Nitrous Fuel Pressure?

[domthebomb11208]

When my car comes into boost just like any other turbo car it raises fuel pressure...So with that happening where do i tap into my fuel system for my fuel silnoid?I wondering because if my pressure goes up it would hurt my fuel jetting on my nitrous wouldnt it?

 

[90laserRSfwd]

I'm assuming that you have a wet nitrous kit. In that case I would tap the feed line off the FPR where you would install a fuel pressure gauge

 

[1992awdlaser]

The fuel pressure going up won't matter. It is the same concept as the fuel pressure going up in the fuel rail. The pressure (boost) pushing against the injector (fuel injector or fuel jet for the nitrous) is going to make it harder for the fuel to come out. To counter this the fuel pressure is raised to an equal amount to the boost. This makes the forces against each other equal there for making fuel come out how it is supposed to.

 

[domthebomb11208]

ok thank you

 

[rhamlinii]

When my car comes into boost just like any other turbo car it raises fuel pressure...So with that happening where do i tap into my fuel system for my fuel silnoid?I wondering because if my pressure goes up it would hurt my fuel jetting on my nitrous wouldnt it?

Yeah it will hurt your jet's setting, because even a 50 shot is jetted to a certain mixture at 40-45 psi. Once you add more boost and have fuel pressure sit at 55 psi, it throws everything off.

 

[1992awdlaser]

Yeah it will hurt your jet's setting, because even a 50 shot is jetted to a certain mixture at 40-45 psi. Once you add more boost and have fuel pressure sit at 55 psi, it throws everything off.

No it doesn't. Read my other post in this thread to understand why.

 

[propeine]

Flow of any fluid is based on a pressure differential. It is the difference between the pressures that causes the fluid to move. For example

At base pressure on a 2g

At WOT before boost
43.5psi fuel pressure - 0psi air pressure in intake(Approx)= pressure differential of 43.5psi

Because your FPR rises with boost at 10psi

53.5psi fuel pressure - 10psi air pressure in intake = pressure differential of 43.5psi

Your nitrous jet actually needs to have the 1:1 rise in order to not lean out as boost increases.

 

[420a-t]

So, you should take it from the fuel filter (or somewhere else before the fpr) and not the fpr or later?

 

[rhamlinii]

No it doesn't. Read my other post in this thread to understand why.

It's one of the reasons me and my friends cars run seperate fuel system now. So now that's avoided altogether and it's alot easier to tune. I know what your trying to say, but if depends on your fuel pump. If it can keep up with the fuel flow demand you shouldn't see a pressure drop. My car was once a 20g with a single fogger setup. I had a 190lph intank and a 255 hp inline with 550cc injeceters. My cars that i've setup are different then yours, and i'm not trying to discredit you. I'm not stating my opioion, but just the facts of what i've come across. I didn't see a pressure drop, and the 1-to 1 regulator did effect the air/fuel mixture to run extremely rich. I got tire of trying of playing with it, and after talking to an old-school man about nitrous. I've been doing it my way, and it works VERY well.

 

[rhamlinii]

Flow of any fluid is based on a pressure differential. It is the difference between the pressures that causes the fluid to move. For example

At base pressure on a 2g

At WOT before boost
43.5psi fuel pressure - 0psi air pressure in intake(Approx)= pressure differential of 43.5psi

Because your FPR rises with boost at 10psi

53.5psi fuel pressure - 10psi air pressure in intake = pressure differential of 43.5psi

Your nitrous jet actually needs to have the 1:1 rise in order to not lean out as boost increases.

Your fuel pressure rises to meet the fuel demands for the turbo setup. Nitrous in tuned strictly by the jets and timing maps.

 

[propeine]

Your fuel pressure rises to meet the fuel demands for the turbo setup. Nitrous in tuned strictly by the jets and timing maps.

