What is the safe zone for AFR, under WOT?
I have always been shooting for 11.8-12.1. But sometimes, on the same cell, tuned at a nice 11.8, it will dip to 11.3 and in certain cells, under certain conditions it might even go as low as 10.5.
How low can it go before I do damage to the rings?

 

Anyone?

 

I have seen anywhere from 11's to 12 on graphs. Higher pressure applications it seems 11.5's are common.

 

Thanks, but I am still trying to figure out how low the AFR can go before damaging the rings. 11.0? 10.5? 10.0?
I see posts here and there about how running really rich will wash your rings after a while.

 

Lower a/f will not hurt your engine. It will most likely brake up when its too low. Too high will hurt your engine.

 

big boost 25+ psi no lower than 10.8 low boost 11.3 no lower IMO

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by nonvtecallmotor &raquo;</TD></TR><TR><TD CLASS="quote">Lower a/f will not hurt your engine. It will most likely brake up when its too low. Too high will hurt your engine. </TD></TR></TABLE>

NEGATIVE.

too much fuel can wash your cylinders out. it will take a quite of bit to do so but can very easily happen.

and no, most likely it wont break up.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by WHITFIELD-TUNED &raquo;</TD></TR><TR><TD CLASS="quote">big boost 25+ psi no lower than 10.8 low boost 11.3 no lower IMO</TD></TR></TABLE>

i run ~11.8:1 afr

 

ive run high 10s for short periods of time (weeks) with no adverse effects.

my car now runs 11.3 or so, making it way up toward 11.9
.

ive run up around 12.5 or so before and had no detonation issues. this was mid 300hp and a little more than 10 psi

 

It normally runs from 11.3-12. The ECU has a hard time keeping up with the boost spikes I get from running such a small turbo. Sometimes it just dips to high tens (for a tenth of a second or so).
I'm not going to worry about it too much, since it's on the safe side. I'll jsut keep fine tuning it.
Thanks for the replys!

 

my eagle talon TSI ran 9.8:1 a/f and it was almost stock. i would never run that rich on a honda, but dsm did it to keep the cars reliable and not blow up within 50k if some idiot driver modified the car or had a lead foot. plus our hondas are much more efficiant and can run on slighty less fuel and be reliable. on a daily driven boosted car i run 12:1 -11.8:1 slightly richer mixture will help cool cylinder temps but can hurt peak hp/tq. i like reliability

 

yeah i second that, all my friends dsm's run pig rich
11.5 is the number i like to stick with, yeah you can get away running closer to 12 but i like a to have that little buffer it makes me sleep better at night. Yeah washing the rings out can have some advese effects, id imagine with our hondas and excellent head/combustion design youd have to be in the low 10's to really start doing any harm, maybe high 9's? correct me if im wrong. lets get the right info in here for sure.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by quicksilver1689 &raquo;</TD></TR><TR><TD CLASS="quote">yeah i second that, all my friends dsm's run pig rich
11.5 is the number i like to stick with, yeah you can get away running closer to 12 but i like a to have that little buffer it makes me sleep better at night. </TD></TR></TABLE>



I wouldn't sweat washing cylinders out unless you're sub 8:1.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mike93eh2 &raquo;</TD></TR><TR><TD CLASS="quote">
and no, most likely it wont break up.</TD></TR></TABLE>

Excessive fuel (ex. 10.0:1) can cause the motor to 'break-up', hesitate, and of course cause the power curve to be somewhat unsmooth in certain circumstances.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by PrecisionH23a &raquo;</TD></TR><TR><TD CLASS="quote">

Excessive fuel (ex. 10.0:1) can cause the motor to 'break-up', hesitate, and of course cause the power curve to be somewhat unsmooth in certain circumstances.</TD></TR></TABLE>

i think its going to take a lower afr than 10.0:1 to start seeing some break up.

 

I've seen motors produce some funky looking power curves with this a/f ratio and especially richer as you've mentioned. If I had time, I'd pull up a few dynocharts and post them for you... But I don't.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mike93eh2 &raquo;</TD></TR><TR><TD CLASS="quote">

i think its going to take a lower afr than 10.0:1 to start seeing some break up.</TD></TR></TABLE>

I'd have to agree with this, especially seeing as how many factory turbo cars run sub 10:1 in some parts of the powerband.

 

I agree with all that ^. Put a wideband on and evo, talon or srt4 and you could very well see single digit AFRs by redline. Many subarus run 10s up top as well.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by PrecisionH23a &raquo;</TD></TR><TR><TD CLASS="quote">

Excessive fuel (ex. 10.0:1) can cause the motor to 'break-up', hesitate, and of course cause the power curve to be somewhat unsmooth in certain circumstances.</TD></TR></TABLE>
This is very true. Every time it dipped below 10, I got a miss, or hesitation, usually in the lower RPM ranges. 10.5 not as often.
Since starting this thread, I have been able to limit the dips to &gt;11.2. Only during tip-in does it go any lower.

 

what about low boost i have a centrifugal charger and my AFR on low low boost say 2-3psi is about 12:1 is this ok or should i aim towards that 11.8 all the way across to 10psi???