Awesome. well keep me in the loop on that, and thanks for your insight.
Ill research the walbro and put it on the to-do list.
quickly though, with EFI, and a normal pump out put of 55-60 psi, if you put in 72+psi, would it have worked? I dont ever expect to get 500hp out of this engine (like, ever) but I was just wondering about fuel presure and if it overloads the injector... Im not familiar with TBI or boosted applications etc.
so yeah.
ok ttyl.
The thing to keep in mind is that the vehicle’s ECM had no idea what the fuel pressure is. So, unless you have a wizard doing your programming, you can get in trouble in a hurry.
What we try to do with forced induction is keep the fuel pressure constant, relative to the manifold pressure. When the injector pee’s into the intake manifold, the amount of that leak is directly proportionate to the fuel pressure vs the atmosphere pressure it is peeing into.
Let’s say for sake of argument, that the manifold pressure was 60 psi and the fuel pressure was 60 psi. Nothing would happen when the injector would trigger.
So, in other words, if you have 15 pounds boost, you would add 15 pounds to the fuel pressure at it’s nominal setting with no vacuum hooked to the regulator.
The trick is to raise fuel pressure in sync with the rise in manifold pressure as the boost comes up. That way, the milliseconds of squirt actually relates to a predictable volume of fuel. It with that assumption that all ECM programs are written.
Some cheaper fuel pressure regulator’s act more like a on/off device and go up too fast and can’t actually follow the boost in sync. That makes for difficult tuning. Also, when the pressure is increased, all pumps put out less volume. It is a balancing act. Most of the time it does not become an issue. I discovered that I am running out of fuel on the dyno, when I hit the top end. I have not had a chance to get back on the dyno, since I increased the alternator output. I know for a fact I was not over 12 volts, during the last dyno tests. I am now at 14 volts ALL the time. I need to see if that additional voltage is enough to make the difference before I start plumbing again.
When you engine is idling, it has vacuum. When you open the throttle all the way, you drop to zero, or in other words, the MAP goes up. The fuel pressure regulator on a stock application simply follows that amount of change. I think that is why the kPa scale was invented to be able to state a pressure which begins in a vacuum.
I’m sure you run across MAP sensors that are for 1 Bar, (N/A) 2 Bar and 3 Bar. Those three versions handle from 30 inches of vacuum, to 30 psi boost.
By the by, there are voltage booster’s out there to get more out of a fuel pump by going over the normal operating voltage. I think most pumps are rated at 14 volts. Have not seen one in person or know of anyone that has tried it, just read about it.
I hope this helps……….Del
