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What FP with wet n2o kit?

  • Thread starter Thread starter Marlboro_Man
  • Start date Start date May 14, 2006
M

Marlboro_Man

Member
Sep 30, 2005
437
1
18
Houston, TX
May 14, 2006
#1
  • May 14, 2006
  • #1
So what should i set my fuel pressure to? It is a "WET" kit. I have read anywhere from 40 to 50 psi but that was not mustang specific. If it helps I will be starting with a 50 shot and then working my way up to a 100 shot.

I have everything hooked up except a msd window switch, FP safety switch, micro switch, and relay. Once I have these things I will be ready to spray.

I was wanting to do some testing so I hooked up a button to the fuel sylenoid and then turned the fuel pressure to 48 psi vacuum line off. I took it for a drive and hit the button at 3k rpm's @ WOT to simulate spraying. I watched my fp gauge. It instantly dropped to like 30 psi for only a split second and then it went right up to 48 and stayed there. Is this normal for it to drop for less than 1 second and then jump back to where it should be?


I posted this in the "power adders" forum as well but since there isn't very much traffic in there i thought i would post it here as well.

:SNSign:
 

N8Miller

I need NOS....make it 2 of the big ones
Founding Member
Jul 26, 2000
2,661
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0
Kingston, PA, USA
May 14, 2006
#2
  • May 14, 2006
  • #2
I cant comment on the slight drop in FP, but mine went right up when i had it. as for your fuel pump, a 190 or 255 will do the trick!
 
M

Marlboro_Man

Member
Sep 30, 2005
437
1
18
Houston, TX
May 14, 2006
#3
  • May 14, 2006
  • #3
N8Miller said:
I cant comment on the slight drop in FP, but mine went right up when i had it. as for your fuel pump, a 190 or 255 will do the trick!
Click to expand...
It already has a 255 in it. I was asking what should i set the Fuel Pressure at?
 

N8Miller

I need NOS....make it 2 of the big ones
Founding Member
Jul 26, 2000
2,661
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0
Kingston, PA, USA
May 14, 2006
#4
  • May 14, 2006
  • #4
Marlboro_Man said:
It already has a 255 in it. I was asking what should i set the Fuel Pressure at?
Click to expand...

my bad, i read it wrong. you should just be running your normal FP for when your not on the bottle, but when you hit the button, it should nearly double.
 

Rick 91GT

Mustang Master
Nov 29, 1999
9,692
95
99
PA
May 14, 2006
#5
  • May 14, 2006
  • #5
Set it for what ever the kit tells you to, the jets are sized based on the FP and different brands use different pressures.
 
M

Marlboro_Man

Member
Sep 30, 2005
437
1
18
Houston, TX
May 14, 2006
#6
  • May 14, 2006
  • #6
N8Miller said:
my bad, i read it wrong. you should just be running your normal FP for when your not on the bottle, but when you hit the button, it should nearly double.
Click to expand...


So i should run it at 40 psi (WOT) like normal and when i hit the button your saying it should jump to 70-80 psi? Hows that?
 
M

Marlboro_Man

Member
Sep 30, 2005
437
1
18
Houston, TX
May 14, 2006
#7
  • May 14, 2006
  • #7
Rick 91GT said:
Set it for what ever the kit tells you to, the jets are sized based on the FP and different brands use different pressures.
Click to expand...
Well there wasn't any instuctions with the kit because it was second hand.

However on the coldfusion website their jet calculator lets you choose what fuel pressure you want to run and it will tell you what size fuel jet to use. It does say that "most efi systems use 38-45 psi" .
 

N8Miller

I need NOS....make it 2 of the big ones
Founding Member
Jul 26, 2000
2,661
0
0
Kingston, PA, USA
May 14, 2006
#8
  • May 14, 2006
  • #8
Marlboro_Man said:
So i should run it at 40 psi (WOT) like normal and when i hit the button your saying it should jump to 70-80 psi? Hows that?
Click to expand...

from what i understand, yes.
 
M

Marlboro_Man

Member
Sep 30, 2005
437
1
18
Houston, TX
May 14, 2006
#9
  • May 14, 2006
  • #9
N8Miller said:
from what i understand, yes.
Click to expand...

I'm not knocking what your saying (typing lol) and i really apreciate the help. However i have never heard of this and it doesn't seem to make sense to me how the fuel pressure would rise above what the fuel pressure regulator is set at. Can you explain? or can anyone else confirm this?
 
M

Marlboro_Man

Member
Sep 30, 2005
437
1
18
Houston, TX
May 14, 2006
#10
  • May 14, 2006
  • #10
ttt
 
M

Marlboro_Man

Member
Sep 30, 2005
437
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18
Houston, TX
May 15, 2006
#11
  • May 15, 2006
  • #11
ttt
 
M

Marlboro_Man

Member
Sep 30, 2005
437
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Houston, TX
May 16, 2006
#12
  • May 16, 2006
  • #12
ttt
 

Curse

Member
Apr 8, 2004
791
2
16
El Paso, TX
May 16, 2006
#13
  • May 16, 2006
  • #13
I believe N8Miller is thinking about a dry kit, which uses some nitrous to increase fuel pressure in order to get the proper mixture.

Rick gave you your answer. I would call customer service and see what they say. Your fuel pressure will determine what fuel jets to use. My kit had different jets for different pressures. At 40 psi for a 75 shot my fuel jet size would be 24, at 50 psi the fuel jet would be 22. Your kit might be different. Good luck.
 

352Ford2

New Member
Oct 12, 2005
393
0
0
Seattle,WA
May 16, 2006
#14
  • May 16, 2006
  • #14
only dry kits kick up your fuel pressure, what is the make and modle of your kit? you can get jet cards on the compnays website usaly. One thing to note, most online jet calcs are usaly not optimiesed for the higher fuel pressures of FI.

this one is pretty good:

http://www.phasechangeracing.com/nitrous/N2OCalc.N2OCalc.html

Keep in mind NOS is well known for having very conservitive tunes.
it is usaly a good idea to flow them, if you are woried about it.
 
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