I have a coworker that just purchased an SRT-4 that has an AGP returnline setup. He bought a nitrous kit and was planning on installing it last night until I told him that it probably wouldnt work properly.
My thinking is, when you install the fuel jets for one fuel pressure and then the pressure is constantly rising during the pass it is either going to start lean or end up rich, and be almost impossible to tune.
Since he obviously dont want to spend the money on a dedicated nitrous fuel supply like I am, and he needs the rising rate for his 3076 turbo.
I told him he needs to install another fuel pressure regulator after the fuel rail but before the fuel noid (he has an 03 rail). Was this the best advise or can anyone think of a better solution?
His next question was, what is the least expensive FPR for his needs that will work? Obviously he doesnt want rising rate.
His computer is broke or I would have him ask his own questions.
I remember someone saying one time that they used a seperate FPR on their system and it allowed them to use larger fuel jets so they wouldnt clog as easy. Anyone remember what regulator they used? I cant find it now.
Rhunter, You follow the nitrous section pretty close, any ideas?
so you guys are talking about how to run a nitrous setup using a lets say " agp return line setup."...
i would say get a fitting for your an-3 fuel line coming off the extra port of the fuel pressure regulator like were the fuel pressure gauge is, but on opposite side. run a line from there to your fuel solenoid. yes, since you are using a 1:1 regulator the fuel pressure will rise as the boost does. Theoretically speaking, you'll be running more fuel than what you need. even though your jet says one thing, fuel pressure will do another. i think to successfully run this setup with ideal AF's ( 11.3-11.5 ) you would need some type of tune specifically for running nitrous. an SAFC 2 could work since they do have the option of more than one tune i believe ( the cheap route )sct or Diablo would be better of course.You could have your regular boost tune, then change the tune for running nitrous..
i could be wrong, but i've ran nitrous a lot, but never using a fuel return set up. lol where are the JDM owners when we need them. all of them have fuel return set ups lol
someone correct me if i'm wrong but, I would say maybe having a T of some sort like this one
This way the regulator will get it's own fuel AND the nitrous noid gets its unregulated fuel as well.
you wouldn't want the solenoid to get unregulated fuel. cuz running nitrous on a stock srt the jets are only seeing that 58psi...
i know that..but i could be wrong about unregulated fuel pressures vs regulated with solenoids, they may act the same?? but they could act like a fuel injector..even though you have 570'cc on your srt4 using 58psi, if you went to 65 psi your would be "570's" are now throwing fuel like 650'cc...
Reason i know this is on first gen neon we all use RRFPR ( rising rate fuel pressure regulators )...stock ecu, and bolt on a SRT turbo. use stage 0 injectors ( wayyyy to big for a neon )..but we turn the fuel pressure down to like 28psi. now im getting the same fuel as a stock injector would do, but when boost kicks in the regulator builds boost and now im making that stage 0 fuel amount.
hopefully i wasnt just blaping my mouth! thats my 02 cents.
You guys have to remember that for every pound of boost it effectively lowers the fuel pressure the fogger sees by 1 pound just like the fuel injectors,so having a rising rate is actually better because the fuel pressure the fogger sees is consistent, doesn't fluctuate with boost.I ran a 18 fuel jet and a 35 nitrous jet and the afr's where spot on mid 11's the whole way down the track with a rr returnline.
You guys have to remember that for every pound of boost it effectively lowers the fuel pressure the fogger sees by 1 pound just like the fuel injectors,so having a rising rate is actually better because the fuel pressure the fogger sees is consistent, doesn't fluctuate with boost.I ran a 18 fuel jet and a 35 nitrous jet and the afr's where spot on mid 11's the whole way down the track with a rr returnline.
Im not trying to argue with you but I am trying to understand what you are saying.
If the fuel jet remains the same but the fuel pressure is constantly rising, the amount of fuel flowing should constantly rise as well, which should lead to a rich condition.
Since the nitrous is a seperate power adder and gets tuned seperately, I would think that injectors, amount of boost, ect would all be taken out of the equation because they are already set to run properly.
I thought the only thing the fuel jet has to do is properly match only the nitrous that is flowing which remains constant reguardless of boost (because it comes out of the bottle), so wouldnt I want my fuel pressure to remain constant as well?
Again, Im not disagreeing. Just bringing the discussion a little deeper.
Im not trying to argue with you but I am trying to understand what you are saying.
If the fuel jet remains the same but the fuel pressure is constantly rising, the amount of fuel flowing should constantly rise as well, which should lead to a rich condition.
Since the nitrous is a seperate power adder and gets tuned seperately, I would think that injectors, amount of boost, ect would all be taken out of the equation because they are already set to run properly.
I thought the only thing the fuel jet has to do is properly match only the nitrous that is flowing which remains constant reguardless of boost (because it comes out of the bottle), so wouldnt I want my fuel pressure to remain constant as well?
Again, Im not disagreeing. Just bringing the discussion a little deeper.
No arguing its all cool ..........
The fuel pressure actually decreases with boost on a 1/1 ratio....when the injector fires it has to fight boost pressure to leave the injector.If you had 20 psi of fuel pressure and 20 psi of boost when the injector fired nothing would happen,the same scenario is true with the fuel jet in the fogger....if you've got 58psi of static fuel pressure 25psi of boost the actual fuel pressure at the fogger is 33psi.Now if your running a stock turbo as the boost falls towards redline the fuel flow through the fogger increases because its fighting less boost,a 1:1 boost referenced regulator keeps everything constant.The nitrous flow is effected the same way but a 25psi drop in bottle pressure is alot less noticable than a 25psi drop in fuel pressure.
Last edited by 93stang434 : 09-27-2009 at 02:15 PM.
No arguing its all cool ..........
The fuel pressure actually decreases with boost on a 1/1 ratio....when the injector fires it has to fight boost pressure to leave the injector.If you had 20 psi of fuel pressure and 20 psi of boost when the injector fired nothing would happen,the same scenario is true with the fuel jet in the fogger....if you've got 58psi of static fuel pressure 25psi of boost the actual fuel pressure at the fogger is 33psi.Now if your running a stock turbo as the boost falls towards redline the fuel flow through the fogger increases because its fighting less boost,a rising rate keeps everything constant.The nitrous flow is effected the same way but a 25psi drop in bottle pressure is alot less noticable than a 25psi drop in fuel pressure.
Thats intresting, never really thought of it that way.
Your friend is using a rising rate regulator on an srt-4? Why? What is the rate of gain he is using? Are you using the correct terminology, or do you mean he is using a 1:1 regulator with the boost reference line attached. That makes a big difference in what you're describing.
Your friend is using a rising rate regulator on an srt-4? Why? What is the rate of gain he is using? Are you using the correct terminology, or do you mean he is using a 1:1 regulator with the boost reference line attached. That makes a big difference in what you're describing.
1:1 i'm sure, which your only going to get with the boost reference line attached without it its static.
It's called dynamic fuel pressure, people! 93stang434 is correct in his explanation of how it all works.
Effective fuel pressure is another way of explaining it. If you have 50 psi at the rail while at atmospheric pressure in the intake manifold, then you have an effective 50 psi of pressure being ejected at the injector.
If you have 50 psi of fuel pressure at the rail, but have 20 psi of boost in the intake manifold, you only have an effective fuel pressure of 30 psi, because the fuel pressure is fighting against the manifold pressure.
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Rising rate fuel presure and nitrous.
never really thought of it that way.
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