Oleo Hydraulics And Pneumatics

Hydraulic Water Pump

The Cummins Lift Pump

     CUMMINS FUEL SYSTEM

                       The Cummins Lift Pump

 

This article is number one in a six part series on the Cummins fuel system (1994 to 1998 equipped with the P pump). This applies to the Cummins 5.9 and 8.3 diesel, as they share the same lift and injection pump. During the prototype stage of designing new products for the P7100 and the Cummins fuel system, we completed hundreds of tests and thought it was necessary to share this information with diesel owners and Cummins performance enthusiasts.
 
 

THE BOSCH P7100 IS THE KING OF INJECTION PUMPS

 

 
The Cummins 12 valve enjoys incredible popularity because of its simplicity, durability, ease of maintenance and the low purchase price of the truck. Power increases are about as cheap as they get, without the complexity of electronics and fault codes. Power levels in the 400 HP+ range are not uncommon for the Cummns 12 valve, and it can still be driven on the street! The Bosch P7100 (P Pump) is the king in sled pulling competition. Several of these torque monsters exceed 1000 horsepower on only 5.9 liters !!
 
Let's dig in with some interesting comparisons on the lift pump. The Carter lift pump is a basic hydraulic piston pump. Industrial piston pumps are typically made from high strength castings while the lift pump body is made from an aluminum die casting. Piston pumps rarely use check valves, while our Cummins transfer pump uses three. The piston on a hydraulic piston pump is connected to the swash plate by a connecting rod or with the use of a ball and socket design. The piston in the Cummins lift pump is actuated by a plunger, while the return stroke is by spring pressure. Hydraulic piston pumps have precision ground cylinders and pistons. Our lift pump doesn't share any of the features of industrial pumps, but it is still is a time tested design.
 

  THE PEAK FUEL FLOW NUMBER AND IT'S NOT GOOD

 

In spite of its draw backs, the lift pump is very reliable! My 98 has 376,000 on the original Cummins lift pump. Unlike its industrial cousin, our lift pump is only 35% efficient at rated RPM. For all of the tests, rated RPM is 2500. 35% is INCEDIBLY LOW, and by the end of article number two, you will know why. With that knowledge in hand, you will be able to increase the efficiency of your system and make HP improvements more easily.
 
Let's start with a few specs on the Carter lift pump (aka the Cummins lift pump). During the development stage of our fuel products, we collected a large amount of information on the lift pump from shop manuals, diesel forums, and we requested additional information from the manufacturer. Cummins rates the pump at 52.8 GPH (gallons per hour). 52.8 divided by 60 equals .88 GPM. To be candid, the rated and actual flow ratings were very different.

Normally a piston pump's flow will increase, to a point, as RPM increases (in a well designed system). Not so with the lift pump. The numbers go down after 2200 RPM. I will explain in detail WHY this takes place, in article number two. Some of you may be thinking that the lift pump is bad because the efficiency is so low. We tested all GPM flows with a brand new lift pump and fuel filter. There were no visible air bubbles in the clear hoses leading to and from the flow meter. 35% efficiency is a very low number and we will explain why.
 
As mentioned above, we have made several hundred tests using precise flow meters and accurate pressure gauges. Sometimes our assumptions were very close and other times the readings didn't make sense. The findings that didn't match hydraulic principles, forced us to dig deep to find out why. Remember, one good test is equal to a thousand expert opinions.

SOME BASICS ON THE LIFT PUMP

 

Contrary to popular belief, the Cummins lift pump produces flow on the return stroke of the piston, not the forward stroke. Spring pressure on the return stroke, NOT the forward plunger movement, is what produces the flow in the fuel system. In article number two, you will discover why you cannot efficiently run your fuel pressure higher than 32 PSI.

HOW DO WE FIND THE PUMPS DISPLACEMENT?

 

 

How do we determine the calculated displacement of this pump. Here is a handy formula to determine cubic inch displacement of any cylinder (pump) or engine. This formula is easy and works great for finding the cubic inch displacement of your engine or any piston pump. Bore x bore x stroke x .7854 x number of cylinders = displacement in cubic inches.

1.180 x 1.180 x .25 x .7854 (constant) x 1 = .273 in³.

For every stroke of the piston, it should produce aproximetely 1/4 cubic inch of fuel flow.

