My question is rather simple and straight forward, but here its is: I was recently watching a video in the multimedia section here of an in car clip of a 306 s-trim fox on the interstate. The camera is focused at the fuel psi gauge the whole time, and whenever he gets into the throttle the psi spikes from 38ish to maybe 60psi. On my s-trim my base fuel psi is set to about 40psi, and it stays there no matter how I drive. Is this maybe because I'm not running an FMU?
Supercharged Fuel Psi
s-trimmed
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My question is rather simple and straight forward, but here its is: I was recently watching a video in the multimedia section here of an in car clip of a 306 s-trim fox on the interstate. The camera is focused at the fuel psi gauge the whole time, and whenever he gets into the throttle the psi spikes from 38ish to maybe 60psi. On my s-trim my base fuel psi is set to about 40psi, and it stays there no matter how I drive. Is this maybe because I'm not running an FMU?
You would need a boost sensitive fuel pressure regulator. They raise fuel pressure by 1psi per 1 psi of boost, 1:1.
How much boost are you making?
What regulator do you have on there now? What does the rest of your fuel system consist of?
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He was probably using a FMU. When I first installed the KB I used a FMU. Under boost the pressure would peak at 70+psi in order to flow enough fuel through the 19 lb squirters. That was enough for me to rethink the whole process. 42 lb injectors and stand-a-lone AEM-EMS. Now my FPR (stock) is boost referenced. Every 1 psi of boost is matched with a 1 psi increase in fuel pressure.
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YES. The FMU's R calibrated based on inj size(Generally) & boost. example 19# inj's(12:1 ratio) & 6# of boost would equal appx 90# of fuel pressure..Formula 12 X 6 + appx of 40(Base pressure)= appx 90.... Although there is normally a specific calibration for a specific size inj, U could calibrate the FMU to what ever U want.. Prob would drown it, but could/can be done..l
To answer the question in the second post, my fuel system is rather basic. 255lph walbro in tank pump, t-rex external pump, through stock lines and rails, with a pos bbk regulator (non boost referencing) and 42lb injectors.
Would it be worthwhile to ditch the bbk for a boost referencing aeromotive afpr? Oh yeah, i see about 10 psi of boost.
Would it be worthwhile to ditch the bbk for a boost referencing aeromotive afpr? Oh yeah, i see about 10 psi of boost.
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well this is the idea behind it, set the fuel pressure at let say 50psi so then at idle with vacuum on pulls fp down to 40 at idle. hit the gas goes back up to 50. then builds boost 1psi per 1 psi of boost. Dont really have to have boost sensitive regulator. Helps if you are maxing out you injectors though. I keep my fp at 55psi, then under 12 psi hits 67 with 42 lbs injector make 552rwhp with duty cycle on injectors at 97%. More fuel pressure = less injector duty cycle (to a point)
if i was you i would just crank your base pressure up to 50-55psi to assure enough fuel flow. How much rwhp do you make and how much boost?
Jay
if i was you i would just crank your base pressure up to 50-55psi to assure enough fuel flow. How much rwhp do you make and how much boost?
Jay
Is my bbk afpr boost reference? I had originally thought that only the nice anodized aeromotive ones that accept the AN fittings were boost sensitive, until recently reading that any afpr that has a vacuum port references boost anf raises fuel psi on a 1:1 ratio. Is this true?
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