Lean burn mode rules 64.8mpg

[Tygen1]

Would you say the turbo is what has made this possible?

Pictures of these modified spark plugs....please

[tjts1]

WOW and I thought I was pushing the envelope running 15.4afr at mid range part load on my mercedes MS installation.
http://img.photobucket.com/albums/v2...FRtargets2.jpg

[naturalextraction]

Originally Posted by Tygen1

Would you say the turbo is what has made this possible?

Pictures of these modified spark plugs....please

Is this question to me? if so I'm not seeing the pictures of the modified spark plugs.

[cfg83]

naturalextraction -

Originally Posted by naturalextraction

...
Also keep in mind cylinder chamber temperatures are much lower due to the fact you are NOT burning the same volume of fuel. Note your exhaust temperatures under those conditions. But the fuel cannot change its burn rate under those conditions. It's the fuel that creates the problems primarily, keeping in mind the other issues stated above.

Other people have stated that it's smart to have premium gas (91 Octane in California) under lean-burn operating conditions. It "sounds" like what you just wrote would agree with this. Am I correct?

CarloSW2

[cfg83]

naturalextraction -

Originally Posted by naturalextraction

...
While droplet size from modern day injectors are quite small, in a hot chamber they still can create pinging or complete detonation damaging pistons or valves. Thus why engineers developed DPI for better fuel distribution with higher fuel pressures. Other factors that create anomalies from injected engines would be pump pressure consistencies due to possible voltage drops at pump, restrictions, fuel density changes due to ambient temperatures, to name a few. ...

I googled this acronym but I couldn't find anything. Do you mean DFI, Direct Fuel Injection?

CarloSW2

[naturalextraction]

To answer your question straight forward, yes. Typically there would be a gain in power with advancement in timing. However under "normal" ignition timing there will be less of a chance of pre-detonation. Compression ratios are important here as well. On higher compression engines (9:5.1+) flame front changes. Also is the factor of intake air temperatures related to oxygen densities thus altering burn rate of any fuel and changing cylinder temperatures. It is a "safer" bet with todays fuel mapping on most any ECM vehicle to venture with higher octane under a lean burn condition. Especially on lower compression engines. However the benefits in power are nominal to non in low compression engines. There are many factors that may and can change the "state" of a fuel, some more radically than others, all that will effect the burning of the fuel and it's work force in the cylindar.

Yes to Direct Port Injection or Direct Fuel injection. To those around me we use DPI. Realizing there is a difference in terminology DFI is more common under what I'm referring to. Primarily fuel injected into the combustion chamber other than from behind the intake valve. Here is a good paper from MIT http://www.ethanolboost.com/LFEE%202008-01%20RP.pdf Also Dr. John Heywood has patents related and other papers related. The methodology is something similar to what we use but with a different "injection" system if you will.

[pgfpro]

Originally Posted by naturalextraction

Thanks for the info links to the Neptune info CarlosSW2. pgfpro-in regard to idle: your turbo is helping at higher rpm related to pressures even at ambient although you may not read any psig. It is still helping to push air. It is also helping the fuel to burn when the natural vacume of the engine otherwise would not sufficient enough to allow for lean mixture to burn. Thus why at idle it suffers.
This bringing me to air temperature and potential damages. (I've been studying and experimenting related to different fuel distribution methods and management for the ICE for over 4 years now. I in list the help of some of my physicist and mathematical friends from Sandia labs when the information or findings exceed my temporary limitations. I have access for testing at the labs Los Alamos or Sandia and use of typical dynometers rear and engine.) Lean burn will not hurt your pistons from the standpoint there is not much to burn. This in keeping the combustion chambers within an "ideal" temperature range. What damages them under a lean burn condition is fuel droplet sizes, particularly when the chamber is hotter and this is where timing is a factor as well as the fuels ability to burn, and flame front travel. I've run two engines at the 18:1 to 21:1 just fine and maintain some levels of usable power in both a motorcycle and car. (car being a 1972 Duster 318). After 36K miles the engine was torn down to find no burnt valves, very clean piston tops all while running the engine mostly on low grade unleaded. (Stretched head bolts were the only culprit)
While droplet size from modern day injectors are quite small, in a hot chamber they still can create pinging or complete detonation damaging pistons or valves. Thus why engineers developed DPI for better fuel distribution with higher fuel pressures. Other factors that create anomalies from injected engines would be pump pressure consistencies due to possible voltage drops at pump, restrictions, fuel density changes due to ambient temperatures, to name a few. Your management system is constantly monitoring and trying to make changes quickly but can not compensate as quickly or as well under leaner conditions. Leaner conditions basically require changes to the fuel itself, delivery, air temperature controls and more accurate consistencies in all areas to the induction and fuel delivery systems. Delivery and firing timing becomes much more critical. Without your turbo you would expect to have the same issues you experience at idle but at higher rpms without other control devices. I personally do not recommend inter coolers in relation to obtaining economy in the ICE. Their good for power but not for economy. That gets into a whole other discussion regarding adiabatic/thermal issues and other control issues. Keep in mind the basic efficiencies of most ICE's to be at ->30% anyway. Most of it is lost to heat energy. This being why I like the volumetric efficiency gains turbos make while using expended heat energy. Thus bringing up the overall efficiency factors of the ICE, although not by a big margin.
Also keep in mind cylinder chamber temperatures are much lower due to the fact you are NOT burning the same volume of fuel. Note your exhaust temperatures under those conditions. But the fuel cannot change its burn rate under those conditions. It's the fuel that creates the problems primarily, keeping in mind the other issues stated above.

