Hot Rod Forum banner

How does a bypass regulator work?

15019 Views 8 Replies 5 Participants Last post by  WaylonOKC
Gents; I'm running a warmed over 350 Chevy in a 4-speed Camaro with 3.70 gears and a 750 CFM Q-jet and now I want to install a 100 HP shot of nitrous. From my research it looks like the Q-jet takes about 5psi to run and the nitrous also needs about 5psi to keep from hurting a piston. The Holley Blue pump should fit the bill because it runs about 14 psi @ 110 GPH. My question to you knowledgable gents is what kind of regulator should I install? I'm leaning towards a bypass regulator but I really don't know exactly how it operates. If using the bypass style regulator I adjust the pressure down to 5psi so the q-jet runs correctly and then hit the nitrous button will the bypass feature be closed off to the fuel return line or will fuel still flow in the return line resulting in less fuel to the carb and nitrous at WOT? If that is the case then a "dead head" regulator is the way to go for a nitrous equipped my thinking way off?
1 - 9 of 9 Posts
The bypass regulator opens up to allow excess fuel volume to return to the tank so as not to exceed the set pressure. As your nitrous and carb demand more fuel the bypass regulator will reduce the amount of bypass fuel going to the return line and more volume goes to the 'load' - providing that the pump produces more than the required volume.

The Holley pump is probably fine for the job. It is designed to work with a dead head type of regulator which is likely simpler to plumb in and cheaper. Both would work though.
I did read that the Holley red and blue pumps have an internal bypass (spring and ball like an oil pump) in them that might conflict with a bypass regulator but the post didn't go further than that. I guess the best thing to do is to install a fuel pressure gauge (electric) in the auto and monitor the pressure while I hit the nitrous button to see what happens to the pressure.
A bypass reg will work well for you it regulates pressure AFTER the carb and nitrous are supplied.Therefore no restrictions before the carb ensuring proper volume of fuel which is what we worry about.As far as conficting with the internal bypass no problem it will never open because the pressure will not climb to the preset 14 psi.Also using a bypass reg keeps the pump and fuel cooler by constantly recirculating it back to the tank giving longer pump life.
barnym17: Would mind telling me how this is plumbed? The way I would presently run this setup is...Holley pump to bypass regulator then from the bypass regulator to a teed off 3/8th inch hose to the carb and the nitrous selenoid. The fuel return line runs from the bottom of the regulator to the fuel tank. Is your system plumbed with the regulator AFTER the carb and the nitrous selenoid?
The set up I use I got from Mike Ulrichs book on Holley carbs go's like this: Please see my next post this one was incorrect.
I have an inline electric pump in my 59.

from the tank to the front filter---to the carb (where it is teed off) back to the bypass regulator---into the tank.

My regulator is also mounted close to the tank in the rear of the car.
Works just fine----but have to crawl under the car to make an adjustment or check pressure.

I did not want a visible gage or regulator in the engine compartment and my return line is kind of invisible---have to be looking for it to see it.
Guys I have to correct myself, I gave the wrong plumbing instructions it goes like this.1.Main line from pump will be teed with one branch to the carb ,another plumbed with gauge, 3rd leg will go to the outlet port(as marked on reg) of the regulator.The other port marked out is plugged.Return line runs from the port marked in back to the tank.I doubled checked when I got home and found my boo boo.
Regulators have been a touchy subject for me lately. I upgraded my fuel system because I'm going to be running 2 stages of nitrous (250 fogger off the line, 100 plate at 2nd gear). Before the addition of the fogger, I always had one dead-head regulator for the carb set at about 6.5 psi and another dead-head regulator for the nitrous plate set at 4.5 psi (seperate pumps).

With the addition of the fogger, I added a fuel distribution block and used the two dead-head regulators on that since the pump and feed line are plenty big (currently only working with carb and fogger and will setup 2nd stage when that's working). I never use to have problems with pressure creep and now all of a sudden I do. So I've been looking at the different regulators. A bypass regulator goes "tank - pump - carb/solenoid - bypass - tank". This is suppose to give you better fuel delivery, but the bypass should be close to the carb/solenoid so you need to find a place and method to mount it.

I just spent $300 on the current upgrade and hate to fork over a bunch more money to replumb everything so if anyone has any suggestions, I'm all ears.
See less See more
1 - 9 of 9 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.