Lean-burn engines; anyone make them?

[badtlc]

Originally Posted By: NateDN10

This is false. The NASA study you're referring to is specifically studying what happens when solar flares hit the earth. Almost no one in the scientific community denies that CO2 is a major factor in global warming.

source: http://wattsupwiththat.com/2013/03/28/a-...ing-the-rounds/


Not quite, but good try. NASA was very clear about what they now know and what they don't.

CO2 emissions have been increasing at a dramatic rate for 20+ years but the global temps have not followed like predicted. This is why they had to update the model. Most of the non-biased scientific community agrees there has been nothing to show CO2 is a greenhouse gas that causes global warming. The numbers don't lie.

The only thing that seems to correlate to global temperatures at this point is CFCs and even then that is highly debated. The science community hasn't come up with anything relevant or definite at this point. Any scientist claiming otherwise is most likely highly biased.

 

[artificialist]

Originally Posted By: eljefino
Originally Posted By: JHZR2
In our infinite wisdom, we trade TONS of CO2 and other garbage for a tiny bit of NOx.


In my utopia a car would "know" it's in a smog zone (LA basin) and tune out its NOx only where necessary. Save the country some CO2.

Could easily be done with GPS, FM radio subcarrier, etc.

I think some trucking fleets have such things that can change the ECU map based on where the vehicle is.

However, I heard it was used so that truckers could only use maximum power on mountain roads.

 

[jrustles]

Originally Posted By: badtlc
Originally Posted By: NateDN10

This is false. The NASA study you're referring to is specifically studying what happens when solar flares hit the earth. Almost no one in the scientific community denies that CO2 is a major factor in global warming.

source: http://wattsupwiththat.com/2013/03/28/a-...ing-the-rounds/


Not quite, but good try. NASA was very clear about what they now know and what they don't.

CO2 emissions have been increasing at a dramatic rate for 20+ years but the global temps have not followed like predicted. This is why they had to update the model. Most of the non-biased scientific community agrees there has been nothing to show CO2 is a greenhouse gas that causes global warming. The numbers don't lie.

The only thing that seems to correlate to global temperatures at this point is CFCs and even then that is highly debated. The science community hasn't come up with anything relevant or definite at this point. Any scientist claiming otherwise is most likely highly biased.


Good points. Also the recent intense deforestation should only be exacerbating 'warming' combined with the increase in CO2 production

 

[jrustles]

Originally Posted By: badtlc
Originally Posted By: Miller88

AH! So that's why Al Gore sold Current TV ... must be his Carbon Trading stuff is going to be coming to an end?


It should, but I think they'll milk as much money out of it as long as they can.


"You can pollute all you want, you'll just become indebted to us"

Yeah, that's an idea that not going away anytime in the foreseeable future

 

[Clevy]

So as far as lean burn is concerned I've got a tuner. How do I go about tuning my engine to "lean burn" as far as timing and fuelling is concerned.
My Harley is custom tuned on a dyno and I had them write the tune to burn very lean on the highway. I'd like to try doing something like this.
I use 91 octane if it matters. I assume it will if timing needs to be advanced.

Thanks in advance for any insight.

 

[jrustles]

Don't newer GDI engines in have a lean burn mode, but limited to only a very narrow spectrum of operation ie extremely light load when combustion temps can be low enough for acceptable NOX emissions? Has anyone seen this on a scangauge/wideband?

Because lean homogenous mixtures at light loads are even less stably ignited than lean mixtures at higher loads, the DI can allow the cylinder to fill with pure air, or a super-lean homogenous intake charge with the DI injecting during intake, then as the piston reaches TDC a small pilot squirt is injected around the plug and the entire thing is set off? I remember reading about this somewhere and related to why the skyactiv piston has a small bowl where the DI and sparkplug converge, in which pilot fuel is concentrated. Combined with the very high static compression, this would ensure reliable ignition of a lean mixture. I can see when an emission solution presents itself (cost effective nox traps etc), that newer DI engines can be converted to full lean burn engines with not much more than programming.

I remember Honda's CVCC used to have a specially enriched chamber but in the head, and it was closed off by a valve since injection let alone DI wasn't available back then.

 

[blackman777]

Honda used special NOx traps on their Insight and Civic hybrids (G1). The technology exists and was used, but doesn't seem to be used anymore (since 2006).

I can understand filtering pollution that is bad for humans (soot, carbon monoxide, hydrocarbons) but not stuff that is harmless. The human body makes its own NOx internally.

 

[blackman777]

Got my Civic Hybrid with lean burn engine (versus the CARB-compliant engine with no lean-burn). It's tricky to stay in lean burn but it makes a huge difference. +20 mpg with practice and patience.

I am amazed the EPA wrote the regulations in such a way that lean-burn is eliminated and MPG drops so dramatically. It's as if the EPA wants everyone to burn more gasoline. (More likely the EPA just doesn't hire workers smart enough to figure this out.)

 

[jrustles]

Nice! I read about the 65MPG that's awesome. How much operation in lean burn were you doing? Also how's the IMA battery condition

 

[blackman777]

About 70% of the time.
I just let the cruise control handle the throttle.

