Featured Hyundai IONIQ - Prius competitor?

EGR gas does not burn. It reduces the combustion temperature so less NOx is generated. It also allows the throttle plate to be opened to reduce pumping losses. It is a common technique in diesels and advanced engines like the Gen 3 Prius since 2010.

The challenge with GDI is formation of soot and particles compared to mixing with the air before ignition. This really sounds like a low-pressure diesel-like engine, a Mazda variant. But GDI makes no sense if it has an Adkinson-like cycle. Part of the intake charge gets pushed back into the intake manifold for the next cylinder. You really want a low-pressure injection system upstream of the intake valves.

Still, testing will have to prove it out.

Bob Wilson

 

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Don't take it personal:

It is not the first time I've read a 'press release' and realized an engineer did not write it: Volkswagen's Clean Diesels Eligible for Alternative Motor Vehicle Federal Tax Credit -- re> HERNDON, Va., Sept. 19 /PRNewswire/ --

HERNDON, Va., Sept. 19 /PRNewswire/ -- Volkswagen of America, Inc.
today announced that buyers of the Jetta TDI sedan and SportWagen are
eligible for a $1,300 Federal Income Tax Credit. The Internal Revenue
Service has issued a certification letter affirming that the vehicles
qualify for the Advanced Lean Burn Technology Motor Vehicle income tax
credit.

"The $1,300 tax credit provides an even greater value to the upcoming
Jetta TDI sedan and SportWagen," said Mark Barnes, COO, Volkswagen of
America, Inc. "Our clean diesel vehicles offer consumers the fuel
efficiency that they're looking for while providing power, utility,
performance, safety and excellent value." (Sept 19, 2008)
. . .​

The proof is in the testing and it didn't take long to realize the superior efficiency of 'diesel' was not competitive with a Prius. Yet a series of sandbagged demos including the 8,000 mile, Portland-to-Portland stunt were performed . . . and the efficiency claims did not stand up to inspection. Now we know they were 'cheat' diesels and even defeating their emissions control laws, they could not match Prius efficiency by any objective point of view.

I have no idea if this Beta will or will not deliver the hype. But it doesn't bode well when a press release uses non-engineering descriptions about the engine. Skepticism about press releases is a good thing especially when based on engineering principles.

Bob Wilson

 

This is mostly right, but since I saw comment's bellow so to clarify -

EGR cools and returns the mainly spent charge. There is some carbon monoxide and hydrocarbons left to combust in a gasoline application but is mainly inert nitrogen and carbon dioxide, that allows a smaller charge of gasoline - resulting in less energy and less NOx and more efficient cooler combustion. The intake valve timing (Atkinson timing) that stays open to push out the mixed air and exhaust gas is what is responsible for lower throttling and pumping losses, cooled egr is pumped and has those pumping losses. Diesels do lean burn and reduce pumping losses with turbochargers, and do not use throttle plates. These lean diesel burns with or without cooled egr seem to require SCR of the NOx to meet us or european emissions, but the cooled egr reduces the amount of work the SCR system needs to do. My gen III prius built in 2009 was one of the first gasoline production cars with cooled egr.

Mazda, GM, Hyundai gasoline engines that can do the otto/atkinson valve timing trick don't have a problem pushing the gasoline through the intake valves, they simply wait until the valves are closed to inject the gasoline. The challenge is getting the charge dispersed and mixed well in the short time of a late valve timing. My guess is toyota can wait longer using port injection or the port plus direct injection it uses in the Lexus ISh.

Attacking GDI engine particulate emissions - SAE International
particulates seem to occur primarily at cold starts and high loads. These conditions can be minimized for soot with a normally aspirated hybrid or phev application. Small turbo gasoline direct injection engines that need high boost while cold probably are the worst case. As injectors get better so will fuel dispersal. The agressive cooled egr of this hyundai engine should keep it low. The di allows greater otto compression allowing the 1.6L hyundai to have greater hp than the 1.8L toyota while both have the same 40% peak efficiency. We need to see long term maintenance records to see if particulates are a problem, and bsfc graphs and epa ratings to see engine efficiency from the hyundai.

