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Fuel Pump Comparison Test

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RSP Fuel Pump Battle



Fuel Pump Flow Comparison Test

With the recent release of Aeromotive's popular new Stealth 340lph in-tank fuel pump, we wondered, which of the 4 most popularly sold pumps on the market performed the best. We compared 4 fuel pumps total consisting of 3 in-tank pumps and 1 inline Pump:

  • Bosch 044 (inline)
  • Denso 290lph Supra Pump (in tank)
  • Walbro 255lph GSS342 (in tank)
  • Aeromotive 11142 340lph (in tank)

 


The Test

We sent one of each pump out to get tested at the respected, independant, and fully capable test facilty at Kinsler Fuel Injection. All tests were completed using a Sorenson DCS 20-50 power supply with Fluike 73 series D.V.O.M. for pump terminal voltage monitor, and a Fischer Porter tapered tube flow meter and Ashcroft temperature compensated Pressure Gauge with +/- .25% accuracy. The flow and amperage draw of each pump was tested at pressure levels of 40psi to 105psi in 5psi increments, the results were quite surprising. The voltage was held constant at 13.2V (the industry standard for fuel pump testing, helping to compare apples to apples)

Test Results

Test Voltage: 13.2V

What does this mean for you?

Read this chart as a list of rows. Each row represents how each of the 4 pumps performed at a specific fuel pressure. They are color coded per row by performance in order of Green=Best, to Red=Worst. The performance got worse as the color gets hotter in each row.

  • Green: Highest Flow
  • Yellow: Second Highest Flow
  • Orange: Third Highest Flow
  • Red: Worst Flow

According to Injector Manufacturers, 43.5psi is considered "Base Fuel Pressure" ... this is how much pressure your regulator will be set to with the vacuum signal unplugged. For the sake of understanding this data, we will round "base fuel pressure" down to 40psi, and from here on out in this article, "base fuel pressure" will refer to 40psi.

All Motor Cars

In an all-motor car, your fuel pressure will most likely not ever exceed "base fuel pressure" because your vacuum signal will never see a positive pressure reading. The most extreme pressure condition your fuel system will see is at base fuel pressure (40psi). So we scroll to the 40psi row of the table. At 40psi we see:

Flow @ 40psi Fuel Pressure (Base)
  • Green: Aeromotive 11142: Highest Flow (500 lb/hr)
  • Yellow: Bosch 044: Second Highest Flow (465 lb/hr)
  • Orange: Denso Supra Pump: Third Highest Flow (440 lb/hr)
  • Red: Walbro 255: Worst Flow (368 lb/hr)

Again, what does this mean for you, the person deciding on a fuel pump? Lets convert this Fuel Flow data into something we understand: Horsepower. And to do that we will use some widely accepted conventions and assumptions layed out here by Garrett, and may others before them. Don't rely on these numbers exactly, as every engine's VE will be different. Some engines will be able to make more power with a specific pump than others based on their efficiency (for example, 2valve vs 4valve heads, etc)

Running through some quick math (equations can found on the Garrett Link above), 500lb/hr of fuel (gasoline) at 40psi fuel pressure, maintaining an air/fuel ratio of 12.0:1 on an all motor car is enough fuel to support ~1000hp. So depending on what engine platform you are working with your single Aeromotive 11142 in-tank pump could potentially get you all the way up to 1000hp. Below, I will repeat the 40psi list in terms of horsepower.

Horsepower @ 40psi Fuel Pressure (Base)
  • Green: Aeromotive 11142: Highest Flow (~1000hp)
  • Yellow: Bosch 044: Second Highest Flow (~930hp)
  • Orange: Denso Supra Pump: Third Highest Flow (~880hp)
  • Red: Walbro 255: Worst Flow (~736hp)

And there you have it. A horsepower rating for each pump based on measured flow characteristics.

