Nitrous install - part 1
Burning Brakes
Joined: Jun 2004
Posts: 1,012
Likes: 5
From: Granbury, TX
Hmmmm. if your pump is set to 6.5 psi, you might have a problem. Under acceleration, you might not get enough fuel... My pump is like 14 psi at the pump and my regulator regulates it down to 6.5 - 7 psi... You will lose pressure under heavy acceleration and that's why you want to run the regulator very close to the carb..
What are your thoughts on the jets? I previously had twin nozzels spraying down the TBs on my CFI set up and my jets were 38 N/ 28 F on each for a A/F of ~12-1. Pressure was ~9 PSI. BTW this bumped my 200 hp basically stock engine to ~350 based on ET calculations.
Woah!
You are correct. The chart I was looking at is for EFI. Time to order new jets. Thanks for helping me not melt my engine.
For a carb setup they recommend the following:
100 hp- 46 N/ 43F
125 hp- 54N/ 52 F
150 hp- 62N/ 53F
175 hp- 67N/ 62F
A lot closer to your "Square jets"
I questioned the small fuel jet increase on the 100 to 125. He said it was the way the plate is set up. I plan to start with a 75 shot and keep a close eye on F/A mixture. I figure 12.5 or less is OK.
The regulator is on the opposite side of the carb. I also used a shorter fuel to spray plate line so it does not loop around the thermostat housing.
Last edited by Clint's C3; Jan 2, 2007 at 03:02 PM.
Safety Car
Joined: Aug 2001
Posts: 3,892
Likes: 13
From: Pettis Performance 565 with two stages of Nitrous Supply nitrous 1.082, 4.61 at 155, 7.17 at 192
If we ever meet you owe me a beer Those EFI jets would have hurt it for sure.
Do not use the data logger to read the A/F ratio when it comes out of the exhaust. The last time I talked to the Pro-mod guys I know they said the data loggers get screwy trying to read nitrous motors exhaust info. Learn how to read a nitrous plug, that is the right way to do it.
The tech guy is pulling your leg about "that is how the plate is set up" The N/F ratio of the 125 and 150 shot is within what they consider safe. Either the 125 or the 150 makes more or less power than advertised, no big deal. NX runs the jets over square (6.5 lbs. fuel pressure), that is closer to a correct tune than what NOS is telling Oliver to run.
I do not fully understand where your regulator is in comparrison to your selinoids. It is not best case scenerio to have the fuel trying to push up hill (towards acceleration) after it has been regulated down to 6 lbs. or so. A little up hill is ok, a lot can cause issues.
Those EFI jets would have hurt it for sure.Do not use the data logger to read the A/F ratio when it comes out of the exhaust. The last time I talked to the Pro-mod guys I know they said the data loggers get screwy trying to read nitrous motors exhaust info. Learn how to read a nitrous plug, that is the right way to do it.
The tech guy is pulling your leg about "that is how the plate is set up" The N/F ratio of the 125 and 150 shot is within what they consider safe. Either the 125 or the 150 makes more or less power than advertised, no big deal. NX runs the jets over square (6.5 lbs. fuel pressure), that is closer to a correct tune than what NOS is telling Oliver to run.
I do not fully understand where your regulator is in comparrison to your selinoids. It is not best case scenerio to have the fuel trying to push up hill (towards acceleration) after it has been regulated down to 6 lbs. or so. A little up hill is ok, a lot can cause issues.
Burning Brakes
Joined: Jun 2004
Posts: 1,012
Likes: 5
From: Granbury, TX
Yep, I owe you a beer for saving my bacon. Let me know if you are ever in the DFW Texas area or maybe at the Fall Nationals in Ennis. The in tank fuel pump pushes up to a "T" to the fuel soleniod, a "T" to the front bowl of the Holley double pumper, a "T" to the second bowl, through the regulator and back to the tank. It sounds more complicated than it is.
I will send a picture. Don't they use an O2 sensor for dyno tuning? I have had good luck tuning with my LM-1. Reading plugs sounds rather "old school" but you run much faster than me so who am I to question?
Safety Car
Joined: Aug 2001
Posts: 3,892
Likes: 13
From: Pettis Performance 565 with two stages of Nitrous Supply nitrous 1.082, 4.61 at 155, 7.17 at 192
Yep, I owe you a beer for saving my bacon. Let me know if you are ever in the DFW Texas area or maybe at the Fall Nationals in Ennis. The in tank fuel pump pushes up to a "T" to the fuel soleniod, a "T" to the front bowl of the Holley double pumper, a "T" to the second bowl, through the regulator and back to the tank. It sounds more complicated than it is.
