I can't tell what the unpredictable will be. That's why I qualified my numbers to the observed data, which is quite limited and more observation is required. Those observations indicated that most of the variation in pressure is predictable.Bill,
How can you say what the unpredictable pressure variation is?
If you are seeing 1.5psi static error, the error is going to be at least that since the pumping variation and fluid viscosity changes will only make it worse at lower temps. The back pressure will also drop as the gasoline heats up.
The back pressure will be cross-sectional area an length dependent barring kinks and bad bends.
The pressure is going to be low (by EFI standards) so it doesnt much matter what the material is so long as it is compatible with the fuel.
Thinwall stainless is often used, I've seen thinwall aluminum too but I would worry about corrosion with all the ethanol they are putting in the fuel.
EDIT:
Looked back at the thread and saw that Bill was seeing 1.5psi static error not 1.75.
Even still that is a huge back pressure compared to what it should be.
I thought the idea of the pressure gauge was to determine the as yet unknown pressure variation, both predictable and non-predictable.
I am not familiar with the term "static error". What does that mean?
Bill