On 1/23/05 8:16 AM, "Ed Anderson" <eanderson@carolina.rr.com> wrote:

Some excellent observations, Barry.
 
Regarding the workings at altitude - there would certainly be a different fuel flow required at WOT at 4000 vs WOT at 12000 assuming NA engine.  A manifold referenced fuel pressure regulator should maintain a constant pressure differential between the pressure in the fuel rail and that in the manifold therefore insuring that the same amount of fuel in injected for the same injector-on time duration (pulse).  So as you increased altitude(and decreased manifold pressure at WOT) I would expect to see the fuel pressure drop correspondingly to maintain the differential.  Or if turbocharged, I would expect to see the fuel pressure increase as the boost goes up.
 
My fuel map has always been a bit rich at the lower rpm range (idle), so it could be that when manifold pressure is low (such as at idle) that the pressure differential is much larger meaning more fuel flows per millisecond of injector on time than at higher manifold pressure.
A  different make of pressure regulator is likely the only way I will know for certain.
 
Ed A
 
 

Hi Ed, here is the one I’m using from Summit Racing Part#AEI-13109.
Bulent