Rep Power: 313

I've read so many threads but cant find a clear explanation on how it works and what parts are needed. Do I still need a Fuel Managment system?

 
Rep Power: 0

You'll just need an FPR to adjust the fuel pressure back to stock.

You need to modify your fuel rail for a return line, install an FPR, upgrade the pump in-tank, run lines, and block off in-tank FPR.

It works by sending unused fuel back to the tank for recirculation. Returnless systems are engineered to send the only the amount of fuel needed.

 
Rep Power: 413

http://www.7thgencivic.com/forums/fa...q#faq_turbo_q9

 
Rep Power: 305

I would assume this pertains to adding some sort of forced induction, where more fuel volume is needed at the fuel rail.

A returnless fuel system is weak due to the fact that the system does not compensate for increased need in volume. The 7th gen has a fuel regulator in the tank. Thus the fuel pressure will be 40-47 psi at the fuel rail. If increased volume is required beyond the factory design, the system cannot compensate, thus volume will not increase. Realize that to achieve proper mixture, when you force more air into the cylinders, you must add more fuel. Otherwise, you will run lean and blow up your motor.

The trick is where the pressure regulator is located. If it is in the tank, it will only send 40-47 psi down the line. If the need for fuel is greater than that, too bad so sad.

Now converting to the 6th gens type of return style fuel system you gain one important advantage.

The fuel pump will flow its maximum output (gallon per minute governed by the size of the fuel line) to the rail. The injectors will use all availabe fuel. Any excess over the desired fuel pressure will be released and sent back to the tank. Thus the maximum flow rate of the pump is supplied to the fuel injectors.

All doing a return system is going to add is the available amount of fuel to the injectors, it will not increase the amount they spray into the cylinders.

To increase fuel into the cylinders, you can do one of two things.

1. Use a rising rate pressure regulator. When the car is under boost, it increases the pressure of the fuel in the rail and forces more fuel into the injectors, causing more fuel to be sent to the cylinders. This works, but is bad for two reasons. One, increasing the pressure to the injectors is harder on the injectors, and two, unless some sort of electronic control of this is done, all you can do is ensure that the mixture is always rich, but never optimum. It is a band aid at best.

2. Use a programmable ecu that can recognize boost and change the fuel maps according to this boost. You would most likely need bigger injectors to handle the increased amount of fuel. With a suitable pump (able to flow the volume required), return style fuel system, and tuning, you could achieve a 20 percent gain over the system in 1. The down side is cost. 4 more injectors, a programmable ecu, increased fuel system, and tuning.

By the way the faq is wrong.

The ecu controls the injectors to open and close. The ecu may use signals from the map sensor to determine need and use the appropriate fuel map, but it only opens and closes the injectors.

You could convert a stock 7th gen to a return style system and change nothing on the ecu. Converting would only allow more volume available to the injectors, it would do nothing to alter the amout of fuel delivered, unless you increased pressure.

The ecu does not vary pressure. It only turns on the fuel pump. Nothing more. Fuel pressure on a 7th gen is determined by the regulator in the tank.

A stand alone or piggy back ecu allows the injectors to stay open longer, or use bigger injectors.

 
Rep Power: 313

Thanks for the info guys this really helps. I have all the parts for my custom turbo setup except for the fuel management. Thanks again.