18:1 AFR is "cleaner"?

[rmay635703]

Originally Posted by oil pan 4

I like how they just ignore increasing fuel economy as a way to fight pollution, as if the gasoline just miracles it's self into your gas tank tail pipeemission are the only way a car can damage the environment.

I like how that we are laser focused on 1 specific kind of pollution as a percentage (that has been very good vehicle emissions wise for over a decade)
while ignoring others altogether and not caring about grams per mile
all the while ignoring massive sources of that type of pollution from industrial sources.

Then also forgetting that supply side pollution
groundwater, heavy metals and outright spills dwarf the associated vehicle pollution .

At some point you would think we would look at the other sources along with combating a recent trend on lax maintenance and inspection of industrial systems sometimes close to 70 years old.

[Piotrsko]

Easier to mandate to the individual than to a large company that can afford to fight slap lawsuits.

[RustyLugNut]

Originally Posted by rmay635703

The cat should burn off the hc and co using the excess NOx

The catalytic reaction needs a minimum heat/energy level. Without this, the reaction is either too slow or non-existent. We can program the engine run regimes to oscillate between lean-burn and stoichiometric to keep the catalysts hot enough to function.

Also, if you want to use the oxidation potential of NOx to convert the growth in HC and CO in ultra-lean mixtures, you will not have enough to complete the reaction equation. Look at the original graph - there is exceedingly small amounts of NOx the further lean you operate.

The trick to running ultra - lean is in reducing the COV and reducing the quench thickness. This gives you more power to use and reduces HC and CO respectively.

[Ecky]

I'll probably try running 18:1 in a few days. However, there's something to consider with leaner mixtures: ignition timing needs to change quite a bit.

When the mix is leaner, flame spreads more slowly. When timing is adjusted such that peak pressure is where it needs to be, a larger percent of burn will be before TDC or where piston angle is poor. The more I've read about it, the more it surprises me Honda was able to improve economy with ultra-lean burn. Maybe it was the lack of infinitely variable gearing, and lean AFRs were a way to virtually reduce displacement on demand.

In order to get ignition timing right without a dyno, I'll likely need to buy an exhaust gas temperature sensor.

[California98Civic]

Originally Posted by Ecky

I'll probably try running 18:1 in a few days. However, there's something to consider with leaner mixtures: ignition timing needs to change quite a bit.

When the mix is leaner, flame spreads more slowly. When timing is adjusted such that peak pressure is where it needs to be, a larger percent of burn will be before TDC or where piston angle is poor. The more I've read about it, the more it surprises me Honda was able to improve economy with ultra-lean burn. Maybe it was the lack of infinitely variable gearing, and lean AFRs were a way to virtually reduce displacement on demand.

In order to get ignition timing right without a dyno, I'll likely need to buy an exhaust gas temperature sensor.

How important are such timing changes under light load? You are at like 20% load at 60 mph, right? Seems slight risk of problems under such conditions, no?

[Ecky]

Originally Posted by California98Civic

How important are such timing changes under light load? You are at like 20% load at 60 mph, right? Seems slight risk of problems under such conditions, no?

You're right in that at light load I'm not going to hurt anything, it's more about efficiency.

If the timing is too retarded, cylinder pressure won't peak until the piston is already well down the cylinder, and a lot of potential work will go out the exhaust. Advance it too much and a larger portion of the work will happen while the piston is still rising on the compression stroke, and will be essentially trying to turn the engine backwards. Either way, fuel economy and power both suffer. Even been a couple of degrees off and the differences will outweigh and gains.

I want to say the Insight's stock engine advances ignition timing 20+ degrees when it goes into lean burn, and being off 3-4° is significant, so simply leaning out without adjusting timing isn't likely to do any good.

I *think* it can be done with an EGT sensor, but may require dyno time.

[California98Civic]

One of the bummers of Cali smog regs is that exploring such modifications of an engine makes your daily driver illegal. I would not pass smog with such mods. They make me remove my brake booster canister intake tube. Go to the wrong shop, and I get rejected for my gearing. Extra sensors and a non-standard ECU sound like instant fail territory.

[Piotrsko]

Extra sensors maybe not, haven't had a Cali smog done in 15 years so I can't say how deep the software queries your OBD2 only ECU which is the only way they know it was changed. I do know on the F250 ECU, they can't detect an aftermarket box but make notice the software version installed, unsure about a eprom chip . On the VW TDI, they definitely check software revision against a published list. I also know I couldn't add EFI to my 72 superbug which imho was flat stoopid..

Then there's the friend of a friend smog guys.............

[rmay635703]

Originally Posted by Piotrsko

Extra sensors maybe not, haven't had a Cali smog done in 15 years so I can't say how deep the software queries your OBD2 only ECU which is the only way they know it was changed. I do know on the F250 ECU, they can't detect an aftermarket box but make notice the software version installed, unsure about a eprom chip . On the VW TDI, they definitely check software revision against a published list. I also know I couldn't add EFI to my 72 superbug which imho was flat stoopid..

Then there's the friend of a friend smog guys.............

By the book
Making a Hybrid into a plug in is illegal because it modifies emissions equipment to make fewer emissions

Pure stupidity of cookie cutter protectionist law

[Gasoline Fumes]

Originally Posted by Ecky

I want to say the Insight's stock engine advances ignition timing 20+ degrees when it goes into lean burn

I see as high as 30-31 degrees in lean burn on my ScanGauge.