Correct A:F Ratio @ WOT?

[Bruce]

EGT is just another indicator.
It just tells you how close you are to the thermal limits of the engine, and
nothing more.  you can error in timing and fuel, and be miles off from best
HP.

I'd sure look around alot if I was at 13:1 AFR with a turbo and think I was
at max HP.  At a glance it sounds like not enough timing and fuel.  Which
would show a proper/hi EGT but be down on HP.

Suggesting AFRs as being safe, sure is assuming alot.
Bruce







From: "Jeff Meager" <jmeager at bigpond.com>
Subject: RE: Correct A:F Ratio @ WOT?
> Having said that, nearly all engine perform best in lean conditions,
> however, this is not conducive to a long running engine.  Take my turbo
> nissan.  It loves 13:1, however at this it is sitting right on its ping
> threshold, as found under differing situation, and the EGT's go off the
> dial.
> The only real way to tune is EGT and AFR.  You want to make sure you're
not
> melting the engine where it "wants" to be vs where it "needs" to be.
>
> As a basic safe rule of thumb.
>
> WOT
> Non-turbo 12.5-13.5:1
>
> Turbo anwhere from 10.5 - 12:1.
>
> My factory turbo cars have always run 10.5:1 out of the factory.  It tune
> mine to 12:1 on big turbo engines, and small factory engines I tune to
> 11-11.5:1
>
> JEff
>
> -----Original Message-----
> From: owner-diy_efi at diy-efi.org [mailto:owner-diy_efi at diy-efi.org]On
> Behalf Of Bruce
> Sent: Thursday, 28 September 2000 8:13 AM
> To: diy_efi at diy-efi.org
> Subject: Re: Correct A:F Ratio @ WOT?
>
>
>
> You never,
> ever,
> tune to an AFR.
> You tune for performance and note trends, or validate corrections made
with
> a WB.   In tuning you let the engine tell you what it wants, you never try
> to force it to run where you **THINK** it should be.
> A WB is just one more tool in your box, it, in and of it's self is
nothing.
> Bruce
>
>
>
> ----- Original Message -----
> From: "Timothy J Burgess" <tjburgess at west.raytheon.com>
> To: <diy_efi at diy-efi.org>
> Sent: Thursday, September 27, 2001 6:36 PM
> Subject: Correct A:F Ratio @ WOT?
>
>
> > Now that we have the ability to determine the average A:F ratio using
the
> > WB O2 sensor, is there a typical A:F ratio to tune for @ WOT?
> > In the TPIS catalog, they have a picture of the WB sensor & meter that
> they
> > sell, and there is a marker @ 12.8:1, so I'm guessing that that would be
> > the value to tune for @ WOT.  Any recommended variance to that value
when
> > using a wet NOS system, compared to normal aspiration?
> >
> > Tim Burgess
> >
> >
>
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