[Diy_efi] Peak EGTs occur at the stoichiometric ideal AFR of14.65-70:1

[Stefan Hamminga]

Hello, I'm usually just lurking, but perhaps I can give some input on this...
My experience is that EGT alone doesn't say a whole lot. EGT combined with
accurate coolant temp is a lot more usefull.
The basic rules used where I raced where:
EGT up / CHT up -> more power
EGT up / CHT down -> slower burn / less power (mostly lean condition)
EGT down / CHT up (rapidly) -> detonation
EGT down / CHT up (slowly) -> (too) much ignition advance
EGT down / CHT down -> too rich (slow burn, but the extra fuel cools the
gasses)


On Thu, April 7, 2005 23:05, gary said:
> Phil,
>>
>> Any search of the millions of available articles from the SAE (soc.
>> Automotive Engineers) will show that peak EGT for petrol occurs at
>> Lambda 1.1 or 16.17 it is also the A/F ratio of peak efficiency. The
>> bad news is that the NOX output at this A/F ratio is also the highest.
>>
> Of those millions, could you possibly forward a link that substantiates
> such claim, along with test results to validate the accuracy of this link?
> Open minded to allow the weighing of results of any tests conducted.
>>
>> Not logical or intuitive but physics doesn't seem to mind.
>>
> I'd prefer facts gathered from testing, in lieu of engineering theory.
> Again, any test results you could link me to, would be appreciated.
>>
>> Heat is a function of rate of burn as well as A/F ratio.
>>
> OK.  Burn propagation is fastest at the AFR that generates the most
> power, i.e. 12.5 AFR.  It becomes progressively slower the further from
> that point (on either side).  So Phil, what's your point?  Please explain,
> preferably with along with results of controlled test to validate.
> Thanks.
>
> GAS
>
>
> ----- Original Message -----
> From: "Phil Lamovie" <phil at injec.com>
> To: <diy_efi at diy-efi.org>
> Sent: Thursday, March 31, 2005 7:50 PM
> Subject: [Diy_efi] Peak EGTs occur at stoich ideal AFR of 14.65-70:1
>>
>> "Peak EGTs occur at the stoichiometric ideal AFR of 14.65-70:1"
>> is simply wrong.
>>
>> Any search of the millions of available articles from the SAE (soc.
>> Automotive Engineers) will show that peak EGT for petrol occurs at
>> Lambda 1.1 or 16.17 it is also the A/F ratio of peak efficiency. The
>> bad news is that the NOX output at this A/F ratio is also the highest.
>>
>> "how can you possibly generate more combustion heat with less fuel?
>> Not logical."
>>
>> Not logical or intuitive but physics doesn't seem to mind. Heat is a
>> function of rate of burn as well as A/F ratio.
>>
>> Hope this helps,
>> Phil
>
>
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