Stand Alone Fuel Pressure Question/Discussion:
02-26-2006, 09:16 PM
#1
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Stand Alone Fuel Pressure Question/Discussion: Okay I am inmstalling the stand alone to feed my NX MAF kit. I can run low pressure ~10-30 or 30-60...my numbers may be off. My promary fuel system runs at 63 psi.
If I set the secondary fuel pressure to say 55psi and use a FPSS, it will have to drop SUBSTANTIALLY to meet the 3.5-10 (adjustable) psi in the FPSS to shut down the system. By that time i'll be leaving a trail of parts. If we run the pressure with the low pressure spring and adjust to say 20 psi, the secondary pump should still flow its rated litre/hr but at a lower pressure. Now we get the added benefit of having the FPSS come into play at say 1/2 the pressure drop if iys' set fpr 10 psi. In other words my chances of catastrophic failue due to a lean condition are reduced. The main question is what is the effect on the fuel jetting at a low pressure system?
Or do I have this all wrong?
If I set the secondary fuel pressure to say 55psi and use a FPSS, it will have to drop SUBSTANTIALLY to meet the 3.5-10 (adjustable) psi in the FPSS to shut down the system. By that time i'll be leaving a trail of parts. If we run the pressure with the low pressure spring and adjust to say 20 psi, the secondary pump should still flow its rated litre/hr but at a lower pressure. Now we get the added benefit of having the FPSS come into play at say 1/2 the pressure drop if iys' set fpr 10 psi. In other words my chances of catastrophic failue due to a lean condition are reduced. The main question is what is the effect on the fuel jetting at a low pressure system?
Or do I have this all wrong?
02-26-2006, 09:50 PM
#2
the biggest benifit I have been told is you get to run a larger jet in the fuel side and the chances of clogging are much lower then with the high pressure system.
I also have looked into it. seems to be a bigger issues with Direct port systems where you have tiny fuel jets
I also have looked into it. seems to be a bigger issues with Direct port systems where you have tiny fuel jets
02-26-2006, 10:15 PM
#3
I have thought of the low/high pressure standalone many times.
In a low pressure if you loose 1 psi some how, it will make a big change in AFR. Thats why they are supposed to be flowed before each use.
In a high pressure system(52-55) a 1-5psi change won't change the afr as much. I know when I do my standaloe I will be using high psi
In a low pressure if you loose 1 psi some how, it will make a big change in AFR. Thats why they are supposed to be flowed before each use.
In a high pressure system(52-55) a 1-5psi change won't change the afr as much. I know when I do my standaloe I will be using high psi
02-26-2006, 10:51 PM
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You need to pick a FPSS to fit the systems needs. on high pressure its 35psi + on low pressure its under 10. The low pressure jetting will alow you to tune for smaller hp levels. now 200hp on low pressure and 200hp on high pressure is just that 200hp.
The fpss must be set low enough to allow the system to flow with out tripping the switch.. meaning at 55psi settting your fpss at 50 you are going to have a problem.
So now its time to make a tuning adjustment. On low pressrue set up just a little tweeking of the regulator usually can show some results. On high pressure you would more than likely need to make jet change or make a much larger move on the regulator.
Also on low pressure tuneups your pump is not under near the load as in a high pressure. With that bypass system you are returning all the fuel back to the tank until that fuel noid opens.
so all that high pressure fuel is slaming back into the tank, possible airiating the fuel in that tank. Now low pressure you will have a much large volume of fuel moving at a low pressure.
No matter which you choose, I recommend you burp the system before showing and going,,,, just turn the pump on and crack the line at the noid, until the fuel weepss out of that fitting..just once should all that is needed.
Hope this helps
Ricky
The fpss must be set low enough to allow the system to flow with out tripping the switch.. meaning at 55psi settting your fpss at 50 you are going to have a problem.
So now its time to make a tuning adjustment. On low pressrue set up just a little tweeking of the regulator usually can show some results. On high pressure you would more than likely need to make jet change or make a much larger move on the regulator.
Also on low pressure tuneups your pump is not under near the load as in a high pressure. With that bypass system you are returning all the fuel back to the tank until that fuel noid opens.
so all that high pressure fuel is slaming back into the tank, possible airiating the fuel in that tank. Now low pressure you will have a much large volume of fuel moving at a low pressure.