Flow is driven by pressure differential not base pressure. If you take the fuel for the nitrous jet from a source that doesn't rise 1:1 then you will flow less fuel as you build boost and lean out. This is only for a wet setup by the way. This is not speculation, or even experience. This is basic fluid dynamics principles. Yes I agree with it being a problem if you get a fuel pressure drop when the nitrous is enabled and yes its going to be easier to tune if you have a separate system but either way you have to have the fuel pressure rise with boost or else you're just compensating for it with your injectors.

Also I suppose you could tune nitrous by changing the jets but it will never be optimal even if it is "old school". It will be rich before spool if you tune for on boost conditions and lean on boost if you tune for off boost conditions unless you're using your injectors to make a wet/dry system. Carburetors are old school but we don't use those any more either.

 

[bastarddsm]

Flow is driven by pressure differential not base pressure. If you take the fuel for the nitrous jet from a source that doesn't rise 1:1 then you will flow less fuel as you build boost and lean out. This is only for a wet setup by the way. This is not speculation, or even experience. This is basic fluid dynamics principles. Yes I agree with it being a problem if you get a fuel pressure drop when the nitrous is enabled and yes its going to be easier to tune if you have a separate system but either way you have to have the fuel pressure rise with boost or else you're just compensating for it with your injectors.

Also I suppose you could tune nitrous by changing the jets but it will never be optimal even if it is "old school". It will be rich before spool if you tune for on boost conditions and lean on boost if you tune for off boost conditions unless you're using your injectors to make a wet/dry system. Carburetors are old school but we don't use those any more either.

+1million. propeine is exactly right!!!!!!!

 

[rhamlinii]

Flow is driven by pressure differential not base pressure. If you take the fuel for the nitrous jet from a source that doesn't rise 1:1 then you will flow less fuel as you build boost and lean out. This is only for a wet setup by the way. This is not speculation, or even experience. This is basic fluid dynamics principles. Yes I agree with it being a problem if you get a fuel pressure drop when the nitrous is enabled and yes its going to be easier to tune if you have a separate system but either way you have to have the fuel pressure rise with boost or else you're just compensating for it with your injectors.

Also I suppose you could tune nitrous by changing the jets but it will never be optimal even if it is "old school". It will be rich before spool if you tune for on boost conditions and lean on boost if you tune for off boost conditions unless you're using your injectors to make a wet/dry system. Carburetors are old school but we don't use those any more either.

Any fuel injected FPR on a 1:1 scale will raise fuel pressure one pound, for one pound of air. If your" Base" fuel pressure is set to 40psi at 0psi. Your turbo builds 15 psi of boost, you're then running 55 psi of total fuel pressure with your setup. With the help of your injecters and fuel pump, our cars deals with it's own fueling needs. You tune any car like this without nitrous first, to maintain a safe and reasonable air/fuel level. Be safe with the tune, and try to plan for spikes in boost if needed at this step. You have to understand with a with a conventional "wet kit" you never tune the air/fuel ratio of a nitrous kit, with nothing other then the fuel jet or jets.

If you run a nitrous kit and your fuel pump meets the horse power demands of the nitrous kit, and turbo setup together. You won't experience a drop in fuel pressure like it was stated earlier on a starter EFI kit. I never have experienced that before on a 75 or lower shot, end of story. To make it worse for you, if the kit was designed by Nx, NOS, ZEX, or anyone you choose. If they have a set air/fuel ratio of 11.5 to 1 with the recommend fuel jet's at 40psi. When you run the kit at 55psi total fuel pressure, it will run richer then it truely needs to be. This could leave power on the table, and could be bad for safty reasons if nothting esle. What did I choose to do? Run two fuel pump, two fpr, and two fuel tanks in my car and my friends. His car was just finished before mine with a 150 shot on his 16g. It works very well, as intended. Since I have a seperate fuel system for nitrous system. It's alot easier to manage and tune.

