Boost Referenced?
Thread Starter
Staging Lane
Joined: Jun 2014
Posts: 77
Likes: 0
From: Dome Valley, AZ
Boost Referenced? Is boost referencing needed on efi or does the duty cycle just pick up on the injectors as boost is applied? I know on a procharged blow through carb setup I had it needed a pound and a half for every one pound of boost but the efi runs such a high pressure already so I just wondered if it was necessary? I doubt I'll see much over 15 lbs if that makes a difference. I have been checking out the fuel labs digital fuel pump and regulator which has an 1/8" port just for referencing. Anyone use these yet?
Staging Lane
Joined: Apr 2013
Posts: 97
Likes: 0
You're talking about boost referencing the fuel pressure I'm guessing?
Normally on a boost referenced fuel pressure regulator the fuel pressure would climb on a 1:1 ratio with boost. There are ways to tune around a boost referenced FPR but depending on how much boost you are running it isn't the best method.
For example, if you are running a base fuel pressure of 43 psi, but you pressurize the intake to 25 psi the fuel will only flow at 18psi (43-25=18) which might not give the injector enough time to stay open in between valve events.
In your case, if you run base pressure of 58 psi (stock on most ls applications) and you run a max of 15psi positive intake pressure you could probably get away with not boost referencing, depending on your injector size. As mentioned above you would have to tune around this though. The injector duty cycle will not automatically compensate for fuel pressure.
Normally on a boost referenced fuel pressure regulator the fuel pressure would climb on a 1:1 ratio with boost. There are ways to tune around a boost referenced FPR but depending on how much boost you are running it isn't the best method.
For example, if you are running a base fuel pressure of 43 psi, but you pressurize the intake to 25 psi the fuel will only flow at 18psi (43-25=18) which might not give the injector enough time to stay open in between valve events.
In your case, if you run base pressure of 58 psi (stock on most ls applications) and you run a max of 15psi positive intake pressure you could probably get away with not boost referencing, depending on your injector size. As mentioned above you would have to tune around this though. The injector duty cycle will not automatically compensate for fuel pressure.
9 Second Club
Joined: Nov 2003
Posts: 13,616
Likes: 185
From: Norn Iron
Is boost referencing needed on efi or does the duty cycle just pick up on the injectors as boost is applied? I know on a procharged blow through carb setup I had it needed a pound and a half for every one pound of boost but the efi runs such a high pressure already so I just wondered if it was necessary? I doubt I'll see much over 15 lbs if that makes a difference. I have been checking out the fuel labs digital fuel pump and regulator which has an 1/8" port just for referencing. Anyone use these yet?
The idea is to maintain a constant pressure difference across the injector at all times, regardless of pressure in the intake.
Is it essential to do this ? No. But it makes sense to do it.
Staging Lane
Joined: Mar 2007
Posts: 52
Likes: 0
all my non boosted ls swaps are returnless unless i'm reusing the factory fuel lines and it was a return system
this is because i am lazy and cheap and 1 fuel line is easier/cheaper than 2
anything with boost "should"(and does if i'm building it) have a return type system (boost referenced)
this is because i am lazy and cheap and 1 fuel line is easier/cheaper than 2
anything with boost "should"(and does if i'm building it) have a return type system (boost referenced)
