Dodge Challenger Forum banner
  • Hey everyone! Enter your ride HERE to be a part of this month's Ride of the Month Challenge!

1 - 7 of 7 Posts

·
Registered
Joined
·
511 Posts
Discussion Starter #1
I've been running some logs and my average AFR is around low 14's. What is ideal for a NA engine running a 91 cai tune on a diablo? I assume I should check what the AFR is at certain RPMs and add fuel to get the ratio down a little if need be? Any input is appreciated.


Sent from AutoGuide.com Free App
 

·
Registered
Joined
·
511 Posts
Discussion Starter #3

·
Registered
2009 R/T
Joined
·
1,371 Posts
Yea at WOT it's around 11.5-11.8:1. Does that seem ok?


Sent from AutoGuide.com Free App
It used to be that 12.5:1 was considered the best power ratio, but with improved combustion chambers and hotter ignition systems, the ideal now is around 12.8:1 to 13.2:1. I wouldn't go any leaner than 13:1 myself.
 

·
Registered
Joined
·
511 Posts
Discussion Starter #5 (Edited)
It used to be that 12.5:1 was considered the best power ratio, but with improved combustion chambers and hotter ignition systems, the ideal now is around 12.8:1 to 13.2:1. I wouldn't go any leaner than 13:1 myself.

So theoretically, I should subtract more fuel at WOT?

EDIT: accidentally typed add instead of subtract the first time
Sent from AutoGuide.com Free App
 

·
Premium Member
The Bacon Hauler (‘12 Cop Charger)
Joined
·
8,481 Posts
So theoretically, I should subtract more fuel at WOT?

EDIT: accidentally typed add instead of subtract the first time
Sent from AutoGuide.com Free App
Unless the AFR number is coming from a wideband, it should not be used to make adjustments to the open loop air & fuel parameters in the loaded tune.

The lack of a MAF sensor on these cars means there are some calculations made on best guesses about operating conditions, and that results in a less-than-accurate number being shown for AFR when monitoring via something like a tuner's datalog.

---------------------------------------------------------------------

I'm pretty certain the 1st part above is correct, as I have seen it used in responses to posts in the past which asked similar questions as yours.

The 2nd part above is a liberal interpretation of what I understand to be the reason for the statement made in the 1st part, so it should be taken with a grain of salt I suppose.

And if you are already using a wideband to get the AFR readings, then you can ignore my whole post, as you are already "The Man With The Plan"!

Nuke
 

·
Registered
Joined
·
1,067 Posts
It used to be that 12.5:1 was considered the best power ratio, but with improved combustion chambers and hotter ignition systems, the ideal now is around 12.8:1 to 13.2:1. I wouldn't go any leaner than 13:1 myself.
I've yet to meet an N/A HEMI that liked to be much leaner than 12.5:1 at WOT. We find peak power on stock engines between 12.3 and 12.5:1

Thanks
 
1 - 7 of 7 Posts
Top