I was able to fine tune his nitrous syetem using the FPR at constiant fuel pressure without a pressure source like you stated I couldn't do. Once I had the fuel jet I wanted in the car. His nitrous kit comes on at anything over 80% percent trottle, in any gear but 1st gear. He has to be going over 35mph for it to engage. It's not depended upon his 1:1 FPR he uses for the motor/turbo setup like you said it had to be. It's simple math, the proper amount of n20 with fuel = a stable air/fuels because it's chemical based. Your injecting a metered amount of no2 with metered amount of fuel to make a mixture. It's not boost or rpm relative. You could spray that car at whatever rpm ,in vacuum. It'll still work as intended as long as the motor is able to rev freely. That is how nitrous works. The only way the air/fuel would be off, is if you didn't tune the car without the spray engaged.

You sir, don't understand the basics of nitrous operation. I undertsand you have knowlegde, and I don't even care to question that. If you truely don't know, why don't you just say so?

 

[rhamlinii]

+1million. propeine is exactly right!!!!!!!

ARE YOU KIDDING ME? WTF






Ok, i'm done with you.

 

[90laserRSfwd]

I posted this 3 months ago and I'll post it again. IF (1) your using a wet nitrous system and (2) you have a good FPR (like an aeromotive) just tap off the FPR where the fuel pressure gauge would go.

 

[propeine]

I'm don't want to start any sort of flame war but your simple math isn't so simple. I have no doubt you tuned his car this way and it works fine but like I said, you're not running at 11.5 to one with your "metered" mixture the whole time. Let me explain it another way. When you're filling a tire from dead flat to full. Why does the airflow slow down as the tire fills up? The pressure differential across the valve decreases! As boost pressure rises you are getting less fuel out of your nitrous jet than you were at 0psi.

Tell you what, go crank your boost up to 40lb, leave your non rising FPR in there, enable your spray and see if you don't frag a motor. Not really obviously because I wouldn't wish that on anyone. Let me ask you this, if he changes his peak boost do you have to change the fuel jet? You shouldn't have to. Any chance I can get you to post two logs, both WOT in 3rd, one with spray and one without?

Also I realize that the nitrous flow drops as well due to the boost "pushing back" but the ratio is nowhere near the same for the pressure differential.

You seem to have the knowledge to tune nitrous effectively with your method, but please don't spread misinformation to these guys that are gonna slap in a wet kit and don't know much but what the instructions tell them.

 

[1992awdlaser]

propeine IS right. He is explaining what I said in my first post. If you don't think we are right, call a nitrous manufacturer like Holley who makes the NOS products and ask them. Their answer will be the same.

 

[90laserRSfwd]

propeine IS right. He is explaining what I said in my first post. If you don't think we are right, call a nitrous manufacturer like Holley who makes the NOS products and ask them. Their answer will be the same.

Maybe someone should email them and then post a trans xerox of it here for all to see.

 

[rhamlinii]

propeine IS right. He is explaining what I said in my first post. If you don't think we are right, call a nitrous manufacturer like Holley who makes the NOS products and ask them. Their answer will be the same.

I'm not trying to argue with fellow dsm owners, and there is no need to go back and forth. Everyone has made there points. I'm not going to call Holly sir, and research something. That i've already tried, and works. I also really don't want anyone like Propeine said,(newbie) to risk what i've tried and blow there motors. I've been there before, with no money to fix my car 7 years ago. My friends setup is all in the tune, and knowone seems to run a setup like ours. I'd like to think i've learned something in these past years. All I can say, is that it seems to work fine for me. I'm having alot of fun with spray and I'd never run a big boost setup again, so 40 psi would never happen for me Propine. With my setup on the 14b setup, i'd be lucky to get 15psi by my 7k redline. So, I think i'll be fine. Thanks for the time guys.

 

[1992awdlaser]

Here is confirmation from Holley(the makers of the NOS brand).

