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Reply With QuoteWhat is the difference between low and high impedance injectors?
The amount of voltage an injector needs to open. High impedance basically means it needs a higher amount of voltage sent to the injector to have it open fully and properly. Lower impedance injectors are just vice versa. High impedance injectors as far as voltage go need anywhere up to 12 Ohms, low impedance are around 3-5 ohms but of course, this depends on the vehicle and engine management system.
Do I need to upgrade my fuel system if I run a nitrous kit? (wet or dry kits)
Not to get too off topic but a brief description of how each kit works and why you would or wouldn’t need to upgrade with either one. I am assuming that you already know how nitrous affects an engine as well:
A wet nitrous kit basically means that as nitrous is being injected into your air intake stream it is also spraying fuel to keep a well balanced air fuel ratio inside your combustion chamber. Depending on how this kit is installed and the vehicle you’re using, you can either tap into the fuel line or the fuel rail for a source of fuel.
Do you need to upgrade your fuel system on a wet kit? Depends. Your fuel injectors, no you don’t need to upgrade them because the fuel that you are supplying along with the nitrous is coming from an outside source and not being sprayed through your fuel injectors. Your fuel pump, maybe. Depending on the stress that is made on the fuel pump to keep a certain demand of fuel (GPH), it might need to be to keep from starving the fuel injectors as well as keeping your “wet line” supplied with enough fuel.
Do you need to upgrade your fuel system on a dry kit? Yes (or at least I suggest it). With a dry kit, you’re just spraying nitrous alone and now you’re taking the fuel management side into your own hands by relying on your fuel system for fuel supply during nitrous injection. Same rules apply as far as overworking your injectors or fuel pump. It’s all about maintaining a proper fuel supply and demand. When things are off balanced and over looked, bad things will start to happen which typically results in lean air/fuel mixtures if it’s not adequate enough during a dry shot injection.
Some cars have return-less fuel systems and some have return fuel systems. Why is it like this? What’s better for performance?
Return-less fuel systems were created, for one, help the computer control more of the amount of fuel being sent to the fuel rail and to also reduce on the likeliness of fuel leaks by reducing the amount of lines used.
What’s better for performance? Return fuel systems are. They are better for performance in the aspect that all fuel that is entering the rail is entering the fuel injectors at an about equal rate and they are getting an about equal amount of fuel. What typically happens with return-less fuel systems is that as fuel is coming in from one side of the fuel rail, it might be starving the farther injector(s), so they aren’t getting sufficient amount of fuel into the injector(s), hence, not supplying the proper amount of fuel into the combustion chamber which could result in lean mixtures that cause detonation & possible engine damage. Now, this is of course speaking from a high performance point of view and not necessarily in a stock or near stock situation.
What are rising-rate fuel pressure regulators?
Rising rate fuel pressure regulators basically do the same job as your stock (OEM) fuel pressure regulator. Your stock fuel pressure regulator raises fuel pressure as vacuum pressure drops. It has a line that connects from the fuel pressure regulator to the intake manifold to read the air pressure inside the manifold, which helps determine the desirable fuel pressure inside the fuel rail.
On an OEM unit for a naturally aspirated engine, if you were to turbo-charge the engine, as you’re increasing above atmospheric pressure (boost pressure), it will rail fuel pressure inside the fuel rail on a 1:1 ratio (for every pound of boost, it will raise the fuel pressure 1 PSI inside the fuel rail).
On an rising rate fuel pressure regulator, depending on the unit, it will raise the fuel pressure higher than the OEM 1:1. It can be anywhere from 6:1 to 12:1 ratio of fuel pressure to boost pressure.
Increasing fuel pressure will also increase the amount of fuel going through the fuel injector every time it opens but also understand that too much fuel pressure on an underrated fuel injector can cause that fuel injector to not operate properly from internal damage. Another thing to look out for is your fuel pump (which will be explained) as it is also rated to send a certain amount of fuel to your fuel rail. As you’re increasing pressure by restricting the amount of fuel returning to the fuel pump, you’re also slowing down the amount & speed of the fuel to travel from the pump to the fuel rail. Basically, as you’re increasing pressure, you’re also decreasing the rating on the fuel pump.
I want to get a new High Flowing Fuel Pump, which one should I get?
Once again, changing the fuel pump is to keep up with the demand of the rest of the fuel system. Your fuel pump is rated typically either by lbs per hour or gallons per hour.
As you shop for a fuel pump, you will run into different descriptions of the fuel pump, which will refer to: Capacity (lbs/hr or gph), Voltage & Fuel Pressure (PSI). The fuel pressure part is referring to the amount of fuel pressure that in the fuel system that your fuel pump has to constantly supply towards.
The equation to figure out what fuel pump you would need is as follows:
Flow Rate = Horsepower x BSFC
Flow Rate = X lbs/hr
So lets use an example:
Say you have your, once again, 2003 Pontiac Sunfire with a 2.2 ECOTEC engine. Your goal is 300 Flywheel Horsepower with a turbo-charger, you’re assuming 0.55 BSFC, and your constant fuel pressure is 50 PSI.
Flow Rate = 300 x 0.55
Flow Rate = 165 lbs/hr
Now, if your fuel pump you’re shopping for is rated in gallons per hour (GPH), then you take that number and divide it by 6. Your answer is 27.5 GPH.
What happens if I don’t provide enough fuel for my engine?
Your engine is basically meted by a certain amount of air to fuel. You basically need air in order to burn fuel. If there isn’t enough fuel being supplied, this can cause it to run into what is called a lean condition. Lean conditions can cause improper combustions to knocking (detonation) and quite possibly engine damage depending on how bad the condition is.
Can I use fuel injectors from another car?
Yes. The most common fuel injector is the Bosch pintle type injector, if you’re able to find larger injectors that are the same style as your vehicles, you should be able to use those injectors.
If I wanted brand new injectors, what manufacturers can I buy from?
Bosch, Accel, RC Engineering for starters.
If I wanted to buy a new fuel pump, what manufacturers can I buy from?
MSD & Walbro are bigger name companies. You can check them out and see if they have a fuel pump that is rated for your application’s fuel system needs.
How do I convert flow rates? What’s the calculation?
To convert from CC/Min to Lbs/Hr
CC/MM = lbs/hr x 9.71
To convert from lbs/hr to cc/min
Lbs/hr = cc/min x .103
Gallons Per Minute = (lbs/hr) / 369.8
Originally Posted by KronosPerformance 
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