Aftermarket computers

[ken sampson]

I have a question about adjustable FPR's. When running with an AEM, TEC-3 or any aftermarket computer do you still run with the FPR set to add more fuel per each pound of boost? Or would you want to just set it at a fixed location and do all the adjustment through the computer?

 

[MiamieNeSeX]

We run set maps as O2 sensors seem to fail.


Armando

 

[ken sampson]

We run set maps as O2 sensors seem to fail.


Armando

So you run one fuel pressure?

 

[MiamieNeSeX]

So you run one fuel pressure?

No, fuel pressure rises and falls dpending on demand all of which is programmed into the AEM.


Armando

 

[HYPERTUNE]

I have a question about adjustable FPR's. When running with an AEM, TEC-3 or any aftermarket computer do you still run with the FPR set to add more fuel per each pound of boost? Or would you want to just set it at a fixed location and do all the adjustment through the computer?

Ideally, you use a standard linear pressure regulator. (Like a stock reg) If you need an aftermarket reg (your fuel pump flows so much that your stock reg can't control pressure at low loads) just get a linear one. (not rising rate)

Rising rate regs are CRAP!!! One of the best reasons to go with an aftermarket computer is so you don't have to run one.

Note that a standard type reg does change fuel pressure, but changes it in proportion to manifold pressure.

Also, Armando's post could give you the impression that the AEM has control of fuel pressure. this is not the case. The pressure regulator is there so the ECU does not have to account for a changing pressure differential across the injector.

 

[ken sampson]

Ideally, you use a standard linear pressure regulator. (Like a stock reg) If you need an aftermarket reg (your fuel pump flows so much that your stock reg can't control pressure at low loads) just get a linear one. (not rising rate)

Rising rate regs are CRAP!!! One of the best reasons to go with an aftermarket computer is so you don't have to run one.

Note that a standard type reg does change fuel pressure, but changes it in proportion to manifold pressure.

Also, Armando's post could give you the impression that the AEM has control of fuel pressure. this is not the case. The pressure regulator is there so the ECU does not have to account for a changing pressure differential across the injector.

Ok I'm lost now. What is the difference between a Rising rate regulator and a standard linear pressure regulator. Because you say that a standard type regulator does change fuel pressure, but changes it in proportion to manifold pressure.
To me it would seam that a fixed pressure is what you would get from a standard unit.

Everyone I have talked to so far has said that they use the Rising rate type and currently that is what I have. So I guess the question should be how many of you are running the fixed pressure type?

 

[HYPERTUNE]

Ok, there is often some confusion here. What I know as a rising rate reg, is one that increases fuel pressure at an increasing rate (not linear) once under boost conditions.

So, say your base pressure was 50 psi (set with manifold pressure at atmospheric) with a linear reg, at 10 psi boost you would get 60 psi fuel pressure (thus maintaining a pressure differential of 50 psi) With a rising rate reg (say, 2:1) you would get 2 x 10 psi = 70 psi total pressure. Therefore, the rising rate reg tries to supply the extra fuel needed under boost by increasing the fuel pressure disproportionally to boost pressure.

There are no cars I know of that have a pressure reg that supplies a constant pressure. Any reg that has a vacuum line running to the intake manifold is referencing manifold pressure, and hence trying to achieve a constant pressure differential across the injector (unless it is a rising rate reg, which I doubt ANY factory reg would be)

The only time I have seen people run a fixed fuel pressure is with NA multi throttle setups with big cams (not VTEC) where the vacuum signal fluctuates so much that it can make tuning difficult and inconsistent.

To remove the possibility of any confusion when you buy a reg, just make sure it is 1:1 ratio. (same as stock) that is the best to go with if you have programmable ecu and appropriately sized injectors.

 

[Mase]

actually your standard 'stock' fpr is a 1:1 regulator. For every pound of boost, it rises 1 psi.

Its important to select injectors/fuel system around what type of power level/boost pressure you are running.

many of the newer cars (fords for example) the ecu changes voltage to the fuel pump to modulate fuel pressure to be constant.

most older hondas are the 1:1 tho

 

[ken sampson]

Ok I think my fuel problem or tuning problem the last time I tried to tune this may have been due to the FRP I am using. http://www.holley.com/512-505.asp
This unit can be set anywhere from 1:1 to 4:1 so what is everyone else using.

 

[Elite]

A couple common choices are these, depending on your need:

http://www.aeromotiveinc.com/listing.php?cat=2

The A1000 or A1000-6 to be specific. And they are 1:1

 

[01blacks4]

Ok I think my fuel problem or tuning problem the last time I tried to tune this may have been due to the FRP I am using. http://www.holley.com/512-505.asp
This unit can be set anywhere from 1:1 to 4:1 so what is everyone else using.

what was/were the problems ?