What kind of a/f meter do you have? I am only aware of two types, one is an
exhaust gas analyzer (extremely inacurate), and the other uses an O2 sensor
(and even the wide-band sensors are only useful right around stoich). (of
course it can be done indriectly via MAF or MAP and injector pulse-width,
but this is just reversing what the computer has already done). Anyhow, if
you (or anyone else) could tell me of a good method of determining a/f ratio
(or name a good meter for this) I'd love to hear about it.
By the way, I would be surprised if you see a large loss of power until you
get into a a/f ratio greater than 14.5:1. I belive your peak is around
11:1, but at WOT this is a bad thing (being pretty lean), and increases the
chance of hot-spots. Also, decreasing the advance will almost always
decrease power (unless your advance is set high enough for full flame
propogation to occur before the piston reaches TDC in which case you are
probably knocking anyway). The only reason to retard the spark is to
prevent knock.
P.S. All my engine tuning knowledge comes from working on supercharged
motorcycle engines, I can't see why the numbers wouldn't hold, but I most
certainly could be wrong.
.Geoff
-----Original Message-----
From: Tim Berry [mailto:coolva1@home.com]
Sent: Friday, August 18, 2000 4:18 AM
To: dakota-truck@buffnet.net
Subject: DML: Re: Re: Supercharger Guru's (or anyone else thats a guru
with tuning an engine)
i have an air/fuel ratio meter... tis how I can see
___________________
Tim Berry
Chesapeake, VA
97 CC, 4x2, auto, 318
Best 1/4: 14.10@96.8
ŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻ
----- Original Message -----
From: "Ransom T Holbrook" <ransom@setel.com>
To: <dakota-truck@buffnet.net>
Sent: Friday, August 18, 2000 6:23 AM
Subject: DML: Re: Supercharger Guru's (or anyone else thats a guru with
tuning an engine)
> Under Boost conditions and using pump gas you should be no leaner than a
> 12.5 to 1 Air/Fuel. Somewhere in the 11s to 1 Air/Fuel is fine. Richer
> than 11 to 1 Air/Fuel and the power starts to drop off. Being ignorate on
> what type of S/C and setup you have, how are you determining if running
> rich?? The only way I know that you can get a true air/fuel curve reading
> is using a Dyno with a probe.
>
> Of course the leaner the more power, BUT..like it has been said before; it
> is much, much better to run rich than lean. Running Lean you will brake
> something!
>
> ----- Original Message -----
> From: "Tim Berry" <coolva1@home.com>
> To: <dakota-truck@buffnet.net>
> Sent: Thursday, August 17, 2000 11:02 PM
> Subject: DML: Supercharger Guru's (or anyone else thats a guru with tuning
> an engine)
>
>
> > Okay...
> > Long time ago (month?) I put 24# injectors in my truck, and all was good
> > (supercharged)
> > Stock FMU was 12:1 and i put the 11# pully on it... and now push 8# of
> > boost.. It cause the air/fuel ratio to go wayy rich under alot of
> boost...
> > (almost off the scale)
> >
> > My question is... With the 12:1 FMU, i didnt need to retard the
timing...
> > but she ran realllllllly rich under boost..
> > I've re-calibrated it to 8:1 (recomended for 24# injectors) and its
> staying
> > on the rich side, but now I ping with out retarding it..
> > Which is better for power? the 12:1 running rich... or the 8:1 which is
> > just on the rich side, with some retard (less than 1* per pound of
boost)
> >
> > I'm lost... some times it feels stronger with the retard, other times it
> > dosent... HELP!!! =)
> > ___________________
> > Tim Berry
> > Chesapeake, VA
> > 97 CC, 4x2, auto, 318
> > Best 1/4: 14.10@96.8
> > ŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻ
> >
> >
>
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