4.1 stroker motor & 120# injectors

[incharge]

base pressure is set a 45 with vac line off it drops to 40 then it rises to 58-60 at 20 # of boost then it starts to fall down below 50 # if I stay in it .

 

[tom j]

Fuel pump gets my vote

 

[incharge]

Ok I jumped out each pump seperately and they both put out 40 psi with key on and motor off together they are making 55# key on motor off in the garage i keep it jumped out for 3 or 4 miniutes and the pressure never dropped. I think the pumps are fine and The stock lines cannot supply enough fuel... i guess

 

[GNVYUS 1]

Remember you need 28% MORE fuel volume than GN owners who'd have your EXACT setup on gas. Supplying this through the stock lines IMO is not worth wasting another day testing parts over. The stock line is 3/8ths and has 90 degree bends all over the place adding a tad more backpressure every time.

-10 or -12 and call it a day, BTW Magnafuel has a -10 post pump Stainless Element Fuel Filter MP-7008 . I run a -12 line on my E85 GTO because I plan on going FI in the next two years and supporting 600-1000hp doesn't make sense through a -6 line.

 

[87GN_70GS]

Assuming both pumps are ok, like posted previously, it's the lines. The attached chart shows you should have another 20 psi or so of fuel pressure. The plot shows the typical performance of a double pumper along with six of 120 #/hr injectors (corrected for the increased density of E85, i.e. 120 pph gas injectors become 112 pph of E85). These curves do not take into consideration losses from lines, connections, etc. It shows that you should have adequate flow and pressure to 120 gph and 70 psi respectively (with 20 psi boost, 13.5 volts, 100% dc). Even at only 12 volts of pump voltage, you should still be good to 60 psi. So obviously something is up.