a/f for a stock car w. bolt ons

[Konstantin]

98 ls1 with ls6 intake, vararam, LG pro headers and catted x pipe what should be the a/f mix for the best results. i got 326rwhp and 340 rwtq with what i got, but didnt have a/f mixture reading, so going back to dyno soon and id like to know what to aim for. thanks - Kons

[mowton]

Usually 12.8 to 13.2 is the range. The car will lean out a bit from the Dyno to the street so add a bit of safety. If you are heading for the Dyno again, keep track of the readings in the area know as "power under the curve". Here the key is matching the AFR and timing to produce the highest torque levels across the entire power band. Normally the timing actually is reduced a bit as you reach the maximum torque reading (highest cylinder pressure) and then comes back in after. The Dyno torque readings will tell you when the best combination is reached. This will give you the maximum power across the power band, and not just a Peak number which while interesting isn't the end all. I would much rather have an engine running at peak through the entire band than just at the peak.

There are some good books and threads in HPTuners and EFILIve websites.

Good luck

Ed

[tblu92]

I would deff have the AFR at WOT checked with a wideband ---You can get it close with the stock narrowband 02's but just error a bit on the side of rich to be safe--With the narrowbands look for an 02 voltage of .890-.905---that will get you around a safe 12.7-12.8
ALSO---with LT headers the 02 sensor bungs are further back than they were with the stock manifolds--This makes your P/T closed loop commanded AFR of 14.68-1 way rich (usually)--and your fuel mileage really suffers----have that checked with the wideband as well--My hds/cam 98 was a pig rich 12-1 after the LT's---Corrected it with a tune-

PS: Some people prefer to run a leaner 12.9-13.0 AFR and run less timing--others like to run it somewhat richer and are able to bump the timing up a few degrees--So 2 schools of thought--the leaner mixture i believe shows more HP but the richer mixturs make more TQ---

[Brian@RPT]

I shoot for 13.0:1 on the street when I tune cars. That is, from the peak HP to redline. I will fatten the mixture at the torque peak and below to increase torque.

[0Arun@ChampionMotors]

Originally Posted by Konstantin

98 ls1 with ls6 intake, vararam, LG pro headers and catted x pipe

what should be the a/f mix for the best results.

i got 326rwhp and 340 rwtq with what i got, but didnt have a/f mixture reading, so going back to dyno soon and id like to know what to aim for.

thanks

- Kons

Are those numbers standard or SAE corrected? it's always best to perform a before and after to see what you gain.

I always put in the wideband and shoot for 12.8 on the street and then i'll make a few pulls on the dyno to verify. The street tuning will put alot more load on the car and actually let the vararam do it's job.

Did you tuner do any street tuning?