Thanks for all the great info. I'm going to ponder this for a while.

What do you think I should do at this point?

I did another run today. At 22:1 A/F I could actually notice a loss of power. So I went back to yesterdays fuel map. It kinda scared me. Something just didn't feel right.

But it did get 66.1 mpg today on the old fuel map.

Do you think running more exhaust gas into the engine would help?

quote> Engineering Fundamentals of the Internal Combustion Engine by Willard Pulkrabek

"lean mixtures have lower combustion tempertures, caused by the excess nonreacting gases, and this eases the knock problem"

What do they mean by nonreacting gases?

[naturalextraction]

Originally Posted by pgfpro

Thanks for all the great info. I'm going to ponder this for a while.

What do you think I should do at this point?
I did another run today. At 22:1 A/F I could actually notice a loss of power. So I went back to yesterdays fuel map. It kinda scared me. Something just didn't feel right. But it did get 66.1 mpg today on the old fuel map.

Do you think running more exhaust gas into the engine would help?

quote> Engineering Fundamentals of the Internal Combustion Engine by Willard Pulkrabek "lean mixtures have lower combustion tempertures, caused by the excess nonreacting gases, and this eases the knock problem"

What do they mean by nonreacting gases?

Spent hydrocarbon gasses. Not having any internal chemical energy available through the spark ignition process or combustion. Nitrogen and Oxygen (NOX). It's inability to do work through this particular process. However still recognized as a gas as their single elements (Gases are considered the lighter element "fuels" ie: CH4 being methane, C3 H8 being propane on up till you get to the C7-9 H8-14 and above being liquid fuels up to thicker Naptha etc. Gas being typically C8H18. Technically speaking "gasoline" is not a gas but should be referred to as a liquid fuel.)
Your EGR valve is what does exactly that. Designed specifically to reduce the NOX emission gasses caused by normal to lean A/R ratios in the combustion processes. (google to read how it does this, there are many engineers who find it counter productive and NOT provide a "complete" burn as suggested) It injects a small amount of exhaust gasses to the intake system or directly to port. Your lean condition, by the way, is creating a very high output of NOX. One of the down sides to the combustion of those A/F ratios. Some try to increase this input but find it WILL limit your ability to run the lean A/F ratios you currently show.
Understand your vehicles engine by design has limitations. Your ECM will not be able to control or keep up past where you are right now. I'm surprised it's running much at all at where you're at with your A/R readings now. A-typical for your type of fuel delivery and management system. You can run into detonation problems due to the fuels characteristics (there still is a surface tension issue even at the mole count that is entering the chamber at this point without further disassociation of the fuel molecules) and duty cycle of the injectors, two quick thoughts to limitations.

[pgfpro]

naturalextraction thanks a bunch!!!

Ok I'm kinda freak out now.

I'm starting to think my knock sensor is not working. Its not picking up any knock at light load with these lean A/F's.

I have seen a few counts of knock when I was tuning wot at 10psi. But I adjusted the timing and haven't seen any knock since.

I need to test it and see if its still working.

[pgfpro]

Also I noticed that the cat is working over time trying to deal with the high output of NOX emission gasses. But I was going to address that at a later date. Lucky where I live there's no emission testing.