Texas_WS6

iTrader: (9)

I noticed my cars computer is trying to make 11.7to 11.8 AF Ratio at WOT (acording to the easylink). Is this the ideal AF Ratio for my car? I also noticed that when I put the car on the dyno and had it sniffed with the NX Juice I was running very lean (14.0) so I keep installing bigger fuel pills till I reached 12.5. Shouldn't I be running around 12.5 at WOT without the juice too? For best power what should the AF Ratio be (no juice)? How can I change that? How can I tell for sure what my car is really making AF Ratio wise at WOT?

v8 ute

12.5 - 12.8, maybe fatter for NO2 to be on the safe side

Orange Krush

I have always gone with the numbers outlined in this article!

http://www.c5forum.com/diy/ltft.php

Texas_WS6

iTrader: (9)

Ok, acording to that articale my car should be targetting 12.5 at WOT not 11.7 . So why is my cars computer targetting 11.7 and not 12.5? How do I change that? How much of a power incress do you think I will see if I change it? What are the, if there are any, drawbacks to doeing this?

Thanks for the help

TaTommyWS6

Most say fatter near peak torque (12.5), and leaner near peak HP (13.0) for a NA car.

Colonel

Forget what your PCM is supposedly "trying" to do. Get it on a wideband before you assume it's rich.

When we dyno tuned my '02, here is what we found (and different combos will see somewhat different results so this is just in general.)

12.7 = - a few HP for sure
13.0 = - maybe a couple HP
13.3 = 0
13.6 = - maybe a couple HP

So, I went with 13.3:1 which is right where it was to begin with. When the hot whether got here I moved it to 13:1 to fight detonation.

Of course, for nitrous use we want it nice and fat. I'd much rather gain power with more nitrous and a fat mixture than with running a lean mixture and less nitrous.

CHRISPY

It really depends on the combo. Some cars make the most power at 12.5:1 others at 13:1.

If you are stock I would shoot for around 13:1 and timing in the 28-30 degree range at WOT. (assuming premium gas is used)

Cheers,
Chris

Colonel

I agree, for a bolt-on NA car, 13:1 and 28-30 degrees (depending on how ping prone your car is) normally works great.

BTW, I notice that the '01s-'02s can't get away with quite as much timing advance before pinging as the older LS1s for some reason. I used over 30 degrees with my '00. With my '02 it's more like 28-28.5.

Jorday

I had a lot of trouble in my 02 with pinging, but I think I had some bad gas in it or something because it was pinging like crazy at 27 deg advance.

Colonel

Jorday, a few other things that help to get rid of pinging...

160 thermostat and cooler fan settings.
Getting rid of or gutting the cats (this is a BIG help!)
New plugs if the old ones are worn.
Cooler plugs.
(And an obvious one) A richer mixture.

Texas_WS6

iTrader: (9)

So what is a wide band exactly?

soundengineer

iTrader: (16)

I think mark(RMS) got me in the 13.3:1 range....any richer and I started loosing power.......I could see 12.5:1 for a nitrous car...but not for a stocker with minor bolt-ons.
so 12.5:1 should be good for you..and your NOS...play with it a bit on the dyno and see what +/- a few tenths of a/f makes

soundengineer

iTrader: (16)

and wideband o2's are a very well calibrated oxygen sensor...wideband tuning on a dyno typically uses a sniffer tube to smell the exhaust and report the Air/Fuel mixture....Most dyno tuners use a wideband type sensor to fix your air/fuel for maximum power potential

Texas_WS6

iTrader: (9)

Ok, I did have my car sniffed out one tail pipe when I had it Dynoed. So I guess my dyno shop can check it again for me. Now every one is saying 12.5 would be good for a Nitrous car. I agree with that but, shouldn't my car be tunned for 13 or so without the nos and then I should tune my NX Wet system to be about 12.5 with the juice on? That way when I do not use my juice I will be at my best power around 13 but when I hit the wet system the juice will be 12.5 because of my fuel pills? I did tune the juice for 12.5 earlier by changing the fuel pills out. But I did not pay any attention to what my AFR was without the juice. Basically, what I am asking is shouldn't it be best to tune the AFR to be in the 13 range without the bottle and then tune the NX system to be 12.5? That way I have the best of both worlds?

I know I sound like an idiot so please don't bash me. The reason I ask is because all of ya'll sound like ya'll know your sh*t and I value ya'lls oppinions.

Thanks again guys.

Colonel

You got the idea. Tune it for NA. The nitrous kit will provide it's own fuel enrichment. I'd rather have it at about 12:1 on the bottle (even 11.5:1 is fine.) 12.5:1 is running on the lean side for nitrous use, IMO. I'd rather run a bigger shot of nitrous at a rich mixture than a smaller shot at a lean mixture. Lean and nitrous are NOT a good combo.

Texas_WS6

iTrader: (9)

Ok great, that makes cents. So can I change my WOT and COT with a Preditor or do I have to have LS1 Edit?