Let me add a few things since you guys seem to be confused on quite a few things here.

1. Changing the AF ratio does not change power much. We dyno'd many times with the AF ratio at different areas.

2. Running a smaller pulley would not have made more power. Possibly 1 or 2 HP but more boost doesn't make more HP unless it's done efficiently and this car had just over 16psi which is the limits of safe. The PCM is setup to pull timing as IAT and airflow rise. This would mean that adding more boost would tax the IC system as well as pull timing. You'd have the same power with less safety margin.

3. You guys need to learn to read dyno charts better. The percieved 'curve' of the AF ratio is based on the parameters setup on the dyno. Most of the dyno's posted here from intense and many others (such as the example I have posted on bottom) have the AF chart in the range of one inch. This makes any AF ratio look nice and flat. It doesn't give an accurate measure of it though. In the example below the guy was in the 14's all the way to 10's and back up with no one saying anything. This is because his AF chart is in a one in range going from 5 to 20. There is no resolution. I have given an example in pictures one and two by reprinting the same dyno with different parameters. Same exact dyno but one gives the appearance of a wild AF while the other looks flat. They are indeed, the same chart.



The range of the entire top two dyno's is within 1.1 points of AF ratio, which the one on bottom is more like 6. Shrank down a variation of 6 appears less than a variation of 1.1. I'm sure if you look at other dynos posted on this site, you'll find the same thing.
Here's a dyno of a stock Cobalt. Goes from 15 to 11.

 

I don't think anyone is confused. The lowest his AFR went was 11.9, highest was 13, with an avg of 12.4. That's a full point higher than it should be with this engine. AFR should be 11.4-6 all the way once you tip in to PE. That scares us because his engine won't last. Pop...

 

We've seen engines blow at all sorts of AF ratios. Some in the 10's. There are a lot of factors that come into play, especially when you run 60# injectors. The tune above is safe. We feel that low 11's is too rich and can cause problems. Especially when you overtax the pump or injectors and #4 goes pop from detonation. An AF ratio of 11.9-12.0 seems very ideal. Initially you don't need to run that rich though as detonation comes from heat build up. Also, lower power levels do not require as rich of a mixture. Boost and heat are much lower at lower rpms and initial tip in.

 

Alright I guess I have to be the first to call BS you can adjust those numbers on a mustang dyno I'm sorry just don't beleive it I have 273 with a 2.7 and 21 degrees of timing so unless this was on full race gas and something like 25+ degrees bullshit. Cough Cough

 

The cyl #4 issue has been related to the construction of the lower intake manifold.

I can understand where you are coming from regarding temperatures, but with everything I've researched and experienced, that AFR is too lean. I will respect your opinion seeing as you do this for a living; however, I would never run my own vehicle with that tune...

Read the dyno charts, that's a dynojet, not mustang...

 

Yeah ive heard that the best a/f ratio is around 11.5. Isnt the richer you are the cooler your engine will run??? I know its a stupid question but after being on this site for a couple months im so confused seeing all these opinions on a/f ratio. Im used to n/a cars and we always kept ours around 13 to 13.4. Leaned out just a little bit. But i know its different for f/i vehicles so this is why im confused.

 

Yes, fuel does cool down cyl temps. When cyl temps get too high, the car will dump fuel to lower temperatures. You wouldn't want to dump fuel just to lower temperatures for daily driving though. You'll wash out the cylinders...

It's more of a safety feature thing than a tuning thing...

 

number for destroys itself due to cylinder pressures. cracked and broken ring lands. not detonation. the ring lands are higher on the piston itself for emissions reasons. forged pistons have rings lands that are set lower on the piston itself. these pistons can take more extreme cylinder pressures.

i have seen 267 on a mustang before. TTP did this actually.

11.9 on a forced inducted car with weak ring lands is not a good idea. i want to see the chart without any smoothing what so every on it. this is a true sign of how good the map is.


zoomer, im not doubting anything, im not confused. i just tell it like it is.

 

I think an 11.5-12.0 ratio is ideal

Thats what i run in my car

Tho something is screwy to give u that hp on a mustang dyno Cars with those mods only make about 245ish whp on a mustang. Something is up

 

For N/A it is. Not for F/I.

 

12.5-12.8 is for a NA motor

What i listed is perfect for a FI motor. I've been one of the longest modded members here and have yet to have a piston problem. 1 yr with a 2.6 pulley and no motor problems. Now im turbo and still none

Tho my timing chain tensioner failed which is why my motor is rebuilt (well getting started tonight)

 

lsx series motors }ls1/2/3/4/6/7{ like 12.8

our motors. it comes down to personal preference. i run mine at 11.4 heat is a bitch here.

some run at 10.8, which is bad. some run at 12.0. i put down my highest hp at 12.3 a/f.


there is a line of being safe, and being stupid.

 

How is 10.8 bad? There's nothing bad about running rich.

 

Yes there is. Too rich will wash the oil off the cylinders causing premature wear.

 

You guys worry too much. I'd much rather cause premature wear then have detonation.

 

Uh, that's why you choose a happy medium. It's not worrying, it's proper tuning. Too rich = wash out, too lean = boom.

Proper AFR = Happy car.

 

Not only do you wash cylinder walls with gasoline, but you burn down the head and the exhaust.

Go try an EGT probe on your car at 10.5-1 then run it at 12-1 and tell me which runs hotter temps.

 

Exactly, more fuel does not always cool the car down. Too much more fuel causes afterburn, which is bad for everything.

 

yah i think anywhere from 11-11.5 AFR is good, i wouldnt run it as high as 12 unless I had a built motor but anything lower than 11 is just a waste of gas, unless you live an extremely hot region where temps reach 95+ degrees outside and you decide to run your car WOT. Which then its your own stupid fault if you car overheats and goes BOOM!!!!

 

Good info. Thanks guys

 

ding ding!

 

nice #s

 

Very impressive!

 

Woah, nice numbers!! I didn't think that much HP was possible with so little work.....let me rephrase...so few modifications.

When is ZZP going to come out with more products? I always bought from your company when I had my 97 GS.

 

what if you adjusted the fuel regulator giving more fuel behind the injectors on WOT would that give it more horse or more towrds detonation