 

EASY FORMULA TO CALCULATE GPM

We now know that our lift pump displaces .273 cubic inches. How do we figure the calculated GPM flow of the lift pump? The formula is very easy.  .273 in³ x pumping cycles per minute (remember that the pump is at half speed of the crank) divided by 231 (cubic inches per gallon of water) = GPM.

.273 x 1250 (half speed of 2500 rated RPM) = 341 divided by 231 = 1.477 GPM. The carter lift pump is calculated at 1.477 (rounded up to 1.48) GPM at 100% efficiency.
 

AND NOW THE GOOD STUFF!

 

This photo shows the GPM flow at idle, which is 800 RPM. We are now going to use the formulas. Please bear with me, it's straight forward, and rather easy.  .3 GPM meter reading x 1.0495 = .315 corrected GPM. This is the actual flow from the Carter lift pump at idle. What is the calculated flow of this piston pump? 400(half engine speed) x .273 cubic inches = 109. 109 divided by 231 (cubic inches in a gallon) = .47 GPM. At 100% efficiency, our lift pump should flow .47 GPM. So, we now take .315 (actual flow) divided by .47 (calculated) = .67 or 67% efficient. Not the best efficiency number, but OK.

This is the GPM flow at 1500 RPM. My apologies for the faint image.  .4 x 1.0495 equals .42 GPM. If this pump were 100% efficient, it would flow .89 GPM. At 1500 RPM our Cummins transfer pump is only 47% efficient. .42 (actual) divided by .89 (calculated GPM flow) = .47 or 47%. Are you starting to see a trend? As the RPM increases, the efficiency goes down !!

THE NUMBERS GET WORSE !

 

 

At 2500 RPM, we are flowing .52 GPM (.5 x 1.0495 correction) At 2500 RPM, the efficiency has dropped to 35%. That's .07 GPM less than at 2200 RPM.  We reached peak flow of .59 GPM at 2200 and everything thereafter is going down hill. If you installed a 4000 RPM governer in your P pump, your fuel flow is in the neighborhood of .44 GPM. My mathematition son, Curtis, arrived at this number by using calculus.

So, our Cummins lift pump is capable of flowing 1.48 gallons per minute of diesel fuel at 2500 RPM. I'm here to tell you that the Carter lift pump is no way near its calculated GPM flow of 1.48. Not even close!! The Carter lift pump only flows .52 GPM at 2500 RPM. That equates to ONLY 35% efficiency. It flows .59 GPM at 2200 RPM, which is 45% efficient. To calculate efficiency take the actual GPM divided by calculated GPM.  

.59 divided by 1.3 GPM = .45 or 45% efficient. That's at peak fuel flow. At rated RPM it's much worse!

OUR LIFT PUMP NEEDS HELP!

800 RPM           .315 Actual GPM       .47 Calculated GPM           67% Efficiency
1500 RPM         .42 Actual GPM         .89 Calcualted GPM           47% Efficiency    
2200 RPM              .59 Actual GPM          1.3 Calculated GPM           45% Efficiency
2500 RPM              .52 Actual GPM          1.48 Calculated GPM         35% Efficiency  
  
The following numbers were arrived at by using calculus.

4000 RPM         .44 GPM                   2.36 Calculated GPM         18.6% Efficiency

From an industrial point of view, this lift pump would have to be replaced with a better, more efficient design. Industrial piston pumps are a minimum of 85% efficient. Some models are 90 to 95% efficient. There are several reasons why the efficiency of the Cummins lift pump is so low and it's not the pump's fault !! The secrets on how to improve your fuel system will be revealed in article number two.

When the fuel system on the 94 to 98 Dodge Cummins was designed, they failed to follow basic hydraulic principles. This failure (or intended design to limit HP) is the reason why the lift pump only flows 35% of it's capability at 2500 RPM.

We will cover the reasons why the efficiency goes down as the RPM goes up, and what can be done about it, in article number two. New articles will be published about every 2 weeks. If you want to subscribe to the series of articles, drop me a line at robsr@torkteknology.com and I will send the series to you FREE of charge. When i say free, that's exactly what I mean! This information series is intended to provide accurate and tested information to the diesel community.

