E Dogg

iTrader: (1)

Finally taking the plunge and running 1600 primaries and upgrading fuel preesure regulator. I hear that its important to bump the psi for decent idle using the 1600's...

What kinda pressure are you all getting best idle from? and any recommendations on a good FPR? i prefer simplicity whenver possible and dont want anything i dont need.

moremazda

iTrader: (4)

I turned my pressure down to ~45psi and I get a pretty decent 13.5 idle right now. I ran 35psi and I ran 50psi, at 50psi the lag time starts to be effected and 35psi has crappy atomization.

E Dogg

iTrader: (1)

so its 45psi @ idle, do you know what pressure you are using under load?

WaachBack

iTrader: (21)

Whatever boost you running add that to your base.

E Dogg

iTrader: (1)

got ya, ill start with 45 and see what happens

thanks for the help

E Dogg

iTrader: (1)

hey weren't you at the Iowa/Ill meet @ old chicago about a month back?

moremazda

iTrader: (4)

No, I haven't been out to many meets this year and I found out about that meet way to late.

E Dogg

iTrader: (1)

OK so are you running 45 psi at idle or base? 45 @ idle would be 50-52 base correct?


I'm going through my old research here and i just wanted to be 100% clear.

mazda rx2 rotary

When everybody talks about base fuel pressure it is a standard that the engine is running at idle.you earlier post about fuel pressure under boost is as fallows.if your fuel pressure is at 40psi at idle,your fuel pressure at 10psi boost should be at 50psi.the fuel pressure regulater will rise your fuel pressure 1 pound of fuel pressure per 1 pound of boost pressure.so if your fuel pressure is at 40 psi at idle and negative manifold pressure it is all good.(mine idles fine at 40 psi,if yours runs betterat 45 psi then that is what your combo whats)if your combo likes 45psi at idle good.if your are in the positive manifold pressure of 20 psi your running fuel pressure should be at 65 psi fuel.55 psi fuel pressure @ 10 psi boost,65 psi fuel pressure @ 20 psi boost,75psi fuel pressure @ 30 psi boost,and so on.this is only the case if you have a boost sensitive fuel pressure regulator.

E Dogg

iTrader: (1)

shouldn't base pressure be the pressure the regulator is set at when there is 0psi of manifold pressure? the stock regulator is checked with the vacul ine dissconnected if i recall.
In my case i have about 7 lbs of vacuum at idle -so if the base pressure is set at idle- when i run of 20psi positive pressure i have an increase of 27 psi over base correct?

moremazda

iTrader: (4)

Both, I have a vacuum check valve so that I have 45psi throughout the vacuum range.

moremazda

iTrader: (4)

Yes Base pressure is the fuel pressure when the boost gauge says zero.

E Dogg

iTrader: (1)

ahh that makes sense.

rotorholic

iTrader: (53)

correct, fuel pressure must me set with vacuum line disconnected

rx72c

iTrader: (8)

Ive tuned cars with 1700cc primaries with fuel pressure as low as 30psi. Your ecu is your biggest limitation.