Hey guys just ordered my s-trim today should be here next week going to be running around 10-12lbs. Anyways is the t-rex fuel pump manditory if i already have a 255?
I also wish somebody would clear up this debate/issue. I have heard that the t-rex will actually restrict the 255 in tanks. For what I remember, the t-rex is a super old design that came out before all of these companies started making larger intanks. The guy that can answer this is Rick ...
I asked the same question a while back. After much debate, I went ahead and installed the T-Rex, even though I already had the 255. Seems to work OK for me...
I posted an in-depth look at fuel system theory that should help you with your problem. Here.
Your specific problem can be answered by looking at your current pump because not all pumps are created equal.
42# injectors x .85 duty cycle x 8 cylinders = 286 lbs/hr = 136 lph
So by first looking at your average fuel needs we can say that yes, your current pump is adequate. However, we need to know what pressure you are running at. An engine under boost invariably needs a higher fuel pressure to see good results. The reason for this is due to the higher manifold pressure.
Injector pressure + Boost = Rail pressure
Therefore, if you are looking for 39 psi at the injectors and will be running 12 psi boost, you need to actually run your system at 51 psi. You just have to find out what volume of fuel your current pump is able to move at 51 psi. The T-Rex is capable of 70 gph (265 lph) @ 50 psi, you need a max of no less than 160 lph.