Why no more lean burn??

[Zoltan1]

Originally Posted by MetroMPG

Another major reason it may be gone could be driveability issues/consumer acceptance...

This is very true for many fuel/weight saving technologies. Six+ speed transmissions, direct injection engines, removal of overun clutches in auto transmissions, neural idle, ect, all make measurable improvements in economy. The fact of the matter is, fuel is still considered cheap to the average new car buyer. Until fuel economy becomes a real concern for most people, they will not accept anything that feels any different than what they are used to.

[slownugly]

Originally Posted by RustyLugNut

You must compare apples to apples.

Most of the "econo - cars" I have seen are much bigger and heavier than the Metro's and Civics of 20 years ago. The Dodge Dart II's, the Chevy Cruz and the Ford Focus all seem to be around 3000 pounds and still they get 40+ MPG. Their aero is marginally better than the econo cars of the 90s but the real thrust of the package is still buyer bling. Cut out the fat on a Dart II and I have no doubt it will hit 50 MPG. I've owned several llittle Hondas and Metros and I can assure you, I'll never own one again. I'm too old to be beat up like that. Noisy, rough and cramped for my six foot frame.

If you look at the situation in Ton*MPG, you can see that late model cars are actually quite efficient as a package. The only issue is that they weigh a ton! Not all the added weight is useless bling as the structural design as well as the added safety of side airbags are worth a few hundred pounds of mass. And remember, this current crop of econo cars doesn't use lean burn in EPA
trim. But, in a few years they will. Some may have HCCI or PCCI combustion technology. Some may have advanced clean diesel Tech or hybrid diesel injection. They may have a combustion engine not discussed yet. And they may become lighter as aluminum and composite structural assemblies become advanced enough to be used in mass production situations.

My point is, if you took today's production car technology and applied it to yesterday's light-weight econo cars, 50 +MPG would only be the starting point.

And pgfpros work is impressive. He, along with several others, have added much to this forum's knowledge base in the difficult area of engine mods. It is simply beyond the capability of most people for many reasons. But, his research is simply that - research. You are comparing a research vehicle to a production vehicle that has a ton of restrictions applied to it's design parameters.

The best way to compare engine efficiency across time and space is still BSFC ( brake-specific fuel consumption ). Can you produce power with as little fuel as possible, and can you adjust your gearing and chassis load to maximize the time you spend in your BSFC sweet spot? That is the essence of constant velocity ecomodding.

Agree to disagree i guess. It all about tradeoffs and personal preferences. It's a question of where I put my money and what's the best probability of a good ROI.

Even if I was excited about this technology it still wouldn't influence me to go buy a new car. Is the cool factor enough to go buy a new car and LOSE money on increased fuel costs alone? (comparing a 1993 no hybrid vs a 2014 non hybrid) its a large gamble in my opinion. Everyone keeps saying this technology is coming but I have yet to see it. Until that changes my thought process will not.

Like you said about the comfortability factor. It's all about where an individual is willing to make compromises. I hope when I'm old I'm driving my 28 model a around. My crappy 20 year old civic will feel like a Cadillac compared to that haha.

[RustyLugNut]

Originally Posted by slownugly

Agree to disagree i guess. It all about tradeoffs and personal preferences. It's a question of where I put my money and what's the best probability of a good ROI.

Sure, it doesn't mean that there is reason to run out and buy a new econo car. But, my contention that advances in technology trump what was available 20 years ago still stands. And that we are on the verge of even more breakthroughs. And my 85 Mercedes trumps your Honda in ROI by a large margin - and I drive with free fuel.

[slownugly]

I didn't know there was an argument haha

Yes true the mileage to weight ratio has increased. Does it impress me ? Not in the least. You win I surrender. Whether the technology is superior or not does not change the fact that my 1993 vx gets better mileage than a comparable class new vehicle non hybrid.

Gettin back on topic, if they do achieve extremely lean afrs above 50:1 what effect will that have on performance? My car has significant power loss at just 20-22:1 afrs. What kind of driving characteristics can we expect out of ultra lean burn engines?

[gone-ot]

Originally Posted by slownugly

Gettin back on topic, if they do achieve extremely lean afrs above 50:1 what effect will that have on performance? My car has significant power loss at just 20-22:1 afrs. What kind of driving characteristics can we expect out of ultra lean burn engines?

Most likely, only during constant load applications such as powering generator for EV...sorta like the Mazda Wankel is being resurrected to do.

[RustyLugNut]

Originally Posted by slownugly

I didn't know there was an argument haha

It is the classic flow of any discussion. But never mind, I had too much college.

Originally Posted by slownugly

Yes true the mileage to weight ratio has increased. Does it impress me ? Not in the least. You win I surrender. Whether the technology is superior or not does not change the fact that my 1993 vx gets better mileage than a comparable class new vehicle non hybrid.

It was your assertion that current tech was inferior. Impressing YOU was not the goal of the manufacturers.

Originally Posted by slownugly

Gettin back on topic, if they do achieve extremely lean afrs above 50:1 what effect will that have on performance? My car has significant power loss at just 20-22:1 afrs. What kind of driving characteristics can we expect out of ultra lean burn engines?

Your "high tech" lean burn engine flames out at 22:1 AFR. A similar engine was used in an Xprize endeavor with heated fuel resulting in the ability to run 24:1 AFR. A small change in the the combustion enthalpy is the reason for this. They set the ratio at 20:1 to provide acceptably snappy response which still resulted in excellent fuel economy from their lightweight aero tri-wheeler.

