Thanks Jeremy.. I appreciate it HUGE!!

Thank You Alberto.. I will try that and see what happens..

Seems log 5 didnt do it like log 4 did..

 

went out and did another run... tried to get too redline but couldnt happen.. too much traffic on the interstate..

looks pretty good..??

 

yeah man, it brought the average up a lot, a little more tuning and you will have it perfect!!



ttyl

 

Thanks for all the help.. I really appreciate it..

J-

You should do a write-up about tuning the UTEC NA.. I bet you would make tons of peeps happy..

 

I logged #16 today...

I think its pretty close, but I could be wrong.. It seemed to me that when I started to adjust my A/F closer to 12.8, the more I had to advance the timing.. stock timing seemed to 'catch up' with the UTEC settings..

I cant believe the way the car runs now vs. a few days ago.. HUGE difference!

#16

 

looks a lot better, i would still keep doing runs and adjusting the fuel at a few point to get them closer to 12.8 to 1. shouldnt take too long to do..

 

great thread help

from a great community

 

Even though I'm not going to use UTEC for my NA tuning, this is good preliminary reading so I know what to look for when I begin tuning.

 

Why is 12.8 the goal for NA?

I've seen a couple of threads with that figure but no explanation on the reason behind it...

 

Depending on the engine and the thermal management requirement, an AFR from 12.5-12.9:1 is good for ideal max TQ number for a NA aspirated engines. Depending that the timing at those load points are optimal as well.

There are more physics behind why the atomization of fuel at that given AFR is ideal for NA engines, but if you do a quick search on google you can get a more indepth explanation on why this is so.

AC

 

Hey great post..

A little more in depth...


In internal combustion engines, the air-fuel ratio refers to the proportion of air and fuel present during combustion. The chemically optimal point at which this happens is the stoichiometric ratio (sometimes referred to as stoich), where all the fuel and all the oxygen content in the air of the combustion chamber will perfectly balance each other out during combustion.

For gasoline fuel, the stoichiometric air/fuel mixture is approximately 14.7 times the mass of air to fuel. This is the mixture that modern engine management systems employing fuel injection attempt to achieve in light load cruise situations. Any mixture less than 14.7 to 1 is considered to be a rich mixture, any more than 14.7 to 1 is a lean mixture -- given perfect (ideal) "test" fuel (gasoline consisting of solely n-heptane and iso-octane). In reality, most fuels consist of a combination of heptane, octane, a handful of other -tanes, plus additives including detergents, and possibly oygenators such as MTBE (Methyl tert-butyl ether) or ethanol/methanol. These compounds all alter the stoichiometric ratio, with most of the additives pushing the ratio downward (oxygenators bring extra oxygen to the combustion event in liquid form that is released at time of combustions; for MTBE-laden fuel, a stoichiometric ratio can be as low as 14.1:1). Vehicles using an oxygen sensor(s) or other feedback-loop to control fuel to air ratios (usually by controlling fuel volume) will usually compensate automatically for this change in the fuel's stoichiometric rate by measuring the exhaust gas composition, while vehicles without such controls (such as most motorcycles, and cars predating the mid-1970's) may have difficulties running certain botique blends of fuels (esp. winter fuels used in some areas) and may need to be rejetted (or otherwise have the fueling ratios altered) to compensate for special botique fuel mixes.

In industrial fired heaters, power plant steam generators, and large gas-fired turbines, the more common term is percent excess combustion air. For example, excess combustion air of 15 percent means that 15 percent more than the required stoichiometric air is being used.

In theory a stoich mixture has just enough air to completely burn the available fuel. In practice this is never quite achieved, due primarily to the very short time available in an internal combustion engine for each combustion cycle. Most of the combustion process completes in approximately 4-5 milliseconds at an engine speed of 6000 rpm. This is the time that elapses from when the spark is fired until the burning of the fuel air mix is essentially complete after some 80 degrees of crankshaft rotation.

Catalytic converters are designed to work best when the exhaust gases passing through them show nearly perfect combustion has taken place.

A stoichiometric mixture unfortunately burns very hot and can damage engine components if the engine is placed under high load at this fuel air mixture. Due to the high temperatures at this mixture, detonation of the fuel air mix shortly after maximum cylinder pressure is possible under high load (sometimes referred to as pinging). Detonation can cause serious engine damage as the uncontrolled burning of the fuel air mix can create very high pressures in the cylinder. As a consequence stoichiometric mixtures are only used under light load conditions with more fuel added for acceleration and high load condition to prevent detonation and cool down the combustion gasses.

In theory a stoich mixture has just enough air to completely burn the available fuel. In practice this is never quite achieved, due primarily to the very short time available in an internal combustion engine for each combustion cycle. Most of the combustion process completes in approximately 4-5 milliseconds at an engine speed of 6000 rpm. This is the time that elapses from when the spark is fired until the burning of the fuel air mix is essentially complete after some 80 degrees of crankshaft rotation.

Catalytic converters are designed to work best when the exhaust gases passing through them show nearly perfect combustion has taken place.

A stoichiometric mixture unfortunately burns very hot and can damage engine components if the engine is placed under high load at this fuel air mixture. Due to the high temperatures at this mixture, detonation of the fuel air mix shortly after maximum cylinder pressure is possible under high load (sometimes referred to as pinging). Detonation can cause serious engine damage as the uncontrolled burning of the fuel air mix can create very high pressures in the cylinder. As a consequence stoichiometric mixtures are only used under light load conditions with more fuel added for acceleration and high load condition to prevent detonation and cool down the combustion gasses.


The Air fuel ratio is the most common reference term used for mixtures in internal combustion engines. It is the ratio between the mass of air and the mass of fuel in the fuel-air mix at any given moment.

For gasoline the stochiometric mixture is 14.7:1 at sea level

In Naturally Aspirated engines maximum power is frequently reached at AFR's ranging from 12.5 - 13.3:1

http://en.wikipedia.org/wiki/Air-fuel_ratio