normally a car makes more power as the a/f ratio is leaned out, but i had the opposite happened to me. first of all, the car was street tuned @ 9 psi on 91 pump gas. a/f was low 12's @ 6000-7000, high 11's @ 7000-8000 and mid 11's from 8000-9000. made a base run on the dyno and put down 292 whp. gave it some timing and hit 308whp. then decided to lean out the a/f , pwr went to 302whp. wtf! went back and add fuel to where it was, pwr went back up. added more fuel and the pwr went up to 318whp and 210 ft. today now, went to check the a/f on the highway, a/f was low 11's from 7000-8000 and high 10's from 8000-9000. why was this happening? could it be the octane of the gas (91)???

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">normally a car makes more power as the a/f ratio is leaned out</TD></TR></TABLE>

Where did you hear that? The opposite is true. Leaning out the mixture hurts output but improves economy.

 

What does your torque curve loolk like? Your fuel curve should mirror your torque curve. Sounds like the engine wanted more fuel.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by RA166E &raquo;</TD></TR><TR><TD CLASS="quote">What does your torque curve loolk like? Your fuel curve should mirror your torque curve. Sounds like the engine wanted more fuel.</TD></TR></TABLE>

i don't have a scanner, so i can't post a pic. the torque curve is al most flat. it peaked around 6500 and slowly drops to 205-202 till 8700. it does seem that the engine likes a lot of fuel.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by beepy &raquo;</TD></TR><TR><TD CLASS="quote">Where did you hear that? The opposite is true. Leaning out the mixture hurts output but improves economy.</TD></TR></TABLE>

Are you sure? I was was always under the impr that richer is safer and slower, learner is riskier (hotter) but can make more power. I see it as the air is the part that is the main factor of the combustion and expands to make power, so the more the better. Hence why we add turbos to our cars

 

This was posted by "blundar" on the pgmfi.org wiki.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">Originally posted by blundar

The ratio of the mass of air taken in my an engine to the mass of fuel. 14.7:1 is chemically ideal in order to get the greatest efficiency from every gallon of fuel. However, due to the inefficiencies of any engine, the greatest amount of power is usually obtained with a lower Air Fuel Ratio, but not usually less than 13.4:1 for non-race gasoline engines.</TD></TR></TABLE>

 

What management are you running can you post your fuel maps. Your fuel values should stay the same across your rpm band if your torque curve is flat. Don't get to hung up on A/F ratios for power. Thats one thing EFI101 class showed us on the dyno that A/F will not affect torque/power like people think.
Example. 12.5 to 11.0

Just keep it on the rich side build in a saftey net so to speak. I'm running my
load-boost A/F ratios in the mid to low 11's now since the class. Also I have back off the timing because richer A/F have a faster flame speed then leaner A/F.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by RA166E &raquo;</TD></TR><TR><TD CLASS="quote">

Just keep it on the rich side build in a saftey net so to speak. I'm running my
load-boost A/F ratios in the mid to low 11's now since the class. Also I have back off the timing because richer A/F have a faster flame speed then leaner A/F.</TD></TR></TABLE>

ah interesting thats probably why my car doesnt need much timing at my 11ish afr. I need to take that class