A/F ? on wideband
A/F ? on wideband Should my a/f stay the same threwout the pull or should it vary? ex: 13.0 threwout or 13.0 at 3000rpm to say 13.5 at 5000 rpm.I have heard that it should vary something about max tq is one number and max hp should be another. Is this correct?
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Joined: Jan 2002
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From: Austin, TX
Re: A/F ? on wideband Try to make it stay @ 13 all the way across to red line at WOT. I like to keep it @ 12.5 all the way across just to be safe. But that is just me.
Anything above 13 it is just too lean IMO.
Anything above 13 it is just too lean IMO.
TECH Enthusiast
Joined: Jan 2003
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From: Birmingham, AL
Re: A/F ? on wideband I have my dyno sheet here in front of me and mine personally went like this... At 2500 RPM it began to rise gradually from 11.2 and at 3800, leveled out at 12.9 for the rest of the pull. My car is stock.
Re: A/F ? on wideband </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by RUF SS:
<strong> Try to make it stay @ 13 all the way across to red line at WOT. I like to keep it @ 12.5 all the way across just to be safe. But that is just me.
Anything above 13 it is just too lean IMO. </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Here are just some of my observation that I see working. This gets bounced around alot, "How lean is too lean."
1) Lean is mean, but you break ****. If the timing isn't a problem, some cars respond very well to a 13.2 a/f ratio (as a result of loading differences I would then set the a/f to 13.0). The biggest problem and damaging factor that I think plays in with lean running is detonation more than heat rate.
2) We get actual race cars in the shop quite often....people who primarily tune their car on the track for best results (circle and drag), rather than the dyno. For alot of them the theory is "lean until you melt a piston". Naturally, this isn't right, but it gives me a glimpse of what kind of a/f starts to put some noticeable wear on an engine.
Here are my observations for Naturally asprirated tuning.
--- to 12.6 too rich, leaving power on the table
12.6 to 12.8 good safe street tune for a daily driver. Enough fuel to give you a good timing buffer on hot dry days.
12.8 to 13.2 the sweet spot for the most power. Unfortunately, you no longer have a buffer, so you have to be very conscience of how much timing your setup can really take with out detonation. Or, you can give the IAT vs Timing some thought.
13.2 to 13.4 no change in power.
13.4 to 13.8 power begins to trail off
13.8+ No good. Above this I think you will see heat damage under performance environement conditions (road racing, drag racing etc...)
<strong> Try to make it stay @ 13 all the way across to red line at WOT. I like to keep it @ 12.5 all the way across just to be safe. But that is just me.
Anything above 13 it is just too lean IMO. </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Here are just some of my observation that I see working. This gets bounced around alot, "How lean is too lean."
1) Lean is mean, but you break ****. If the timing isn't a problem, some cars respond very well to a 13.2 a/f ratio (as a result of loading differences I would then set the a/f to 13.0). The biggest problem and damaging factor that I think plays in with lean running is detonation more than heat rate.
2) We get actual race cars in the shop quite often....people who primarily tune their car on the track for best results (circle and drag), rather than the dyno. For alot of them the theory is "lean until you melt a piston". Naturally, this isn't right, but it gives me a glimpse of what kind of a/f starts to put some noticeable wear on an engine.
Here are my observations for Naturally asprirated tuning.
--- to 12.6 too rich, leaving power on the table
12.6 to 12.8 good safe street tune for a daily driver. Enough fuel to give you a good timing buffer on hot dry days.
12.8 to 13.2 the sweet spot for the most power. Unfortunately, you no longer have a buffer, so you have to be very conscience of how much timing your setup can really take with out detonation. Or, you can give the IAT vs Timing some thought.
13.2 to 13.4 no change in power.
13.4 to 13.8 power begins to trail off
13.8+ No good. Above this I think you will see heat damage under performance environement conditions (road racing, drag racing etc...)
