L98 fuel psi question
Thread Starter
Racer
Joined: Sep 2000
Posts: 402
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From: Beaverton OR
L98 fuel psi question
you know, no one has ever told me exactly how fuel psi is rated on these. i mean there is a 10lb difference with and without vacume. when someone says get it around 48psi..do they mean 38psi at idle with vacume? or? just curious about the tech explaination on this. :chevy
Drifting
Joined: Mar 1999
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From: Norcross GA
Re: L98 fuel psi question (importeater)
You give no reference to your question.
Injectors are rated at x amount of fuel @ y amount of pressure. For GM, that pressure is 3bar = 43.5psi That means you have 43psi @ the injectors w/o vacuum.
The engine vacuum is used to reduce the fuel pressure @ the injectors. The result is an increase in fuel pressure when you loose vacuum (blip the throttle). It acts like an accel pump shot (from the carb day's).
Injectors are rated at x amount of fuel @ y amount of pressure. For GM, that pressure is 3bar = 43.5psi That means you have 43psi @ the injectors w/o vacuum.
The engine vacuum is used to reduce the fuel pressure @ the injectors. The result is an increase in fuel pressure when you loose vacuum (blip the throttle). It acts like an accel pump shot (from the carb day's).
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Re: L98 fuel psi question (importeater)
you know, no one has ever told me exactly how fuel psi is rated on these. i mean there is a 10lb difference with and without vacume. when someone says get it around 48psi..do they mean 38psi at idle with vacume? or? just curious about the tech explaination on this. :chevy
I always thought it was at Idle with no vacuum.
Melting Slicks
Joined: May 2000
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From: Chandler AZ
Re: L98 fuel psi question (Marcho Polo)
Yeah- what Craig said. Fuel pressure is measured at idle with the vacuum hose pulled off the regulator. Increased fuel pressure increases injector flow rate, as well as providing better spray patterns and atomization.
Team Owner
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From: SE NY
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Re: L98 fuel psi question (importeater)
Our injectors are rated at 22lb/hr at 43.5psi; that's steady state flow.
I believe stock fuel pressure is 44psi with the vac hose disconnected (simulates WOT condition).
Indeed fuel flow increases as the SQRT of the pressure increase.
I believe stock fuel pressure is 44psi with the vac hose disconnected (simulates WOT condition).
Indeed fuel flow increases as the SQRT of the pressure increase.
Thread Starter
Racer
Joined: Sep 2000
Posts: 402
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From: Beaverton OR
Re: L98 fuel psi question (65Z01)
i thought as much guys, just wanted to double check as i've ran 44psi with vac & it's pretty rich, right now i'm at 39psi with vac attached or just under 50 with no vac & it seems to be stronger, run smooter & not sputter on occasion like it did with higher psi
