Full Answer
What does 255 LPH mean on a fuel pump?
These assemblies use a Walbro 255 lph fuel pump. 255 liters is the volume of fuel that the pump will flow at 40 psi. While this is a more accurate rating than a free flow rating, the 255 lph rating is only accurate if you are running your engine at 40 psi and your pump is being supplied with 13 volts. Sometimes pumps are rated based on pressure.
What is the flow rate of a fuel pump?
Fuel Pumps are sized by flow rate. Flow rate is the amount of fuel a pump can supply over time. It is usually measured in gallons per hour (gph) or liters per hour (lph). How do I know what flow rate I need? Minimum flow rate needs can be calculated by multiplying peak horsepower by BSFC. This will give you fuel usage in lbs./hr. For example:
How are fuel pumps rated?
Different fuel pump manufacturers rate their fuel pumps in different ways. Some manufacturers for instance rate their fuel pumps at free flow. The problem with this rating is that no fuel system operates at zero psi. Other fuel pump companies may rate their fuel pumps at a given psi.
How much HP can a 50 gph fuel pump support?
For example if your pump flows at 50 gph it should be able to support a 500 hp engine (50 x 10 = 500). However, to actually know the gph you must also consider the fuel pressure required for your engine.
How do I know if my fuel pump is Lph?
How do I know what flow rate I need?500 X 0.5 = 250 lbs./hr. A gallon of fuel weighs 6 lbs. To get gph divide lbs./hr. by 6.250 lbs./hr. ÷ 6 = 41.67 gph. A liter of fuel weighs about 1.6 lbs. ... 250 lbs./hr. ÷ 1.6 = 156.25 lph. You need the minimum flow rate at your fuel system's operating pressure.
How many LPH is a 1200 hp?
To estimate flow, simply multiply 1,200 horsepower x 0.9 BSFC = 1,080 pounds of projected fuel per hour.
What is the stock fuel pump pressure?
Required fuel pressure can vary depending on your vehicle's engine and fuel system. Carbureted engines may require as little as 28 kPa (4 PSI), while modern multipoint fuel injected high-performance engines can require as much as 414 kPa (60 PSI).
What PSI is 255 LPH?
43.5 PSIDescription. The Walbro 255 liter per hour (LPH) high pressure (HP) fuel pump is the most popular in-tank fuel pump upgrade for the NSX. The pump flows 255 LPH of fuel at a base pressure of 43.5 PSI at 13.5 volts (an increase of approximately 65% over the factory pump).
How many Lph do you need for 500hp?
Horsepower A good estimator of volume to power is approximately 10 hp per gallon or 2.64 hp per liter. For example if your pump flows at 50 gph it should be able to support a 500 hp engine (50 x 10 = 500). However, to actually know the gph you must also consider the fuel pressure required for your engine.
Can a fuel pump be too powerful?
Fuel pressure to the carburetor will range from 4 psi to 7 psi, with some vehicles using higher pressure. Using the wrong fuel pump that delivers excess pressure can cause problems ranging from poor performance and lower gas mileage to flooding and carburetor damage.
Does fuel pump increase horsepower?
The technical answer is yes; fuel injectors can add 10 extra horsepower at peak. However, for some car owners, that minimal difference does not offset the increased cost and complexity of switching to fuel injectors or upgrading the existing stock fuel injectors.
What is stock fuel pressure on a LS1?
For those of you not familiar with the LS1 fuel system, a typical working setup should run 58 psi of base fuel pressure, where as ours was around 52 and would drop well into the 40s under mild acceleration.
What psi should mechanical fuel pump be?
The output pressure of a mechanical fuel pump is typically quite low: only 4 to 10 psi. But little pressure is needed to keep a carburetor supplied with fuel.
How much HP will a Walbro 450 support?
The conservative horsepower rating of this pump is that this pump can support 800 HP on 12 volts and up to 950 HP on 13.5 volts.
What does Lph mean on a fuel pump?
liters per hourElectric fuel pumps for EFI applications are rated in liters per hour, or lph. Factory electric fuel pumps can flow around 180-190 lph in early EFI cars, and high-performance, late-model Vette pumps can flow more than the popular "255-lph" aftermarket fuel pumps.
