AFRs
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It's been a long time since those technical readings, but I'd venture a guess that the difference in power between 12.5 and 13.0 AFR is probably not that big if at all, and yet, the extra fuel gets you a healthy safety margin... I remember back to my tuning days that at a certain point, going leaner reaches a point of diminishing returns, and sometimes, no gains... so, I didn't see the point in leaning it without gains.
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There are two ways you can tune a car. Sweeping or steady state. When you sweep you are doing what most of you are use to, hammer the pedal to the floor and stop at redline. What this doesn't allow you to do is tune a specific area...closely.
I steady state tune. This means we pick a KPA and RPM band and hold the dyno there. Dyno Jets can not do this so you have to use something like Mustang, Dyno Pac, Dyno Dynamics etc. By doing this we can tune specifically that area to be what we want. What is interesting is by doing this you know what works and what doesn't.
For example on the car in the pictures. That was set in each band. We set the AFRs (injection ) portion of the file on a conservative timing base. Once all the levels were tuned to the target AFR then we went back to those RPM bands and worked on the timing. You could see that while doing the AFR tuning the numbers changed little to none. That is right LITTLE TO NONE. Strange thing wouldn't you say. We know this because as we are removing or adding fuel the TQ will go up or down. We can watch that TQ on the screen as we hold that band. A couple of TQ/HP here or there is all it would do. We are not talking about big sweeps here people.
When doing the same to the timing the HP would change by 15 or more. What this tells us is there is a range of fuel where the car is fine. The VE can not change. The motor is built and does what it does..The timing will change the power. Often when tuning these guys say they changed the AFR, but they also changed the timing. What I do believe is if you are at 12.2 verses 13.1 and have a good amount of timing in the system it is acting as a cooling agent. If you look at the old days of Webbers we would over jet them on cars that were high CR and not twin plugged. This pushed the system to the line, but would cool the chamber from the over jetted Webber.
Not everything is black and white in a number.
I steady state tune. This means we pick a KPA and RPM band and hold the dyno there. Dyno Jets can not do this so you have to use something like Mustang, Dyno Pac, Dyno Dynamics etc. By doing this we can tune specifically that area to be what we want. What is interesting is by doing this you know what works and what doesn't.
For example on the car in the pictures. That was set in each band. We set the AFRs (injection ) portion of the file on a conservative timing base. Once all the levels were tuned to the target AFR then we went back to those RPM bands and worked on the timing. You could see that while doing the AFR tuning the numbers changed little to none. That is right LITTLE TO NONE. Strange thing wouldn't you say. We know this because as we are removing or adding fuel the TQ will go up or down. We can watch that TQ on the screen as we hold that band. A couple of TQ/HP here or there is all it would do. We are not talking about big sweeps here people.
When doing the same to the timing the HP would change by 15 or more. What this tells us is there is a range of fuel where the car is fine. The VE can not change. The motor is built and does what it does..The timing will change the power. Often when tuning these guys say they changed the AFR, but they also changed the timing. What I do believe is if you are at 12.2 verses 13.1 and have a good amount of timing in the system it is acting as a cooling agent. If you look at the old days of Webbers we would over jet them on cars that were high CR and not twin plugged. This pushed the system to the line, but would cool the chamber from the over jetted Webber.
Not everything is black and white in a number.
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Originally posted by PorschePhd
There are two ways you can tune a car. Sweeping or steady state. When you sweep you are doing what most of you are use to, hammer the pedal to the floor and stop at redline. What this doesn't allow you to do is tune a specific area...closely.
I steady state tune. This means we pick a KPA and RPM band and hold the dyno there. Dyno Jets can not do this so you have to use something like Mustang, Dyno Pac, Dyno Dynamics etc. By doing this we can tune specifically that area to be what we want. What is interesting is by doing this you know what works and what doesn't.
For example on the car in the pictures. That was set in each band. We set the AFRs (injection ) portion of the file on a conservative timing base. Once all the levels were tuned to the target AFR then we went back to those RPM bands and worked on the timing. You could see that while doing the AFR tuning the numbers changed little to none. That is right LITTLE TO NONE. Strange thing wouldn't you say. We know this because as we are removing or adding fuel the TQ will go up or down. We can watch that TQ on the screen as we hold that band. A couple of TQ/HP here or there is all it would do. We are not talking about big sweeps here people.
When doing the same to the timing the HP would change by 15 or more. What this tells us is there is a range of fuel where the car is fine. The VE can not change. The motor is built and does what it does..The timing will change the power. Often when tuning these guys say they changed the AFR, but they also changed the timing. What I do believe is if you are at 12.2 verses 13.1 and have a good amount of timing in the system it is acting as a cooling agent. If you look at the old days of Webbers we would over jet them on cars that were high CR and not twin plugged. This pushed the system to the line, but would cool the chamber from the over jetted Webber.
Not everything is black and white in a number.
There are two ways you can tune a car. Sweeping or steady state. When you sweep you are doing what most of you are use to, hammer the pedal to the floor and stop at redline. What this doesn't allow you to do is tune a specific area...closely.
I steady state tune. This means we pick a KPA and RPM band and hold the dyno there. Dyno Jets can not do this so you have to use something like Mustang, Dyno Pac, Dyno Dynamics etc. By doing this we can tune specifically that area to be what we want. What is interesting is by doing this you know what works and what doesn't.
For example on the car in the pictures. That was set in each band. We set the AFRs (injection ) portion of the file on a conservative timing base. Once all the levels were tuned to the target AFR then we went back to those RPM bands and worked on the timing. You could see that while doing the AFR tuning the numbers changed little to none. That is right LITTLE TO NONE. Strange thing wouldn't you say. We know this because as we are removing or adding fuel the TQ will go up or down. We can watch that TQ on the screen as we hold that band. A couple of TQ/HP here or there is all it would do. We are not talking about big sweeps here people.
When doing the same to the timing the HP would change by 15 or more. What this tells us is there is a range of fuel where the car is fine. The VE can not change. The motor is built and does what it does..The timing will change the power. Often when tuning these guys say they changed the AFR, but they also changed the timing. What I do believe is if you are at 12.2 verses 13.1 and have a good amount of timing in the system it is acting as a cooling agent. If you look at the old days of Webbers we would over jet them on cars that were high CR and not twin plugged. This pushed the system to the line, but would cool the chamber from the over jetted Webber.
Not everything is black and white in a number.
Thanks for your help. I'll leave my ratios alone then. The only thing that bothers me are the constantly black tips.
Oliver
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