Plan on running big shot----few questions
10-20-2008, 12:10 PM
#1
Plan on running big shot----few questions
Ok right now im running the nx wet kit with a 75 shot jet. I like it a lot but would like to go higher. I was planning on getting the walbro 255 fuel pump and adjustable fpr. My question is what my fuel pressure should be for running a 100+ shot and how i would adjust it so i know the first time i spray a higher shot i won't blow it up. any input would be greatly appreciated. Thanks guys
10-20-2008, 12:40 PM
#2
Stock fuel pressure. With Nitrous Express, you adjust the size of the fuel nozzle, not your fuel pressure. Dry kits must adjust the fuel pressure. That is a benifit of the wet kit, keeps your fuel pressure at a safe level.
Nitrous Express or members here should be able to recommend a fuel jet size for your 100 shot. You will need to check your AFR's and your plugs and adjust from there. From what I have seen from Nitrous Express, they are usually pretty close.
Nitrous Express or members here should be able to recommend a fuel jet size for your 100 shot. You will need to check your AFR's and your plugs and adjust from there. From what I have seen from Nitrous Express, they are usually pretty close.
10-20-2008, 01:57 PM
#3
Stock fuel pressure. With Nitrous Express, you adjust the size of the fuel nozzle, not your fuel pressure. Dry kits must adjust the fuel pressure. That is a benifit of the wet kit, keeps your fuel pressure at a safe level.
Nitrous Express or members here should be able to recommend a fuel jet size for your 100 shot. You will need to check your AFR's and your plugs and adjust from there. From what I have seen from Nitrous Express, they are usually pretty close.
Nitrous Express or members here should be able to recommend a fuel jet size for your 100 shot. You will need to check your AFR's and your plugs and adjust from there. From what I have seen from Nitrous Express, they are usually pretty close.
EDIT 7:15 PM. I just looked up the old Jime-recommended 100-shot jets and they are N2O=52 Fuel=31 ...
.
Last edited by grey99max; 10-20-2008 at 05:16 PM.
10-21-2008, 07:41 AM
#5
^ ^ ^ what he said.... update your plugs, use race gas for safety, a 300ZXTT fuel filter for the volume, a change of underwear, and 100-shot jets - call NX and ask..... jet sizes depend on the hot bottle pressure and what your fuel pressure is set to - you do have gauges for both, right? NX expects 43 psi for most imports..
EDIT 7:15 PM. I just looked up the old Jime-recommended 100-shot jets and they are N2O=52 Fuel=31 ...
.
EDIT 7:15 PM. I just looked up the old Jime-recommended 100-shot jets and they are N2O=52 Fuel=31 ...
.
Now I'm confused. Id upgrade regardless. Never know when you might go F/I.
10-21-2008, 10:15 AM
#10
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Join Date: Oct 2006
Posts: 6
Isn't fuel pressure and fuel flow directly proportional. If you increase one, the other must as well. Any engineer knows that ρ a v = ρ a v. ρ = density a = area of opening v = velocity. It is safe to say that we can replace v with fuel flow, and ρ with pressure since in this case density and pressure are proportional. If we keep a (area, the opening) the same, for both sides, and increase pressure, the velocity must also increase. If you increase pressure, then velocity must also increase. Dunno if this helps clarify anything for anyone, but hope it does.
10-21-2008, 11:04 AM
#11
10-21-2008, 11:15 AM
#12
Isn't fuel pressure and fuel flow directly proportional. If you increase one, the other must as well. Any engineer knows that ρ a v = ρ a v. ρ = density a = area of opening v = velocity. It is safe to say that we can replace v with fuel flow, and ρ with pressure since in this case density and pressure are proportional. If we keep a (area, the opening) the same, for both sides, and increase pressure, the velocity must also increase. If you increase pressure, then velocity must also increase. Dunno if this helps clarify anything for anyone, but hope it does.
Last edited by grey99max; 10-21-2008 at 08:35 PM.
10-21-2008, 01:30 PM
#13
I was saying that the stock pump is going to be hard pressed to provide enough fuel volume to maintain proper fuel pressure at the requirements of a 100 shot of nitrous. 255lph pumps are cheap, $85 is better than a $500 motor and the time to replace it.
10-21-2008, 01:33 PM
#14
Isn't fuel pressure and fuel flow directly proportional. If you increase one, the other must as well. Any engineer knows that ρ a v = ρ a v. ρ = density a = area of opening v = velocity. It is safe to say that we can replace v with fuel flow, and ρ with pressure since in this case density and pressure are proportional. If we keep a (area, the opening) the same, for both sides, and increase pressure, the velocity must also increase. If you increase pressure, then velocity must also increase. Dunno if this helps clarify anything for anyone, but hope it does.
10-21-2008, 04:54 PM
#15
when once I ran a 85shot and confirmed with a incabin fuel psi gauge that the stock pump was not able to maintain psi at high rpms
when I would 1st hit the nitrous psi would go up to 50psi then slowly taper off so I got a 255 and never had that problem again
when I would 1st hit the nitrous psi would go up to 50psi then slowly taper off so I got a 255 and never had that problem again
10-23-2008, 08:58 PM
#17
For a piece of mind....I have the hp high pressure pump part#GSS342 hp
http://forums.maxima.org/group-deals...hipping-2.html
http://forums.maxima.org/group-deals...hipping-2.html
10-24-2008, 12:04 PM
#18
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iTrader: (7)
Join Date: Jan 2008
Location: Greensboro, NC
Posts: 3,468
There's alot of misunderstanding about why you need a bigger fuel pump in this thread.
Consider it this way. The stock pump can easily keep the pressure needed to run the engine stock. The way a wet shot of nitrous works, it pulls fuel from the fuel line that goes to your injectors and puts it into the intake.
