Why no more lean burn??

[Cobb]

People want power, lean burn doesnt offer that.

With direct injection coming out the afr is really a moot point.

[gone-ot]

Originally Posted by Cobb

People want power, lean burn doesnt offer that.

With direct injection coming out the afr is really a moot point.

Not really, as the Air Fuel Ratio (AFR) is still the ratio of AIR-to-GASOLINE, except with Direct Injection (DI) it occurs *instantly* within the cylinder when the injector pintle opens and injects a specfically-metered amount of GASOLINE into the compressed AIR inside the cylinder...it's still a ratio.

With DI, AFR can become more dynamic, but only *IF* the Engine Control Module (ECM) "brain" is smart enough to make "right" changes rather than just "some" changes...which boils down to intelligent algorithms and software/firmware inside the ECM. Thus, some manufacturers will have it, some won't.

The *problem* comes back to what's coming OUT of the exhaust pipe, and DI (as currently implemented) has been shown to INCREASE exhaust particle pollutants...and, particles "plug" catalytic converters.

And, NOx scrubbing isn't currently *up* to meeting current EPA emission requirements, much less, the anticipated FUTURE requirements coming down the pike. So, *lean-burn* (AFR ~ 16-18:1 or more) is not likely to come-back soon, without new break throughs in both DI and catalytic converters...ie: probably something like urea purge injection, etc.

[California98Civic]

Originally Posted by MetroMPG

NOx emissions were actually NOT a problem for the gen. 1 Insight. 2 catalytic converters, one specifically designed to store/process NOX meant the lean-burn car was rated ULEV (Ultra-Low Emissions Vehicle) by CARB, with 50% lower emissions than an average new car (ie. non-lean burn). Independent dyno testing supposedly found no NOx in the Insight's exhaust. (Source).

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

[slownugly]

The way manufacturers are currently going is kind of disappointing. I think there will be a larger increase in cam phasing before lean burn is brought back. It's hard to find a car now that doesn't have cam phasing. Personally it seems like band aid after band aid after band aid. While the technology increases the cost of operation goes up. Some of these timing belts and chains take an intricate installation process due to the phasers. If a phaser goes bad it may cost from 600-1000+ to get it fixed. How much gasoline will 600 bux buy you?

[RustyLugNut]

Originally Posted by slownugly

The way manufacturers are currently going is kind of disappointing. I think there will be a larger increase in cam phasing before lean burn is brought back. It's hard to find a car now that doesn't have cam phasing. Personally it seems like band aid after band aid after band aid. While the technology increases the cost of operation goes up. Some of these timing belts and chains take an intricate installation process due to the phasers. If a phaser goes bad it may cost from 600-1000+ to get it fixed. How much gasoline will 600 bux buy you?

You make the assumption that hi-Tech engines mean high failure rates. This is far from the truth. On the whole, most car engines survive to 100K miles with ease. 200K is quite common and 300K+ is not unthinkable. The biggest cost for most new car owners is not the repair costs, simply because most modern cars are very reliable in comparison to cars just a few decades ago. And they have more power as well as being much cleaner emissions wise.

As Old Tele Man pointed out, the technology is pretty much in place to re-introduce lean burn into the market. No, it is not used when power is needed or wanted so it does not effect wide open throttle settings. It will be transitioned in when light load and cruising regimes are detected.

Cam phasing is becoming common and reliable and allows internal EGR to occur dispensing with external EGR valves and passages that can be problematical as Metro pointed out.

As Old Tele also pointed out Gasoline Direct Injection (GDI) causes increased sub micron particulates to occur but technology such as Transonic's critically heated fuel injectors can minimize or eliminate that.

And as pgfpro pointed out, high turbulence will allow even leaner AF ratios, resulting in minimal NOx being produced. If you look at the chart posted on the first page, you will see that NOx as well as CO taper off drastically when you go past 20:1 AFR. Honda lean burn systems could operate as lean as 22:1 AFR. The HC output does climb as miss-fires increase as well as partial burns. However, implementing high turbulence combustion chambers can cut HC emissions.

One area of continuing research is in effective catalytic converters and NOx traps which can operate at reduced temperatures as constant lean running can reduce the exhaust temperatures to the point that the CATs and TRAPs are unable to work for a period of time when the engine transitions back to stoichiometric AFR (14.7:1).

To make a lean burning engine even more effective would be to couple it to a light weight and aerodynamically efficient body as Honda did with the first Insight so as to allow the system to run in lean burn mode a greater percentage of the time the vehicle is operated.

[slownugly]

Hey more power to ya but my 20 year old technology currently outperforms current technology in the fuel mileage region. My fiances car has cam phasers and can only return 32mpg. 35 if im driving. You are def correct in the longevity. I'm seein cars at my shop that have 150-200k miles on them and the valve covers never been off. Nothing wrong with that. But on the other hand I'm starting to see variable valve timing codes come up.

Probably the earliest cam phaser used is the 2.0 zetec. That is used just for egr imitation. Ive been to classes on cam phasing and variable valve timing so I know how it works. I'm just saying I'm not impressed In the least. When they start getting in the 28:1 and higher afr range I'll be sure to edit my post. I'm more impressed by pgfpros work with his work on his talon. 9 second in the quarter mile and 50+ mpg capability. THAT'S impressive.

[gone-ot]

FWIW -- EPA requires Heavy Duty Diesel Emissions equipment have a 10-year/435,000-miles warranty life...yes, that's NOT a typo!

[RustyLugNut]

Originally Posted by slownugly

Hey more power to ya but my 20 year old technology currently outperforms current technology in the fuel mileage region. My fiances car has cam phasers and can only return 32mpg. 35 if im driving. You are def correct in the longevity. I'm seein cars at my shop that have 150-200k miles on them and the valve covers never been off. Nothing wrong with that. But on the other hand I'm starting to see variable valve timing codes come up.

Probably the earliest cam phaser used is the 2.0 zetec. That is used just for egr imitation. Ive been to classes on cam phasing and variable valve timing so I know how it works. I'm just saying I'm not impressed In the least. When they start getting in the 28:1 and higher afr range I'll be sure to edit my post. I'm more impressed by pgfpros work with his work on his talon. 9 second in the quarter mile and 50+ mpg capability. THAT'S impressive.

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.

[Xist]

For the record, this 6'2" economodder loves his HX!

[RustyLugNut]

Originally Posted by Xist

For the record, this 6'2" economodder loves his HX!

And the coming of the Beetles?

Seriously, I do drive a 40 MPG car from 1985. But it is a Mercedes that is quiet and smooth and cushy! And it runs on used veggie oil. And it has 600,000 + miles (estimated - ODO broke at 549,000 - like 10 years ago ).

My back loves the old Mercedes seats. Not so much the Honda seats. And certainly NOT the Metro seats! And the NOISE! I'm partially deaf from working in machine shops as a young boy and I still hear too much background noise in those early cars.

But, those Honda Civics and Geo Metros were fun and easy to work on. My wife drove them into the ground as she was the spokes model at the time, for a large Telcom and she covered the California , Nevada and Arizona areas. 3 cars in 6 years she destroyed. Her fourth car, a little Daihatsu, survived and I am in the process of rebuilding the little 1 liter engine.

But I will be putting in aftermarket seats!