383 Fuel Pump? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

CPride · 12-04-2018, 11:17 PM

I have a side project...a 69 land cruiser with a fuel injected 383 Chevy. Trying to figure out how to calculate the fuel pump psi..or should I just go over and put a regulator? If so what psi should it be set at? Any help or clues to figure it out would be sorely appreciated.

**mongocanfly** · 12-04-2018, 11:28 PM

What type fuel injection you have?...better to be over and control with a regulator

CPride · 12-05-2018, 03:59 AM

HERE are the two on it now.

**mongocanfly** · 12-05-2018, 05:09 AM

Youll need something capable of 85pph and 21psi.....according to the specs

CPride · 12-05-2018, 10:45 AM

Thanks but that's not entirely true. 60 PPH@12 PSI 85 PPH@21 PSI

To quote a Holley rep when I asked this question:

Quote:

depends on application, the injectors are designed to work with a factory GM style fuel system for 90-95 pickups, so 11-12 PSI, but the injectors can handle up to 21-22 PSI. It depends on how much flow your horsepower needs dictate.

So therein is the question. How much flow does a 383 need?

**mongocanfly** · 12-05-2018, 11:14 AM

Gotcha....the holley rep wouldnt recommend one ?

weq92f · 12-05-2018, 02:37 PM

22psi doesn't sound high for FI. Just run a pump into a regulator then adjust to your engine's needs.

My big block with 4 80#/hr injectors runs happily at a regulated 35 psi on a return line system.

Hth,

-klb

**Captainfab** · 12-06-2018, 12:21 AM

I think first you will need to come up with an approximate HP number that the 383 is developing. Then the necessary fuel flow can be calculated.

https://fuelinjectorclinic.com/hp-calculator

B. W. · 12-09-2018, 05:56 PM

You need to know the approximate HP of your engine. Use a program like desk top dyno or the Comp Cams calculator. Then you can calculate your fuel pressure based on injector size.

If you are running a modified GM TBI setup you will need the ECM tuned or run a program like Tuner Pro so you can tune it yourself. If you run Tuner Pro it has a utility that you can plug your #s into & play with different fuel pressures.

For example, I have a 383 with a big block throttle body & 80# injectors, my fuel pressure is set at 22 psi. This setup will support 393 HP. Obviously, if you have a 200 horse motor & run 80# injectors at 22 psi you will be over fueling. That's why it's important to know your approx. HP.

(What Captainfab said, just more words!)

Here's a link with a lot of info:

https://www.dynamicefi.com/Tune_Intro.php

12-04-2018, 11:17 PM	#1
CPride Registered User Join Date: Sep 2018 Location: Long Beach, CA Posts: 7	383 Fuel Pump? I have a side project...a 69 land cruiser with a fuel injected 383 Chevy. Trying to figure out how to calculate the fuel pump psi..or should I just go over and put a regulator? If so what psi should it be set at? Any help or clues to figure it out would be sorely appreciated.

12-04-2018, 11:28 PM	#2
mongocanfly Post Whore Join Date: May 2015 Location: Alabama Posts: 14,579	Re: 383 Fuel Pump? What type fuel injection you have?...better to be over and control with a regulator __________________ Mongo...aka Greg RIP Dad RIP Jesse 1981 C30 LQ9 NV4500..http://67-72chevytrucks.com/vboard/s...d.php?t=753598 Mongos AD- LS3 TR6060...http://67-72chevytrucks.com/vboard/s...34#post8522334 Columbus..the 1957 IH 4x4...http://67-72chevytrucks.com/vboard/s...63#post8082563 2023 Chevy Z71..daily driver

12-05-2018, 03:59 AM	#3
CPride Registered User Join Date: Sep 2018 Location: Long Beach, CA Posts: 7	Re: 383 Fuel Pump? HERE are the two on it now.

12-05-2018, 05:09 AM	#4
mongocanfly Post Whore Join Date: May 2015 Location: Alabama Posts: 14,579	Re: 383 Fuel Pump? Youll need something capable of 85pph and 21psi.....according to the specs __________________ Mongo...aka Greg RIP Dad RIP Jesse 1981 C30 LQ9 NV4500..http://67-72chevytrucks.com/vboard/s...d.php?t=753598 Mongos AD- LS3 TR6060...http://67-72chevytrucks.com/vboard/s...34#post8522334 Columbus..the 1957 IH 4x4...http://67-72chevytrucks.com/vboard/s...63#post8082563 2023 Chevy Z71..daily driver

12-05-2018, 11:14 AM	#6
mongocanfly Post Whore Join Date: May 2015 Location: Alabama Posts: 14,579	Re: 383 Fuel Pump? Gotcha....the holley rep wouldnt recommend one ? __________________ Mongo...aka Greg RIP Dad RIP Jesse 1981 C30 LQ9 NV4500..http://67-72chevytrucks.com/vboard/s...d.php?t=753598 Mongos AD- LS3 TR6060...http://67-72chevytrucks.com/vboard/s...34#post8522334 Columbus..the 1957 IH 4x4...http://67-72chevytrucks.com/vboard/s...63#post8082563 2023 Chevy Z71..daily driver

12-05-2018, 02:37 PM	#7
weq92f Registered User Join Date: Oct 2016 Location: Dallas Texas Posts: 2,860	Re: 383 Fuel Pump? 22psi doesn't sound high for FI. Just run a pump into a regulator then adjust to your engine's needs. My big block with 4 80#/hr injectors runs happily at a regulated 35 psi on a return line system. Hth, -klb __________________ 67 C10 fleet fuel injected '70 402, 700r4, 3.73 posi 07 335 sport turbo 6sp 94 Trans Am GT LT1 6sp posi -- sold after 22yrs 99 540 sport V8 6sp -- sold 73 240z L24 4sp -- given to friend 68 C10 step 350/350 3.73 open -- sold

12-06-2018, 12:21 AM	#8
Captainfab 60-66 Nut Join Date: Mar 2007 Location: Coeur d'Alene, Idaho Posts: 23,246	Re: 383 Fuel Pump? I think first you will need to come up with an approximate HP number that the 383 is developing. Then the necessary fuel flow can be calculated. https://fuelinjectorclinic.com/hp-calculator __________________ Power Steering Box Adapter Plates For Sale HERE Power Brake Booster Adapter Brackets For Sale '63-'66 HERE and '67-'72 HERE and '60-'62 HERE and "60-'62 with clutch HERE Rear Disc Brake Brackets For Sale. Impala SS calipers HERE Camaro Calipers HERE D52 Calipers HERE 6 Lug HERE Hydroboost Mounting Plates HERE

12-09-2018, 05:56 PM	#9
B. W. Registered User Join Date: Nov 2014 Location: Bigfork, Montana Posts: 1,137	Re: 383 Fuel Pump? You need to know the approximate HP of your engine. Use a program like desk top dyno or the Comp Cams calculator. Then you can calculate your fuel pressure based on injector size. If you are running a modified GM TBI setup you will need the ECM tuned or run a program like Tuner Pro so you can tune it yourself. If you run Tuner Pro it has a utility that you can plug your #s into & play with different fuel pressures. For example, I have a 383 with a big block throttle body & 80# injectors, my fuel pressure is set at 22 psi. This setup will support 393 HP. Obviously, if you have a 200 horse motor & run 80# injectors at 22 psi you will be over fueling. That's why it's important to know your approx. HP. (What Captainfab said, just more words!) Here's a link with a lot of info: https://www.dynamicefi.com/Tune_Intro.php



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