howarmat

mustang dyno = 10% less than a dynojet

12-13 for a NA car is fine.....FI car 11-12 is best

NickSezz

I talked to someone thatI know about this and they told me that an engine will typicallymake the most torque at about 13.5 AFR. Now, when tuning for best performance, igition timing is advanced. You can't advance the timing to it full potential at a 13.5 AFR. So when tuning with timing and AFR, the target is 12.5-13.0 AFR with timing just under the detonation point. If you keep the AFR at 13.5 you cant advance timing as much and just "shift" the engines power curve. Kinda makes more sence now...

GT Bob

Nick, your on the right path... All other things being equal, 13.5 will make the most power, but overall, you get more by going richer with the AFR's and adding timing.

If you really wanna get some good info on tuning... "Engine Management: Advanced Tuning" by Greg Banish (published by Cart5ech Books) is an excellent read. Greg has spent years working for Ford and has just recently moved to GM developing OEM tunes. Most tuners consider this book their Bible, and I cannot recommend it enough.

dr350rider

Since every car is different, even with the same equipment does anyone know how the factory tunes the new cars? Do they put each one on a dyno before they leave the factory? Do they create tunes that cover all bases for cars leaving the factory?

NickSezz

Hmmm I never thought about that. Good question, but I bet they are mostly the same and thats why some cars run better out of the factory.

TJ

Just some things I will add and you might want to check.

I was running a Innovate WB XD16 w/LC 1 controller on a S/C 4.0.

One thing is the location of where you install the bung it is supposed be upstream of the cat, if for some reason it was installed down stream of the cat the afr will read leaner, so this is one thing I would check.

The bung should also beinstalled either in the 3 o clock or 9 o clock position, This is to prevent mosture/water from forming on the sensor which will affect the accuracy of the afr reading.

The other thing before I started the car Idid a clean air calibration on the sensor.

I ran Dougs mail order tune wriiten for this S/C & modsit was spot onfor FI wot started at 10.5/8 thenavg 11.5-6/ 6.2Kwhich is a great afr imo for FI.

There were times during the course of 12 months I had to adjust my afr, it would start to lean out at wot started climbing/hitting 11.9 –12.4 in which case at that point I would add fuel. I would only have to had around 2-3 percent fuel to get it back to 10.5 to 11.4.

One other thing I’ll mention when you go in for a dyno some will test the afr with a probe in the tail pipe vs in the up steam 02 sensor. This will not give as accurate afr reading as in the up steam 02 sensor.

NickSezz

I had it installed by a very good shop and it is all done correctly (I watched him). The bung is right after the driver side manifold on the little down pipe right before the cat. It also has the correct angle. There is not doubt I was running lean because now I have more power, and even more to come.

Like ive been saying, as soon as I get the AFR where it runs best, I will call Brent about any timing changes to see what I can do myself. Then after I get the money its off to the dyno for some base runs and a 93 tune. I might try a bama or vmp tune for the hell of it too. I just have a few other things to take care of on my car and then it will all be good.