Featured Toyota Prius SUV Reportedly in Development

Actually SkyActiv-G is also atkisonized Otto at lighter loads, so not sure if you'd call it true.

The difference in efficiency of SkyActiv-G and SkyActiv-D EU Mazda6 is 20%, which is likely attributed to 20% higher energy density of diesel. Take that out and the efficiency the same, which makes sense since they are about the same size 2.0L vs 2.2, and have the same 1:14 compression ratio and likely use similar timing advancing. The 1.5L SkyActiv-D has 1:14.8, but it must have worse thermal losses due to smaller size.

Here is more info on 1.5L: MAZDA:Next Mazda2 will Feature New SKYACTIV-D 1.5 Small-Displacement Clean Diesel Engine | News Releases

It would be nice if they'd bring it here but I don't think it is likely, unless Toyota pays for certification.

IMHO if were ever see Mazda diesel the best candidate would be Mazdaspeed.

The 2015 Mazda 3 Ditches SKYACTIV-G for New Diesel-Electric Hybrid Powertrain, Additional Details Expected Soon; Air Herald

 

I'm not sure where you got the idea that I said that compression was linear with efficiency. I said nothing of the sort. I simply said that efficiency increases with effective compression, this is quite non-linear. i do admit, I never took physics 101, just ap physics in high school and higher level physics in college. Not part of the problem here. I quite agree that it is not linear with effective compression.

um, ok. you may want to give this a read
The Future for the Naturally Aspirated Engine Is Grim – Feature – Car and Driver | Car and Driver Blog

First part, well no P*T/V is only true for an ideal gas without heat losses and constant number of particles. An efficient turbo charged engine should have an intercooler which removes some of the heat of the compression from the turbo charger, then the direct injections adds liquid fuel after more compression this vaporizes cooling the engine. DI normally aspirated gasoline engines like skyactiv-g use this same trick to increase compression. The turbo can scavenge the cylinder removing hot gasses, further lowering temperature. Turbo can be down sized and down speeded because it makes higher torque at lower rpm than normally aspirated engines. Unfortunately these savings are not great until the normally aspirated engine reaches 3L.

The turbo charger and intercooler add cost though.. A diesel does all of this but does not have the waste gate or blow off valve that a gasoline DI turbo has. That is because the diesel can lean burn, with the side effect of much higher NOx. All of the US diesels now have SCR systems to reduce the NOx pollutants. Mazda claimed that it could meet US regulations but still has not been able to meet the NOx levels and desired hp without a SCR system yet. It is likely to meet us regulations without scr the mazda diesel would be less efficient than those other systems. Cost for the diesel ice and particulate filter are still higher than for turbo charging for similar acceleration.
Mazda Diesel Still On Tap, But Performance Must Be Suitable, Exec Says

Compare Side-by-Side
You can see the vw diesel is about 20% more efficient than the faster accelerating vw turbo (regular gas,15% more efficient than the normally aspirated 2.5L it replaces), but the mazda 3 with similar acceleration as that diesel uses only 6% more fuel, and given fuel costs that normally aspirated di mazda will be cheaper to buy and operate.

This is not true. The native compression is reduced and engine is downsized for the same power. Effective compression gues to 23 bar today, while the best normally aspireated is 14 bar and that requires premium gas.

that prius c has a less than 10:1 compression level because of its valving, it has a 13.4:1 expansion ratio so it can use more of the power of the combustion. Skyactive g has a 13:1 compression ratio, but can valve down as far as the prius in aktinson mode.

Again for US market something like the skyactiv g will be less expensive to hybridize than a diesel or a turbo but not give up much in terms of efficiency. The turbo charged gas ice might be better in a hybrid like the Lexus RXh instead of the six cyclinder engine. If they hybridize the diesel and bring it to the US I doubt it will sell and mazda and toyota know this. If they do it, it would be for Europe and/or Japan where taxes are very different than the US on fuel.[/quote][/QUOTE]

 

I briefly thought about this thread waiting behind a Highlander this morning. It already comes in hybrid version.

Bob Wilson

 

yes, but this would be smaller.

 

Other newer, with advanced valve control engines can do the same. Under heavy loads, they do go full Otto at that compression ration. Engines labeled Atkinson don't do that. Which is why I say it is better to read their published compression ratios as expansion ratios instead.

