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Understanding and Modifying High-Pressure Fuel Pumps for Cummins, Duramax, and Power Stroke Engines

Posted on 1/12/2016 4:30:01 PM

There are many important components in the modern diesel-powered pickup trucks, cars, and SUVs.Turbochargers, for instance, are a given among passenger vehicles, as the painfully slow naturally aspirated diesels of the past are all but forgotten. We could find another vital components is the common rail fuel injection which could be found in  every new road vehicle produced in the U.S. and Europe, as well as in most off-road platforms.So what's exactly the common rail fuel injection system is?

how the common rail injection system works

 
Here is simple view how the common-rail injection system works.Comparing to the traditionl systems which have one line from the high-pressure pump to each injector,
high-pressure fuel is fed into a rail (inline engines) or rails ("V" engines), with a small line from the rails feeding each injector.The timing and quantity of fuel is counted and decided by the injector and engine's ECU.
 
In the old direct injection system,fuel was fed (at low pressure/5 to 20 psi) from a fuel pump (or lift pump) to an injection pump, which then ramped up the pressure to 15,000 to 25,000 psi, before flowing through separate lines, into the injectors and the engine. 
 
This immense amount of pressure is needed because modern diesels are direct-injection engines; that is, the fuel is injected separately from the air, instead of mixing with it before the combustion chamber.As soon as fuel leaves the nozzle of the injector, it starts burning and creating power.Meanwhile there are many defects for this injection system.like the noise of engine and also variable timing.Even the legendary Bosch P7100 pump in cummins engine lacks variable timing.So the common-rail injection is highly required to come out now.
 
With the common-rail injection system,high-pressure fuel is pumped through and stored in a rail that feeds many injectors at once, instead of through a pump that directly feeds an injector. 
The actual injection events transpire with electronically controlled injectors, rather than simple poppet-style units. While this adds a lot of complexity to the injectors themselves, multiple injection events, variable timing, and precise control are now possible.
 
CP3 vs. CP4.2 vs. K16
There are three different types of common high-pressure pumps used on ’01-to-current GMs, ’03-and-up Rams, and ’08-and-newer Fords. Bosch CP3 pump,a radial-piston pump,is used in the ’01-to-’10 Duramax-powered trucks and ’03-current Rams.It can supply up to 29,000 psi in some applications.Maybe it is recognized to be the most popular modified high-pressure pump on the market.
 
Secondly we are going to talk about BOSCH CP4,which is used in ’11-to-present Power Stroke and Duramax engines.It is more advanced pump comparing to CP3,flowing about 20 percent less fuel with external high-pressure circuits and a maximum pressure of 29,000 psi.
 
Last but not least, is the big daddy of the group, the Siemens VDO K16,which we could find on ’08-to-’10 Ford F-250s and F-350s. One of its feature is to compound turbochargers.The other is to offer impressive power, with only simple programming in the 6.4L engines.It is also because of K16 pump,it could reach the maximum pressure at 24,650 psi.In the same time the winner of Ford engine also bring its reason to this pump's volume.
6.4L Ford engines
 
In order to offer enough fuel to support power levels much greater than stock,the electronically controlled common-rail injection systems could also be modified like older mechanical systems.While exactly how much an OEM fuel system can support varies, in GM, Ford, and Ram ¾- and 1-ton applications, most pumps can handle 500 to 600 rwhp before they'll start draining the rail and pressure drops.
 
What's "Draining the Rail(s)?"
Fuel pressure and volume are related in a common-rail injection system. If the injectors demand a much larger fuel quantity than stock, the factory pump and rail system might be able to keep up, but at a lower pressure. While this may not sound bad, the lower injection pressure actually leaves a lot of horsepower on the table, produces more smoke, and creates more heat. When looking for maximum performance, it's crucial to keep rail pressure as high as possible. Doing so ensures power stays up, and it helps keep smoke down. We’ve seen a gain of more than 100 hp at the rear tires (on an 800hp truck), when injection pressure is increased from 22,000 psi to 26,000 psi. Yes, injection pressure is a huge factor in performance.
 
Twin Pumps
In order to increase the volume in a common-rail system,the best solution is to install a second twin pump which we could see used in Fords, GMs, and Rams.Because by doing this,the twin pumps could double the horsepower to as much as 1,000 to 1,200 hp immediately.Installing service could be available in ATS Diesel Performance,China Balin Parts Plant,Industrial Injection,etc.
 
Modified Pumps
There are another solution is to increase the existing high-pressure pumps for more flow and more pressure in some diesel shops like Industrial Injection without adding a second pump.For example,the CP3 stroker pumps can flow 800 to 1,000 hp with just a single pump.
 
Beyond Twin Pumps
Although modified CP3s provide much more flow and pressure than the stock versions—even when using twin stroker pumps (which is quite a cash outlay)—maintaining rail pressure when performance reaches the 1,500 to 2,000hp range is difficult.
Recently, we've seen many Duramax and Cummins combinations equipped with three, four, or even five CP3s, in order to try and keep up with the mammoth 400- to 600-percent-over injectors that are now being installed in these engines.
 
The Future
Although we can't know what will happen to multiple pumps in the future,we are sure that the common rail injection systems will stay with us for a long time.Because in order to meet the performance and injection pressure demand,much more common rail parts manufacture like China Balin Parts Plant,is working hard to develop new products in this industry.

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