Nitrous fuel supply ??? - Hot Rod Forum : Hotrodders Bulletin Board
Hotrodders.com -- Hot Rod Forum



Register FAQ Search Today's Posts Unanswered Posts Auto Escrow Insurance Auto Loans
Hot Rod Forum : Hotrodders Bulletin Board > Tech Help> Engine
User Name
Password
lost password?   |   register now

Reply
 
LinkBack Thread Tools
  #1 (permalink)  
Old 05-25-2007, 10:07 PM
67 Deuce 4 Me's Avatar
Bowtie or Die!
 
Last photo:
Join Date: Dec 2004
Location: TN
Age: 43
Posts: 637
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Nitrous fuel supply ???

Im having a problem with my fuel supply on my N20 solenoid. I have a 388 approx 450+ hp with a 100 shot plate kit on it. I have a pressure safety switch in my fuel line just before the fuel solenoid. Im running the engine with a maniacal fuel pump. Its a very big pump! Holley 130 gph with a regulator set @ 7.5 psi. I used a test light to confirm that my switch was going open under WOT with nitrous armed. System would come on for less than 2 seconds and cut off. When Im just on motor the switch will remain closed under WOT. New tank, 3/8 lines and tank unit. This is the second pump, same problem, this pump just keeps the pressure up a little longer before switch opens. Car runs 11.80s on motor. According to NOS requirements I don't even need a pump upgrade for 100 shot. And my 130 gph Holley produces more fuel output than a blue pump. But thats volume, I don't know if the pressure would be the same on a blue pump or not under WOT. I hate the noise of an elec pump. Is my switch mounted in the wrong place? Do I need to move it to before the regulator? Or is there no choice but an electric pump? NOS website has zilch on this subject. Thanks.....

    Advertisement
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 05-26-2007, 12:04 AM
DoubleVision's Avatar
Not Considered a Senior Member
 
Last photo:
Join Date: Oct 2002
Location: Heart Of Dixie
Age: 40
Posts: 10,658
Wiki Edits: 0

Thanks: 15
Thanked 60 Times in 57 Posts
Volume without pressure is useless.
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 05-26-2007, 07:50 AM
RPM's Avatar
RPM RPM is offline
World Class ASE tech
 
Last photo:
Join Date: Nov 2004
Location: Hills of TN
Age: 64
Posts: 704
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
temporaly mount a fuel pressure gauge that you can see from in side the car and go try it and see what that gauge does. This will tell you if the pressure is dropping or you have a bad switch.
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 05-26-2007, 08:17 AM
ZipZ28's Avatar
Nitrous Junkie
 

Last journal entry: Reflooring The Bed Pt. 2
Last photo:
Join Date: Jan 2005
Location: Near Bridgeport, Tx.
Age: 63
Posts: 90
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
It sounds like you have plenty of fuel pump there, the problem is probably with the fuel pressure safety switch being set at a higher pressure than what your system requires, like for an injected car application perhaps? You can test this by just putting a jumper across the 2 terminals on the switch and trying it again. If it stays activated you'll know where the gremlin is I dumped my fpss years ago after trying to get it to work reliably for several weekends, IMO a filter on the nitrous feed line is a neccissity tho',,,

Hope that helps
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 05-26-2007, 09:49 AM
Member
 
Join Date: Dec 2004
Location: Madison, WI
Posts: 1,885
Wiki Edits: 0

Thanks: 0
Thanked 1 Time in 1 Post
The pressure switch should have a small rubber cover in the center of it. They can and need to be fine tuned. In your nitrous instructions it should have mentioned this as well as what the preset was on the switch.

Running though for 2 seconds and then opening tells me you have a fuel pressure drop and as mentioned prior, you need to install a gauge to see what is happening. My guess is your current fuel line is too small.
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 05-26-2007, 11:35 AM
F-BIRD'88's Avatar
Yada Yada Yada
 
Last photo:
Join Date: Oct 2005
Location: Ontario, Canada
Posts: 9,284
Wiki Edits: 0

Thanks: 5
Thanked 399 Times in 393 Posts
Ya need to get beyond your fear/lothing of electric fuel pumps.
A Carter 4594 7psi 72 GPH pump is good for at least a 250-300 hp shot. At the working pressure (5 to 6psi). Under $100. OEM reliability. Low noise when mounted right.
I would install a small 1 to 3 gallon fuel cell (Summit, JAZ) under hood to supply the nitrous plate using this pump and a regulator. That way your not working against G force on launch and exposing the fuel to a lot of heat.

