What AFR to tune to for WOT? and How to Adjust?

[PowerKraus]

Well, I finally got my AEM wideband installed. So, now I can get a little better tune, than using the stock O2s and Int/BLM readouts. I also connected it to my power logger for logging the readings along with all the other cool stuff, i.e. fuel pressure, 3bar boost etc....
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Now GENERALLY SPEAKING what range should I begin with for WOT blasts. And would you suggest two different 'acceptable ranges' for pump gas vs. high octane unleaded. If this is the case, I woud assume, you'd go a little fatter for pump gas.
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I am starting with 'low timing'....19 to 21 degrees of timing in low gears, droppping to 17 to 19 in high gear, but think I need more like 25 degrees +/- to realy uncover the powerpotential. Please refer to my 3,600lb car, which set up for 1/8th racing and curret combo noted below:

Stock cubed, steel caps, Stock exhaust manifolds
Mild port on iron heads and port matching
Stock TB and plenum + cold air mod + free flowing exhust (bullets)
Extemder Extreme Rev F, MAFT+ timing control
65lb high impedance and Walbro in tank, old 307...but delivers nearly 70psi with no drop off at WOT runs (but I'll keep an eye on this, it or alky is the next upgrade))
TE63 3 bolt with pte ported .63 housing (the smaller housing, but ported)
9" AC n/l 3,500 stall and big PTE front mount
224 HR cam with highlift (yes overkill for the cubes, but this is what i have to work with)
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keeping in touch with tuning of max boost to where you see no knock, and still gain power from increased pressure.....and timing. On pump gas should I be shooting for 10:1 to 10.5:1,or more like 11.5:1 to 12:1?

If you would, help me with a starting point on 93 pumps gas.
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Then the big question on how to adjust. Currently all BLM are running great with very little trim changes. For a stock ECM, is it best to adjust by boost pressure, fuel pressure, and timing...Or should I look elsewhere.
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Again, I would really really appreciate your opinions on the tuning and 'how to dial it in' as I am not havingany real luck with my searches.


Sorry for the long post, but after nearly 20-years of car ownership, I feel like I have only now accessed one of the most important tuning parameters and respectfully request some help with which to 'fine tune' this buggy. Afterall, she deserves it after over 20-years of reading O2s, knock retard, and BLM tweaking.

much appreciated guys and gals !!!

I humbly bow to the Buick Forum Gods to bless me and to steer thine path to that of Buick righteousness and dominance amongst the pegan flesh of 'flash memory' and soulness mail order speed parts! My thy knowledge passeth from the mouths of gods to thy humble servant!

 

[bison]

Without alky you will have a hard time leaner than 10.8:1 at 17 psi and 20degrees. With c16 i would go as high as 28 psi and 24 degrees and 11.5:1. You really need alky on that thing. Ive gone 27 psi on 93 octane with it with the same stuff in my sig. I just got back from pounding my other GN with the engine i just dropped in and its brutal at 25 psi and 11.0:1. Only has a TE 44 but i have no doubt it would nail down 120 mph easily. I may throw on the T72 but the bottom end is stock in this one. I generally tune to 11.3-11.5:1. There is little to be gained going leaner but much greater chance of melting something. Some go as lean as 12.2:1. Not me though.

 

[PowerKraus]

bison,

Thanks for the quick and 'straight to the point' response. I ran some 'base line' pulls last night in 90 degree temp. For a starting point, I was able to run 25lbs of boost with no knock on pump gas (93 octane) with low gear timing of 21 degrees, and high gear of 19 degrees. AFR was 11.1:1 ish.

At this point, I think I'll run the same set-up with the G-tech pro and get some ET and mph base lines. Then I will slowly bump up timing (which will indirectly lean the AFR), keeping it to no knocking, and an AFR no leaner than 11.5:1.

And I agree, from what I am hearing, alky is really the way to go, especially if running pump gas.

Again, I appreciate you sharing the information.

 

[Boost231]

this is a good post by the way but are you saying you running 25 pounds on pump gas and no alky?

 

[PowerKraus]

this is a good post by the way but are you saying you running 25 pounds on pump gas and no alky?

yes, but I don't let it go into overdrive. Also, i went back and checked my timing and i was actually running 2 degrees lower in both low (19) and high gear (17).

 

[87NAT]

I think he meant 25 DEGREES not pounds of boost.


Powerkraus if you did mean 25#'s of boost on 93 be sure to take a "Headgasket Changing Class 101"

 

[Boost231]

the way im reading it is he is running 25 pounds of boost on pump gas. i hope im wrong.

 

[bison]

Either your boost gauge is wrong or your knock sensor isnt functioning. I have never seen more than 21 psi on irons in any combo without KR. Even then the timing was under 20 degrees and it was in first and second gear only. Better inspect the rod bearings. Bumping timing up actually appears richer for me not leaner. EGT's go down with more timing.