550cc injector fuel pressure
- Thread starter Aidan-G
- Start date
weeJohn
Lifer
Do you mean the injectors are leaking when you switch the car off?
To get 550cc of flow and good atomisation in the fuel, pressure needs to be 3 bar, as thats how they are rated as you know.
But they should hold 3 or more bar behind the seals when they are closed, or there is a problem.
Do you notice this on starting back up again or on stopping the engine?
To get 550cc of flow and good atomisation in the fuel, pressure needs to be 3 bar, as thats how they are rated as you know.
But they should hold 3 or more bar behind the seals when they are closed, or there is a problem.
Do you notice this on starting back up again or on stopping the engine?
eptercel82
Member
what type of injector is it?? meaning if you know who made this injector look at there specs or ratings for that perticular injector..
???cc @ ?? psi...
for example rc engineering rates there 550's as follows---
Flow Rate - CC's:
550 CC's / MIN @ 43.5 PSI
Flow Rate - LB's:
52 LBS / HR @ 43.5 PSI
30psi minimum psi/100 psi max..
so if your injectors are flowing 550cc @ 43.5 raising the rail pressure to lets say 72psi. they would flow 707.59cc's ... so it really depends on how your tune is going.. good luck mate
???cc @ ?? psi...
for example rc engineering rates there 550's as follows---
Flow Rate - CC's:
550 CC's / MIN @ 43.5 PSI
Flow Rate - LB's:
52 LBS / HR @ 43.5 PSI
30psi minimum psi/100 psi max..
so if your injectors are flowing 550cc @ 43.5 raising the rail pressure to lets say 72psi. they would flow 707.59cc's ... so it really depends on how your tune is going.. good luck mate
Fatman
Member +
I can't say that I've ever actually checked but if you're referring to the fuel rail pressure dropping after you turn the car off, I'm hardly surprised.. without the fuel pump functioning it's always going to drop off.. it doesn't necessarily mean that the injectors are leaking.
Ideal fuel pressure is a pretty indepth conversation if you want to get into the inner workings of fuel injectors, I will say that if 3bar fuel pressure will flow your required power that's probably where you should leave it.
You can sometimes gain some efficiency in the spray pattern with higher pressures but the significant down side is the increase in 'dead time', that is to say the time between the ECU sending the signal to fire and the injector actually responding and opening all the way.
Increased dead time will lead to a disproportionate increase in duty cycle required to keep the required air to fuel ratio, this non-linear progression of duty-cycle to actual volume of fuel delivered due to increasing dead time wreaks havoc with temperature or voltage correction. For example if your intake temperature compensation adds 10% (numbers are examples) more fuel for every ten degree drop in air intake temperature but you're running at the upper limits of the injectors capability that additional 10% duty cycle might only translate into an additional 5% of fuel in the real world, leading to a lean condition and potentially the end of your engine.
All injectors are not created equal, the later generations of bosch or siemens injectors aren't even comparable to the earlier generations like the standard starlet injectors, they are far more tolerant of increases in fuel pressure, so much so that the latest generations will quite comfortably function without significant detriment at 130psi flowing 70% more than their rated flow
Ideal fuel pressure is a pretty indepth conversation if you want to get into the inner workings of fuel injectors, I will say that if 3bar fuel pressure will flow your required power that's probably where you should leave it.
You can sometimes gain some efficiency in the spray pattern with higher pressures but the significant down side is the increase in 'dead time', that is to say the time between the ECU sending the signal to fire and the injector actually responding and opening all the way.
Increased dead time will lead to a disproportionate increase in duty cycle required to keep the required air to fuel ratio, this non-linear progression of duty-cycle to actual volume of fuel delivered due to increasing dead time wreaks havoc with temperature or voltage correction. For example if your intake temperature compensation adds 10% (numbers are examples) more fuel for every ten degree drop in air intake temperature but you're running at the upper limits of the injectors capability that additional 10% duty cycle might only translate into an additional 5% of fuel in the real world, leading to a lean condition and potentially the end of your engine.
All injectors are not created equal, the later generations of bosch or siemens injectors aren't even comparable to the earlier generations like the standard starlet injectors, they are far more tolerant of increases in fuel pressure, so much so that the latest generations will quite comfortably function without significant detriment at 130psi flowing 70% more than their rated flow
sx_turbo
Lifer
the pressure drops off cos the fuel goes back into the tank, only a small ammount of pressure stays in the fuel rail.
the more likely cause of your car struggling to start is something to do with management or how it's tuned (injectors setup)
350ep70gr
Member +
Should hold close to standard pressure for 2 min or so tho..after the engine is off!
Chris
weeJohn
Lifer
Next time you go to start it, give the starter a quick blip, not enough to start the engine but enough to turn the starter. This will activate the fuel pump to run for about 3 seconds, filling and pressurising the fuel line.
See if that helps, if not, generally on start up, the injectors are fully open on cranking. This could be flooding your engine so ask Chris if there is anyway to lean them out on cranking.