Mustang Dyno results

[mysocal911]

Originally Posted by PeteKz

Chris, you are correct about AFRs and how they vary, depending on fuel mix.

For 10% ethanol contamination, stoichiometric is about 14.13. That's why I prefer to display lambda. However, AFR in the 11 and lower ranges that the dyno print out showed is way too rich, even for preventing detonation.

Per Bosch, best economy lambda is 1.05, and best power is 0.90. Going rich to 0.85 provides additional cooling and prevention of detonation. More than that wastes fuel and loses power. For 10% ethanol/gasoline, lambda 0.85 is about AFR 12.0.

One other fine point for everyone to keep in mind: The "AFR" usually is not measured directly. Instead, an O2 sensor is used to measure lambda, and then a multiplier is applied to compute AFR. Thus, if you are running a 10% ethanol contaminated fuel, and the lambda is 1.0, the AFR meter/printout displays 14.7, even though it's really 14.1.

Yes, basically a quote from my reference in post #17,
"Automotive Handbook - Second Addition", Bosch, 1986, pg 439, ISBN 0-89883-518-C

A key point of this thread should be that once the AFRs are near optimum, more significant torque improvements typically result from tweaking ignition maps, not withstanding detonation.
This doesn't imply, though, that ignition tweaking may not be detrimental. Without knock control, a high load, high temp, and/or low octane fuel are problematic with an excessive timing advance.
The issue of detonation is not easily simulated/determined based on "dyno results".

[PeteKz]

Chris, all good discussion. You have picked up a lot of good info from those sources. When you tune for best power and torque, You end up at Bosch's numbers, or very close to them. Bosch has done more research and development on fuel injection, ignition, emissions, engine management, and other vehicle systems than anybody else, and owns most of the patents which other makers and OE manufacturers license from them. Therefore, I tend to take what they publish as gospel.

Let's see what crashmy911's subsequent tuning yields.

[ChrisHamilton]

Yeah Pete, the more I've learned about I.C.E. in general as well as EFI I'm learning g that everything is dependent on something else and more often than not there is no one right answer to something. "It depends" seems like the answer that best fits most questions. Fun learning new things though I still like tuning a Weber sidedraft carb more than EFI. That has been a real learning curve for me.

[crashmy911]

The grind on my cams #171e/149i

[targa72e]

Thanks, for the cam info.

john

[Jeff Alton]

Forget all the hypothetical discussion.

Tune the car on the dyno, adjust AFR and timing live on the dyno to make max HP/TQ. Back timing off 1-2 degrees at peak for safety.....

You will find that the AFR will likely be in the range of the posted numbers of others....

If this car was actually live tuned on a dyno that produced that AFR, maybe look for a different tuner, unless, they spent lots of time moving the AFR around and those numbers produced the peak HP/TQ

[mysocal911]

Originally Posted by Jeff Alton

Forget all the hypothetical discussion.

Tune the car on the dyno, adjust AFR and timing live on the dyno to make max HP/TQ. Back timing off 1-2 degrees at peak for safety.....

You will find that the AFR will likely be in the range of the posted numbers of others....

If this car was actually live tuned on a dyno that produced that AFR, maybe look for a different tuner, unless, they spent lots of time moving the AFR around and those numbers produced the peak HP/TQ

The "tuning" never ends, does it?