[Diy_efi] Intro, and q's about fuel economy

[Greg Hermann]

At 5:39 PM 12/15/02, James wrote:
>On Sun, 15 Dec 2002, Greg Hermann wrote:
>
>> You are going to have a _difficult_ time finding a small enough injector to
>> run digital !!
>
>We have one, I am told.
>
>> How big (displacement) is this one lung engine ?? How many rpm do you plan
>> to turn it ??
>
>Believe it or not, I haven't been able to find the displacement yet.  And
>yes, that annoys me.
>
>It's a 3.5 hp briggs and stratton lawnmower engine.  RPM will vary with
>clutch engagment point and final gearing, but it's probably in the
>neighborhood of 3-4k, maybe 5k but probably not.

OK--A 3.5 HP engine. Say _MAYBE_ you hop it up/improve its efficiency to
where it's good for 6 HP. This will require about a 3 lb/hr. of fuel. Or,
at, say, a 60% duty cycle at full power, a 5 lb/hr. injector. Smallest
injector _I_ know of is a 13.5 lb/hr one, made by Bosch. Check the archives
here, there have been a number of times folks have been looking for little
injectors.

Either somebody has found something a LOT smaller than anybody here has
been able to find, or they are blowing smoke, or they think they are going
to get decent fuel metering accuracy (not to mention reasonably decent idle
performance) with a short injector duty cycle--which simply is NOT true !!

Greg





>
>-j
>
>
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