Is corvette fuel filter/regulator a straight swap to Fbody?
08-04-2017, 10:31 AM
#47
Neither one actively adjusts pressure.
I haven't heard of the fbody failing at an unknown pressure either. It does become a restriction at one point, but they are not too bad up to the mid 400s at the wheels. Trying to run a 340 and e85 through the fbody ones would be an issue but the 255 doesnt have an issue mostly.
Ill post some more info on how the computer tries to adjust fuel pressure so to speak in a different way in a bit. Gotta find my notes.
I haven't heard of the fbody failing at an unknown pressure either. It does become a restriction at one point, but they are not too bad up to the mid 400s at the wheels. Trying to run a 340 and e85 through the fbody ones would be an issue but the 255 doesnt have an issue mostly.
Ill post some more info on how the computer tries to adjust fuel pressure so to speak in a different way in a bit. Gotta find my notes.
08-04-2017, 11:04 AM
#48
TECH Senior Member
My understanding of most pressure regulators is they put a "cap" on the pressure, not allowing it to exceed a known limit, much like an oil pressure relief valve, only in the fuel regulator's case the excess is plumbed to the fuel tank.
08-04-2017, 11:14 AM
#49
Not really. they don't release the fuel into a bypass or puke it back into the tank, it just provides a metered restriction on the line which causes the pressure in the first place. The vacuum operated ones work a bit different where they actively try to keep the pressure differential based off manifold vacuum the same. It is fairly seamless so you cant really see it even with a fuel pressure gauge. The none sourced regulators use a different way of supplying fuel for demand. like i said ill post that in a bit.
The new vehicles fitted with fpcm or fscm use pulse width modulation or voltage increase to change the output of the pump and accordingly the flow rate of the fuel injectors. But the fbodys and c5s def dont do that.
The new vehicles fitted with fpcm or fscm use pulse width modulation or voltage increase to change the output of the pump and accordingly the flow rate of the fuel injectors. But the fbodys and c5s def dont do that.
Last edited by tech@WS6store; 08-04-2017 at 11:20 AM.
08-08-2017, 08:38 PM
#50
TECH Senior Member
From what I see of the F-car fuel system, the T-fitting just before the fuel filter goes to the FPR in the tank (near the top of the fuel pump module), it dumps fuel back into the tank thru here; this FPR is un-referenced, meaning it references whatever pressure is in the air space in fuel tank (which is close to barometric pressure otherwise the fuel tank would damage itself)... so this FPR works just like a MAP-referenced FPR except that the reference is constant.
( edit: I didn't hyperlink/underline those words, the forum software did that )
( edit: I didn't hyperlink/underline those words, the forum software did that )
08-08-2017, 08:52 PM
#51
A software bias compensates the injector on-time because the fuel pressure regulator is not referenced to manifold vacuum. The injector pulse width varies with the signal from the MAP sensor.
^ From gm manual on the 99-02 fbodys.
Thats somewhat how all inj pw works but this is an extra overlay factor
^ From gm manual on the 99-02 fbodys.
Thats somewhat how all inj pw works but this is an extra overlay factor
08-09-2017, 05:32 PM
#53
TECH Senior Member
A software bias compensates the injector on-time because the fuel pressure regulator is not referenced to manifold vacuum. The injector pulse width varies with the signal from the MAP sensor.
^ From gm manual on the 99-02 fbodys.
Thats somewhat how all inj pw works but this is an extra overlay factor
^ From gm manual on the 99-02 fbodys.
Thats somewhat how all inj pw works but this is an extra overlay factor
08-13-2017, 09:57 AM
#56
A software bias compensates the injector on-time because the fuel pressure regulator is not referenced to manifold vacuum. The injector pulse width varies with the signal from the MAP sensor.
^ From gm manual on the 99-02 fbodys.
Thats somewhat how all inj pw works but this is an extra overlay factor
^ From gm manual on the 99-02 fbodys.
Thats somewhat how all inj pw works but this is an extra overlay factor
The software bias is limited. It can only go so far.
08-13-2017, 04:52 PM
#57
TECH Senior Member
For boost you really should use MAP referenced FPR... this means removing the in-tank FPR and installing a new FPR at the rails, and installing a return line.
08-13-2017, 05:05 PM
#58
Being more realistic, there are many MANY builds out there running boost with no issues.
There is more than one way to accomplish the end product.
No maggie kit uses a fpr on the ls apps. No reg procharger kit either. They work just fine.
Is it better to use a boost ref/rising rate fpr? Yes. But its not going to kill anything otherwise honestly, esp at the normal levels these systems are ran.
60psi isnt realistic and neither is 30. Nor is 30 anywhere close to 60.
The software is pretty accurate and grows with the tune as well. This is not some import with a limited range.
There is more than one way to accomplish the end product.
No maggie kit uses a fpr on the ls apps. No reg procharger kit either. They work just fine.
Is it better to use a boost ref/rising rate fpr? Yes. But its not going to kill anything otherwise honestly, esp at the normal levels these systems are ran.
60psi isnt realistic and neither is 30. Nor is 30 anywhere close to 60.
The software is pretty accurate and grows with the tune as well. This is not some import with a limited range.
08-14-2017, 10:34 AM
#59
Being more realistic, there are many MANY builds out there running boost with no issues.
There is more than one way to accomplish the end product.
No maggie kit uses a fpr on the ls apps. No reg procharger kit either. They work just fine.
Is it better to use a boost ref/rising rate fpr? Yes. But its not going to kill anything otherwise honestly, esp at the normal levels these systems are ran.
60psi isnt realistic and neither is 30. Nor is 30 anywhere close to 60.
The software is pretty accurate and grows with the tune as well. This is not some import with a limited range.
There is more than one way to accomplish the end product.
No maggie kit uses a fpr on the ls apps. No reg procharger kit either. They work just fine.
Is it better to use a boost ref/rising rate fpr? Yes. But its not going to kill anything otherwise honestly, esp at the normal levels these systems are ran.
60psi isnt realistic and neither is 30. Nor is 30 anywhere close to 60.
The software is pretty accurate and grows with the tune as well. This is not some import with a limited range.
It only barely passes 'legit' because the power output is low enough to pass.
2. with 30psi of boost and 60psi of fuel pressure, you lose half of your injector.
With 15psi of boost (a reasonable number) and 60psi of fuel pressure you are cutting 25% of your injector away. Still not a "desirable" situation to be in since now you need oversized injectors by 25% which hurts idle control quality depending on the size of injector. You can buy those 25% larger injectors, or, you can raise the pressure 1:1 with boost pressure, and get back that 25% of your injector that went missing. Last time I checked, 25% is a huge chunk of injector to be plus or minus. Combined with the fact the pump will probably last longer with the increased 25% injector output (due to referencing vacuum which brings down pressure at other times) makes it far more desirable as a solution.
3. the range isn't in the software, the range is in the injector. All computers work in the same based principle, stand-alone to stock, for every engine, they all use a trigger system and have something called duty cycle for the injector. You lose software bias when the software increases duty cycle in order to compensate for low fuel pressure. Once duty cycle hits 100% thats it- you are out.
cliffs;
referenced fuel pressure allows us to run smaller injectors and get the same fueling in forced induction applications
referenced fuel pressure may extend fuel pump longevity by reducing pressure during vacuum situaitons (in any application)
referenced fuel pressure gives more headroom for duty cycle at the injector during boost situations