If you have any questions about anything in this article, or are interested in purchasing any parts, please feel free to contact us at sales@rsrace.com

Turbo / Supercharged Cars

In a turbo car, if you have the boost controller set to 25psi, at full boost, your pump is producing 65psi through the regulator. So if we take a look at which pump will perform the best at 25psi in your turbo car, we scroll down to the 65psi row of the table. At 65psi of fuel pressure we see:

Flow @ 65psi Fuel Pressure (25psi of Boost if Base is 40psi)
  • Green: Bosch 044: Highest Flow (430 lb/hr)
  • Yellow: Aeromotive 11142: Second Highest Flow (410 lb/hr)
  • Orange: Denso Supra Pump: Third Highest Flow (330 lb/hr)
  • Red: Walbro 255: Worst Flow (300 lb/hr)

Again, what does this mean for you, the person deciding on a fuel pump? Again, lets convert this Fuel Flow data into something we understand: Horsepower. And to do that we will use some widely accepted conventions and assumptions layed out here by Garrett, and may others before them...again. Don't rely on these numbers exactly, as every engine's VE will be different. Some engines will be able to make more power with a specific pump than others based on their efficiency (for example, 2valve vs 4valve heads, etc)

Running through some quick math (equations can found on the Garrett Link above), 430lb/hr of fuel (gasoline) at 65psi fuel pressure, maintaining an air/fuel ratio of 11.5:1 on a forced induction motor running 25psi of boost is enough fuel to support ~824hp. So depending on what engine platform you are working with your inline Bosch 044 pump could potentially get you all the way up to ~824hp. Below, I will repeat the 65psi list in terms of horsepower.

Horsepower @ 65psi Fuel Pressure (25psi of Boost if Base is 40psi)
  • Green: Bosch 044: Highest Flow (~824hp)
  • Yellow: Aeromotive 11142: Second Highest Flow (~785hp)
  • Orange: Denso Supra Pump: Third Highest Flow (~632hp)
  • Red: Walbro 255: Worst Flow (~575hp)

Before you ask "...but what if im running more/less than 25psi of boost?" Well i've gone through and modified the pump flow table by converting all of the flow numbers at each pressure into horspower. The assumptions being that you are using gasoline at an air/fuel ratio of 11.5:1 with the base fuel pressure set to 40psi ... if you want to calculate these numbers for a different fuel or a different air/fuel ratio, take a look at the equations in the link to Garrett's website above.


If you have any questions about anything in this article, or are interested in purchasing any parts, please feel free to contact us at sales@rsrace.com

Test Voltage: 13.2V


Amperage

Up until this point in this test we have only discussed flow performance of each pump. There is at least one other characteristic you should be concerned with when selecting a fuel pump: Amperage. Ideally you would want a pump that pulls less amperage, putting less load on your vehicles electrical system.

The only real point worth mentioning in this part of the test is that the Denso pump pulls considerably more amps than all of the other pumps, so it puts the highest load on the vehicles electrical system.



Bosch 044 In-Line Fuel Pump Review

This pump clearly out performed all of the other pumps at any fuel pressure level over 50psi (~10psi of boost). If you have a turbo/supercharged car and you are looking for the highest horsepower potential from a single pump, this is your best option.

HOWEVER, this is a universal in-line fuel pump, not an in-tank fuel pump, so it will take some considerable modifications to your fuel system to make this pump work. This pump comes without any installation hardware or setup kit so right off the bat, fittings will need to be purchased. Your fuel tank will either have to be modified to add a lower sump, allowing the fuel to gravity feed into the in-line pump, or be completely replaced by a fuel cell with a lower sump. This is not a feasable solution for many of us who still drive our toys daily. Another option is to run 1 in-tank pump as a feeder pump, supplying fuel into a Bosch 044 in-line fuel pump. To do this correctly, it requires additional components like a surge tank (or swirl pot) between the in-tank pump and the in-line pump. This setup is definitely do-able, but know that it is much more in-depth of a solution than just dropping a replacement pump in your tank.

What comes in the Box?
  • Bosch 044 Fuel Pump (in-line)


If you have any questions about anything in this article, or are interested in purchasing any parts, please feel free to contact us at sales@rsrace.com



Aeromotive 340lph Stealth In-Tank Fuel Pump Review

From the chart you can see that up to 50psi of fuel pressure, this tiny in-tank pump out-performed even the mighty Bosch 044 in-line pump. At base fuel pressure (40psi-50psi) its clear that this pump easily out performs all of the others, making it the highest flowing pump for a naturally aspirated setup, and the highest flowing IN-TANK pump for forced induction setups as well.

According to the math, at base fuel pressure (40psi), using gasoline, assuming an 12.0:1 air/fuel rato, this pump can support ~1000hp which is important for you all motor guys. For those of you in the 15-30psi boost range (most turbo guys), assuming gasoline at a 11.5:1 air fuel ratio, this pump can still support about 747hp-843hp. Thats a pretty impressive number for a single pump.