No matter which you choose, I recommend you burp the system before showing and going,,,, just turn the pump on and crack the line at the noid, until the fuel weepss out of that fitting..just once should all that is needed.
Hope this helps
Ricky
02-26-2006, 11:25 PM
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Originally Posted by NXRICKY
You need to pick a FPSS to fit the systems needs. on high pressure its 35psi + on low pressure its under 10. The low pressure jetting will alow you to tune for smaller hp levels. now 200hp on low pressure and 200hp on high pressure is just that 200hp.
The fpss must be set low enough to allow the system to flow with out tripping the switch.. meaning at 55psi settting your fpss at 50 you are going to have a problem.
So now its time to make a tuning adjustment. On low pressrue set up just a little tweeking of the regulator usually can show some results. On high pressure you would more than likely need to make jet change or make a much larger move on the regulator.
Also on low pressure tuneups your pump is not under near the load as in a high pressure. With that bypass system you are returning all the fuel back to the tank until that fuel noid opens.
so all that high pressure fuel is slaming back into the tank, possible airiating the fuel in that tank. Now low pressure you will have a much large volume of fuel moving at a low pressure.
No matter which you choose, I recommend you burp the system before showing and going,,,, just turn the pump on and crack the line at the noid, until the fuel weepss out of that fitting..just once should all that is needed.
Hope this helps
Ricky
The fpss must be set low enough to allow the system to flow with out tripping the switch.. meaning at 55psi settting your fpss at 50 you are going to have a problem.
So now its time to make a tuning adjustment. On low pressrue set up just a little tweeking of the regulator usually can show some results. On high pressure you would more than likely need to make jet change or make a much larger move on the regulator.
Also on low pressure tuneups your pump is not under near the load as in a high pressure. With that bypass system you are returning all the fuel back to the tank until that fuel noid opens.
so all that high pressure fuel is slaming back into the tank, possible airiating the fuel in that tank. Now low pressure you will have a much large volume of fuel moving at a low pressure.
No matter which you choose, I recommend you burp the system before showing and going,,,, just turn the pump on and crack the line at the noid, until the fuel weepss out of that fitting..just once should all that is needed.
Hope this helps
Ricky
02-27-2006, 10:18 AM
#7
I plumbed mine the one i made a little different than the one you bought. My fuel runs from the intank pump to the 2 fuel noids then back to the regulator on the tank and then returns into the tank with a downspout that keeps the returning fuel from airing up the tank. It always circulates fresh fuel at the noids. I wish i had got the regulator you use mine is only high pressure. I have a guage mounted by the noids for setting the pressure. I ordered the jets using 40# fuel pressure and have had great luck adjusting a/f without jet changes. I log a/f with my wideband
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02-27-2006, 11:42 AM
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Originally Posted by koolrayz
I plumbed mine the one i made a little different than the one you bought. My fuel runs from the intank pump to the 2 fuel noids then back to the regulator on the tank and then returns into the tank with a downspout that keeps the returning fuel from airing up the tank. It always circulates fresh fuel at the noids. ...
Thanks!
02-27-2006, 12:11 PM
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Originally Posted by Macon
Ricky you are my hero! I owe you another haircut. It makes good sense. Sounds like low pressure ~ 20 psi would make more sense...i'm only doing 150 so...the fuel jet stays the same as std 150 wet jetting? .032 ish as I recall. The FPSS can probably stay at the 4.5 psi it's set at? Try that I guess? Now do I burp before every Nirtrous run or just after the inital setup?
Give me a call so I can talk with you one on one, Jeremy keeps telling my type sucks. lol///
Ricky
02-28-2006, 10:32 AM
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Originally Posted by NXRICKY
I need to know what system we are talking about. If its the Maf stay with high pressure more history with tune up on that kit, Direct port go low pressure..Sorry I did not see which kit we were talking about.. Jetting will totally change between 58 and 20 psi. Just burp after the intial set up...
Give me a call so I can talk with you one on one, Jeremy keeps telling my type sucks. lol///
Ricky
Give me a call so I can talk with you one on one, Jeremy keeps telling my type sucks. lol///
Ricky
