Boosting a 12a @ 5 psi without using rising rate fuel pressure regulator
11-19-05, 12:47 PM
#2
Old [Sch|F]ool
I assume you mean for a blow-through carb application.
I don't know if you mean what you are saying. You want to have a pressure referenced fuel pressure regulator, referenced to the air pressure in the fuel bowl (referencing to the carb hat is much easier nad has the same effect) so that you always have the same pressure variation between the fuel line and the bowl. So for example, your fuel system is normally 4psi. Under 5 pounds of boost, there will be 5 pounds of air pressure in the carb, making the fuel pressure effectively negative one PSI. The regulator must be referenced to the air pressure in the bowl at a 1:1 ratio so that the fuel pressure in this case will go up to 9psi or 4psi higher than the air pressure in the bowl.
This is also why port EFI cars reference the fuel pressure to manifold vacuum, so the fuel pressure is always 42psi (or whatever) higher than manifold pressure.
Rising rate fuel pressure regulators, on the other hand, are simply Band-Aids for EFI cars (NEVER EVER EVER on a carbed car) that cannot recognize boost. And a rally bad Band-Aid at that. Once manifold pressure goes above atmospheric, the RRFPR makes fuel pressure go up at a faster rate ("rising rate") than manifold pressure is going up, so for example if it was a 4:1 then for every one pound of boost the fuel pressure goes up 4psi. 5 pounds of boost makes fuel pressure go up 20psi. You can see why you never want to use one for a carb!
I don't know if you mean what you are saying. You want to have a pressure referenced fuel pressure regulator, referenced to the air pressure in the fuel bowl (referencing to the carb hat is much easier nad has the same effect) so that you always have the same pressure variation between the fuel line and the bowl. So for example, your fuel system is normally 4psi. Under 5 pounds of boost, there will be 5 pounds of air pressure in the carb, making the fuel pressure effectively negative one PSI. The regulator must be referenced to the air pressure in the bowl at a 1:1 ratio so that the fuel pressure in this case will go up to 9psi or 4psi higher than the air pressure in the bowl.
This is also why port EFI cars reference the fuel pressure to manifold vacuum, so the fuel pressure is always 42psi (or whatever) higher than manifold pressure.
Rising rate fuel pressure regulators, on the other hand, are simply Band-Aids for EFI cars (NEVER EVER EVER on a carbed car) that cannot recognize boost. And a rally bad Band-Aid at that. Once manifold pressure goes above atmospheric, the RRFPR makes fuel pressure go up at a faster rate ("rising rate") than manifold pressure is going up, so for example if it was a 4:1 then for every one pound of boost the fuel pressure goes up 4psi. 5 pounds of boost makes fuel pressure go up 20psi. You can see why you never want to use one for a carb!
11-19-05, 11:21 PM
#5
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no, you just need a 1:1 fuel pressure regulator. you need this for fuel injection as well... sooooo why not use the carb that's already on there? 
i love mine! hahaha
i love mine! hahaha
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trickster
2nd Generation Specific (1986-1992)
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07-01-23 04:40 PM
41, boost, carb, carburetor, fuel, manifold, pressure, psi, raising, rasing, rate, referenced, regulator, regvulators, rising
