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"Darkness"
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Try this some time. Calculate your area then flow it with the correct jet. Record the flowing psi. Then flow with a jet that is .015 smaller, then .015 larger. See what you get.

It takes allot to make a little difference. So instead of wasting time at the track calculating area plug a jet in the tool and forget about it.

Yes I used to worry about area at one time. Now I use the same pill(.074,what I had). I feel its for reference only and if you keep the same jet it will be more consistant.
 

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Try this some time. Calculate your area then flow it with the correct jet. Record the flowing psi. Then flow with a jet that is .015 smaller, then .015 larger. See what you get.

It takes allot to make a little difference. So instead of wasting time at the track calculating area plug a jet in the tool and forget about it.

Yes I used to worry about area at one time. Now I use the same pill(.074,what I had). I feel its for reference only and if you keep the same jet it will be more consistant.


WELL Said.... Mike
 

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Discussion Starter · #4 ·
the flowing fuel pressure will go up and down with the change in area. Now what about a high pressure jetting where flowing fuel is more sensitive to jet change? Imagine if you didn't have control of the regulation of fuel pressure, and the only fuel pressure you had to work with is what is available. Are you still going flow with a .073? What happens when you cross over the total area of .073? Will the tune up start to lean out?
 

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Ive done that (.015) and it does not do anything..... question, if you were going from 350 to 400 shot but always using a .073 flow tool jet what would you do to your fuel psi with the added 50 hp of nitrous?


Try this some time. Calculate your area then flow it with the correct jet. Record the flowing psi. Then flow with a jet that is .015 smaller, then .015 larger. See what you get.

It takes allot to make a little difference. So instead of wasting time at the track calculating area plug a jet in the tool and forget about it.

Yes I used to worry about area at one time. Now I use the same pill(.074,what I had). I feel its for reference only and if you keep the same jet it will be more consistant.
 

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I do it because it's the common jet around the nitrous world and if you want to refrence your tune up with a tuner you'll will be on the same page
 

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"Darkness"
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the flowing fuel pressure will go up and down with the change in area.
You would think. Unless you go from a .073 to a .023 you wont see shit on your flow gauge.

Imagine if you didn't have control of the regulation of fuel pressure, and the only fuel pressure you had to work with is what is available. Are you still going flow with a .073?
If you have no control you have no reason to flow other than to check what you have. Yes you can use the .073 or whatever you want. Sounds like you are playing with late model EFI. If thats the case and it needs more or less fuel you need to adjust with jetting.
 

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"Darkness"
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Ive done that (.015) and it does not do anything..... question, if you were going from 350 to 400 shot but always using a .073 flow tool jet what would you do to your fuel psi with the added 50 hp of nitrous?
If you add nitrous jet you usually add fuel jet also correct? Most guys keep the same jet spread so the fuel is added without a pressure change. Although you still may need to add or remove pressure to adjust the tuneup after reading plugs.

All you need to know is if it needs fuel you give it more pressure from where you are at. With the same jet in the flow tool you always know where you were at.
 

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Discussion Starter · #10 ·
You would think. Unless you go from a .073 to a .023 you wont see shit on your flow gauge.



If you have no control you have no reason to flow other than to check what you have. Yes you can use the .073 or whatever you want. Sounds like you are playing with late model EFI. If thats the case and it needs more or less fuel you need to adjust with jetting.

I did go from .073 to .020 and the difference was almost 10 #'s of flowing fuel pressure with no other change, just the jet. and yes it is late model fuel injection.

Say you are flowing 8 .028 jets and the calculated area is around .080 do you still flow with a .073? wouldn't there be a cross over at this point, and the tuneup actually start to lean out?

I understand flowing at or around 5 psi you will not see much change, if any at all, by changing the area of the jet flowed, but weather or not you see a big change on the gauge, you still changed the area.

Now with a higher flowing fuel pressure and a larger split, the flowing fuel pressure is much more sensitive to changes in regulated fuel pressure. Do you still flow with a .073?
 

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"Darkness"
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I did go from .073 to .020 and the difference was almost 10 #'s of flowing fuel pressure with no other change, just the jet. and yes it is late model fuel injection.

Say you are flowing 8 .028 jets and the calculated area is around .080 do you still flow with a .073? wouldn't there be a cross over at this point, and the tuneup actually start to lean out?

