Optimizing A/F Mixture & Quality

[marchildon at usa.net]

At 09:56 PM 6/10/97 -0500, you wrote:
>Since there has been some recent talk about Air/Fuel ratios, Heat/Energy
>content of various fuels/additives, & other fuel delivery related
>topics, I would like to get some opinions on the following:
>
>1. Re: Optimum A/F ratios
>
>  I understand that most O2 sensors have a fairly narrow band of
>operation and give primarily indications of 'too rich' or 'too lean'.  I
>assume that for this reason, they are used mostly (some say always) at
>either idle or cruise.  Most agree that they are useless at WOT & part
>throttle (agrees w/earlier assumption).  A recent post in one of these
>lists mentioned a new spin-off of Fel-Pro called FP Performance that has
>a computer-controlled FI setup with a wide-range O2 sensor (high dollar
>option?) that can sense a 12.5 (or whatever the optimum WOT A/F is).  If
>this is so - then wouldn't it be best to be in closed loop almost
>always? (after engine has reached operating temp of course)  Anyone with
>experience here?  I was thinking seriously about running down to
>Ashland, MS (home of FP Performance & about 40 min drive from Memphis
>8-) and insisting they hire me on.
>
>2. Re: Optimum conversion of fuels potential for energy (combustion)
>
>After being intrigued for many years about engine intake designs -
>nothing mixes up conversation better than Smokey Yunick (& other
>Otto-cycle designs) and his miracle engines that got 50-60 mpg with no
>performance loss (40% gains instead 8-) by HEATING the incoming A/F
>mixture to around 400 degrees.  Most say 'yeah right - then why are the
>factories all producing intercoolers?'  Well, I have read many of
>Smokey's articles and have the one with the design drawings of his Fiero
>experiment in Hot Rod June '84.  I understand that internal combustion
>engines probably average around 25% efficiency of converting fuels
>potential for energy (BTU's?) into actual usable energy (read flywheel
>horsepower).  And that current designs might be between 30-40 percent in
>optimum conditions (read hardly ever).  Seems to be alot of room for
>improvement here!  This is the basis for Smokey's design.  Further -
>according to several sources (nice one at
>http://www.autoshop-online.com/auto101/fuel1.html about all sorts of
>things including description of operation of Chrysler X-Ram intakes) the
>optimum condition of the incoming mixture are something like:
>
>"Dry fuel vapor is an ideal form of fuel charge, but present-day fuel
>prevents this unless the mixture is subjected to high temperature."
>
>Attempts to achieve a greater conversion rate (efficiency) are commonly
>known as supercharging & turbocharging that 'pump up' the incoming
>mixture causing a side effect (cant remember exact mixture
>condition/problem) thus the need for intercoolers (say what?
>contradiction?), additives, etc. for correction.
>
>Seems kinda confusing I know - Why not skip the whole mechanical attempt
>at regulating all these variables and let a computer control all
>(especially temperature/condition of incoming mixture) for an optimum
>(under all conditions 8-) conversion/combustion/BURN!
>
>Comments welcome!
>
>
>"We have the technology... We can build it..."
>
>
>-- 


You are mixing two very distinctive things here the air and the fuel.

I am not a ME but from reading for the past 15years all that I could find I
cam to the conclusion that the air has to be as cold as possible to be as
dense as possible thus the more oxygen molecules per pound of air, and that
the fuel has to be several hundred degrees to be able to burn as quickly as
possible this is what Smokey Yunick attempted to do but at the time they
didn't have the micros necessary to do it maybe today we could be able to
inject the high temperature fuel directly in the combustion chamber.

This is just a thought. And my own simple conclusion and if you ask a
similar question tomorrow the answer might be different.


// marchildon at usa.net                                            //
// Alain Marchildon                                              //