I will send a picture. Don't they use an O2 sensor for dyno tuning? I have had good luck tuning with my LM-1. Reading plugs sounds rather "old school" but you run much faster than me so who am I to question?
Ya, just to be sure, maybe post a pic of your fuel set up.
I have not used an 02 sensor for tuning a nitrous motor. They can be a very usefull tool for an NA motor, but from what I have been told they do not work well for a nitrous motor. The Pro-mod guys I talked to said that when their nitrous tune was dead on the wide band would read 9 to 1 A/f ratio. You could do both I guess, but if you are going to run much nitrous you need to learn to read a nitrous plug, it is easy. Not to mention the A/F ratio has nothing to do with timing, so ya gotta pull the plug and look at it anyway.
Safety Car
Joined: Aug 2001
Posts: 3,892
Likes: 13
From: Pettis Performance 565 with two stages of Nitrous Supply nitrous 1.082, 4.61 at 155, 7.17 at 192
Ok, sorry....but I can't figure out where the nitrous side fuel is getting regulated?? Can you walk me through where the nitrous fuel pressure is getting regulated and then where it goes from there?? How far is has to travel before it gets to the selinoid?
Burning Brakes
Joined: Jun 2004
Posts: 1,012
Likes: 5
From: Granbury, TX
The fuel travels 1' though a braided #3 AN line from the red "T" on the metal supply line (#1 circle) to the solenoid.
Safety Car
Joined: Aug 2001
Posts: 3,892
Likes: 13
From: Pettis Performance 565 with two stages of Nitrous Supply nitrous 1.082, 4.61 at 155, 7.17 at 192
It is killing me I am not fully getting this. Ok, the way the arrows are pointing your fuel is going through the regulator AFTER it goes past the carb. If this is the case the fuel then gets regulated and goes to the fuel selinoid. I think you probably have the arrows pointing the wrong way or else I would expect the fuel to shoot out of the carb vents since it is not regulated before going into the carb.
If the arrows are backwards then it means the carb bowls are getting regulated fuel pressure and the fuel selinoid is getting the left over fuel before it returns to the tank.
It is not best case to have the fuel travel that far up hill (towards acceleration) after it has been regulated. Acceleration (g-forces) add effective weight to the fuel and the selinoid can end up with less fuel than what you flowed it at, or what it needs. I can not say for sure it will be a problem, but it could be. It is best case to have the fuel travel downhill after being regulated.
Ok, the way the arrows are pointing your fuel is going through the regulator AFTER it goes past the carb. If this is the case the fuel then gets regulated and goes to the fuel selinoid. I think you probably have the arrows pointing the wrong way or else I would expect the fuel to shoot out of the carb vents since it is not regulated before going into the carb. If the arrows are backwards then it means the carb bowls are getting regulated fuel pressure and the fuel selinoid is getting the left over fuel before it returns to the tank.
It is not best case to have the fuel travel that far up hill (towards acceleration) after it has been regulated. Acceleration (g-forces) add effective weight to the fuel and the selinoid can end up with less fuel than what you flowed it at, or what it needs. I can not say for sure it will be a problem, but it could be. It is best case to have the fuel travel downhill after being regulated.
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Burning Brakes
Joined: Jun 2004
Posts: 1,012
Likes: 5
From: Granbury, TX
Boggles the mind, huh?
The arrows are correct. This is how the original CFI is set up with the fuel going to the TBs and the regulator is in the second TB on the downstream side.
The regulator provides the restriction, the more open - the less pressure, tighten it up and the pressure rises. The carb and solenoid see guage pressure. The carb and solenoid drink all they want and the rest goes back to the tank.
On this set up, I disabled the stock regulator and used my Mallory on the return line, after the second TB, to regulate pressure which I measured between the TBs.
The arrows are correct. This is how the original CFI is set up with the fuel going to the TBs and the regulator is in the second TB on the downstream side.
The regulator provides the restriction, the more open - the less pressure, tighten it up and the pressure rises. The carb and solenoid see guage pressure. The carb and solenoid drink all they want and the rest goes back to the tank.
On this set up, I disabled the stock regulator and used my Mallory on the return line, after the second TB, to regulate pressure which I measured between the TBs.
ok, go run it and tell us how it went
