Ok, lets do some math...
Gasoline is .0267lbs/in^3
So lets say we have 100" of fuel line.
Take the 3/8" diameter
So 3.1415 x .375"^2 x 100"x .0267lbs/in^3= 1.17 lbs mass
So at 1g of acceleration, 1.17lbs, is applied to the 3/8" fuel line area.
1.17lbs x .375"^2 x 3.1415=.5psi of pressure towards the rear of the vehicle.
Looking at the 1/2" fuel line calc...
So 3.1415 x .5"^2 x 100"x .0267lbs/in^3= 2.1 lbs mass
2.1lbs x .5^2 x 3.1415 = 1.65psi in the rear direction.
These rear direction forces cancel out the head pressure in the forward direction normally there.
1.65psi is a pretty good sized increase over .51psi
If the pump motor can barely meet the 6~7lbs of fuel pressure requirment, the 1/2" line PSI force during a 1g launch is a pretty significant jump..
It just depends on the pump then I guess. If the pump is marginal, or can't make much pressure over 6~7psi normally needed. The line diameter could be a factor.
Thoughts?...