AFR?

[bobfo]

What is the best AFR at WOT for power on the LS1? How much total timing should I be starting at?

Thanks in advance.

[Black LS1 T/A]

What is the best AFR at WOT for power on the LS1? How much total timing should I be starting at?

Thanks in advance.

I'll put in a bid.

Naturally aspirated, start rich (around 12.5 or so) and, assuming no KR and timing is in a good range, progress toward max AFR of about 13:1.

Along the RPM curve, you should tune to be at your richest at peak torque and lean it out to its leanest at peak HP.

My 2-cents. Good luck!

[Black LS1 T/A]

On the timing:

Naturally Aspirated, start from stock timing, check KR and adjust up or down from there.

If there is no KR, increase timing 1 or 2 degrees and try again, continuing to checking AFR.
If you have KR, adjust timing down a degree below the amount of KR you have and try again, checking AFR.

Check with your dyno operator how much off he thinks his dyno's AFR is compared to "street". Some estimate .5 AFR leaner on the street than the dyno. so, you'd want it on the rich side, on the dyno. Check KR again when you get back on the street, and try to figure out if you need more fuel to kill the KR, less timing or a combination of both.

A wideband O2 would be best for this, but you can (arguably) get a better idea about the fuel by checking your O2 values at WOT. (Some say this is totally useless to judge rich or lean with the stock O2's, and technically they are correct. But, I've found some correlation for rough estimation.)

Again, my2cents. :)

[bobfo]

Thanks for the input. I am tuning my 98 Vette, I use LS1edit (since EFI doesn't support 98's yet :( ) to program and EFIlive to scan. I don't have access to a dyno and don't have a WBO2 yet. WOT I am coming in at 12:1 AFR and getting about 4.5 KR at 5800-6000 RPM, but is seems the retard is kicking in as I shift. Any ideas? Where should I go from here?

Thanks.

[Black LS1 T/A]

Thanks for the input. I am tuning my 98 Vette, I use LS1edit (since EFI doesn't support 98's yet :( ) to program and EFIlive to scan. I don't have access to a dyno and don't have a WBO2 yet. WOT I am coming in at 12:1 AFR and getting about 4.5 KR at 5800-6000 RPM, but is seems the retard is kicking in as I shift. Any ideas? Where should I go from here?

Thanks.

I'm sorry... if you don't have a wideband, how do you know you are kicking in at 12:1 AFR?

[Black LS1 T/A]

...getting about 4.5 KR at 5800-6000 RPM, but is seems the retard is kicking in as I shift. Any ideas? ...

You A4 or M6?

Maybe your timing jumps high at that shift point?
Perhaps you have some physical noise (exhaust banging, etc) that affects the knock sensors? (BTW, it seems we with 98 F-Bodies have a lot more problems with KR sensors ... could it be the same for '98 Corvettes? )

Try high octane fuel and see if you can eliminate some of the possible reasons for the knock. If it still knocks same amount, check for banging exhaust. If you are fairly certain this is not a problem, decrease the timing and/or give it more fuel in the area of the KR...

A great tuning scenerio for me would be the ability to vary timing and fuel differently per gear.
For instance, I get more KR and consume more fuel in 2nd than in 1st, then 3rd, than I do in 2nd.

If I could keep the higher timing, less fuel in 1st, drop timing some/add more fuel in 2nd, then modify it some more in 3rd, I could get more out of it. As it is, I have to accomodate all three gears with optimized timing and fuel for 3rd... the gear where I have the most chance of KR. :?

If anyone knows how to work with this, let me know. :)

[bobfo]

Don't really know for sure, it is an estimate based on commanded AFR and the stock O2's. I plan on getting a WBO2 soon, but for now I am trying to work with what I have :(

[turbolou]

Thanks for the input. I am tuning my 98 Vette, I use LS1edit (since EFI doesn't support 98's yet :( ) to program and EFIlive to scan. I don't have access to a dyno and don't have a WBO2 yet. WOT I am coming in at 12:1 AFR and getting about 4.5 KR at 5800-6000 RPM, but is seems the retard is kicking in as I shift. Any ideas? Where should I go from here?

Thanks.I wonder if this is a function of burst knock retard ?

[bobfo]

It is an M6. It is really hard to tell, but looking at the charts, it looks like the KR is hitting as I take my foot off the gas, I will try and log some more data and post a pic tomorrow.

[SinisterSS]

Don't really know for sure, it is an estimate based on commanded AFR and the stock O2's. I plan on getting a WBO2 soon, but for now I am trying to work with what I have :(

Get a wideband before you get too much further into tweaking your tune. I'd bet large amounts of money that your AFR is not even close to commanded or what the narrow band O2s are *trying* to say.

[bobfo]

Here is a screen shot of the KR, any ideas? Could it be the noise form the clutch engaging?

http://folkes.us:85/kr2.jpg