Fuel Pressure

[Fuel]

all turbos need a rising rate FPR.

You you mean you wont need a High rising rate ie 1.7:1

[TOMSUN]

FUEL...
I'll be using the standard Sontata FPR (Naturally Aspriated - Obviously) but I don't know if it is a rising rate. It could be 1:1 in vacuum but I don't know about when it is boost.

I knew a guy who was running a Mazda Turbo BP motor in his Astina. He was running a Malpassis 3:1 rising rate FPR and it was very difficult to tune. It had a crazy fuel map where the fuel map actually decreased as the RPM and boost increased and then started to increase again. He was running approximately half the injector pulse width at just about on boost as compared to a bit off idle...

I'm running an aftermarket computer so I don't really care about the FPR if it is rising rate or not. The computer will be able to control the fuel so as long as the fuel pressure is repeatable that is all I care about.

If it starts to max out the injector pulse width, then I'll care...

[mrb1]

Rising rate - all FPRs on turbo cars are rising rate. 1psi extra fuel pressure, for every 1psi of boost is normally the go, known as 1:1 rising rate. However another common one is the 1.7:1, which adds more fuel pressure per pound of boost, which is beneficial if your injectors really suck, but most car tuners prefer 1:1 (as its easier for them to work with) and for you just to buy decent injectors (assuming you are running an aftermarket ECU).

Your fuel pressure regulator description is missleading in saying all turbo cars have "rising rate" regulators this terminology is incorrect.
All EFI cars have manifold pressure reference regulators. They maintain the same fuel pressure differential across the injector under different manifold pressures whether it be positive or negative.
This is so for any given injector pulse width the same amount of fuel is delivered regardless of manifold pressure.
If you did not have this and you were running 30psi fuel pressure and 30psi boost no fuel would come out of the injector! With a manifold pressure referenced regulator you would have 60psi fuel pressure at 30psi boost but the injector still only see's 30psi across it.

[SpidersWeb]

Ahh :D

Thanks for the correction.

[Cookiemonster]

Nothing wrong with using the standard Sonata FPR. It'll work fine.

Have you tested the fuel pressure on boost using this FPR or when you were using the L300 FPR?

No need. Fuel mixtures are spot on at 17psi boost with injectors running at 65% duty cycle.

[mrb1]

Have you tested the fuel pressure on boost using this FPR or when you were using the L300 FPR?

Yes I have tested the stock L300 regulator it's spot on. That's what I run with VR4 injectors on my L300 setup.
Why burn up money for no good reason?

[Fuel]

Have you tested the fuel pressure on boost using this FPR or when you were using the L300 FPR?

Yes I have tested the stock L300 regulator it's spot on. That's what I run with VR4 injectors on my L300 setup.
Why burn up money for no good reason?

I have a good reason. My fuel pressure was dropping when i ran more boost. On 9psi it was fine, started around 45psi or so and ended up on around 55psi once it hit 9psi boost. But on 15psi boost the fuel pressure drops off, so i figured it was the fuel pump not being able to keep up, so i changed the pump to a VL pump, however i assume (have not actually tested the fuel pressure now) it is still dropping as i am getting the same symptoms.

So i am looking at the FPR as a possible problem. I need to figure out a good way to test the fuel pressure on boost without putting it on the dyno...

[mrb1]

I have a good reason. My fuel pressure was dropping when i ran more boost. On 9psi it was fine, started around 45psi or so and ended up on around 55psi once it hit 9psi boost. But on 15psi boost the fuel pressure drops off, so i figured it was the fuel pump not being able to keep up, so i changed the pump to a VL pump, however i assume (have not actually tested the fuel pressure now) it is still dropping as i am getting the same symptoms.

So i am looking at the FPR as a possible problem. I need to figure out a good way to test the fuel pressure on boost without putting it on the dyno...

Maybe you have a faulty reg? Check the hose from the manifold to the reg to make sure it has no leaks. Maybe it only leaks over 10psi! I have seen stuff like this before where a hose seals ok for a while and then a spilt will open up and start leaking over a certain pressure.

