Powerjection III Tech

Technical Information

Various Types of Injection
With today's aftermarket injection systems there are two basic types. The throttle body style of injection has the injectors mounted in the throttle body itself. This usually limits this type of injection to four injectors. The other style called "port injection" has the injectors mounted in the intake manifold over each intake port. These systems still have a throttle body but its only purpose is to meter the amount of air allowed in the engine.

How do the two systems compare?
Professional Products manufactures and sells both types and has conducted a number of tests comparing the two. For most street driven applications there is no appreciable difference in performance. However, due to the throttle body style being limited to four injectors, it is only suitable up to a certain horsepower level. The current Powerjection III 750 CFM units are limited to about 550 HP using 62 lb./hr. injectors. Yes, you can use larger injectors than those supplied but only up to a point. The problem with larger injectors is even at their slowest opening rate (at idle and low speed performance) they still allow too much fuel into the engine. So idle and low speed characteristics are not ideal. If you are using the system on a race vehicle, this may not be an issue. Port systems, such as the Professional Products Powrjection II, use up to eight injectors so much higher horsepower levels can be achieved without compromising idle and low speed performance. Using the same 62 lb/hr injectors used in the Powerjection III, a port system can service up to 1,100 HP.

What are some of the advantages of the Powerjection III Throttle Body EFI Kits?
There are several major advantages to this system compared to competitive units. Aside from its low price, foremost is the fact that the Engine Management System (computer) is mounted directly on the throttle body. This not only eliminates the hassle of remote mounting it (usually under the dash) but also eliminates 90% of the ugly harnessing found on other systems. This also means you do not have to cut a hole in your firewall for the harness. Some customers have asked if engine heat affects the function of the computer. Professional Products ran tests on four diffrerent vehicles for over a year with no adverse effects. Computers were also subjected to endless testing in hypabaric chambers that equalled years of use in extreme heat and cold with no problems. The systems have been sold and used (at this writing) for nearly two years. Additionally, the Powerjection III is equipped with a 2.5 BAR map sensor which is also mounted on the throttle body eliminating additonal remote mounting challenges. This allows you to run up to 20 pounds of boost through the system. Other competitive throttle body systems will not work in a supercharged or turbocharged application. Another major feature is the unique clamp-on bung for the oxygen sensor. Other brands supply a weld-on bung which can be difficult to install if you don't have access to a full service shop. With the Powerjection systems you simply drill a hole in the head pipe and clamp on the supplied stainless steel bung using a supplied proven leak proof high temp gasket. On the kits that come with a fuel pressure regulator, the regulator comes assembled as part of the inlet kit. All the fittings on the inlet kit and regulator use o-ring type straight thread connections. This assures easy adjustability and leak proof connections. The recently redesigned and improved regulator is one of the very best available and is fully adjustable.

Do I need a return line?
Professional Products offers kits that do require a return line and those that don't. The kits that do not require a return line are more expensive because they include the company's FuelOnDemand kit which not only eliminates the need for a return line, it provides the user with infinite control over the fuel delivery to the EFI system. You can read more details on this kit here.

How important is sequential injection?
Most new cars with fuel injection do offer this feature and it is also available on some aftermarket port style injecition systems. The OEM's use it primarily to lessen emissions at idle or low speed operation. The engineers at Professional Products see no performance value in it and the amount of emissions reduction is infintesimal. This is important to the OEM's but not justified in an aftermarket system.

What is sequential injection?
This provides for a squirt of fuel from the injector over the port at approximately the same time the intake valve opens. However, once engine RPMs rise, this becomes almost a constant spray of fuel which is the same as what a non-sequential system provides.

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