valve needed

[john_carroll]

At altitude, the engines we care about are often run at WOT with far less than 1"Hg drop across the throttle body or carburator.  The engine will be operating at perhaps 80% of sea level rated power. I am becoming concerned that the valve will need to have a lot of capacity. The engines displace from 3 to 4.5 liters. If we are to influence the flow by even 1 percent the valve will have to pass a couple of cubic feet per minute with very little pressure differential.

Most large recip aircraft engines are not routinely operated at WOT for extended periods, but many of us experimental catagory builders need all we can get all the time. 

The question that really disrupts the air bypass approach is: If it is possible to get more air in at WOT why are we not doing it allready? 

I believe I need to add fuel to control the mixture. All thought are welcome.

John Carroll

>No, the part I am referring to is not part of an EFI system, at least as far
>as I have been able to determine. The air control valve you speak of is the
>idle speed control. There is a possibility you could use this device, but
>it's flow capacity is an order of magnitude higher than the unit I was
>thinking of.
>
>According to "how to keep your subaru alive", page 206, '80 California
>Soobs, all 81-82 models, and all 83-84 non 4wd, non California models have
>Electronic Control Carbs. These "duty solenoids" regulate the air/fuel ratio
>in response to sensor input.
>
>The units I have, (have one in my hand) bolt onto the intake with 2 6mm
>bolts each, stand 2.5 " +/- high, with 2 3/16" hose nipples on each, at
>roughly 15 degrees separation. Each has a 2 wire oval plug. I am unable to
>find any identifying marks or part numbers, but the coil section is roghly 1
>" in diameter, steel, with a square flange with 4 screws connecting it to
>the aluminum valve. Looks a little bit like a short, stocky, slightly
>mis-shapen injector with no tip.