 

I'm not an engine or combustion expert, but I gather that part of EGR is that by partially recirculating exhaust in place of fresh air into the intake manifold they reduce excess oxygen in the combustion mixture thus reducing opportunities for oxides of nitrogen to form and also slowing the combustion process due to less oxygen which reduces the risk of pinging or premature combustion under higher compression pressures.

 

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It would seem that simple. Reality is, there's more at play than capacity alone.

Toyota's system is highly refined. There's been 18 years of advancement following the original rollout. It's more efficient.

In other words, Prius likely takes far less electricity to accomplish the same thing... so, less would be needed.

 

The Sonata hybrid has been a good first effort and done well in the market. This car looks to be their Gen 2. Still, I am patient as in a year or so we'll see the EPA numbers and actual car.

The irony is seeing how the Toyota and Hyundai are still putting investments in more efficient engines. In contrast, the Volt and other plug-ins have been using less advanced engine technology. In effect using large batteries instead of advanced engines. Of the two approaches, the improved engines have the greatest potential of reaching back into their general, engine-only cars.

As for the combustable products in ordinary, untreated exhaust, I'm still firmly in the 'fire extinguisher' camp. There are traces of NOx, CO, and HC but in such small ratios compared to the CO{2}, it is really cooling combustion if nothing else by increasing the mass of gas to the combustion heat. It also means the valves can be opened a little more because the hugely inert exhaust gas replaces air that would have come through the fresh-air throttle plate. Pushing part of the charge back into the manifold also helps reduce pumping losses.

Good point about delaying the gas injection after the intake valves close. But the technical challenges of getting a uniform mix remains. Testing will reveal how well their system works.

Bob Wilson

 

Ford C-Max specs ... Battery, 1.4kWh Lithium-ion (Li-ion); Any reason for such a small battery in Gen IV?

 

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Yes, but not high compression.

The application is different than diesel or turbo, but here we see hyundai, toyota, and gm (in malibu hybrid) using agressive cooled egr with atkinson valume timing. The key here is the charge is mainly inert, meaning it doesn't have much oxygen, carbon monoxide, or hydrocarbons left.

Let's use the 13 as expansion stroke, and 9 as the maximum compression stroke (prius). Simply the longer expansion stroke will run the engine cooler, and as long it is in the right temperature range it won't use cooled egr. But say you only need power of say compression to 6 and that smaller charge. You can say use 25% egr and 75% of slightly rich stoich air and fuel, which gives you an expansion of 8. This is the same power wise of gasoline as valving to 6, and the gen III prius can do either.

A few things happen here. The explosion is slower and more efficient. It is slower because of the greater mix of inert material. It is more efficient because of the higher compression. The slower explosion lets the car advance the timing making it more efficient still with more complete combustion. That inert exhaust gas absorbs part of the heat of the explosion making fewer hot spots. That makes for less NOx formation, cooler combustion.

The downside is this has slower flame front which means you can't use it as aggressively at higher power settings. The gen IV prius adds more powerful spark plugs to make sure high mixes combust. There are also more pumping losses versus that more aggressive Atkinson valving. Also the formation of NOx and CO are reversible and slowed down by their presence, so it lowers the formation more than just pumping N2 into the cylinder. This pumping loss moves air instead of creating heat inside the engine. Other downside which is the reason we don't see it more often in gasoline cars is it cost money, but lower NOx and slightly more efficiency at low power levels are a good trade off.

Yep it appears that toyota simply picked lithium to match the nimh energy. This minimized weight, but not size. The car had to be designed for the size of the nimh option. I was expecting the slightly larger 0.9kwh of the toyota alpha. The hyundai with the larger battery can use it more agressively.

 

I've not studied the Honda Accord. Regardless, my confidence in the Honda Accord would go up if the 17 vehicles in the user reported MPG did not average 43 MPG. There is a broad range of user reported mileage suggesting the control laws are optimized for EPA testing and there may be 'pathological' driving patterns that give disappointing performance. Fortunately, this is 'PriusChat' not "Honda Headache".