I sent this message to them:

"My car came from the factory with a turbocharger. As a result the fuel pressure regulator raises the fuel pressure 1psi for every psi of boost. I am installing one of your direct port kits. I just want to make sure I have part of the insall correct. If I'm not mistaken, the source for the fuel solenoid should be before the fuel pressure regulatoar so the pressure in the fuel solenoid rises with boost also, right? What will happen if the fuel pressure doesn't rise in the fuel portion of the nitrous kit when boost raises?"

Their response was:

"Yes that's correct if the nozzles are under boost pressure the fuel pressure supply needs to be boost rising rate of 1 psi of fuel pressure rise per lb of boost to keep from running to lean. For example if the fuel pressure is 30 and the boost is 30 the boost pressure would cancel out the fuel and and no fuel would come out of the nozzle. Thanks Shane WhitescarverTechnicalService Representative"

 

[rhamlinii]

Here is confirmation from Holley(the makers of the NOS brand).

I sent this message to them:

"My car came from the factory with a turbocharger. As a result the fuel pressure regulator raises the fuel pressure 1psi for every psi of boost. I am installing one of your direct port kits. I just want to make sure I have part of the insall correct. If I'm not mistaken, the source for the fuel solenoid should be before the fuel pressure regulatoar so the pressure in the fuel solenoid rises with boost also, right? What will happen if the fuel pressure doesn't rise in the fuel portion of the nitrous kit when boost raises?"

Their response was:

"Yes that's correct if the nozzles are under boost pressure the fuel pressure supply needs to be boost rising rate of 1 psi of fuel pressure rise per lb of boost to keep from running to lean. For example if the fuel pressure is 30 and the boost is 30 the boost pressure would cancel out the fuel and and no fuel would come out of the nozzle. Thanks Shane WhitescarverTechnicalService Representative"

Boost is set at 20 psi and fuel pressure is now at 58psi on that fpr on the new shot. It does have a nasty boost spike in his car but his base tune is prepared around that with a soft tune. He also is now on the 175 nitorus jets and still a stock motor with a single fogger setup. It felt really "F"ing good, accept now his clutch has started to slip after launching as soon as he get's into second with the nirtous. So now the clutch will need to be changed. Everything else seems to be top notch in the car. Thanks for the information, but i'll continue to use the kit in this way. At normal nitrous pressure, air fuel ratio only varies from 10.8 richest to 11.4 at the leanest.

 

[selmerguy]

How did this turn into an argument.......???? It is basic commen since. Tap after the rising rate and you will have nothing to worry about. I use a Aeromotive FPR. It has two outlets. One goes to my rail. The other goes to my nitrous fuel solenoid. It has a gauge port aswell. The fuel pressure needs to rise the same as the boost. 1:1

 

[rhamlinii]

How did this turn into an argument.......???? It is basic commen since. Tap after the rising rate and you will have nothing to worry about. I use a Aeromotive FPR. It has two outlets. One goes to my rail. The other goes to my nitrous fuel solenoid. It has a gauge port aswell. The fuel pressure needs to rise the same as the boost. 1:1

It's not an argument. They are only trying to state facts about there beliefs and what supports them. I'm not againt that/them and support them for it. I have since move on to a bigger shot with the car in question. It keeps making more power, what a surprize?. I've only stated what i've tried, and how it works in real life situatuions. That's all, nothing more. I have said I didn't want anyone to use/copy my setup, as I believe the car's safety is all in the tune it has. I also said this way works alot better for me, and I'd continue to using this method of running nitrous for his car and my car when it's finished. With that said, that's all that needed to be said on my part. My post before this was nothing more then an update on that car in question. For shits and giggles maybe i'll tap a pressure souce to the regualtor and see how she does with the new clutch is installed. My last setup with a hundred shot on my 2nd 20g setup ran very rich, and it was a pain in the ass changing plugs (br8es) all the time after a nitrous pass. I always felt like the kit had more power to be found or had. It's wasn't reliable, as you'd never know when it would start to misfire. You had to change the plugs after a nitrous pass. I don't feel that way now, and my friends car feels better/faster then my car did with only a 1/10 of the money in it.