Engine mounted mechanical pumps (with rear mounted fuel tanks) while capable of supplying lots of volume and pressure work well on applications where the G force of acceleration is not too high (boats, circle track, road racing) and tend to not be exposed to heat soak.
Drag racing exposes the mechanical pump and the feed side fuel lines to a lot of heat (while sitting in the stageing lanes and high G force during launch. This causes a pressure actually a partial vacuum drop in the feed side which combined with the heat ( exhaust, engine, pavement) creates in line boiling (vapour lock).
Your carb, with its fuel bowls can get past this momentary fuel starvation cause the bowls store fuel (acts like a capacitor or serge tank) but the nitrous system cannot tolerate a fuel pressure/delivery drop even if momentary.

Some things that will help your mechanical pump work much better.
Get a heat isolating engine mount plate/gasket. www.sealsit.com
Make the feed side fuel line larger than the pressure side outlet fuel line. Should be 1/2" for an 11sec car.
Move all the fuel lines away from heat . Wrap them if near a heat source.
Consider a front mounted fuel tank.
Use a return style fuel regulator and a fuel return line to the tank that way the fuel pump does not keep bypassing/recycling the same fuel internally overheating it.
Use only a screen filter on the feed side and a high capacity or two high capacity fuel filters on the pressure side near the carb.
You want to avoid any pressure drops in the feed side and the outlet side of the pump. (right angled pipe fittings, cheap fuel filters, restrictive fittings)
Any pressure drop along the flow path to the carb will cause/allow a fuel boiling point especially on hot fuel.
The boiling point of any liquid (water,fuel etc) is determined by the acting pressure. Low pressure= lower boiling point high pressure= high boiling point.
A mechanical pump cannot move bubbles especially in the feed side. Does not take a lot of heat/reduced pressure to get bubbles in the fuel line or at a fuel fitting.
Reply With Quote Quick reply to this message
  #7 (permalink)  
Old 05-26-2007, 04:29 PM
67 Deuce 4 Me's Avatar
Bowtie or Die!
 
Last photo:
Join Date: Dec 2004
Location: TN
Age: 43
Posts: 637
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Thanks for all the help guys! I will take all this into consideration and figure this out. I m going to install a fuel pressure gauge at my n2o fuel solenoid and see what the psi is under a load. If the pressure is dropping, I will install a separate fuel system for the n20.
Reply With Quote Quick reply to this message
  #8 (permalink)  
Old 11-11-2007, 10:30 AM
Registered User
 
Join Date: Jun 2007
Location: plano texas
Posts: 374
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
same problem

I have about the same setup. I think what is happening is one of two things. The presure will drop for a few seconds when the o2 is on then go back up. The other thing is at 6000 rpm the pump will only put out 4.5 psi. What did you do? I would like to go to an electric pump but do not wont it to quit one day. I have looked at the blue pump but it might get to hot on the street. I have also looked at the 125hp but it only puts out 7psi and I have allot of money tied up in a reg and lines, so I don't want to eliminate the reg.
Reply With Quote Quick reply to this message

Recent Engine posts with photos

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Hot Rod Forum : Hotrodders Bulletin Board forums, you must first register.
Please enter your desired user name (usually not your first and last name), your email address and other required details in the form below.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Helper electric fuel pump to aid my mechanical?? hotrodf1 Engine 4 06-06-2006 08:39 PM
Fuel Filter Location leejoy Engine 7 05-04-2006 09:50 AM
454, Long Rods, and Nitrous, oh my 83Silverado Engine 1 03-31-2006 10:26 AM
Designing the fuel system 66Caprice Engine 9 05-12-2005 03:57 PM
Holley carb experts? Others? Why is my truck's fuel bowl being sucked dry? MuscleTruck Engine 5 05-23-2003 01:36 AM


All times are GMT -6. The time now is 07:43 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
Copyright Hotrodders.com 1999 - 2012. All Rights Reserved.