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Old 12-31-2013, 09:04 PM   #15 (permalink)
RustyLugNut
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I find current engine tech exciting!

Quote:
Originally Posted by slownugly View Post
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.
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