350 idle air consumption?

Bruce Plecan nacelp at bright.net
Mon Nov 16 03:24:33 GMT 1998


-----Original Message-----
From: Greg Hermann <bearbvd at sni.net>
To: diy_efi at efi332.eng.ohio-state.edu <diy_efi at efi332.eng.ohio-state.edu>
Date: Sunday, November 15, 1998 4:22 PM
Subject: Re: 350 idle air consumption?


>>-----Original Message-----
>>From: Bill the arcstarter <arcstarter at hotmail.com>
>>To: diy_efi at efi332.eng.ohio-state.edu <diy_efi at efi332.eng.ohio-state.edu>
>>Date: Friday, November 13, 1998 4:30 PM
>>Subject: 350 idle air consumption?
>>
>>
>>>Hey listers,
>>> Anyone know an approximate value of air consumption (CFM) a typical 350
>>>would consume AT IDLE??
>>
>>Hot idle min of 15 grams per second comes to mind.  But, have
>>seen lots of variances,  this is just looking at some diacom runs,
>>folks have sent me.
>
>If this is an accurate air mass flow number, it (at a 14:1 idle mixture)
>works out to burning about 1.38 gallons/hour of fuel at idle. Seems kinda
>on the high side to me--but???
>
>Whaddaya get for a pulse width at idle with what size injectors (and with
>what fuel pressure) on a 350 TPI, Bruce??

Geez, after looking at a bunch of stock types, it seems to be

6-7 grams/sec     1.4-2.0  (with a 2.3+2.6 seen)   pulse width
14.7: commanded AFR  rpm 575-800  these would be 22 inj
42 disconnected 34 on FP

One well documented Hot Rod was 10 grams/sec 50 PSI
vac off, probably 44 installed 1.7-1.9 ms inj on time

Different engines, guages, states of tune, not much in common
could be interesting.  After looking at this stuff I'd feel safe in saying
the reason for such large oem injectors is not running out of head
room for injector timing, because of such variances.
Bruce

Let's try backing into a number
>for air flow from that direction, and see how good the agreement is between
>the two approaches!
>
>Somewhere along here we ought to be able to come up with a number for
>parasitic horsepower at idle which is better than a WAG!!
>
>Regards, Greg
>
>>Bruce
>>>
>>> I'm trying to size out some injectors - want to make sure I can provide
>>>a fine enough adjustment for a decent idle control...
>>
>>Hope ya plan on sharing what ya see there!..
>>Bruce
>>
>>>
>>> Thanks!
>>>
>>>-Bill
>>>
>>>______________________________________________________
>>>Get Your Private, Free Email at http://www.hotmail.com
>>>
>
>




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