C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

External vs internal fuel pump

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Old Nov 12, 2021 | 01:38 PM
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Default External vs internal fuel pump

I want to upgrade my fuel pump to support 30lb/hr injectors 383ci. Looking for suggestions on in-tank replacement vs external in-line pump.
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Old Nov 12, 2021 | 02:47 PM
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Walbro 255 in-tank for me, supporting 42lb/hr in a 398.

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Old Nov 12, 2021 | 02:50 PM
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I'd lean toward in tank with a harness upgrade as well. No reason to complicate things.
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Old Nov 12, 2021 | 03:01 PM
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I agree. I have a Walbro 255 in tank with 36 pound injectors. I'm upping that this winter to a 450 lph Walbro in tank pump with Holley 76 pound injectors for my bigger motor and for flex fuel. There isn't much reason to use an external pump anymore.
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Old Nov 12, 2021 | 04:47 PM
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I would talk to one of the folks that sells those Walbro and other "Quality Fuel pumps". I thought the Walbro 255 would support close to 600 horsepower on a Normally Aspirated Engines or something ridiculous. I went from a Holley External Fuel pump to a Internal Fuel Pump and Fuel pressure Regulator In-Tank. I really like the No-Return system that Holley Used in their OEM Fuel Tank Modules.

The difference in the noise level alone was very noticeable, the old external pump makes some racket even though it was isolated from the frame. The In-Tank Fuel Pump is a great system, add the FPR and you have a great solution all buried in the fuel tank.

What kind of engine will you be powering with the Walbro 450 and 76 pound injectors? I understand the Flex fuel systems uses a larger volume of fuel. I know very little about the Flex Fuel as they don't have many stations in the Washington DC area.

My 1968 427 Corvette has a Holley EFI system on it and I think it uses Four 100 pound injectors in the throttle body. Running near 60 psi of fuel pressure the engine is still learning the correct data for every possible situation. It does an awesome job keeping the engine running right where you want it.
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Old Nov 12, 2021 | 04:55 PM
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Originally Posted by ctmccloskey
I would talk to one of the folks that sells those Walbro and other "Quality Fuel pumps". I thought the Walbro 255 would support close to 600 horsepower on a Normally Aspirated Engines or something ridiculous. I went from a Holley External Fuel pump to a Internal Fuel Pump and Fuel pressure Regulator In-Tank. I really like the No-Return system that Holley Used in their OEM Fuel Tank Modules.

The difference in the noise level alone was very noticeable, the old external pump makes some racket even though it was isolated from the frame. The In-Tank Fuel Pump is a great system, add the FPR and you have a great solution all buried in the fuel tank.

What kind of engine will you be powering with the Walbro 450 and 76 pound injectors? I understand the Flex fuel systems uses a larger volume of fuel. I know very little about the Flex Fuel as they don't have many stations in the Washington DC area.

My 1968 427 Corvette has a Holley EFI system on it and I think it uses Four 100 pound injectors in the throttle body. Running near 60 psi of fuel pressure the engine is still learning the correct data for every possible situation. It does an awesome job keeping the engine running right where you want it.
I built a 6.0L nitrous motor. Being it's an LS motor the fuel pressure is 60 psi. So that means you need a bigger pump there. Also you need to go way bigger to run flex fuel. The motor itself will be around 500 hp NA and I'm going to spray a dry progressive 200 shot on it. It worked out on the calculators that I would need around a 73 pound injector at 80% duty cycle. I only need around a 400 lph pump but the 450 is Ethanol safe and has a lot of good reviews so that's the one I went with.
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Old Nov 13, 2021 | 10:00 AM
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Pumps – DeatschWerks. Get an in tank one from here,
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Old Nov 13, 2021 | 06:58 PM
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Originally Posted by TommyFox
Pumps – DeatschWerks. Get an in tank one from here,
Thanks for the link. Good price and comes with installation kit. Ordered!
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Old Nov 13, 2021 | 07:27 PM
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Originally Posted by jayjones
Thanks for the link. Good price and comes with installation kit. Ordered!
I'm running that one as well. Very quiet.
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Old Nov 13, 2021 | 10:56 PM
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I'm running a Bosch 666 external pump. Can't go in tank with a 5 gallon fuel cell. 406 with 36lb injectors.
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