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Turbo bandit


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That sort of boost pressure is in the no-mans land for pumps - its too high for normal hi pressure carb type pumps (that normally top out @ about 10psi) and too low for a EFI pump as although perfectly capable, you'll be bypassing most of the flow back to the tank. This is of course assuming you are using blow through carbs and not EFI . . . . . . in which case most EFI pumps will do 3 bar + 1 bar boost.

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Yes it will be a blow through carb set up i have mad a 6AN adapter to replace my petcock and doing another on the other side of the tank for a return line through the fpr. So i dont need more then 10psi as its perfect with minimal pressure at say 2lb then as boost raises i get a 1-1 ratio of raised pressure to boost but in a perfect world running 7lb of boost im safe. As we all know though things can fail or boost creep can happen then well things go lean. I much rather be safe then sorry with the amount of time and funds spent in my build. 

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1 minute ago, Reinhoud said:

You will need a rising rate fuel pressure regulator

Maybe a difference in terminology but as far as I'm aware, 'Rising Rate' FPR's work by increasing at a fixed %. A turbo FPR should be a boost referenced device that is 1:1 ratio with pressure increased in direct proportion to boost pressure, no more, no less above its static base pressure. Although not the smallest FPR's - Malpassi Turbo FPR's work well once the base spring pressure is reduced to bike carb friendly levels.

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Rising rate is normally used in entry level turbo kits for EFI bikes. So no need for larger injectors or a secondary fuel rail. But fuel pressure can reach high levels so this only works for low boost. 

For carbs this is not an option since it leads to severely overflowing bowls. (and if the bowls would not overflow and fuel level stays the same, it doesnt lead to a richer mixture on WOT. Only a larger main jet does that)

So has to be 1:1 FPR especially made for carbs. I had the malpassi as well, and changing the internal spring to a softer one helps indeed. Also make sure your fuel return is free flowing. 

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Yes peter1127 that is the general direction im going i have an aeromotive boost ref fpr that is set to do exactly that at a 1-1 ratio down to 2lb up to 20 on the light spring and adjusted. It can be used with heavier springs in the 40-100psi range but not using it in that manner. I have done a few blow through carbs on cars with Holley and what i have done is just the same 1-1 added pressure of fuel to match the boost pressure so that fuel would still flow through it or it no longer pulled fuel through and caused lean conditions. On a holley i would tap a barb fitting in to the top of the front and rear bowls to add a vacuum line on the carb hat to raise the bowl pressure and as long as they was sealed then we had no starvation of fuel but it took some true wizardry to dial them in just right. On the bright side we really don't have to deal with power valves. I have seen on post that guys utilise the carb  overflow port to pressurise them. 

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