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Thread: Fuel pressure for blown sbc?
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06-29-2010 #1
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Fuel pressure for blown sbc?
I've got shop beater running. What kind of fuel pressure should I be running. Built motor at 12 psi
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06-29-2010 #2
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I know on our blown 351 clevlend we were running 11 psi fuel pressure, but it was only running 8 psi of boost.
06-30-2010 #3
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I'm planning 16 psi. I think I heard 1.5lb per psi
06-30-2010 #4
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You will need a boost ref. fuel regulator. It will be set at base fuel pressure and rise 1 to 1 with boost. With low boost fuel injection the pressure can stay static and tune around it. Hope this helps.
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06-30-2010 #5
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yeah thats what I understand to setup as. But what should I be looking at for a base and then at full.
07-01-2010 #6
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The base pressure is set just like normal. Around 6-7 for a carb, and usually around 58-60 for fuel injection.
Frank B. 1968 Camaro 355 Procharged 6 speed. 1983 V8 S10. 1984 Monte Carlo Magnusen Charged iron 6.0. Plus a few other junkers!
07-01-2010 #7
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I'm learning everyday! First blower car so things are a little new to me!
07-01-2010 #8
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Hilrod is correct on the fuel pressure and boost referenced regulator.
07-01-2010 #9
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this is the reg I am using!! SO I just need to set the pressure at 6-7 psi at idle and the reg will bump it up from there>
http://aeromotiveinc.com/products-pa...ass-regulator/Last edited by fletcherscustoms; 07-01-2010 at 07:31 AM.
07-02-2010 #10
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Yep. Sounds good.
Frank B. 1968 Camaro 355 Procharged 6 speed. 1983 V8 S10. 1984 Monte Carlo Magnusen Charged iron 6.0. Plus a few other junkers!
07-08-2010 #11
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Just to clarify, some EFI systems operate at 43.5psi, the later LSx engines operate at 58 psi. With aftermarket systems it does not matter. You just have to choose your injectors based on the pressure that you will be running. Make sure you are aware at what pressure the injectors are rated. Also be aware of the fuel pump output at various pressures that you plan to run.
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07-08-2010 #12
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For a carb...(at idle)needles and seats can't handle more than 6-8psi of fuel pressure before they allow fuel to over flow the bowls and flood the engine with raw gas. EFI is a different animal altogether, as Andrew stated.
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07-09-2010 #13
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John is correct. I run 7 psi base on my blow thru with holley style carb. Connect the small port on top the regulator to your carb hat/bonnet. fuel pressure rises 1:1 with boost.
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07-19-2010 #14
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Yep, 7psi on my carb even with a ton of boost. The fuel reg will add psi as required. The trick is the correct size feed, return, rails, pump and pump location. This is all related to power goal however you can never have too much. Cost is a factor as a 2000hp capable system will work on a 500hp set up. If it runs out of fuel pressure under boost it can burn a hole in a piston etc.
Check out the Areomotive or Magnaflow sites for some suggested set ups applicable to various horse power levels.
As a guide
stock fuel lines to approx 600hp Electric pump/s
-10AN feed/return -8 or -6AN to carb/rails to 1500hp Electric pump or pumps
-12AN feed/return -8 or to carb/rails 1500 and up.Belt driven pump or multiple electric pumps....
The guide above is only guestimate off the top of my head and more detail would be needed by the fuel system designer to get it right at the cheapest cost....
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