AllCammedUp

I know this might be somewhat of a hotly-debated topic, but what does everyone think of as the optimum WOT AFR for a NA street setup? My cell 22 LTRIMS are still at +9 right now, so I'm trying to get them in line, and when I jump on the loud pedal, I'm watching my WB gauge go all the way down to 11.5:1!!! I figure that is pretty darn rich, and I am curious as to what I need to shoot for to lean it up to.... I was thinking 13.0:1, but I didn't know where the best power would be at? I want it to be as safe as possible without leaving much on the table. I'd rather err on the side of caution, but not err to darn much!

Thanks!!

hellbents10

iTrader: (10)

If you want to error on the side of caution yet have good power I would shoot for 12.6-12.8 at WOT on a NA car. 13.0:1 is were the power is more then likely at. Allthough every car is a little bit different.

XJGPN

From what I hear the standard baseline to start working from is 12.6:1 up to peak torque, then taper to 12.9:1 at peak HP.

JeremyF

iTrader: (23)

OK I will be flamed for this but experience doesnt lie and with over 500LS1s under my belt and no blow ups...... I have my car @ 13.5:1 AFR It is where it makes best power (no cats). ALL CARS ARE DIFFERENT some will make best power @ 12.5AFR but that is very rare. Much depends on the cam, heads and exh sys. The AFR at the headers collector is different than what is coming out after a cat converter, it is usually richer. I will tune cars to 13.3 and I feel that they are very safe. I feel that timing is something that is just as equal an issue but as long as you are datalogging and no KR then 95% of the time you should be safe. Many time the car will knock and the sensors will not pick it up even when they are within the conditions of detecting.
Jeremy

hellbents10

iTrader: (10)

totaly agree with the all cars are not the same. I have seen a ton of LS-1 cars run awesome at 13.3:1 or so. I was just on the side of caution, but you are right that they can be perfectly safe at 13.3 or higher with a good tuner.

sleeperstyle

iTrader: (4)

what about with cats through a tailpipe sniffer wideband. i was told by the tuner that you are off (up) about .5 through the cats so i got my car to an even 13.5 across the board. no detonation, 02's (hptuners) are around 860-880mv- so im guessing im right around 13.0? this guy has tuned lots of ls1's but i like to have more opinions on tuning w/ cats.

JimMueller

iTrader: (9)

I wouldn't correlate your O2 values with an AFR reading. They may correlate on your particular car. Some folks log O2's and WOT AFR simultaneously to get an idea of what O2 readings correlate to which AFR readings and then try to get their O2's to match.

The last time I blindly tried to set my WOT AFR by using the 'suggested' range of .88-.89, my WOT AFR ended up being at 14-14.5 on the dyno. 13:1 on my car is ~920mv.

horist

Jeremy good info! and thanks for sharing it!
I don't think anyone could flame ya for stating your experiences ... but just in case... if people disagree ... remember it's better to state your opinion using G rated words... (being able to disagree and make a point w/out calling someone names or using unnecessary swear words is a sign of intelligence IMHO)

JeremyF

iTrader: (23)

Sleeperstyle: If a car has cats and mufflers and a sniffer in the tailpipe and you are tuning to 13.5:1 out the back than you should be roughly about 13.0 off of the collector. I think you have it right but it is getting late and my brain is swimming trying to build a bigger better TREX cam. hehehehe. gnight. Thank you guys for the support.
Jeremy

AllCammedUp

Ok guys, thanks a lot for the posts and the info - it helps out a lot.

An additional question I've got now after reading the replies is what RPM point should I shape the PE/RPM table at to start the transition from 12.6 to 12.9/13.0:1 for the max power?

Should I keep it at 12.6 up to 4500 RPM, then just lean it out to 12.9/13.0 at 4600RPM, or should I gradually step it up in increments as I approach redline and have the redline (6500) at 12.9/13.0? I guess dyno time is necessary for this at this point, but I'm curious as to what everyone thinks. I'd think a nice curve would be better than abrupt jumps, but I'm a self-admitted noob at this topic, so I don't know for sure.

Thanks!!

JeremyF

iTrader: (23)

again, its different for every car. I have seen where if the area @ pk TQ is richer (12.7) it will make better power and the pk HP leaner (13.2) it gets the best of both worlds. But 9 out of 10 its better one way or the other all the way accross the board.

Jeremy Formato

Bryan Wilkinson

iTrader: (1)

I thought I would throw this out there. What is the difference between WOT on the street and anywhere else?,

There is no dramatic power loss between 13.5 and 12.5, an A/F of 12.5 @ WOT is where you need to be. If you put your car on a load based dyno, you will see that there is no big difference here. I am running 14.7 to 1 for driving around town, and in the VE table it appears to be everything from 0-55 KPA from 800RPM to 3500 RPM. Then I am running 12.1- 12.5 when the car goes into WOT.

This should not be taken as a recommendation but an example.

JS

iTrader: (4)

My car is tuned exactly like Bryans..
Check out the MILD setup and MPH my car is making.
CLOSED LOOP TUNED TOO.

AllCammedUp

Thanks, Bryan - there really is no difference between street and anywhere else - it's just that I don't drag my car, and as such, I don't need the all-out *****-to-the-wall config that is optimized for a 1/4 run, as I like to go the twisty route much more than the straight route!

HumpinSS

iTrader: (1)

Here is a chart compliments of monodax


Here is a chart that I have that should give you some insight into what standards are for lean cruise etc...

9.0:1 BLACK SMOKE (NO POWER)

11.5:1 RICH BEST TORQUE @ WOT

12.2:1 SAFE BEST POWER @ WOT

13.3:1 LEAN BEST TORQUE @ WOT

14.6:1 STOCHIMETRIC AFR ( CHEMICALLY CORRECT )

15.5:1 LEAN CRUISE

16.5:1 BEST FUEL ECONOMY

18.0:1 CARBURETED LEAN LIMIT

22.0:1 EFI LEAN LIMIT

SSpeedracer

iTrader: (8)

So is 11.5:1 through 13.3:1 best for max torque? I thought that 12's was best.

Bryan Wilkinson

iTrader: (1)

if you are able to enjoy cornering your car you are better than me. I did not on purpose setup my car for drag, however, I also did not plan on 800RWHP. So some of what I have was dictated by the engine. I have been doing some research, and a air bag suspension may be the solution. There was an article recently in Hot Rod I think, I read so many of these things that I lose track of which one it was in, but they hired a race car driver, to drive the car around the track with the stock suspension, and then they replaced all of it with an airride setup. The difference was remarkable in the handling and ride department. I really believe that it is possible to have the soft ride/firm ride and still have the power and take it to the track.

Anyone that would offer any thoughts on this, I am interested in what you would have to say.

Bryan Wilkinson

iTrader: (1)

Really, I would think that at 16.5 or higher piston life would be extremely limited.

HumpinSS

iTrader: (1)

As long as you are under light load/cruising then there isnt a problem. Once you go under load you may want to richen it up a little so you dont put any holes in the pistons

Bryan Wilkinson

iTrader: (1)

Gotcha, I was unlcear about this.
Thanks