Wow, is it that low? I'm tempted to go drop a battery in my WS6 just to see that since I would expect that the mild cam, 117LSA, big timing advance at idle from the PCM and high compression would all add up to a much higher vacuum.

Where are you getting the 205's? Seems like you should be getting them for a decent price if you're using them instead of the walbros…

Huh… must be nice… I think that I've broken just about everything I've touched in the last month.

 

Once again, a conflict in "units".... 9.5-10"Hg MAP = 20-21.5"Hg vacuum..... not particularly low for a "stock" cam.

My original Bosch 205LPH came as part of my NOS 5176 dry kit, so I already had it when I started the stroker buildup. Second Street swears by the Bosch as the most reliable pump, so they simply picked up another one to match what I already had. They aren't cheap.... I think it was around $250. But "cheap" and "fuel systems" are terms that don't mix well. .

 

ahhhh... that makes sense I guess. Much easier to make a pressure gauge that references atmospheric pressure as 0, than it is to have it reference an absolute vacume instead.

The confusion was that the LT1 PCM uses kPa for manifold pressure... on an absolute scale. So when the manual refers to 43.5 psi differential, I was under the impression that it refered to 43.5 psi more than the manifold pressure. Guess that makes sense with the older terminology using vacume measurements... although it sure throws a wrench into the idea of going metric/absolute in the computer design.

So the fuel rails are measured at PSIG... the same way tire air is. Kinda weird considering the manifold is measured absolute. Thanks for the break down... makes more sense now.

so at WOT, the highest a stock LT1 (or any 3 bar system) should experience is 43.5 psiG in the fuel rails (~60psiA)... any most likely, any references to pump pressures are in psiG?

 

Wow with all the INHg and IN psi....I'm feeling like I'm back in thermo and fluid power all over again

Well I just picked up a Bosch 044 pump from LS1 Speed since they have them on sale this month. I'll give one pump a shot and see how it goes. If one doesn't do it...then a second one in parrallel shouldn't be to hard to add to the system. I'll hopefully have pics, lists, and specs when she'll all finished up this spring.