I understand flowing at or around 5 psi you will not see much change, if any at all, by changing the area of the jet flowed, but weather or not you see a big change on the gauge, you still changed the area.

Now with a higher flowing fuel pressure and a larger split, the flowing fuel pressure is much more sensitive to changes in regulated fuel pressure. Do you still flow with a .073?
I never flowed 50 psi EFI stuff but can understand your results. Like I said before. Yes I would still flow with the same old jet (.073 if thats what you use). Because after all it does not matter so much what the gauge reads as long as its consistant and you know where you were at before you made the adjustment. Its just a reference point.

This is my opinion and there will be others that dissagree. Sometimes people think to hard about this. I know I used to. Then I thought about what I was trying to do.......Add or remove fuel from where I was at. Its that simple.
 

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"I did go from .073 to .020 and the difference was almost 10 #'s of flowing fuel pressure with no other change, just the jet"

if your fuel pressure changes that much on a efi car then your fuel system is not up to par imo. efi regulaters should hold same pressure no matter load with minimum pressure change.
 

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I flowed my wilson plate with a .073 jet and the pressure was 7.5. When I put an 82 jet in there my fuel psi dropped to 7. I then had to raise it back up to 7.5 so my tune up would be right.
 

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all the .073 does is give you a consistent reference point. use the same jet and same flow tool everytime for consitent tune ups and read the plugs. they'll tell you what you need to know it doesn't matter what actual pressure the solenoid is seeing as long as the plug is right and you have a consistent refernce point for changes. and stick with the .073 K.I.S.S why reinvent the wheel and overcomplicate things when the .073 has worked for years and is the basis of every professional tuners setup.
 

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I flowed my wilson plate with a .073 jet and the pressure was 7.5. When I put an 82 jet in there my fuel psi dropped to 7. I then had to raise it back up to 7.5 so my tune up would be right.
but what did the plug tell you when you make those kinds of changes you have no basis for making changes based on the plug reading.
 

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"Darkness"
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I flowed my wilson plate with a .073 jet and the pressure was 7.5. When I put an 82 jet in there my fuel psi dropped to 7. I then had to raise it back up to 7.5 so my tune up would be right.
You dropped 1/2 a psi with .009 of jet? I think my fuel system dropped 4 tenths with a increase of .050.

all the .073 does is give you a consistent reference point. use the same jet and same flow tool everytime for consitent tune ups and read the plugs. they'll tell you what you need to know it doesn't matter what actual pressure the solenoid is seeing as long as the plug is right and you have a consistent refernce point for changes.
Yep.
 

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Discussion Starter · #17 ·
"I did go from .073 to .020 and the difference was almost 10 #'s of flowing fuel pressure with no other change, just the jet"

if your fuel pressure changes that much on a efi car then your fuel system is not up to par imo. efi regulaters should hold same pressure no matter load with minimum pressure change.
The fuel system pressure is non adjustable. Put a hole anywhere in the system and the pressure will drop, just simple hydraulics. I tapped into the pressure side. No fuel flowing the pressure was about 53. open the flow gauge flowing threw a .073 and the pressure drops to 42. Change the .073 to the actual jet being used, in this case a .028, and the fuel pressure is now 50 flowing.

So what I gather from all the first hand experience is the .073 provides a level of consistency and reference when tunning small low pressure multi stage systems. Is it right no. Is it wrong no. Is it consistent yes.
 

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...failure to communicate
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And just for fun, the people that flowed my system (before I bought the car) did it with a 0.074 jet. WTF? lol
 

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Good luck with that system Kayzen.
I don't see how you will be able to tune it if the fuel pressure drops when you try to use more of it. If it is a returnless system I would have thought that there would have been a fuel pressure transducer after the regulator somewhere so they could speed-up or slow-down the fuel pump to maintain the correct fuel pressure (most late-models are pwm'ing the fuel pumps).

If it is a return-style system then you don't have enough volume to keep-up with the demand. Fuel pump too small, filter clogged, lines restrictive, etc......
 

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Discussion Starter · #20 ·
Thanx, but I'm not running out of fuel. I have enough pump for about 500 hp. The fuel pressure drops because its a fixed regulator If it was adjustable, I could put the pressure anywhere.

Figured I would ask my questions here, but it seams that no one can give a clear cut answer for this .073-.07whatever way of doing things. Why not just flow the fuel noid(s) wide open if this is the case?

52n 28f at 50psi 950 bottle pressure was the final tune up on the dyno.
 
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