The fuel pump must STILL keep up pressure while supplying both the injectors AND the nitrous fuel solenoid. A bigger pump can push the extra fuel, the stock pump won't be able to keep up with the increased total fuel requirements.
Consider it this way. The stock pump can easily keep the pressure needed to run the engine stock. The way a wet shot of nitrous works, it pulls fuel from the fuel line that goes to your injectors and puts it into the intake.
The fuel pump must STILL keep up pressure while supplying both the injectors AND the nitrous fuel solenoid. A bigger pump can push the extra fuel, the stock pump won't be able to keep up with the increased total fuel requirements.
10-28-2008, 12:57 AM
#20
umm well so far so good..compression is still perfect but the only thing is that i have my nitrous stop at 6000rpm before the trans shifts as to not add that much more stress on it but after it shifts into second gear the afr spikes to like 16.0+. Could this be contributed to the fuel pressure? if i let out of it and get back in it it will go back down to normal...(12.0-12.4)
11-11-2008, 08:20 AM
#22
I use the MSD 8969 RPM switch for several things, and when you wire it as a nitrous window, it always triggers just at the ON rpm, and has to drop 200 rpms below that to turn OFF. If you go up beyond the window for cutoff, it cuts off at the set Off rpms and has to drop 200 rpms below that to come back on.
11-12-2008, 12:17 PM
#23
well i also have the 8969 set to come on at 1500 and cut off at 6k. my only reason as to y it goes lean is the fuel pressure because i have stock fuel pump still. It seems like once i let off completely and get back into it the a/f will be back down around 12.0 or so.
11-12-2008, 12:54 PM
#24
I won't run hard with any less than 1/8 tank - and I prefer going to the track now with 1/2 tank. Spraying a heavy shot really sucks fuel, you know. I have two PLX graphs showing my A/F going very lean in third gear at 150-shot - 1/8 tank wasn't enough - I was sucking air as I got close to the traps.
11-13-2008, 08:32 AM
#25
Sounds like you either ran out of fuel pressure -when you let off, it came back up - or you didn't have enough fuel in the tank and you ran low on fuel pressure.
I won't run hard with any less than 1/8 tank - and I prefer going to the track now with 1/2 tank. Spraying a heavy shot really sucks fuel, you know. I have two PLX graphs showing my A/F going very lean in third gear at 150-shot - 1/8 tank wasn't enough - I was sucking air as I got close to the traps.
I won't run hard with any less than 1/8 tank - and I prefer going to the track now with 1/2 tank. Spraying a heavy shot really sucks fuel, you know. I have two PLX graphs showing my A/F going very lean in third gear at 150-shot - 1/8 tank wasn't enough - I was sucking air as I got close to the traps.
11-17-2008, 06:48 PM
#26
Sounds like you either ran out of fuel pressure -when you let off, it came back up - or you didn't have enough fuel in the tank and you ran low on fuel pressure.
I won't run hard with any less than 1/8 tank - and I prefer going to the track now with 1/2 tank. Spraying a heavy shot really sucks fuel, you know. I have two PLX graphs showing my A/F going very lean in third gear at 150-shot - 1/8 tank wasn't enough - I was sucking air as I got close to the traps.
I won't run hard with any less than 1/8 tank - and I prefer going to the track now with 1/2 tank. Spraying a heavy shot really sucks fuel, you know. I have two PLX graphs showing my A/F going very lean in third gear at 150-shot - 1/8 tank wasn't enough - I was sucking air as I got close to the traps.
11-17-2008, 08:00 PM
#27
Look in your phone book - under Speed Shop or Performance Cars or the like. If a shop sells it, chances are their ad will say so. If you have any roundy-roundy tracks local to you, check with them - they usually sell the stuff...
Use Google to search for outlets. It's out there.
12-16-2008, 09:18 AM
#30
For a piece of mind....I have the hp high pressure pump part#GSS342 hp
http://forums.maxima.org/group-deals...hipping-2.html
http://forums.maxima.org/group-deals...hipping-2.html
Click on link please
http://forums.maxima.org/6754632-post45.html
12-16-2008, 09:19 AM
#31
A Walbro GSS342 HP works fine in my '99, and yes, the '94 pump is the same dimensions and connections as the '99. The full installation kit for the '94 doesn't have the right parts for 95-99 tanks - but the pump is right.
12-16-2008, 01:07 PM
#33
12-23-2008, 07:58 PM
#35
ok guys i'm about to order the 255hp pump and was wondering what afpr you guys are running....do you all have setup pics of them? i need help cause i think my fuel pump is on the way out. today i was driving my car and when i come to a stop after about 10-15 seconds the idle drops to around 700rpm or so and sounds like it has really big duration cams or one of the coil packs is unplugged and running on 5 cylinders....i check those and there all secure. so what is everyone think? any pics of the afpr?
12-24-2008, 06:36 AM
#37
I have a aeromotive, check my cardomain for pic's
I have pic's of a kirban and aero both on there, the kirban sucks azz and would blow the diaphram everytime I sprayed it but the company did replace it 3 times with a brand new one.
I have pic's of a kirban and aero both on there, the kirban sucks azz and would blow the diaphram everytime I sprayed it but the company did replace it 3 times with a brand new one.
12-24-2008, 07:10 AM
#38
ok guys i'm about to order the 255hp pump and was wondering what afpr you guys are running....do you all have setup pics of them? i need help cause i think my fuel pump is on the way out. today i was driving my car and when i come to a stop after about 10-15 seconds the idle drops to around 700rpm or so and sounds like it has really big duration cams or one of the coil packs is unplugged and running on 5 cylinders....i check those and there all secure. so what is everyone think? any pics of the afpr?
12-24-2008, 10:21 AM
#39
12-29-2008, 10:59 AM
#40