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Orrifice on return from catchtank?


Roggaman

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That's how boats float' date=' that's why submarines implode when the pass crush depth, that's why Herion flows from the syringe into the arm, and its why a full liter bottle of Pepsi explodes so nicely when shot with a 30-06.

[/quote']

 

I assume that you aren't speaking from personal experience, John :twisted::twisted:

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Guest Nic-Rebel450CA

I've plumbed a few of these systems on race cars and here's the routing:

 

Fuel Tank > feed line > high volume/low pressure pump > fuel pressure regualtor (2 to 5 psi) > feed line > surge tank > feed line > high volume/high pressure fuel pump > feed line > fuel rail > fuel pressure regulator (43 psi) > return line > fuel tank.

 

Yes, this setup would work, and is something I have heard of. Note the key differences are that there is not a return line from the high-pressure part of the system that returns pressure to the surge tank and there is not a low pressure regulator at the exit of the surge tank which would be a low pressure regulator blocking a high pressure system. In John's setup, the fuel is returned to the primary tank where the pressure is released.

 

Great info John

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Guest Fredrik280zx

 

a low pressure regulator at the exit of the surge tank which would be a low pressure regulator blocking a high pressure system.

How can a low pressure regulator block the system' date=' it will let the fuel pass through at 2-5 psi :?::?: The FPR [i']builds[/i] pressure.
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Guest Nic-Rebel450CA

 

a low pressure regulator at the exit of the surge tank which would be a low pressure regulator blocking a high pressure system.

How can a low pressure regulator block the system' date=' it will let the fuel pass through at 2-5 psi :?::?: The FPR [i']builds[/i] pressure.

 

The pressure after the regulator is 2-5 psi, the pressure before the regulator can build up to whatever the pump's max is, that is what will cause the regulator to rupture unless it is rated to handle the max output of the pump (typically 100PSI+ for FI). Think of it like a dam blocking a river. It can let just a little stream flow out, but it is blocking a huge river with tons of pressure. You wouldnt use wood in place of the Hoover dam.

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Guest Fredrik280zx

 

a low pressure regulator at the exit of the surge tank which would be a low pressure regulator blocking a high pressure system.

How can a low pressure regulator block the system' date=' it will let the fuel pass through at 2-5 psi :?::?: The FPR [i']builds[/i] pressure.

 

The pressure after the regulator is 2-5 psi, the pressure before the regulator can build up to whatever the pump's max is, that is what will cause the regulator to rupture unless it is rated to handle the max output of the pump (typically 100PSI+ for FI). Think of it like a dam blocking a river. It can let just a little stream flow out, but it is blocking a huge river with tons of pressure. You wouldnt use wood in place of the Hoover dam.

The regulator builds up pressure before the regulator and there´s no pressure after it. If you take a look at the stock setup; the fuel pump transports the fuel to the fuel rail. At the end of the fuel rail there´s a FPR that bulids up pressure. if the FPR works like you think it does then you would only get the correct fuel pressure on the return line on a stock setup.
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Guest Nic-Rebel450CA

http://www.diy-nitrous.fsnet.co.uk/pressure-regulator.htm

 

What is a regulator???

A fuel pressure regulator is a small device with a diaphragm inside that maintains a constant pressure (or tries to) regardless of the rate of flow. Basically you can put any fuel pressure in, and get a constant "set" pressure out - however much the input pressure might vary. So a Fuel injected car for example has a pump that might run at anything between 150psi static, and 50psi under flow conditions in use. This is "regulated" by your fuel pressure regulator to (usually) 45psi constant (3 bar).

 

Basically, the fuel pressure leading up to the regulator is whatever the pump can pump, it is what is after the regulator that the regulator controls. For example. My truck has a 15PSI fuel pump, and an 8PSI regulator. Between the pump and the regulator the pressure may reach up to 15PSI, but between the regulator and the carb the fuel pressure will reach no more than 8PSI and should also be no less than 8PSI.

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Guest Fredrik280zx

I do not know how a carburated system works so I can´t argue with that. However on a fuel injected system it´s the fuel pressure combined with how long the injector is open that determines how much fuel the cylinder gets. This is a picture of how the FPR is mounted on a fuel rail:

fpress2.gif If you want to use a rising rate FPR you must install that after the stock FPR in order to get higher fuel pressure.

 

http://www.diy-nitrous.fsnet.co.uk/pressure-regulator.htm

 

the pressure on the fuel line that feeds the fuel rail is around 3bar or 45 psi. This is because there is already a regulator on the fuel rail, and it simply returns the excess fuel at low pressure back to the tank via a second fuel pipe
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