[Gmecm] Ideal gas law and $58

[not a webot]

 centrifugal compressors  are very sensitive to mass flow. At certain
flow/pressure ratios they stall, if the compressor was allowed to stall for
too long the turbine speed could get dangerously high.

 richening the mixture would cool the exhaust and limit power to the
turbine.

as I said just a first guess
Pat

On 9/24/07, Rob Handley <Robin at furyworld.fsnet.co.uk> wrote:
>
> Yes it is a turbo calibration - and I want to use it for a NA engine.
>
> Cold start enrichment is applied via the desired A/F ratio. If it was down
> to the F31M array it would be cold start enleanment!
>
> Curious what you mean by non-linearities. Could you expand?
>
> Rob
>
> ----- Original Message -----
> From: "not a webot" <not.webot at gmail.com>
> To: <gmecm at diy-efi.org>
> Sent: 24 September 2007 20:04
> Subject: Re: [Gmecm] Ideal gas law and $58
>
>
> > compressor (it is a turbo cal right?) nonlinearities? It might also be
> > cold
> > start enrichment related.
> > just the 2 first thoughts I had
> >
> > On 9/24/07, Rob Handley <Robin at furyworld.fsnet.co.uk> wrote:
> >>
> >> Don't know whether anybody's interested :-) but I have now perfectly
> >> matched
> >> every factor in $58's steady state (meaning: no acceleration enrichment
> >> or deceleration enleanment or closed loop or any other special
> >> contributions)
> >> injector base pulse width calculation with its equivalent derived
> >> directly
> >> from the ideal gas law. It is now absolutely clear that the (F31M)
> >> inverse
> >> MAT/IAT
> >> look-up array has been 'adjusted' from theoretically correct, for
> >> whatever
> >> reasons.
> >>
> >> This plot: http://213.162.107.39/temp/GM_inverseIATfactor_vs_IAT.gif
> >> shows
> >> the only contribution that the MAT/IAT makes to the steady state BPW
> >> calculation. The contribution is made via a multiplying factor in the
> >> range
> >> 0 to 1.
> >>
> >> The magenta line is the multiplying factor arising from the values that
> >> GM
> >> put in the (F31M) inverse MAT/IAT look-up array for the Sunbird. The
> dark
> >> blue line
> >> is the theoretically correct multplying factor.
> >>
> >> The GM contribution stops changing at 23.5C but only matches the
> >> theoretical
> >> line at 50 C. So why would GM make it such that the mixture was lean
> >> below
> >> 50 C and rich above it? Is 50 C the normal running air temperature for
> >> the
> >> Sunbird?
> >>
> >> Rob
> >>
> >> ----- Original Message -----
> >> From: "Dig" <turbodig at yahoo.com>
> >> To: <gmecm at diy-efi.org>
> >> Sent: 17 September 2007 18:37
> >> Subject: Re: [Gmecm] Ideal gas law
> >>
> >>
> >> Yup.  In fact, if I remember the Sunbird cal correctly, they're exactly
> >> the
> >> same.
> >> Given that one application is intercooled, and the other isn't, you
> would
> >> have thought these would have been markedly different.
> >>
> >> ----- Original Message ----
> >> From: Rob Handley <Robin at FuryWorld.fsnet.co.uk>
> >> To: gmecm at diy-efi.org
> >> Sent: Monday, September 17, 2007 12:18:23 PM
> >> Subject: Re: [Gmecm] Ideal gas law
> >>
> >> I have no reason to think the lookup isn't working. The values in the
> >> standard Sunbird F31M array are fixed for MAT = 23.5 C and above. Is it
> >> the
> >> same for the Sy/Ty ?
> >>
> >> Rob
> >>
> >> ----- Original Message -----
> >> From: "Dig" <turbodig at yahoo.com>
> >> To: <gmecm at diy-efi.org>
> >> Sent: 17 September 2007 14:37
> >> Subject: Re: [Gmecm] Natural gas law
> >>
> >>
> >> Are you talking about the values in the table, or are you saying the
> >> lookup
> >> isn't working?
> >>
> >> The factory calibration was, "less than perfect".
> >>
> >> The other thing at work here, is the fact that when temps heated up,
> they
> >> wanted a bit extra fuel to keep the detonation demons away.  24 c is a
> >> bit
> >> low to start doing that, IMO.
> >>
> >> Later,
> >>
> >> Dig
> >>
> >>
> >> ----- Original Message ----
> >> From: Rob Handley <Robin at FuryWorld.fsnet.co.uk>
> >> To: gmecm at diy-efi.org
> >> Sent: Saturday, September 15, 2007 10:15:46 AM
> >> Subject: [Gmecm] Natural gas law
> >>
> >> I've been trying to match the $58 BPW calculation with a hand made BPW
> >> calculation spreadsheet - which is based on the natural gas law.
> >>
> >> What's confusing me ATM is that, in $58, the inverse air temperature
> >> correction factor (array F31M) does not change when the MAT value is
> >>  >23.5
> >> C.
> >>
> >> Since gas mass is inversely proportional to gas temperature (if
> pressure
> >> and
> >> volume are constant), the MAT contribution should have an effect at all
> >> temperatures, and this effect IS significant above 23.5 C.
> >>
> >> What am I missing?
> >>
> >> Rob
> >>
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