I put an efi kit on the dart a month ago, and we put the nitrous kit back on. Efi runs at 45lbs nitrous needs low pressure around 6 lbs.
I have a holley 12-803 fuel pressure regulator that is good from 4-10lbs but it will not hold the pressure down from 45lbs to 6. The pressure starts low, but will slowly creep upward. I am assuming it cannot handle the 45lbs of constant pressure? Is there a regulator that I can use to hold 45lbs down to 5 or 6lbs? or do you think i just have a bad Holley regulator?

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Ryan Covalt
62 Plymouth Valiant Race Car 2170# 11.008 @ 117.65 MPH 1/4 Mile Best
72' Dart Swinger Street Car, 4 spd, 3330# 14.061 @96.58 1/4 mile Best

Do yourself a favor and run a second fuel line and make-up a seperate, low pressure fuel system, just for the N2O.
DD

You would need some kind of killer (high $$$) carb regulator for that. I agree with Doug...

Lou

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Home of Slant6-powered fun machines since 1988

Can you just run a bypass line back to the tank from the unused port on the regulator?

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Official Cookie and Mater Tormentor.

Lou/Doug. What is the reason for a separate fuel system? is it just insufficient fuel? I just installed a large (cant remember the exact size) electric fuel pump that I thought (or was hoping) would be more than sufficient to supply fuel to both?? I saw a regulator that was rated at 3-65psi, it was not cheap (around $100 from summit). It sounds like my current regulator is definitely not designed to do what i am trying to do. I would definitely rather not run a complete 2nd fuel system, but if thats what has to be done I will. I was just hoping a good regulator might fix it. Thanks for the help/advice.

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Ryan Covalt
62 Plymouth Valiant Race Car 2170# 11.008 @ 117.65 MPH 1/4 Mile Best
72' Dart Swinger Street Car, 4 spd, 3330# 14.061 @96.58 1/4 mile Best

It's more about fuel pressure control and consistant fuel flow.
As we now, the ratio of N2O to fuel is important and things get ugly... fast, if you get it wrong.
DD

What's wrong with sizing the N2O enrichment fuel jet(s) for 45 psi fuel pressure?

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Joshua

Slantzilla Is right the quickest/easiest fix is to run a return line from a second regulator and bleed off the extra pressure.
Will

OK, I don't really understand the setup on the car, or what you are trying to accomplish. Is EFI on the car now? If not, why did you take it off? You are trying to use the EFI pump to drive a carb and not richen N2O system separately?? Please clarify.

Zilla's plan could work too, if we are thinking about this right.

Lou

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Home of Slant6-powered fun machines since 1988

Ryan installed fuel injection. It looks like a carb with fuel inlets on each end. It came with a pressure reg to set the fuel to 40-45#. On one end of the fuel inlets is a 6AN fitting that is capped. We came off of that port and ran about 1 foot into the 2nd regulator, hoping to cut the pressure to 4-5# and go directly to the fuel solenoid for the nitrous. Since this is a dead end until the nitrous is on , the pressure just keeps building. I'm guessing that the fuel regulator is not designed for 100% lockup on a dead end system. It probably needs a small return line ran back to the tank.

Hope that makes sense?

Rick

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2 Mopars come with Spark plug tubes. One is a world class, racing machine. The other is a 426 CI. boat anchor!

12.70 @ 104.6

I'm guessing that would work too. I guess the manufacturer would have some kind of a conversion chart to tell you what you need?

Rick

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2 Mopars come with Spark plug tubes. One is a world class, racing machine. The other is a 426 CI. boat anchor!

12.70 @ 104.6

What kind of N2O system do you have?

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Joshua

Josh,

I think it is "Compucar" but Ryan will have to verify.

Rick

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2 Mopars come with Spark plug tubes. One is a world class, racing machine. The other is a 426 CI. boat anchor!

12.70 @ 104.6

Lou, The EFI kit I have is from professional products, it is similar to the fast efi kit, but is a more simple setup. The kit is on the car still, and needs 45lbs of pressure to run.

Josh, Nitrous kit is a compucar nitrous plate system. I think they use the same nitrous jet style that the NX system uses. Do you think I could get jets for the plate system to run 45lbs of pressure? If so that may be a good solution. Only problem is I just bought a brand new jet set for the kit with a wider range of jets for more adjustability. I could get new fuel jets though if that is an option.

Do you know of a regulator that can drop from 45psi to 6psi without a return line? I also realize that I may need to add another complete fuel system if I run too much nitrous, but I wont be running a lot of nitrous this year.

I am just hoping to get the nitrous hooked back up in time for mason dixon, but we are so busy at work I will not have time to run return lines or other fuel system components until after the race.

Thanks everyone for the help/ideas.

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Ryan Covalt
62 Plymouth Valiant Race Car 2170# 11.008 @ 117.65 MPH 1/4 Mile Best
72' Dart Swinger Street Car, 4 spd, 3330# 14.061 @96.58 1/4 mile Best

Google "nitrous jetting". There are a bunch of sites with tables on them. Just make sure that when the solenoid opens it maintains 45 psi or something may happen you never know what.

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Official Cookie and Mater Tormentor.