CRX 18

"One will be plummed into the back side of the fuel pressure regulator and due to the pressure from the nitrous bottle will increase the fuel through the regulator diaphram."

Thanks. I understand this part but I dont understand how it forces the fuel. Nitrous does not physically flow to the FP regulator, because that connection is low pressure tubing with zip ties on the ends. The pressure from the nitrous opens a regulator at the solenoids (part of the kit), but how this regulator works I am not sure. Unless the pressure drop from the nitrous flowing past it at a high velocity causes a vacuum, my only guess is that the pressure from the nitrous opens a valve on the reulator at the solenoids that then lets the cars FP regulator (bypassed to it) see 1 ATM (or close to it based on what jet you have installed in the bypass) of pressure there by giving full FP the cars FP regulator is capable of. I wasn't sure if there was any way the system makes more pressure?
Thanks for the discussion

cbender

You might simply call the company that makes your NOS kit and put some of these questions to them. Customer support ought to be part of the sale. In any case, good luck.

CB

blues2k3

"Unless the pressure drop from the nitrous flowing past it at a high velocity causes a vacuum, my only guess is that the pressure from the nitrous opens a valve on the reulator at the solenoids that then lets the cars FP regulator (bypassed to it) see 1 ATM (or close to it based on what jet you have installed in the bypass) of pressure there by giving full FP the cars FP regulator is capable of"...

to the best of my knowledge this is what happens.

CRX 18

Ok, just in case anyone is interested. I called NOS again. I had done this before but got one of the less than knowlegable technicians that says "yep that part number will fit your car" Today with some prodding, and 2 technicians, I was more successful. It turns out I was wrong and nitrous does physically flow from the regulator at the solenoids trough the low pressure lines to the stock FP regulator and directly puts pressure on the diaphragm increasing FP. The vacuum line going to the manifold works as a bypass in this low pressure system for excess nitrous/pressure to flow back into the manifold. FP can be adjusted with a variable jets in this bypass to the manifold. The regulator at the solenoids only lets some nitrous through to the tubes running to the vacuum line and stock FP regulator, which is what makes it a much lower pressure system.
Thanks for the discussion

blues2k3

thanks Chip, I also spoke to a friend who has a dry system and he explained to me that there are indeed two jets just like you said...he also stated the stock fpr leaked due to the increase in fuel pressure.

cbender

FYI, but I had a stock fuel pressure regulator in combination with a rising rate FMU (before I ditched all the kludge approach and got the EMS), which generated a LOT of fuel pressure at the rail, and I never had any leaking problems, so it's not necessarily true that the stock regulator will leak under higher pressures. Just a thought...

Good luck, Blue,
CB

jimknapp

Hey CRX,

If you are messing with NOS at all, or any mods that are going to be producing 300 rwhp, I'd STRONGLY suggest you go to an after market adjustable FP regulator. Given all the other money you've spent they are not that expensive. My experience with an after market fuel pump and a stock regulator was not good. It seemed like it couldn't pass enough fuel back to the tank and I was running with "the choke out" the whole time.

One other suggestion if I may. When working with fuel systems, use the BEST fuel line equipment available. Experience (two cars burnt to the ground on two separate occasions, a night in the hospital on a third and a friend burned to death on another occasion) has taught me that fuel is to be HIGHLY respected. If you are disrespectful enough to use rubber lines and hose clamps, at least use stainless clamps and don't over tighten. Screw it down until it's just even with the surrounding rubber.

FYI every inch of my fuel system is stainless steel lines or Earls AN flare fittings. Even the vent lines.

All the best,

Jim