioned that are not yet on the toyota hybrids are better intake valve and chamber design to produce a better fuel air mix, and an improved piston shape to produce a more even heating explosion. Definitely things that mazda talked about in skyactiv to improve compression ratio without detonation, are now in these Toyota engines. Maybe combined this is good for 0.5%, but should provide better torque at low rpm.

None of this closes the city gap to hybrids. Definitely though these equalizes the playing field when on the highway in cruise control.
Hybrid-focused Toyota turns to new fuel-efficient engines| Reuters

The other tech we can expect from toyota in the next gen prius probably is di. They already have done it in the Lexus ISh (not available in US) and got about a 1% improvement in thermal efficiency. Going from 38% to 39.5% (1% di, 0.5% piston and airflow changes) in the next gen prius gets us closer to the theoretical thermal efficiency limit of normally aspirated engines.

 

Oh well. That is already the case in Europe where hybrids sell poorly, since EU citizens have the option of gasoline engines that are nearly-as-good in MPG but cost far less.

Wouldn't you rather have a non-hybrid direct-injected 13:1 compression Prius C for ~15,000 rather than ~19,000 dollars?

And yet still get the same highway MPG? I would. (Unless I lived & worked in the city... then I'd want an EV.)

 

For the US, the 2016 small toyota replacement of the yaris (now selling very poorly because people choose the prius c), will be based on a 1.3 L skyactiv ice which should be 13:1 compression otto that can run in Atkinson mode.
Toyota's new subcompact will use Mazda's Skyactiv engine
Toyota's new 1.3L appears destined for europe and/or asia but not the US. Part of the lower manufacturing costs is the new mazda2/yaris replacement (don't know if it will be still be sold as yaris) is being built in Mexico and not built with more expensive labor/electricity/transportation in Japan or France.

That should give american's that choice in Toyota's prius c versus more efficient new yaris. In Japan, with higher gas taxes, we know that the aqua(prius c) greatly outsells all non-hybrids.

Toyota is working on new turbocharged engines but that is in different announcements for much more powerful engines. VW is the only company that has gotten cylinder deactivation on 2 cylinders to work, going to atkinson mode as mazda and honda do, is likely as efficient in these very small engines. I'm not sure how offset cylinders improves a 4 cylinders efficiency but don't quite understand all of the technique.

 

Here is Toyotas new 1.0 liter engine in an Aygo (I go). It gets 60mpg on the Euro cycle which would probably be 45 highway EPA cycle: Green Car Congress: Toyota revamps 1.0L 3-cylinder engine for new AYGO; up to 60 mpg in ECO version