Paxton fuel pressure regulator question

[ViperPict]

Can anyone advise as to how the rising rate fuel pressure regulator that comes with the Paxton S/C kit works? Obviously not directly linked to boost so does it just work off of RPM?

And also how the fuel pressure is regulated as standard on a 1996 RT/10?

Thanks in advance.

[stevieturbo]

ViperPict said:

Can anyone advise as to how the rising rate fuel pressure regulator that comes with the Paxton S/C kit works? Obviously not directly linked to boost so does it just work off of RPM?

And also how the fuel pressure is regulated as standard on a 1996 RT/10?

Thanks in advance.

If it's called rising rate, then it must be referenced to boost.

It's a bodge instead of proper ecu tuning, often they just increase fuel pressure at a rate higher than 1:1 with reference to intake manifold pressure.
The rate will vary for each application. For a very low boost setup it will probably be fine though, but not ideal.

[ViperPict]

stevieturbo said:

ViperPict said:

Can anyone advise as to how the rising rate fuel pressure regulator that comes with the Paxton S/C kit works? Obviously not directly linked to boost so does it just work off of RPM?

And also how the fuel pressure is regulated as standard on a 1996 RT/10?

Thanks in advance.

If it's called rising rate, then it must be referenced to boost.

It's a bodge instead of proper ecu tuning, often they just increase fuel pressure at a rate higher than 1:1 with reference to intake manifold pressure.
The rate will vary for each application. For a very low boost setup it will probably be fine though, but not ideal.

Yeah thanks, I've got to the bottom of it now. It's an 'old school' way of 'tuning' S/C cars - linearly increasing fuel pressure (and, therefore, delivery rate) with boost. There a vacuum line from the fuel pressure regulator to the intake manifold and fuel pressure raises by a constant ratio to boost.

I am going to now map fueling properly but also have fuel pressure rising with boost - better atomisation of the fuel into the cylinder and less injection duty cycle. Will also allow me to run more power with the relatively low flow rate injectors that I have (50lb ones).

[stevieturbo]

ViperPict said:

Yeah thanks, I've got to the bottom of it now. It's an 'old school' way of 'tuning' S/C cars - linearly increasing fuel pressure (and, therefore, delivery rate) with boost. There a vacuum line from the fuel pressure regulator to the intake manifold and fuel pressure raises by a constant ratio to boost.

I am going to now map fueling properly but also have fuel pressure rising with boost - better atomisation of the fuel into the cylinder and less injection duty cycle. Will also allow me to run more power with the relatively low flow rate injectors that I have (50lb ones).

NOT linear.

Almost all reasonably modern cars whether boosted or not have their FPR referenced to intake manifold vacuum. Although some of the latest ones run a fixed rail pressure and dead end system..can ignore those for now.
The term rising rate gets bandied about with no thought as to what it means.

Most cars FPR will pretty much track manifold pressure 1:1 with fuel pressure. Other than the dead end systems mentioned, I cant think of any car where it doesnt have a referenced FPR

IMO that is not rising rate.

These FMU's ( fuel management units ) as they call them that companies use to give a fuel increase for a low boost setup rise at a higher rate than 1:1 with intake manifold pressure. This IS rising rate, not a fixed rate.
So that could be 1:2, 1:5, 1:10 or whatever. Some of them are really silly the amount they try to increase pressure and should be avoided at all costs.

[ViperPict]

stevieturbo said:

ViperPict said:

Yeah thanks, I've got to the bottom of it now. It's an 'old school' way of 'tuning' S/C cars - linearly increasing fuel pressure (and, therefore, delivery rate) with boost. There a vacuum line from the fuel pressure regulator to the intake manifold and fuel pressure raises by a constant ratio to boost.

I am going to now map fueling properly but also have fuel pressure rising with boost - better atomisation of the fuel into the cylinder and less injection duty cycle. Will also allow me to run more power with the relatively low flow rate injectors that I have (50lb ones).

NOT linear.

Almost all reasonably modern cars whether boosted or not have their FPR referenced to intake manifold vacuum. Although some of the latest ones run a fixed rail pressure and dead end system..can ignore those for now.
The term rising rate gets bandied about with no thought as to what it means.

Most cars FPR will pretty much track manifold pressure 1:1 with fuel pressure. Other than the dead end systems mentioned, I cant think of any car where it doesnt have a referenced FPR

IMO that is not rising rate.

These FMU's ( fuel management units ) as they call them that companies use to give a fuel increase for a low boost setup rise at a higher rate than 1:1 with intake manifold pressure. This IS rising rate, not a fixed rate.
So that could be 1:2, 1:5, 1:10 or whatever. Some of them are really silly the amount they try to increase pressure and should be avoided at all costs.

Sorry, I meant that the rate of increase (i.e., the ratio) is fixed!