kevmor99

I checked the nitrous co.'s and couldn't find out exactly how a dry system makes the fuel pressure regulator increase the pressure in the fuel rails. Also, wouldn't a dry be safer as long as your injectors are up to the task? Is the stock LT1's good for 100 shot? How would I be able to tell if my fuel pump can flow enough (It's custom, a '95 F-150 pump)?

jcolez28

I think the dry kits usually come with an inline fuel pump that increases pressure when activated. I guess the pressure is still within the stock regulator limits. Then just pray the injectors dont lock. Any reason your not going with a wet kit?

slimdawson

Zex uses a line that goes to the fpr and uses nitrous pressure to force the fpr to increase fuel psi. I don't know how other companies do it. I still don't see that working for an fbody as the fpr cannot increase beyond 48psi or whatever factory limit(or so I thought).

I don't know how much flow that pump is good for but I shot a 100 to mine dry on the stock pump with no problems.

Injuneer

The fuel pressure regulator is not limited to 48psi. The NOS 5176 dry kit uses pressure from the nitrous line (regulated by a blue pressure regulator) to apply a pressure to the vacuum connection on the fuel pressure regulator, and force the pressure as high as 85-90psi. The kit also includes an inline booster pump to insure the fuel system is capable of supplying the required flow volume at the required pressure. I ran the NOS 5176 dry kit for 5 years, on the stock engine, at 125-150HP. No problems.

You need to change the injectors, because the stock RP ball/seat injectors do not like to operate at 90psi. The Bosch/SVO/FMS pintle-type will work fine at that pressure. You also need to change the plugs to a non-platinum plug, with a better ground electrode design. The stock AC/Delco plugs are about the worst possible plug for nitrous.

slimdawson

Yeah, I wasn't sure on the fpr thing. I think I read it in my ATI install book. I also assumed that because of the need for a fmu for my setup. Have any idea why an fmu would be needed if the stock fpr can increase to 90 psi or so?

Darrells93TA

its not that the stock FPR can increase to 90psi, the dry kit forces pressure on it, instead of 0' vaccum (normal WOT) it artificially raises your fuel pressure.

ive never owned a boosted car, but my understanding is an FMU works the same way, it artificially raises FP, but under boost.

i have a set of 30# Accel injectors, an MSD inline pump, stock intank pump, and have used a 175 shot at times.

kevmor99

So you adjust the fuel jet by how much you get from the nitrous pressure increasing the FPR?

Does this make it use less fuel when the bottle pressure is lower?

Darrells93TA

there's a jet that goes in a T off of your FPR. one line goes to the blue pressure solenoid that is right before your nitrous solenoid. line 2 goes to the FPR, and line 3 goes to your intake manifold vaccum line. for example, if you use a .80F jet, that allows more pressure to bleed off and puts less pressure on the FPR, thus, you get minimal raise in FP. if you use a .50F jet, it puts more pressure in the vaccum line to the FPR, thus raising FP more.

the fuel jet is backwords on the dry kit, the smaller the jet, the more FP, the more richer. the bigger the jet, the less FP, runs leaner.

its kinda hard to understand, thats as simple as i can type it though, so bear with me.

my understanding is that bottle pressure doesnt effect the A.F.R. much at all. thats why dry kits are consider "safe". i dont consider any nitrous kit safe though.