If I am planning on adding another injection pump down the road, is it worth the money to get a pressure box between now and then? Would the dual pumps render the pressure box useless? I dont have a warm and fuzzy on the dual cp3 setup, but it seems like if you have 2 feed lines from 2 pumps similar to Industrial's dual feed setup, you are bypassing the relief valve mechanically. If so, i dont want to waiste money on the electronic version just to have to take it off later.

Thanks for the wisdom in advance.

 

Pressure makes a difference with my setup, although I could use smarty for the pressure I prefer to keep pressure stock until needed, the dual pumps are great alone, but when a little pressure is added . . .

 

I still dont understand how they work together. It seems like they both do the same job in bypassing the relief valve, one mechanical, one electronic.

I need a little period of instruction.

 

The way I understand it is even if you are running dual cp-3's, the RP is still only going to be what is called for.So lets say you are running Smarty on RP 1(stock) you are only going to see RP at stock levels.Dual pumps only put out what is called for.The RP sensor is still only commanding X amount of fuel so the pumps will only deliver that amount.The ramp time will be better than a single pump as well as the amount of flow but no difference on RP.

 

That is correct. What's nice about stacking a pressure box is that you can turn it up or down with the simple turn of a ****. With a downloader, you have to re-write the ECM to change the parameters. It's been advised to NOT daily drive with the pressure box turned up.

Jared

 

thanks everyone for the info, but im looking for more like theory of operation.

I thought that when you run 2 supply lines to the rail (dual cp3), you have to remove the relief valve to put the second supply line in. And that is the device that regulates rail pressure correct? so if you are removing the valve to put another supply line in... wouldnt that defeat the purpose of electronically overriding the valve to let more pressure in?

 

The pressure relief valve is a purely mechanical valve. All it does is if the pressure gets to high, it opens and allows some of the fuel to go to the return line. In a lot of cases it only opens once, and then will not close again.

The pressure is actually controlled by a electronic valve in the CP3(s). It's call an FCA. The pressure in the rail is reported back to the computer by the rail pressure sensor. The ECM controls the FCA(s) to raise the pressure until it sees the pressure it wants on the rail pressure sensor. This is true for a single CP3 or duals. A pressure box, basically "fools" the ECM, by lying about what the pressure really is. For example if the ECM wants 22K of rail pressure, and the pressure box tells the ECM that there is only 21K, the ECM will keep trying to raise it.

Not all dual CP3 kits remove the pressure relief valve. For example the PPE kit tees the two output lines coming from the CP3's together, and then goes to the original input port of the rail.

A lot of people will cap off the pressure relief valve (with either single or dual CP3's), because they do leak from time to time. This is what is called "capping the rail".

Hope this helps...
Paul

 

THANK YOU. this is what i was looking for. I allready knew most of this, just didnt know the FCA was separate and part of the cp3. I thought the valve/sensor was all part of that one plug on the back of the rail.