So it sounds like the diesel is less efficient than a traditional diesel which has compression ratios at 1:18+. IIRC, Mazda went with a lower compression in order to help with emissions. The SkyActiv-Ds can pass Japan and maybe Europe regulations without SCR and DEF, but not US. I hope they just bite the bullet and use SCR for the US. The negative perceptions of SCR at the beginning of tighter diesel emission controls are fading. Toyota's new light truck diesel uses it, and I think VW installed it on the newest Jetta.

A hybrid may not need SCR, but the premium costs of the system can't be higher than a gasoline hybrid for it to sell in the US.

Toyota has chosen to price it out of consideration for most.

 

The Honda Pilot is not cheap any more either. The top of the line Elite is $47k. And there is no hybrid anything. Yet they still sell like hotcakes.

 

The main point is that they sell.
The Highlander hybrid will be lucky to break 5000 sold in the year.

 

the advantage of small diesel besides economy would be high torque. 1.5L matches torque of 2.5L SkyActiv-G Just what you need for SUV/truck.

Not sure about efficiency, since they used other tricks like advance timing, recirculation, etc. It may just be the testimony to how efficient SkyActiv-G is.

 

Toyota Europe already uses a BMW 1.6L diesel engine in the Verso (an MPV) and in the just released Auris. MY2015. It also introduced a 1.2L turbocharged gasoline engine with a variable Otto-Atkinson cycle, probably based on Mazda SkyActive ones.

Indeed diesel costs about 7% less in Italy (it's less taxed), giving it a starting advantage.

 

Back in 2012 it was about the same. Cheaper on some stations, more expensive on others. But I loved 70MPG diesel Punto was getting

 

If the hybrid SUV rumor comes to fruition, is their a risk of Toyota following the GM path ... where GM comes up with several different models of the same thing, only they add a little different trim here and there? Is there a need to have a separate platform for a hybrid small SUV? Some rave4 owners wish for, and still miss the smaller platform, but it was done away with, regardless of customers' preference.
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Others are introducing smaller SUVs. It is conceivable Toyota could do the same to fill the space vacated by the bloated Rav4. It could possibly a rebadged Mazda if it happens for the North American market.

A Prius SUV is just a rumor made up by the article writer. The real news is Toyota using Mazda diesels in Europe. While they do have a partnership with BMW, and use their diesels in some models, I suspect Toyota would prefer to give work to a fellow national. Or they simply feel the Mazdas are better suited for their needs. If the SkyAtiv-D 1.5L can pass Euro6 without SCR, it could be the lower cost option.

Mazda themselves may be doing a diesel hybrid. This could be to further improve the emissions, or to simply have further distinction from Toyota's hybrids.

 

Do you have a source for these TDC pressure values?

 

The rumor is this is a mazda cx-3 variant. That is a small crossover, like the juke, honda hrv, etc. The humongous class SUV's like the sequoia have lost a lot of market share but highlander and RAV4 have grown, so toyota building a tall small car type crossover. It sounds like toyota instead of doing there own, is going to share the platform with mazda. This is much like the mazda ford relationship of the past, and not like gm. Ford and mazda gained scale and reduced R&D costs but made each shared platform there own car. Brand loyalty is higher today and mazda has much lower brand customers in the US and Japan, so toyota could probably sell the same car and make money, but it is likely they will be like ford/mazda and make things different. In the ford/mazda relationship they often put their own engine in the car.

Mazda sells only diesel cx-3's in Japan and only gasoline engines in the US. On the most likely true, mazda and toyota are developing a hybrid together. I take with a big grain of salt the rumor that this hybrid may be based on mazda's 1.5L skyactiv diesel which makes 105 hp. We don't have any efficiency figures from mazda, but vw's diesels are 42% efficient (best are much more expensive truck and boat diesels that get up to 52%) and I doubt mazda can reach this level without scr and meet EPA NOx requirements. Toyota has a new 1.2L gas di turbo that has 114hp and 36% efficiency, it gets better gas mileage in an auris (scion im) on the japanese test than the 1.8L with 140hp and 38% peak efficiency the us will get in the scion. A atkinson version of that 1.8L with 98 hp and 38% peak efficiency is in the prius, a 40% peak efficiency is expected on the next prius engine. Mazda also has a 1.5L skyactiv with 99 hp (for 13:1 compression for US regular gas) that can do atkinson mode. I would say the odds are good they try the diesel in the lab in a hybrid, but my guess is the bean counters, marketing men, and engineers will all choose a gasoline hybrid for japan and the US as cost and weight will be lower.

