Hey all you HSR guys, how much fuel pressure is everyone running? I know it will vary depending on mods, but I still have a stumble off idle and a small dead sopt coming through first gear (M6). Stats

TPI w/30 over
TPIS ZZ-9 Cam
Vette alloy heads with mild port, stock size valves
Shortie headers

and yes been tuned a bunch of times and am running a bunch of initial timing, 10 drg.

Thx
Mike

 

Not running I'm at 46
When running its a 40
28 lb injectors
6 degrees BTDC
Hope it helps you with what your looking for

 

dnt lower stock type injectors (bosch type) lower than 43.5psi... as u do this u compromise the injectors ability to squirt fuel correctly. it kind of dribbles out instead of spraying due to loss of pressure. u can run bosch type to like 40psi but again this could cause issues... lower than 40psi and ur guarenntee it. GM injectors are rated to at there LB/HR rate at 43.5psi.... ford rates there injectors at 37.5psi. which means ford injectors can run at lower PSI ranges and work fine, GMs can not. keep the fuel pressure at the stock 43.5psi. all your issues is in the tune. your problem is your fuel at throttle tip in and your lower MAF tables/your lower MAP tables. I had throttle bog at idle when i stomped the throttle... i had to change my lower maf tables for more fuel and increase my AE (accelerator enrichment) i just kept adding until it went away.

my setup is a 9.8:1 383 HSR.
base timing is 8degrees.
patriot 195cc heads, XFI280 cam 230/236 576.571 lift 113lobe
1.6rr and stock 165 ECM maf
im running the billet kirban adjustable regulator and its at 43.5 with my ford SVO 30lb injectors... thats with the vacume disconected. its like 37psi when runing, but since im running my FORD injectors at 43.5psi that means there not really 30lb injectors anymore... my injectors are rated at 30lbs at 37.5psi... when i increase them to 43.5psi they are roughly 31-32lb injectors.

again, set your pressures to stock 43.5 and then mess with the tune (thats where the prob is) when u increase fuel pressure it helps at first but what you dont realize is that the computer will learn that the injectors are pushing more fuel and will compensate for the increase fuel pressure by decreasing the injector pulses... basically countering your fuel pressure increase. so dont tune by increasing fuel pressure unless your injectors arent flowing enough, then increase the pressure to increase the fuel output (no more than 50psi max) if you need more fuel but dnt forget to change the injector constant in the tune otherwise it wont do anything.

also u might want to take alittle timing out... too much can cause stumbing etc. my XFI 280 cam is idling with like 14-16degrees at idle and it ramps up to like 34 by 3400ish. I would start with the stock tune/timing and then increase timing by 2 degrees and see what the motor likes. when u addtiming u will need more fuel etc.

 

Yea my tuner has talked about the tip in fuel, I am also runnung Ford SVO 24 Lb injectors, I will try what you said and maybe start from stock settings again. Thx