1 BLOWN V8

iTrader: (17)

Hey all:

I just want a little input on what everyone would say is a safe A/F margin on a LS1.

I have a 2002 Camaro woth a A4 3,200 stall with all the bolt-ons and heads and cam and had my car tuned and the A/F is 14.0-13.9 all the way across the chart to 6,200 rpm. The tuner says this is perfect.

Also not I am in California with 91 oct gas.

Thanks

Bombguy99z28

Who is your tuner? Jeff Creech?

Billiumss

iTrader: (11)

Um no............ Time to get a new tuner.

A safe A/F is about 12.7-13.2 across the rpm range for an average modded N/A LS1.

12secSS

iTrader: (30)

Yup, I agree with Ben and Billiumss. I have my 2001 Camaro SS tuned from 13.00 to 12.84 transitioning from 3000 to 6200 rpms. And this is with 91 Octane.

HumpinSS

iTrader: (1)

12.8 to 13.2 if you tuners says this is perfect ask for a refund that is too lean and is prolly on the lean side of not making an more power. You will prolly pick up a few by richening it up a little

soundengineer

iTrader: (16)

start low at 12.5...up to peak torque... lean upi to 12.8 by the time you hit peak HP...richen back up to 12.5 by the rev limiter..

thats what I do..has worked great for me

wait4me

iTrader: (10)

Is this the same tuner that put the flat 45 degrees of timing accross the board in the previous blow up post.? lol

rooster433

Thats what he likes to do.

straight off his website
http://www.carolinaautomasters.com/dynographs/

Too lean for me, but hey thats not for me to say.

Bombguy99z28

I dunno... I have friends that use his tunes and like it. I doubt he can run much timing with that lean of a tune. Generally speaking if you have to choose between timing and leaner a/f mix, you want to lean towards the timing side of it, thats where the power is at.

I have never actually looked at a Jeff Creech tune so I wouldn't know what exactly he is doing or why he is doing it.

My personal preferences are in line with soundengineers.

Bombguy99z28

I briefly glanced at some of his dyno graphs and it looks like in most cases he keeps it in the low 13s, in the 13.0-13.3 range. If a wideband is showing your car to be 14.0 ish I'd find another tuner. Keep in mind a wideband in the tailpipe and a wideband closer to the header will read a bit different, but not an integers difference, maybe a few tenths.

HumpinSS

iTrader: (1)

personally i think more power is picked up with leaner mixtures and less timing. Its all about the sweet spot for the AFR combo with timing (peak cylinder pressure). 1-2* of timing wont net you a much of a gain as .5-1.0 point in AFR to a certain extent and not exceeding 13.5:1

1 BLOWN V8

iTrader: (17)

I also meant to state what my timing is set at. He set it at 25.5 WOT

Bombguy99z28

Do you have any dyno time to back that theory up? I've seen on a steady state (brake) dyno the exact opposite. Watched a guy hold the engine at a certain MAP/RPM and add/remove fuel with no real difference in applied power, yet add/remove timing to a vast difference in power.

HumpinSS

iTrader: (1)

I have a tad bit of dyno time with my setup that backs that theory up but if that is what you saw with your own two eyes I cant argue that... That is why I prefaced my post with "personally i think"

Bombguy99z28

Cool. I was just curious. Most guys when they 'dyno' a car they refer to a WOT dyno run, not actually holding it in a certain cell and tuning that cell.

Pretty much every engine combo is going to be slightly different as far as air/fuel and timing, so its within the realm of possibilities that some engines will make more power with leaner air/fuel and less timing. Pretty much everything I've ever heard/seen points to timing being much more important than AFR though.

soundengineer

iTrader: (16)

Timing is extremely important...
you are trying to detonate the fuel at just the right spot so that you get maximum torque generated from the explosion pushing the piston down in its cylinder...
you can dump more or less fuel in...but without the right spark you dont get much diference

In a general blanket statement..I have seen the best power on Ls1's hover around 27* and around 12.8:1 A/F... but every car is different, some cars need less ro more fuel, and some need less or more timing... there is no exact perfect way to do every car.

Tireburnin

iTrader: (42)

You sure your not thinking 12.9 to 13.0? I got tuned the same day you did and was in the shop when yours was tuned...

Mine is at 13.1 - 13.3 flat across.

Maybe yours was off, but I didn't see a single car leave the dyno with that kind of AFR. Was it like that on all runs? Was this on a re dyno? Have an exhaust leak?

HumpinSS

iTrader: (1)

McRat and J-Rod IIRC have posted back to back dyno pulls where 22* or 24* of timing made no more power than 26-28* of timing on a ZO6. On my car there was a 5 horse difference fooling around with timing and I gained more with getting the AFR where i wanted it rather than playing with the timing of the engine. In my case I got more power that way and in your case (and I am not arguing just providing my facts) you seen more with timing.

SideStep

I think what we are seeing here is that different part combinations want different timing/AFR combinations. I cannot see how any ONE answer can fit all the possible hardware combos. LG headers like to run lean (other LG owners have commented the same) and I have noticed that the more overlap my cam has the more timing my combination wants. I have over 82 dyno runs and countless deserted road runs. I have never made more power then with 26-27 degrees timing and 13.6 AFR (at the higher RPMs), with my current parts list. I could easily see a more stock engine/car needing less AFR and allowing less timing.

Bombguy99z28

Considering most of our cars came from the factory commanding around 11.5:1 afr, yes, you can pick decent power up.

Timing is reallly combo dependant. Stock LS6 heads/ LS6 cam, yes, maybe 22-24 is fine. However, any changes to the heads and camshaft will change that timing that will work. Change the static compression, dynamic compression, chamber, airflow, all these things will change what kind of timing your engine will optimally run at.

Air fuel ratio, once you get it dialed into the 12.7 - 13.0 range, doesn't matter. When tuning a car, you can pretty much be safely assured that once you have it running in that range, you won't pick-up or lose much power changing it.

Timing, on the other hand, is much more critical to attaining the maximum power your setup can provide.

I agree that in some setups, leaner or richer air/fuel mix than what I've listed is optimal, but in most cases this information will hold true.