Back to my fuel vapor in the lines.

[55 Tony]

Hmm, if I did that correctly, guessing a little high at 500HP, I get 41 gph and the pump is supposed to be good for 67 gph at 7 psi.

[chevynut]

the pump is supposed to be good for 67 gph at 7 psi.

I don't see where you get that. The graph from Holley shows about 50 GPM at 5 PSI.

[chevynut]

Here's Holley's graph for their Blue pump:

[55 Tony]

So do you think the pump is faulty or rated wrong? Or have I screwed up the calculation?

[55 Tony]

I don't see where you get that. The graph from Holley shows about 50 GPM at 5 PSI.

https://www.summitracing.com/parts/hly-12-801-1

[chevynut]

Your calculations are correct (I get 41.67) and the pump should put out around 5PSI there according to the graph. It looks to me like you should have used the blue pump, if their graphs are correct and you want 7 PSI.

[55 Tony]

Oop's, summit says 67 at 5 psi, not 7 psi. Still I'm going down to about 3.5 psi.

[55 Tony]

Your calculations are correct (I get 41.67) and the pump should put out around 5PSI there according to the graph. It looks to me like you should have used the blue pump, if their graphs are correct and you want 7 PSI.

I think 5psi would be fine, but it's going down to 3.5psi

[chevynut]

I think 5psi would be fine, but it's going down to 3.5psi

If you're measuring that at the engine, you have pressure drop in the lines between the pump and the engine.

[55 Tony]

If you're measuring that at the engine, you have pressure drop in the lines between the pump and the engine.

I'm measuring it at the engine but before the two filters (one clear to see bubbles, and one with the bypass, just temporary). I don't want to get into a war again, but I really don't think it's loosing that much in the line, but anything is possible.