lunitic5454

iTrader: (1)

So I have this idea on how to get away from using low impedance injectors, spend less money, and still get to the fuel requirements needed. What if you could make the effective fuel pressure range from 60psi to 120psi on 15lbs of boost? That would make a 100lb/hr factory style injector flow over 140lbs/hr. These injectors are rated up to 120psi and in conjunction with the Weldon DB-2015 fuel pump rated at 0-160psi, the potential is there.

This is my idea… get 2 boost referenced fuel pressure regulators and connect them is series. Set the static pressure at 45psi. When idling at 15lbs of vacuum, each regulator would be at 30psi (45psi static – 15psi of vacuum) for a total of 60psi of fuel pressure. When at 15lbs of boost, each regulator would be at 60psi (45 static + 15psi boost) for a total of 120lbs of fuel pressure. It would essentially be a 2:1 boost reference FPR.

This is theoretical of course, but if it would work, that would solve my problem of getting 8 injectors to idle on pump gas and still make 1200fwhp on E85. I attached a scribbled up drawing of my idea (hope the link works)

Any thoughts?

chevellepowered

iTrader: (37)

correct me if im wrong..but injectors can only handle so much fuel psi from pump till they pop...120 psi i think would pop them.. i dont kno..

lunitic5454

iTrader: (1)

via fuelinjectorconnection.com: "these will flow 100lb at 58 PSI but can handle pressure to 120psi making these flow much higher!"

Ofcourse you would want to keep the peak fuel pressure as low as possible to prevent excessive heating of the fuel, but on E85 it probably isnt that much of an issue anyway.

chuntington101

can you not just buy a reg that has a 2:1 ratio instead?......

CarsandWomen

iTrader: (19)

or you can boost reference a fuel nozzle to come on, kind of like a TPI setup, right before the TB. That way when fuel requirements pass the injectors you'll get a relatively large amount of fuel evenly across all 8 and the injectors can give it the fine tune.

this is how most sport bikes on the road are setup, 4 cylinders, 4 injectors, and 4 injectors/nozzles. Keeps the primary injectors from doing all the work.

sbcgenII

iTrader: (1)

An FMU would be anouther option.

slow

iTrader: (7)

That is exactly what a FMU is, and there is a reason why people do not use them anymore.


Ryan

70GS455

15 psi of vac is approx 30 inches of vacuum. There's not many engines I can think of that idle with 30 inches of vac. You may have around 20 inches of vac at idle (10 psi vac).

The pintle of the injector opens against fuel pressure. Above around 100 psi, the pintle is slow to open or wont open at all, due to it working against fuel pressure. You will need to keep the fuel pressure below 100 psi.

Get an adjustable boost-referenced fuel pressure regulator, set it to a high number that satisfies fuel delivery requirments for the hp needed, and just trim the pulsewidth back at idle/low speed through tuning.

lunitic5454

iTrader: (1)

Wow, seem like a lot of people aren't onboard with this idea, (especially since someone added the word "stupid" to my title). People use 1:1 boost referenced FPR all the time, why not a 2:1? Granted, this isn't for everyone, but it might be the difference from upgrading to low impedance injectors (and having to live with a rich A/F ratio at idle and cruise) and sticking with factory style injectors like the ones from fuelinjectorconnection.com.

"can you not just buy a reg that has a 2:1 ratio instead?......"
I've never been able to find one.

"or you can boost reference a fuel nozzle to come on, kind of like a TPI setup, right before the TB."
This idea would work, but their would be a concern with proper fuel distribution. Plus, I wouldn't have to mount, plumb, and wire extra injectors. This idea just sounds easier.

"An FMU would be anouther option."
A FMU only controls the pump (at least the ones I've seen). The type with "Pulse Width Modulation" like the one from Weldon is used to decrease the volume of the pump when there isn't demand for extra fuel, and the type like the Boost-A-Pump from Kenne Bell uses a boost reference to increase the flow from the pump. Either way, they only affect the volume of the pump, not the fuel pressure.

"15 psi of vac is approx 30 inches of vacuum. There's not many engines I can think of that idle with 30 inches of vac. You may have around 20 inches of vac at idle (10 psi vac)."
I meant 30psi of fuel pressure, not vacuum. Think of each FPR as a separate unit, then add the resulting pressure from each FPR to get the total fuel pressure. If one FPR would normally be at 30lbs of fuel pressure, then 2 in series would be at 60. If one would normally be at 45lbs of fuel pressure (with 15lbs of boost reference) then 2 would be at 90.

"The pintle of the injector opens against fuel pressure. Above around 100 psi, the pintle is slow to open or wont open at all, due to it working against fuel pressure. You will need to keep the fuel pressure below 100 psi."
If fuelinjectorconnection.com says they are rated up to 120psi, I don't see what the problem is.

"Get an adjustable boost-referenced fuel pressure regulator, set it to a high number that satisfies fuel delivery requirments for the hp needed, and just trim the pulsewidth back at idle/low speed through tuning."
I wish I could. The problem I have is getting 8 injectors to meet all of my fueling needs. I want to be able idle and cruise at stoich using pump gas, and when I switch to E85 meet my 1300fwhp goal. 100lb injectors at 120psi of fuel pressure would get me there, then I wouldn't have to switch to 120's or even 160's.

Has anyone run 100+ lbs of fuel pressure?

CarsandWomen

iTrader: (19)

Well they used it for years using TPI so evidently it works well enough. and id hate to have to count the number of guys running meth injection and that distributes just fine. Also, all those 400lb bikes running around town with 170 whp use it at 16,000 rpms every day of theyre lives, carburetors have been doin it for just over 100 years......just sayin