The battery acts as if brand new, so that's good news. In fact the battery never dropped below two-third. I can drive the car into the ground & likely never need to replace the battery.

 

[antiqueshell]

I thought that lean burn could be used without an emissions issue if the fuel is very low sulfur. Which is coming in the next few years.

 

[blackman777]

ULSG lowers SOx emissions, not NOx, which lean engines produce a lot of

 

[Cujet]

Many here don't know that piston aircraft engines can be operated in "lean burn mode" with some impressive results.

We do it using available instrumentation such as EGT, manifold pressure, RPM and airspeed. We don't use O2 sensors as they tend to fail with leaded Avgas.

Here's how it should work: A pilot establishes cruise flight and speed on something less than 70% of maximum HP. Then leans the mixture to "peak EGT", then slowly continues leaning the mixture to about 50 degrees "lean of peak" EGT. There is some power loss, however, more throttle can help regain the power (if there is more throttle available) .

The guys with experimental aircraft are running high compression pistons, and electronic ignitions with up to 40+ degrees of advance (magneto's are often fixed at 20 degrees advance and don't change) These guys can achieve 100 degrees "lean of peak" EGT with ease and some claim much more. Best MPG's seem to be about 17 to 1 air/fuel.

Klaus Savier has achieved 50MPG at 190Kts airspeed and nearly 100 MPG at slower speeds.

The bottom line is an easy 20% improvement in fuel economy in "lean burn mode"

Just an FYI, these engines are already quite efficient. My 177RG had a published BSFC of 0.38 Lb/fuel/HR/HP way back in 1971. A 20% improvement would bring the engine well into the diesel efficiency range! Too bad my airplane needs all the power the little 4 cylinder makes. In other words, I'd need a slightly larger engine to take advantage of the lean burn mode.

 

[artificialist]

^ I would often see people swap in a specially modified Chevy LS1 engine so that you could burn 93 octane unleaded gasoline use a wideband O2Sensor to more accurately lean out the engine.

I go to the Sun'n'fun fly in often.

 

[KenO]

Originally Posted By: eljefino
Originally Posted By: IndyIan

I imagine some after market tuners must offer a lean burn tune though? Just open the throttle and advance the timing while reducing fuel.


You're right, the 1990 era GM computers had "lean burn" in their programming. It was open loop as it was not stoichometric and the narrowband o2 was helpless. The EPA caught on and made them reflash it, but the code is still in the chip. It's just enabled to start at 255 MPH IIRC. Anyone with an $11 EEPROM burner can get in and mess with it.

The PROM style computers went out of fashion in preparation for OBDII but realistically a few years prior.



I know Lean Burn is still available in the '04 GTO operating system....

 

[440Magnum]

It produces a lot of NOx, and its also very hard on the engine hardware. Spiky high combustion chamber temperatures and free oxygen running around to oxidize the overheated metal components. LOTS of burned valves in the heyday of lean-burn in the late 70s and early 80s, although less so with fuel injection than with carbs. Chrysler was a big user of lean-burn technology, and it got such a bad rap in the early days that they stopped using the term 'lean burn' in marketing after about '79 even though the programming was kept at least through the end of Chrysler carbureted vehicles in 1989. And unchanged cylinder head designs that had NEVER, and I mean NEVER in nearly 20 years of prior production had head gasket, valve burning, or cracking problems developed all of the above at high mileage.

Also, its something of a false economy. Yes, the mixture is lean, but power output at a given throttle setting is also reduced so any time power is needed you have to enrich a little or flow a bigger volume of lean mixture, either of which negates the gain. Staying nearer stoichiometric, designing for more complete combustion, and applying things like DFCO are much better paths to overall fuel efficiency than lean-burn.

 

[blackman777]

(shrug). The Instant MPG on my Honda jumps from 50 to 75 when lean burn turns on. I'd say it's saving fuel, while still providing enough power to maintain speed.

And these engines run 300,000 miles (how many miles I see them selling for on Ebay). The Insight G1's lean burn appears to work better with 91 octane, though it's unverified. Owners have differing opinions.

 

[blackman777]

Originally Posted By: Cujet
Here's how it should work: A pilot establishes cruise flight and speed on something less than 70% of maximum HP. Then leans the mixture to "peak EGT", then slowly continues leaning the mixture to about 50 degrees "lean of peak" EGT.

What's EGT?

 

[OVERKILL]

Originally Posted By: blackman777
Originally Posted By: Cujet
Here's how it should work: A pilot establishes cruise flight and speed on something less than 70% of maximum HP. Then leans the mixture to "peak EGT", then slowly continues leaning the mixture to about 50 degrees "lean of peak" EGT.

What's EGT?


Exhaust Gas Temperature.

 

[rslifkin]

Originally Posted By: 440Magnum
power output at a given throttle setting is also reduced so any time power is needed you have to enrich a little or flow a bigger volume of lean mixture


This is actually how lean burn saves fuel. By opening the throttle further to get a given amount of power, there's less pumping losses in the engine, increasing efficiency.