Xcessive

Has any body run the 850cc high impedence injectors in
the primary side at 60-65 psi base pressure and made a decent Idle. I am running 850X1600cc injectors now and to get to the targeted HP without adding extra injectors
I want to raise the base pressure. If you have done this
what are the lag and size settings you have used?
THX Ralph

Spool Up

what is stock fuel pressure? My brother is running 850cc's on both primary and secondaries at stock fuel pressure w/ perfect idle w/ his PFC

RX794

Ralph, it looks like me and you are in the same boat, I haven't finished my fuel system yet, BUT I have 950primaries(Stock 550's Bored out by RC), and will have 1600secondaries, I'm running a T88 34D and will likely have the same concerns that you are having at high boost. I'm 99% sure that with playing with the lag time you can get the injectors to idle how you want to at 60psi base, the only thing now that you should be concerned with is your fuel pressure, make sure that the fuel pump can supply the needed pressure due to the higher base fuel pressure you're running, as long as it can, I don't see why this wouldn't work. Another thing I was considering because of this issue was running 4X1600SECONDARIES, this would solve the problem also, and you won't have to run resistors this way, BUT my concerns with this are having to run more lines, more stuff to go wrong, fuel atomization, etc. If you can get away with running more fuel pressure, and have the pressure stable with smaller injectors it's a better idea because it's less complicated, and due to the higher fuel pressure the fuel will atomitize better in the motor giving you cleaner more efficient burning, a.k.a. more HP!. Lemme know what comes of your findings, I'll let you know my findings once I go through it as well.

Xcessive

I run and Magnaflow EFI 600 fuel pump and reg, one of the biggest made, even bigger than weldons, so fuel flow and pressure arnt and issue. On the injectors, I run the 1600cc without resistors so the lag isnt to bad, but I
thought about going to 4X1600 also, but the PFC cant drive them all without being to slow. So I figured out that using 65psi base pressure and 850X1600cc you can get about 700rwhp while maintaining only the pfc
as the single controller.
Also we are thinking about modifying a regulator that can do more than raising rate 1:1 like 1.5:1 etc and keep base 40 psi unless anybody knows of one made now? btw I measured 1.8bar @40psi base=85% dc
and 2bar@ 40psi=100%dc with850X1600
all thru 9k rpm
Ralph

IGY

I run a 550/1680 setup with 63psi static fuel pressure. The lag time/ injector settings don't need to be changed when running high fuel pressure. I did have to change the accelerate injector and cranking blocks. I have also tried the 1680x4 setup, and it doesn't work with a sideported motor. The power fc can't fire the injectors at a low enough duty cycle for idle. With a 1/2 bridge port and a 1600rpm idle there were no problems, and the car actually drove smoother than with the 850 primaries.

Xcessive

Thx for your imput igy.

RX794

When I said 4X1600 injectors I meant 4X1600 SECONDARY injectors(Keeping your 850's in the Primary location, and using 4X1600's as secondaries), NOT 4X1600 all around.

Xcessive

I run 1600cc no resistors. which the bosch injectors are about 7 ohms res hot, run w/O res @ 14volts =2amps
draw on PFC. run 2X1600 parellel =4amps on pfc= To muich. If you run 2X1600 series = 14 ohms = 1amp
and injectors to slow, thats why I am trying to raise the fuel pressure to 65psi keeping the original setup.
I calculated that 850ccX1600 @ 65 psi is equivilant to
4X1600cc injectors. Listen I am like everybody else and I really appreciate the imput on this forum, you guys are great. THx Ralph

IGY

What you just said gave me an idea. If I run the 1680 primaries with no resistors, but the secondaries with resistors and use the pfc settings to compensate for the lag time I may be able to run the 1680x4 setup on the side port, and not fry the injector drivers. What do you think?

RX794

Someone told me you don't have to use resistors regardless, because if I'm not mistaken the PFC has seperate drivers for PRI and SEC, so you can use them all w/o resistors. I wonder if Ralph knows if this is true or not to confirm this, cause it's just a theory at this point.

Xcessive

All I know is thaqt the bosch 1600s only are considered low impedence, but are cold 5.5ohms and hot arround
6.5-7ohms that I measured. At that resistance, I figured the drivers are capable of supporting them w/o resistore, Ive run 1.5 years like this. But all the other low impedence injectors that I measured up to 920cc size were all around 2.4 ohms and 14.5volts @ 2.4 ohms=6Amps, to much, but with resistors, 3ohm, these are the same as the 1600s W/O. Bottom line I tried both and one workd and the other didnt so do all at your own risk I did. RALPH

IGY

Screw it, I'll try it! Glad I have 2 pfc's

Jason

iTrader: (5)

I run 1600/1000cc injectors. You might want to try that for more fuel. You wouldnt have to pump the FP as high.

Jason

rotarypower101

iTrader: (1)

How well do the 1000s do for the primaries Jason?
Can you compare it to the 650s or 850s in the primary location, or is it all in the time spent tuning it out smooth.

Xcessive

Im with Igy, screw it Iam going to modify the PFC Fet
drivers to run 4X1600cc injectors scondary only. Igy I have only one PFC keep your fingers crossed {fire in
the hole}

IGY

Apexi actually offers upgraded injector drivers as an upgrade. It costs around $80. I have now been offered a 6 injector setup that was on a budy's car in exchange for my rail and 2x1680's. I guess the next time I'll be trying 4x1680's again it will be on the 1/2 bridge car. Good luck man. Let us know how it turns out.

Xcessive

Iggy Ill check it out with apexi. Ari and others I have talked to havent heard of this option.
Ralph