Fuel Return system needed?
07-07-2009, 08:14 AM
#1
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Fuel Return system needed?
Hey guys,
I'm going to go turbo here pretty soon, waiting on my head gasket and head studs to come in (ordered this morning
)!
Anyway, at about what rwhp level is a return system really needed? I've been looking around at fuel rails and it seems like the AP1 is different in design, and the AP2 vs AP2 DBW are different also.
TIA
Steve
I'm going to go turbo here pretty soon, waiting on my head gasket and head studs to come in (ordered this morning
)!Anyway, at about what rwhp level is a return system really needed? I've been looking around at fuel rails and it seems like the AP1 is different in design, and the AP2 vs AP2 DBW are different also.
TIA
Steve
07-07-2009, 08:42 AM
#3
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Thread Starter
well looking at your sig, you have an AP1, so you have a return fuel system. I'm an MY08, so I don't have a fuel return system. So what I'm asking when do I really need to move to a return fuel system.
So if I went with 1000cc injectors, F/IC, and fuel pump, what rwhp should I be safe with?
I know on the 350z, anywhere around the 500rwhp range, return fuel system is needed.
So if I went with 1000cc injectors, F/IC, and fuel pump, what rwhp should I be safe with?
I know on the 350z, anywhere around the 500rwhp range, return fuel system is needed.
07-07-2009, 08:58 AM
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for a high whp car, i would think so... because you want to run 1000cc injectors, also a fuel pump would be needed to compensate for the large injectors. then With all that pressure where would the excess fuel be dump back to? when your injectors open and close.
IMO yes return fuel system would be nice. But then again their are some members on here who has an 08 that are pushing good numbers. so i hope they chim in.
IMO yes return fuel system would be nice. But then again their are some members on here who has an 08 that are pushing good numbers. so i hope they chim in.
07-07-2009, 09:29 AM
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The correct answer is: it depends on the pump you select for your application.
Most high capacity pumps require a return line in order to prevent overheating or simply because they don't have built-in relief valves or that's just how they were designed. Pump overheating or cavitation will occur if you use a non-bypass high capacity pump that will be moving alot of volume against a semi-deadhead condition (when fuel volume from pump largely overcomes fuel demand at injectors).
If the pump has a built-in relief valve and has been designed for returnless use, then you don't need a return line.
Target horsepower dictates pump size, so you need to determine if the pump you will be using requires a return line.
Most high capacity pumps require a return line in order to prevent overheating or simply because they don't have built-in relief valves or that's just how they were designed. Pump overheating or cavitation will occur if you use a non-bypass high capacity pump that will be moving alot of volume against a semi-deadhead condition (when fuel volume from pump largely overcomes fuel demand at injectors).
If the pump has a built-in relief valve and has been designed for returnless use, then you don't need a return line.
Target horsepower dictates pump size, so you need to determine if the pump you will be using requires a return line.
07-07-2009, 09:33 AM
#6
Registered User
Originally Posted by EngineerX,Jul 7 2009, 12:29 PM
The correct answer is: it depends on the pump you select for your application.
Most high capacity pumps require a return line in order to prevent overheating or simply because they don't have built-in relief valves or that's just how they were designed. Pump overheating or cavitation will occur if you use a non-bypass high capacity pump that will be moving alot of volume against a semi-deadhead condition (when fuel volume from pump largely overcomes fuel demand at injectors).
If the pump has a built-in relief valve and has been designed for returnless use, then you don't need a return line.
Target horsepower dictates pump size, so you need to determine if the pump you will be using requires a return line.
Most high capacity pumps require a return line in order to prevent overheating or simply because they don't have built-in relief valves or that's just how they were designed. Pump overheating or cavitation will occur if you use a non-bypass high capacity pump that will be moving alot of volume against a semi-deadhead condition (when fuel volume from pump largely overcomes fuel demand at injectors).
If the pump has a built-in relief valve and has been designed for returnless use, then you don't need a return line.
Target horsepower dictates pump size, so you need to determine if the pump you will be using requires a return line.
07-07-2009, 09:40 AM
#7
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Thread Starter
Agreed, that was an awesome explanation! I guess I'll have to do some more searching around. This is the first time I've really messed with a car without a return fuel system. So I'm assuming I couldn't get a plain Jane walboro 255 this time
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07-07-2009, 11:09 AM
#8
check this thread out, he did it without converting to return fuel.
https://www.s2ki.com/forums/index.php?showt...&#entry15405385
478whp is pretty nice
https://www.s2ki.com/forums/index.php?showt...&#entry15405385
478whp is pretty nice
07-07-2009, 11:59 AM
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Walbro 255's have an internal relief valve, so they should work ok returnless.
The only problem I can see could be shortened pump life, because the pump *may* be overworking itself pumping against higher pressure all the time. But it's hard to say how much shorter life. It may even last the same! in other words - who knows
The only problem I can see could be shortened pump life, because the pump *may* be overworking itself pumping against higher pressure all the time. But it's hard to say how much shorter life. It may even last the same! in other words - who knows
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