Mikejc wrote:Have a peek at my profile for the mods to date
Yep, I've seen that, but that would have led me down the garden path without this other snippet of info.
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Mikejc wrote:At the time the car was mapped I was infact still using the standed fuel pump, however I do not think this was causing my problem.
How do you know?
Were you monitoring fuel rail pressures?
Mikejc wrote:I base this on the fact that the pump was obviously allowing me enough fuel to reach 100% injector duty cycle, there for the pump must have been doing all that was asked of it!?
I don't see the logic there.
So what if you're having to go up to that duty cycle? That obviously means you don't have enough fuel available.
That could be for a number of different reasons.
You can't do it with guess work.
Mikejc wrote:I believe the AFR was around 11-1.
Boost
@ 1.2 bar.
And in control of the show was the Apexi Power FC
OK, 11-1 is very rich, plenty of fuel that could be taken out there.
1.2Bar is not that much, at least not to affect the fuel pump pressure.
You see, fuel rail pressure rises with boost.
On a turbo car, you want to be using a 1:1 pump pressure-to-boost fuel regulator.
Therefore, if you set base fuel pressure at 40psi, fuel rail pressure will be:
40+14.5psi
= 54.5psi
(at 1Bar Boost)
40+15.9psi
= 55.9pis
(at 1.1Bar Boost)
etc
Now, you have to take into account the characteristics of any given fuel pump.
Any pump's flow capability decreases as the fuel pressure is raised.
Some are better than others in flowing well at high rail pressures.
Also, some pumps have an internal pressure relief valve.
I've seen some pumps actually bypassing most of the fuel back into the tank when the fuel rail pressure reaches the pump's internal relief valve pressure.
You sure as hell ain't gonna get the fuel flow then!
I think that the stock pump starts to have issues in maintaining the desired fuel pump pressure at boost levels in excess of 1.3bar.
Therefore, when you start to run more boost than this, the desired fuel rail pressure becomes too much for the stock pump to maintain.
This is what it seems I'm experiencing at the moment, despite larger injectors, so it seems that no matter what injectors I use, I'll still have an issue with maintaining the right fuel rail pressure when on heavy boost.
Since the guy was wondering what to do for his specific needs, I still believe that he can achieve what he's after with the stock injectors.
An uprated fuel pump and an adjustable fuel pressure regulator are needed, IMHO.
So fingers crossed that new Power Enterprises turbo of mine will be kept in check!
