whats the normal fuel pressure of a lt1 engine and if you added a fuel booster from nos how much should it boost it to and is 250 a safe shot with a fuel booster on a forged engine?

 

Stock pressure is 41-47 psi at idle with the vacuum hose to the regulator removed.

 

Adding an inline fuel pump, like the one sold by NOS, will not raise your fuel pressure all by itself. The inline booster pump is required in the NOS dry system, which boosts the fuel pressure to 85-90psi, by applying a slipstream of nitrous (regulated to lower pressure by the blue pressure regulator in the kit) to the vacuum connection on the fuel pressure regulator. When you aren't actually spraying, the fuel pressure regulator holds the fuel pressure at factory rating, even though you have added the inline booster pump.

 

If the booster pump is applying nitrous to the vacuum nipple on the fpr is it "tricking" your factory fpr into increasing pressure? So is your existing fpr really the one increasing the fuel pressure?

 

The diaphragm on the fuel pressure regulator is intended to compensate for the intake manifold vacuum, to keep the fuel differential pressure (rail minus MAP) at a constant value. If you apply a pressure to that point, it presses the diaphragm/valve closed, reduces the return to the tank, and increases the fuel pressure proportional to the pressure applied to the regulator. Nothing is being "tricked"..... and the fuel pressure regulator is controlling the rail pressure.

 

since the orig. poster's question has been answered, maybe this isn't thread jacking? But, why does the LT1 use the fpr to add fuel pressure w/ dry nitrous set up vs. an LS1 using the readings of the MAF? I mean, an LT1 does have a MAF. Why the different method?

 

simple answer....because the LS1 pcm is better at controlling the fuel enrichment.