Any gains worth talking about leaning out the mixture from 11.8 to 12.8? Or does it vary from car to car? When I asked the tuner why the 11.8, all I got for an answer was better safe than sorry. Safe from what?

 

Your tuner is keeping you on the rich side which is a little rich and there is power to be had from leaning it out. Bryan at Pcmforless set my A/F at 13:1 and power picked up over my previous 12.2:1. If you're N/A then you can go a little leaner...For comparison, LPE says they like 12.6:1 A/F as a safe number...The gains from going from 11.8 to 13 would be significant...

--Alan

 

how can i find out what my a/f ratio is? im just curious because i think my car is runnin rich, exhuast is really raspy and when i changed mufflers the old bullets were black as coal inside... (also outside of my exhuast tips are black.. same as factory but polished instead) srry if im hijacking but if im rich ild like to figure out a way to lean it out a little too (already had both 02s changed)

 

Mailorder tunes will often be a tad on the rich side because it is safe a dyno tune for an NA car will usually be setup 12.5-13 often begining rich and leaning out as it revs higher as from my reading peak torque can be achieved with a little richer mix than peak HP so 12.5 down low tapering to 13 can be a great thing. This is of course dependant on O2 location and calibration. Tailpipe testing is not ideal but a lot of shops use it because it is much easier and cheaper than having to weld in a bung up by the headers. To find out your AFR you need a wideband oxygen sensor and the equipment to operate it probably starts at about $275 for a functional setup and can go up from there depending on what quality level and options you want. So most people just go to the local dyno shop pay $65-100 for 3 runs with AFR testing and get to know what they are putting down for HP at the same time.