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Upping the fuel pressure not giving more fuel?

Old 01-24-2005, 06:32 PM
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Default Upping the fuel pressure not giving more fuel?

This was a topic on another board, and I thought perhaps you guys might know. I figured that if you upped the fuel pressure in the rail, it'll force more fuel through the injector (hence what an FMU is designed to do). Any thoughts?

Stan

Injectors are rated in FLOW RATES cc/min (volume per time), not cc (volume)

Making the theory about pushing more fuel through at higher pressure wrong.

Maximum flow is determined by the size of the opening in the injector not the pressure of the fuel in the system.

Restricting flow in the return line will force the maximum flow of the injector to be used, but after that, no more fuel will enter the engine.
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Old 01-24-2005, 07:03 PM
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Default Re:Upping the fuel pressure not giving more fuel?

I"m pretty sure injectors are rated at CC/min/fuel-pressure/duty-cycle. lol. injectors arn't being maxed out at stock fuel pressure, otherwise how else could a FMU work.
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Old 01-24-2005, 07:34 PM
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Default Re:Upping the fuel pressure not giving more fuel?

Originally Posted by Spenser
I"m pretty sure injectors are rated at CC/min/fuel-pressure/duty-cycle. lol. injectors arn't being maxed out at stock fuel pressure, otherwise how else could a FMU work.
thats a good analogy. fpr's do increase the amount of fuel going through the injectors.
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Old 01-25-2005, 05:10 AM
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Default Re:Upping the fuel pressure not giving more fuel?

Upper fuel pressure does magic alot of people dont want to believe it becasue they have never messed with it. 240 inj. are suppose to maxed out at what like 170 whp. Plenty of all motor set ups have made 220+ whp including a friends of mines b16 that put down 192 on 24o's with 60 psi and a mugen based pr3 chip.
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Old 01-25-2005, 05:54 PM
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Default Re:Upping the fuel pressure not giving more fuel?

To find the new FUEL FLOW rate after a fuel pressure change:



Example 1:

If a 240 CC injector tested at 43.5 PSI is run at 50 PSI. The result would be:



Example 2:

The horsepower value of this injector would increase by the same rate (X 1.0721), if all other engine management systems remain unchanged.

Flow rate at old pressure
240 cc/Min divided by 10.5 = 22.86 Lb/Hr

Flow rate at new pressure
257 cc/Min divided by 10.5 = 24.48 Lb/Hr




240 cc/Min X 1.0721 = 257 cc/Min
22.86 Lb/Hr X 1.0721 = 24.51 Lb/Hr
36.58 Hp X 1.0721 = 39.22 Hp



Taken from here:
http://www.rceng.com/technical.htm
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Old 01-26-2005, 09:35 AM
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Default Re:Upping the fuel pressure not giving more fuel?

I thought you were gonna say that you knew all that off the top of your head.
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Old 01-26-2005, 12:56 PM
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Default Re:Upping the fuel pressure not giving more fuel?

Well, I did...but they had a good write-up and I dislike plagarizing
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Old 01-27-2005, 01:10 PM
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Default Re:Upping the fuel pressure not giving more fuel?

from another physics stand point

Force = Mass x Acceleration
The more force you add the more acceleration/and or mass
In this case the more u increase the fuel pressure the higher the velocity of the fuel will be per unit of time. The mass of the fuel stays the same.
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