They were in the the car and driver blog article I linked, not sure what TDC stands for in this post. In engines I normally read it as top dead center, which doesn't make sense here, so hopefully I am answering the question.

A 50:1 effective compression means a 4 boost turbo ( 5 bar or 145 psi at the intake manifold) on a 10:1 compression ice. They have these operating in the lab. There is really no reason to downsize an engine further than a 2L I4 though so this effectively makes it like a normally aspirated 10 L engine, which may explain why they are still in the lab. A hybrid turbocharger is often used with an electric motor spinning up the turbo or slowing it down.

It would be a very expensive 10 L engine as your block would need to be strong enough for all that pressure, why not do 25:1 in with a bigger 4L engine with cylinder deactivation? BMW makes a 4.4L V8 with 1.5 boost (2.5 bar or 72psi at the intake manifold) with a 10:1 compression ice meaning effective compression is 25:1. BMW has chosen horsepower over efficiency in its design, although it is much more efficient than other naturally aspirated engines with that much horsepower. The V8 is much lighter than the v12 it replaces, and friction is much lower. The turbo v8 also is much more efficient at lower power levels, but uses more gasoline at high power levels than the v12.

Toyota now has a 1.2L turbo di engine for a hybrid application like this, but it gets 36% peak efficiency. Efficiency goes down because cylinder size is so small and some cost savings. You could make it a 2 or 3 cylinder instead of a 4 cylinder to help efficiency but people want at least 4 cylinders.

But the big problem for diesels and turbo engines in a fairly low horsepower hybrid, is they seem to cost more than the improved efficiency gives you back. Why not use a bigger otto/atkinson engine there that costs less? The gen IV prius engine is supposed to be 40% efficient. Why not use a similar design instead of turbo di diesel or turbo di gasoline.

 

AG, the pressures you have indicated are too high to be mean efficiency pressures, that's why I ask for sources.

Edit: I've just read the article, and 22bar have been reached,
"Turbo engines generally start out with a BMEP of 15 bar (218 psi), so nearly every turbo engine is better on specific power than the best NA engines, and now the better turbos are well established at 22 bar (319 psi). There is still huge potential for arriving at up to 50 bar (725 psi)."

Things move quickly, I have to keep up...

 

I believe that bmw 4.4L V8 goes to 24 bar on premium gasoline in M configuration. It is a very expensive engine though.

The lab stuff goes higher. This is from the MIT
http://energy.gov/sites/prod/files/2014/07/f17/ft016_heywood_2014_o.pdf

The problem is the higher the pressure the more expensive that engine gets, so that 20 bar engine often has a better trade off if you can increase size of the engine.

They found dropping a normally aspirated 2.5L engine to a 1.25L turbo di engine of similar peak power could increase efficiency by 40% on the city and highway epa tests, but not on the high speed test (small turbos get inefficient at high power). Toyota released such a 1.2 L turbo di on the auris for europe and Japan.

 

So - to sum up . . . . HiHy - a biger SUV, but at least it comes in a hybrid model. RAV4, smaller, and MAY come in a hybrid model. Anybody wana put odds on whether the 'maybe hybrid' RAV4, will also be a plugin?? Slim odds? Then there's the sure thing; Already delivering over 50,000 units world wide - the latest iteration - soon to be released, 8% mileage improvement over last years rev, the Qick Charge equipped, 20-25miles ev range, 2017 Mitsu Outlander hybrid PLUGIN arriving in Montreal 2016 spring - and they're taking deposit / preorders NOW !!

2017 Mitsubishi Outlander PHEV Pre Order

Or, if Toyota decides to do a 180 .... and stops crushing their plugin sales through publicly slamming them, and limiting sales to select states ... I suppose we could all just wait for that Toyota mind-set to change ... hmmm what EVER should I do . . . .




There's already a waiting list of 10,000 for the Outlander plug in. Heloooo .... Toyota ..... anybody listening? your pro fuel cell / bad plugin PR is not working .... I wonder how long it'll be 'till toyota can even DREAM of selling 50,000 hydrogen vehicles
(yes ... I'm trying to goad them into into playing catch-up !!)
.

 

2106 is a long wait, i don't even buy green banana's.

 

oh! they stole toyota's grille.