What we found more interesting than that however, is this pump's performance at higher fuel pressures. It is clearly the highest flowing in-tank pump available at ANY fuel pressure. It's small physical size makes it a perfect candidate for dual and triple pump setups popular in high horsepower forced induction fuel systems. It is a universal in-tank pump, and thankfully Aeromotive has included a universal setup kit which includes everything you would need to install the pump. The included setup kit even comes with an insulation sleeve that will safely isolate multiple pumps in a single hanger. It is quite literally a full pump solution in the box without the need to purchase any additional parts.

What comes in the Box?
  • Aeromotive 340lph Stealth Fuel Pump (in-tank)
  • Electrical Connector with Pig Tails
  • Rubber Fuel Hose
  • 2x Fuel Hose Clamps
  • Rubber Fitment Sleevek
  • Rubber Fitment Boot
  • Fuel Filter Sock


If you have any questions about anything in this article, or are interested in purchasing any parts, please feel free to contact us at sales@rsrace.com



Denso 300lph In-Tank (OEM Supra) Fuel Pump Review

This pump was always been considered an upgrade to the popular Walbro 255 in-tank pump and from the test results we now see that this is true all the way up to 75psi of fuel pressure (about 35psi of boost) which most people wont exceed in their forced induction setups.

What is more important to notice about the performance of this pump is how quickly the flow performance falls off as fuel pressure is increased. At 70psi of fuel pressure (about 30psi of boost), this pump will support 575hp. Some engine/turbo setups wont exceed 575hp at 30psi, so this pump could be perfectly fine in terms of flow capability for many setups, however if your engine/turbo combination will make more than 575hp at 30psi of boost, this pump is not the best choice for you.

What comes in the Box?
  • Denso 300lph (OEM Supra) Fuel Pump (in-tank)
  • Rubber Fuel Hose
  • 2x Fuel Hose Clamps
  • Fuel Filter Sock


If you have any questions about anything in this article, or are interested in purchasing any parts, please feel free to contact us at sales@rsrace.com



Walbro 255lph GSS342 In-Tank Fuel Pump Review

This pump is easily the most popular fuel pump in the tuner community by far, and has been for years. It has done well by very many people over the years, and is perfectly suitable for the majority of the masses modifying their cars. Your average enthusiast does not exceed 600hp at 20psi of boost, or 700hp all motor. The amperage characteristics are the lowest of the group giving it the least impact on your electrical system's resources. Its also the least expensive of the group, which frees up money for other fuel system components like injectors.

The Walbro pump itself does not come with a setup kit, it needs to be purchased separately. However, many retailers bundle the pump and setup kit together (like us) to reduce the amount of work you have to put into shopping. The setup kits are vehicle specific, but almost all of them come with a fuel filter sock, electrical connector, rubber hose, and clamps

What comes in the Box?
  • Walbro 255lph GSS342 Fuel Pump (in-tank)
  • Setup Kit (Contents are Vehicle Specific)


If you have any questions about anything in this article, or are interested in purchasing any parts, please feel free to contact us at sales@rsrace.com



CONCLUSION

This test ranked 4 popular fuel pumps in terms of flow performance and amperage draw. Whats important to remember is that not every setup needs the biggest baddest fuel pump on the market. We have provided you with a mathmatically calculated engine horsepower chart to help you decide which pump will best suit your needs. For example, although it didnt shine in comparison to the Bosch, the Walbro 255 is not a bad pump by any means. If you're not going to make 1000hp all motor or 820hp at 20psi, you just might not need that much fuel pump, and spending more on a fuel pump bigger than what you need would be a waste of money.

There are some important things to remember when reviewing this information. Todays tuner community talks about horsepower in terms of chassis dyno numbers. All of the horsepower numbers calculated in this article are engine horsepower numbers that do not take parasitic loss from drivetrain and other components into account.

Also, every engine is different, a brand new Acura K20 16valve 4cylinder very well may be able to make more power on a single pump than a 20 year old Volkswagen 8valve engine. These hosepower numbers should be used as an illustration, and not as a rock solid limit of capability.

Please remember this article makes some assumptions on fuel type and target air fuel ratios. If you post this link as a reference in a specific conversation, please be sure that these assumptions can be applied to that particular case.

If you have any questions about anything in this article, or are interested in purchasing any parts, please feel free to contact us at sales@rsrace.com