The Ale'

There is little need to go leaner than this as the gasoline combustion becomes so lazy that even with complete combustion, you would have to gear the vehicle to accommodate very low engine revolutions.

This is where hydrogen augmented combustion becomes viable. Even the small amounts produced by a HHO electrolysis generator can extend the effective lean limit significantly. Much faster flame speeds mean I can run my Daihatsu engine at 28:1 AFR ( the limit of my wide band O2 sensor )at freeway cruise speeds. This engine has a very lazy, low turbulence combustion chamber, so it is far from ideal.

I do not see much point in running 50:1 AFR even if we could get there except at idle and very low load situations. And believe me, in lab tests combustion can be sustained at 100:1 AFR with enough hydrogen augmentation and turbulence. A paper by College of the Desert, has them running an engine with pure hydrogen as a fuel at 180:1 AFR. But, power production is minimal.

[serialk11r]

Lean burn is not coming back. The only way to pass NOx emissions is to rely on the cat to remove most of it, and cats can't do that above stoichiometric without a dedicated NOx treatment device. Direct injection can allow high AFR because it concentrates the fuel in a smaller area, but that fuel will burn hot and produce NOx.

Cam phasing is alright, but isn't SUPER effective with the small duration cams you usually find on cars. With a longer duration cam, in retarded position you can get extremely late intake valve closures which really allows efficient operation. My guess is that the internal combustion engine's final evolution will be to direct injected, phased cams + variable lift as standard, perhaps a novel multipoint ignition like the Mazda experimental laser plugs, or little to no improvements to the engine and just relying on hybridization to improve the performance.

[California98Civic]

Originally Posted by serialk11r

Lean burn is not coming back. The only way to pass NOx emissions is to rely on the cat to remove most of it, and cats can't do that above stoichiometric without a dedicated NOx treatment device.

And if we can use the pricing at Majestic Honda as a guide, that Nox device (a second cat) is really cheap, about $40.

[pgfpro]

IMHO I think we will see Lean Burn technology for the next 10 years. The reason is because gasoline engines are developing very rapidly to meet the tight European 2020 CO2 regulation and LEVIII LD regulation from the California Air Resources Board (CARB). At this time Lean Burn and down sizing are being used to get us into the future.

A good example is the BlueDIRECT petrol engines from Mercedes-Benz

The BlueDIRECT petrol engines from Mercedes-Benz, which to date have comprised the familiar V6 and V8 engines, boast the very latest technology. A new addition is a six-cylinder engine which is being offered for the first time in the E-Class Coupé and Cabriolet not only as a naturally aspirated engine, but also as the E 400 with a displacement reduced to three litres but with a biturbo drive to compensate. With its power potential and formidable torque at low engine speeds, this six-cylinder model sets new standards in its segment. It produces 20 kW more power compared with the E 350. Its torque has increased by 110 Nm and is on tap between 1400 and 4000 rpm. On top of this, the new, efficient six-cylinder engine also fulfils the EU6 emissions standard. The E 500, meanwhile, not only promises sports-car-like performance – it is also making a name for itself as the most economical model in the V8 segment.

Another new addition to the BlueDIRECT petrol engine family is the four-cylinder petrol unit. With a combined fuel consumption in the E 250 Coupé of 5.7 litres and CO2 emissions of 132 grams per kilometre (Cabriolet 6.2 litres and 144 g CO2 per km) and producing 155 kW (211 hp) from a displacement of just two litres, plus 350 Nm of torque across a wide range from 1200 to 4000 rpm, it redefines standards in the four-cylinder segment. Producing a 0 to 100 km/h acceleration time of 7.1 s (Cabriolet 7.5 s), it really underlines the sporty temperament of the Mercedes-Benz E-Class Coupé and Cabriolet.

Lean-burn process with stratified charge operation

Depending on the operating conditions, the new four-cylinder engine operates in stratified charge or homogenous mode. With stratified charge operation, the high-compression engine runs with significant excess air. To achieve this, the fuel is only sprayed into the air, which has already been compressed by the pistons, during the compression phase. A precisely controlled electronic multiple injection system helps to ensure that a fuel/air cloud builds up in a limited area around the spark plug, precisely at the time of ignition. The spark plug lights the ignitable fuel/air mixture around it, while only a very lean mixture with a high proportion of excess air is to be found in the remainder of the combustion chamber. This enables extremely efficient combustion.

A prerequisite for stratified charge operation is fast piezo injectors. They spray the fuel into the combustion chambers several times in succession per power stroke, and as such enable specific control of the mixture formation and thus the flammability.

The new four-cylinder petrol engine from Mercedes-Benz also sees the world’s first use of this stratified lean-burn process in combination with exhaust-gas turbocharging and external high-pressure exhaust gas recirculation. As a result, the E 250 Coupé is the only vehicle in this segment to achieve efficiency class A. In addition, the new BlueDIRECT four-cylinder petrol engines already meet the EU6 emissions standard which will apply from 2015. The new four-cylinder unit also meets the EU6 emissions standard in the guise of the homogenous variant for countries with different fuel qualities.

Source 2014 Mercedes-Benz E Class Cabriolet | Sense The Car

With Lean burn engines they will have lean NOx control (lean deNOx) technologies.

[MetroMPG]

Originally Posted by California98Civic

Two converters is unusual, no? Maybe unique? i went looking to confirm and see what the costs are. Seems the second converter is quite cheap. Here is a parts diagram and list:
http://www.partswebsite.com/honda-pa...00&catid=30152

My bad -- I referred to the expensive conventional 3-way cat. Thanks for the correction.