[jakobsladderz]

Vl turbo pumps (0 280 ... 070) are not that good. They are only rated to 3 bar fuel pressure. if you have a 3 bar FPR, then run 1 bar boost, you're at 4 bar and overloading the pump. worse than that, many places sell the standard VL pump as a turbo pump. The turbo pump can be recognised 1 because of the part number (0 280 has nuts on threaded stud to hold the power connections on, the NA has spade connectors.
VL Turbo pump (0 280 XXX 070) - 130L/Hr, 3 Bar - flow OK, pressure not.
Bosch Motorsports (0 280 XXX 910) - 130L/Hr 5 Bar - flow OK, Pressure OK.

130 L/Hr is just a bit more than 4 550cc injectors can flow at 100% so should do the job just right. too big and your fuel gets hot and battery power is wasted.

[toysrus]

OMG.....I can't believe some of you'se are skimping out on setting up the Fuel System correctly, how are you all compensating for over-run ?

And yeah, the general go with 1.4:1 or 1.6:1 is for guys skimping out on Injectors or Programmable EMSs' on N/A to Turbo conversions........

I don't doubt it wouldn't work fine, just when spending $4K plus on an Engine I thought some of you would prefer the peace of mind incase random boost-spike = FPR limits = too little fuel and knock knocK whos there ? BOOM

[Fuel]

I have a good reason. My fuel pressure was dropping when i ran more boost. On 9psi it was fine, started around 45psi or so and ended up on around 55psi once it hit 9psi boost. But on 15psi boost the fuel pressure drops off, so i figured it was the fuel pump not being able to keep up, so i changed the pump to a VL pump, however i assume (have not actually tested the fuel pressure now) it is still dropping as i am getting the same symptoms.

So i am looking at the FPR as a possible problem. I need to figure out a good way to test the fuel pressure on boost without putting it on the dyno...

Maybe you have a faulty reg? Check the hose from the manifold to the reg to make sure it has no leaks. Maybe it only leaks over 10psi! I have seen stuff like this before where a hose seals ok for a while and then a spilt will open up and start leaking over a certain pressure.

Thanks for the tip about the hose, i think its ok, but havent checked.

I was thinking it might be a faulty reg, so replacing it with an adjustable will tell me if its the reg or the pump.

[Fuel]

Vl turbo pumps (0 280 ... 070) are not that good. They are only rated to 3 bar fuel pressure. if you have a 3 bar FPR, then run 1 bar boost, you're at 4 bar and overloading the pump. worse than that, many places sell the standard VL pump as a turbo pump. The turbo pump can be recognised 1 because of the part number (0 280 has nuts on threaded stud to hold the power connections on, the NA has spade connectors.
VL Turbo pump (0 280 XXX 070) - 130L/Hr, 3 Bar - flow OK, pressure not.
Bosch Motorsports (0 280 XXX 910) - 130L/Hr 5 Bar - flow OK, Pressure OK.

130 L/Hr is just a bit more than 4 550cc injectors can flow at 100% so should do the job just right. too big and your fuel gets hot and battery power is wasted.

VL n/a and VL turbo pumps are exactly the same, there have been a few different models over the years, but all the same spec. The only thing that has changed is they have moved away from the spade terminals and changed them to the threaded stud and nut.

[Fuel]

OMG.....I can't believe some of you'se are skimping out on setting up the Fuel System correctly, how are you all compensating for over-run ?

And yeah, the general go with 1.4:1 or 1.6:1 is for guys skimping out on Injectors or Programmable EMSs' on N/A to Turbo conversions........

I don't doubt it wouldn't work fine, just when spending $4K plus on an Engine I thought some of you would prefer the peace of mind incase random boost-spike = FPR limits = too little fuel and knock knocK whos there ? BOOM

Its not a matter of "skimping" its "why waste money" if things dont need to be changed. Sure if they are at the limit then you should spend the money on upgrading them.

[SpidersWeb]

and you can put a boost cut in, so in those spikes, it shuts off fuel completely. So properly set up, its no danger.

Although personally Id go for the fancy regulator and suitable pump, more so to get it 'done' than a fear of over-boosting.

[toysrus]

I think you mean spark/Ignition cut......

Okay so how big of a Fuel Pump can the L300 or Sonata FPR support at Idle without too much problems assuming Aftermarket EMS and how far can it increase the Fuel Pressure in relation to Boost aka Psi ??