Rob Parelli Sr
Torkteknology.com

About the Author

I operate Tork Teknology, a company that specializes in finding solutions to the pickup diesel market. We made hundreds of tests and we want to share the knowledge.

Hydraulic Water Pump For a Fountain, Codex Atlanticus, 1478-1518 $49.99 Leonardo da Vinci Hydraulic Water Pump For a Fountain, Codex Atlanticus, 1478-1518 - Giclee Print

Hydraulic RAM $70.1 High Quality Content by WIKIPEDIA articles A hydraulic ram, or hydram, is a cyclic water pump powered by hydropower. It functions as a hydraulic transformer that takes in water at one hydraulic head (pressure) and flowrate, and outputs water at a higher hydraulichead and lower flowrate. The device utilizes the water hammer effect to develop pressure that allows a portion of the input water that powers the pump to be lifted to a point higher than where the water originally started. The hydraulic ram is sometimes used in remote areas, where there is both a source of lowhead hydropower, and a need for pumping water to a destination higher in elevation than the source. In this situation, the ram is often useful, since it requires no outside source of power other than the kinetic energy of water. Author: Miller, Frederic P./ Vandome, Agnes F./ McBrewster, John Binding Type: Paperback Number of Pages: 84 Publication Date: 2010/07/28 Language: English Dimensions: 5.98 x 9.01 x 0.20 inches

Water Pump Cover with Impeller $170.99 CNC-machined billet aluminum water pump cover from Pro Circuit features a separate oil pump cover for easy access Designed with an impeller to increase water flow and reduce hydraulic friction and cavitation No-fuss installation Includes all gaskets Actual product may vary from web image Made in the U.S.A.

Water Pump Cover $115.99 Designed by Boyesen Engineering to increase water flow and reduce hydraulic friction for a cooler, more constant temperature Less horsepower loss during the late stages of a race Extends engine life Water pump covers feature a super tough, powder-coated finish that resists weathering and wear & tear Actual product may vary from web image Made in the U.S.A.

Water Pump Impeller $71.99 Designed by Boyesen Engineering to increase water flow and reduce hydraulic friction for a cooler, more constant temperature Less horsepower loss during the late stages of a race Extends engine life Impellers are designed to minimize cavitation Actual product may vary from web image Made in the U.S.A.

Cam Spray 5055HYD Cold Water Hydraulic Pressure Washer $4792.99 Cam Spray is a leading company of industrial water pumps washing systems commercial pressure washers and wholesale drain cleaning equipment. Over the last thirty years we developed a complete line of commercial and industrial pressure washers drain jetting equipment trailer jetters water pumps and other products for industrial and commercial applications. At Cam Spray we take pride in producing high quality equipment that is used by professionals to get their jobs done the right way on time and on budget. Producing 5.5 gallons of water per minute (GPM) this hydraulic powered pressure washer is able to quickly clean large areas like driveways and home siding. It features a triplex plunger pump with ceramic plungers and stainless steel valves that helps extend the overall life of the pump and the seals. This pressure washer connects to most hydraulic power sources and is able to transform hydraulic pressure into water pressure to help clean tough surfaces. Transforms hydraulic pressure to water pressure. Triplex plunger pump with ceramic plungers and stainless steel valves. Nonmarking hose with trigger gun. Heavy duty wand with quick change tips. Attaches to most hydraulic power sources.

Air/Hydraulic Foot Pump $498.95 With shop air as the energy source, this pump has the power and oil capacity (80 cu. in. usable oil) to drive even the large 55-ton rams. It is an ideal all-around power source for dozens of body, frame, and alignment applications. It can be used with a variety of rams, presses, and hydraulic pullers operating at up to 10,000 PSI. An internal relief valve protects the hydraulic components regardless of hydraulic pressure. In addition, a two-stage release mechanism gives fast or metered ram return while reducing hydraulic shock. These pumps require 9 c.f.m. at 100 PSI air pressure at the pump. Develops 10,000 PSI at 100 PSI air pressure. 3/8'' NPTF oil port. 98 cu. in. usable oil capacity in plastic reservoir. Wt., 15 lbs., 3 oz.

