Choosing The Right Fuel Pressure
10-03-2003, 09:59 AM
#16
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ok ! Do you say the higher the pressuer the lower the HP tha the pump can suport?
the 968 Turbo S/Rs ha steh same injectors as teh 951 BUT it runs 60 PSI Fuel pressure.
According to your theoirie It should suport less HP at this high pressure.
I think what you say is right ONLY oif you pass the flow limit and duw turbulence etc you have less flow than you had with lower presure. a 3 bar should suport for sure more HP than a 2 bar FPR
Konstantin
the 968 Turbo S/Rs ha steh same injectors as teh 951 BUT it runs 60 PSI Fuel pressure.
According to your theoirie It should suport less HP at this high pressure.
I think what you say is right ONLY oif you pass the flow limit and duw turbulence etc you have less flow than you had with lower presure. a 3 bar should suport for sure more HP than a 2 bar FPR
Konstantin
10-03-2003, 11:26 AM
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In our systems the fuel pressure is regulated in the line flowing back to the tank. When choking the flow back to the tank to increase pressure, the pump has a bigger pressure to work against and will flow less, but a larger part of the flow will enter the engine, in stead of flowing back to the tank. So raising fuel pressure will give more fuel to the engine until you reach the point where the pumps efficiency is dropping faster than the increase in the engines share of the flow.
For a given pump you can get more flow the lower the pressure. The way to lower the pressure is to lower the restriction to the engine, i.e. bigger injectors.
Correct?
Bengt
For a given pump you can get more flow the lower the pressure. The way to lower the pressure is to lower the restriction to the engine, i.e. bigger injectors.
Correct?
Bengt
10-03-2003, 01:31 PM
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I think that in a practicle sense it would be a rare occasion (like Sean's instance) where
one would reduce pressure to increase fuel actually delivered to the cylinder. Installing larger injectors seems like a more direct way to deal with the problem.
one would reduce pressure to increase fuel actually delivered to the cylinder. Installing larger injectors seems like a more direct way to deal with the problem.
10-03-2003, 03:08 PM
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Konstantin,
Yes the Fuel Pump in that instance will support less horsepower. This is not saying that the fuel pump wont support the 968's horsepower output.
Bengt,
There are three ways to increase fuel to an engine:
Increase fuel pressure
Increase injector pulse width
larger injectors
Russ,
I don't think its that rare for 951s to exceed ~340WHP. Thats the threshold for the 951 at 3bar.
Essentially I want everyone who has a 951 to know this, so they don't make the same mistake I did. The solutions for this problem are quite easy:
1) Lower fuel Presure
OR
2) Replace the fuel pump
Additionally,
I haven't seen anyone come to this conclusion, thats why I posted this.
Sean
Yes the Fuel Pump in that instance will support less horsepower. This is not saying that the fuel pump wont support the 968's horsepower output.
Bengt,
There are three ways to increase fuel to an engine:
Increase fuel pressure
Increase injector pulse width
larger injectors
Russ,
I don't think its that rare for 951s to exceed ~340WHP. Thats the threshold for the 951 at 3bar.
Essentially I want everyone who has a 951 to know this, so they don't make the same mistake I did. The solutions for this problem are quite easy:
1) Lower fuel Presure
OR
2) Replace the fuel pump
Additionally,
I haven't seen anyone come to this conclusion, thats why I posted this.
Sean