How much horsepower will a 340LPH fuel pump support?
1,000 HPThe AEM 340LPH High Flow In-Tank Fuel Pump (PN 50-1000) flows 340 lph (84 gph) at 40 PSI and is capable of supporting over 1,000 HP at 43 PSI.
What is the minimum flow rate for a fuel injection system?
You need the minimum flow rate at your fuel system’s operating pressure. For Carburetors, this is between 4-7.5 psi. Fuel Injectionwill usually be between 35-65 psi.
How many volts does a car pump use?
The green and blue lines show how voltage affects flow rate. Most cars with a charging system and appropriate wiring can supply 13.5 volts to the pump. It’s a good idea to check voltage at the pump to verify this.
How to calculate minimum flow rate?
Minimum flow rate needs can be calculated by multiplying peak horsepower by BSFC. This will give you fuel usage in lbs./hr. For example:
How do I know what flow rate I need?
Minimum flow rate needs can be calculated by multiplying peak horsepower by BSFC. This will give you fuel usage in lbs./hr. For example:
What voltage should a fuel pump be?
The more voltage you feed a pump, the faster it spins which, obviously, will put out more fuel. Rating a fuel pump at 12 volts then, should offer a fairly conservative fuel flow rating allowing you to safely determine the pump’s ability to supply an adequate amount of fuel for a particular application.
What happens if you don't have a fuel pump?
If you don't have enough fuel pump, you'll run lean at the top end, which if severe enough can lead to melting holes in your pistons. Pull a spark plug, and look at it closely for little silver spots (melted aluminum).
Why is the power level reduced in forced induction engines?
Note: For forced induction engines, the above power levels will be reduced because as the pressure required by the pump increases, the flow decreases. In order to do proper fuel pump sizing, a fuel pump map is required, which shows flow rate versus delivery pressure.
Is running lean better than fat?
I doubt its hurting performance, although you may be running lean at the top end. Unsafe, but lean actually is a bit more powerful than fat
Do engines require a certain weight of fuel?
As previously mentioned, engines actually require a certain WEIGHT of fuel, NOT a certain VOLUME of fuel per horsepower. This can offer a bit of confusion since most fuel pumps are rated by volume, and not by weight.
How to choose a fuel pump?
The better way to select a fuel pump to use in your fuel system is to consider three factors: 1 How much horsepower your engine will produce. 2 What fuel pressure is required for your engine. 3 How much voltage is supplied to your fuel pump when the engine is running.
How much horsepower does a gas pump need?
A good estimator of volume to power is approximately 10 hp per gallon or 2.64 hp per liter. For example if your pump flows at 50 gph it should be able to support a 500 hp engine (50 x 10 = 500). However, to actually know the gph you must also consider the fuel pressure required for your engine.
How much horsepower does a carburetor pump have?
Again assuming 10 psi and 13.5 volts the chart shows that the pump will flow at 81 gph. So this same pump will support 810 horsepower on a carbureted car (81 x 10 = 810).
How much pressure does a Walbro pump have?
Sometimes pumps are rated based on pressure. For example the Walbro 255 lph pump is capable of producing a pressure in excess of 100 psi. While this information may be relevant, it only provides one detail about a fuel pumps capability.
What increases the flow rate of a fuel pump?
3. Voltage. Fuel pumps have different flow rates at different voltages. As voltage increases so does the speed of the fuel pump which will increase the flow of a pump at any given pressure. Because of this it is good practice to see how a pump is rated at a given voltage.
How many HP can a 50 gph pump support?
For example if your pump flows at 50 gph it should be able to support a 500 hp engine (50 x 10 = 500). However, to actually know the gph you must also consider the fuel pressure required for your engine. 2. Fuel Pressure. Different engines require different fuel pressure.
Why is it important to know what the max pressure your engine will require?
It is important to know what the max pressure your engine will require because fuel pressure has a large effect on how much flow a pump can produce. A fuel pump will flow at its highest volume when there is no pressure (free flow). As fuel pressure increases, fuel flow decreases.