Water Pump $39.99 Water Pump - Giclee Print

OTC Stinger Air/Hydraulic Pump $304.95 ? Pump operates on shop air (40-100 PSI/ 9 scfm con-sumption), driving a variety of sgl. acting rams, presses, and hydraulic pullers operating at up to 10,000 PSI? Internal relief valve protects the hydraulic components regardless of hydraulic pressure? Two-stage release mechanism gives fast or metered ram return while reducing hydraulic shock? Pump, hold or release load with foot lever control? Reservoir capacity is 105 cu. in. (98 cu. in. usable)

Garmin 2-LITER Pump Kit F/ Hydraulic Steer 0101109700 $946.49 Garmin 2-LITER Pump Kit F/ Hydraulic Steer 0101109700

Water Wheels or Hydraulic Motors $26.07 This book is a thorough description of water wheels from the engineering standpoint. Early turbines like the Fourneyron, Fontaine, and others are also covered in this book. Originally published in 1869, this engineering text was used at the School of Civil Engineers in Paris. The translation was done by Lieutenant F. A. Mahan of the U.S. Corps of Engineers.Amongst the topics covered are: preliminary ideas of hydraulic motors, water wheels with a horizontal axle, water wheels with vertical axles, turbines, machines for raising water, spiral noria, and pumps. Author: Bresse, Jacques Antoine Charles Binding Type: Paperback Number of Pages: 168 Publication Date: 2003/07/22 Language: English Dimensions: 8.00 x 5.00 x 0.38 inches

OTC OTC2510A Stinger Air/Hydraulic Pump $400.05 Pump operates on shop air (40100 PSI/ 9 scfm consumption) driving a variety of sgl. acting rams presses and hydraulic pullers operating at up to 10 000 PSI. Internal relief valve protects the hydraulic components regardless of hydraulic pressure. Twostage release mechanism gives fast or metered ram return while reducing hydraulic shock. Pump hold or release load with foot lever control. Reservoir capacity is 105 cu. in. (98 cu. in. usable).

The Water Pump $34.99 Jean-Baptiste-Camille Corot The Water Pump - Giclee Print

2007 D&D 8 Hydraulic Pump Package $3000 John Deere 4045 Engine, Single Axle Trailer Chassis, Pintle Ring. Seller's Comments: Power Unit, Pump Head, & Hydraulic Line Set

2007 D&D 6 Hydraulic Pump Package $3000 John Deere 4045DF270 Engine, Single Axle Trailer Chassis, Pintle Ring. Seller's Comments: Power Unit, Pump Head, & Hydraulic Line Set

Water pump $316 Buy a water pump and help provide clean, safe drinking water for a whole community.

Water Pump Pulley $36.99 Water Pump Pulley

Water Pump Seal $2.99 Water Pump Seal;

Water Pump Bypass Hose $6.99 Water Pump Bypass Hose;

Water Pump Gasket $3.99 Water Pump Gasket;

Water Pump Fiber Washer $2.99 Water Pump Fiber Washer;

Hydraulic Funk $14.99 Track Listing: 1. Pump up & Down, 2. Pumpin' It Up, 3. Copycat, 4. Hydraulic Pump, 5. Throw Your Hands up in the Air, 6. Generator Pop, 7. Acupuncture, 8. One of Those Summers, 9. Catch a Keeper, 10. Pumpin' You Is So Easy, 11. Generator Pop - (mix), 12. Hydraulic Pump, Pts. 1-2 - (12" Mix)

1993 Mack DM690S Water Truck $6000 East Brand Water Tank, Hydraulic Driven Water Pump, 3 Spray Nozzles, Spray Bar, Mack EM7-250 Engine, Manual Transmission, Camelback Suspension

Advances in Water Resources and Hydraulic Engineering $1349 "Advances in Water Resources and Hydraulic Engineering - Proceedings of 16th IAHR-APD Congress and 3rd Symposium of IAHR-ISHS" discusses some serious problems of sustainable development of human society related to water resources, disaster caused by flooding or draught, environment and ecology, and introduces latest research in river engineering and fluvial processes, estuarine and coastal hydraulics, hydraulic structures and hydropower hydraulics, etc. These proceedings cover new research achievements in the Asian-Pacific region in water resources, environmental ecology, river and coastal engineering, which are especially important for developing countries all over the world. These proceedings serve as a reference for researchers in the field of water resources, water quality, water pollution and water ecology. Changkuan Zhang and Hongwu Tang both are professors at Hohai University, China.