Bob Wilson

 

You probably mean 'combustion' as 'explosion' is associated with engine knock or a 'detonation' event. But this does explain why our Prius is able to use regular without little (or no) risk of engine knock.

Bob Wilson

 

The compression ratio on the prius is at most 9:1, which is very tame for gasoline. The expansion ratio is the 13:1, which allows it to run cooler and produce less NOx at full charge. If the engine gets hot I'm sure the electronic ignition retards the spark to prevent detonation, or adds cooled egr to cool, but not much of a trick. The trick was to do this and get 40% peak thermal efficiency without di.

Mazda's skyactiv was the first engine to run 13:1 in otto mode with regular gas. This uses a number of tricks to clear out more of the exhaust gas, and create a better shaped chamber, high pressure direct injection which cools the cylinder slightly as the gasoline is vaporized. Lots of tiny tricks here. Skyactiv can also run the Atkinson mode like the prius engine. My guess is hyudai used similar tricks to mazda on this engine, plus some of the toyota tricks to get this 1.6L di engine to 105 hp and 40% efficiency. They may have done similar things to both companies but in differnent ways (to avoid patent infringement, or may be licensing some tech. We don't know the compression and expansion ratio of the new engine yet.

 

I recently reviewed the Skyactiv, Mazda YouTube videos and they did a good job. I'm especially impressed with the piston shape that reduces the amount of exposed metal during the initial combustion. Very clever.

About the Prius and regular versus premium, when I was doing my gasoline studies in 2007, I was able to measure a change between regular and premium performance in a maximum power, 8% grade, hill climb test. The data suggest the knock sensor 'backed off' the regular gas run while premium continued up the mountain at maximum power with slightly more efficiency. Of course the knock sensor might be there for places whose gasoline octane rating is 'goal'.

Going back to the effects of EGR, less oxygen is going to make it harder for the fuel to compression-ignite. Use of a hotter spark also suggests it just doesn't want to burn like before. Regardless of specific methods to defeat knock, I suspect all are involved . . . and with miniVCI we can measure these effects.

Bob Wilson

 

The i3 REX is incapable of indefinite range at full performance without additional charging, even without the hobbled CARB software.

No more Insights, but the new Jazz hybrid returned fuel economy numbers better than the Aqua, which forced Toyota to adjust their software in order to reclaim that top spot.

That's why we started using EGR in the early 80's or late 70's, but cooling it is relatively new for gasoline engines, and it has other benefits.

What advance tech does this Hyundai or Toyota engine have that the Volt one doesn't? The lower MPG of the Volt compared to the Malibu hybrid seems to have more to do with the drive train after the ICE, and optimizing it for EV efficiency.

The cost savings would likely include keeping the development costs down for the system software.

To clarify, that is 13:1 on American regular octane. On Japan or European ragular, it uses 14:1 CR.

Because of cost, I don't think any engine doesn't have a knock sensor now. The on the fly tuning it allows means the cars can provide the best performance and efficiency possible, instead of being stuck at preset timing or other settings.

And to dampen the excitement of the gen4 and Ioniq's possible numbers, all EPA testing is done with 93 octane fuel.

 

Some credible posters have reported the Volt does not have cooled EGR.

Double-negatives are sometimes difficult to parse, I think you meant:

'I think all engines have a knock sensor now.' ​

I sure hope so especially if tied to an engine controller that tweaks the car for efficiency.

Bob Wilson

 

with NOx being much of the enemy of diesel - and with the ability to run natural gas in a diesel - and (at least for now) with a glut of low priced natural gas on the market . . . . . . . what am I missing ...
seems like that might even be a not too difficult remedy for at least some of the tainted VW's. Decades ago I converted a 75 Ford Econoline to run on straight propane. It went from a horribly stinky van to an incredibly clean van.
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I want to thank all of the above writers for their input and explanations. I find the discussion fascinating, although I am not knowledgeable enough to join in, and in truth, barely understand the concepts explained. Keep up the fascinating discussion.

Merry Christmas to all.