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Fuel Injector Information, possible sticky?

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  • Fuel Injector Information, possible sticky?

    This is a little right up I found which I am pretty much going to copy paste. It is some good information.

    We've found detailed specs for nearly 100 different injectors and summarised that information in a single comprehensive table. The information is rare and useful! So why would you want to know all of the stuff in the table anyway? It's damn important to know injector flow rates when you are sizing injectors for either a new system or an upgrade to an existing system. The flow rates shown in the table are those achieved at 100 per cent duty cycle, that is, with the injectors held fully open. In a well-sized system the injector duty cycle should not rise this high - a duty cycle maximum of about 90 per cent or so is about right.

    For example, the Bosch 0 280 150 100 is listed as flowing a maximum of 185cc (cubic centimetres or millilitres) per minute when tested at a fuel pressure of 300kPa (~43psi).

    So, how much power is this injector good for? That depends on the air/fuel ratio that is used, but a good rule of thumb is to divide this flow figure by 5 to get a hp capability. So, 185cc divided by 5 = 37hp maximum fuel flow with this injector. If you want to be pedantic, it's the mass of the fuel (not the volume) which is the critical factor. Assuming a "normal" fuel density, the mass of the fuel in pounds per hour can be worked out by multiplying the cc per minute figure by 10.2. For this Bosch injector, that gives a mass flow of 18.1 pounds/hour. To convert from pounds/hour to horsepower capability, multiply the figure by 2.04. So 18 pounds/hour multiplied by 2.04 gives a horsepower capability of 37hp - the same as we got from the cc/minute figure.

    Incidentally, if all of this mixing of units (pounds/hour, cc/minute, hp, kPa and psi) gives you the horrors, don't worry about using them all. Instead just pick the system you're happiest with (eg cc/minute and hp) and stick to that.

    The power ratings discussed above are for each injector. This means that you need to multiply this rating by the number of injectors that are to be used. So, if you were using the Bosch 0 280 150 100 injectors in an eight cylinder engine (with one injector per cylinder) the max power that the injectors could deliver fuel for would be about 300hp.

    In addition to the variations in fuel flow from injector to injector, you will also notice that the injector resistance (ohms) varies. Injectors fall into two broad classes in terms of their coil resistance - "low" and "high". Low resistance injectors have 2-3 ohm coils, while high resistance injectors are up around 14-16 ohms. If you are upgrading a car to larger injectors, the new injectors should be of the same resistance class as those being replaced. If you are fitting programmable management, you must make sure that the ECU will be happy with the coil resistance of the injectors that you have selected.

    Note also that injectors vary substantially in their size and shape. Some cars run side-feed injectors, while others are end-feed O-ring types, where the fuel rail holds the injectors in place. Still others use barbed hose fittings. Unless you are prepared to do custom machining and fabrication work, you need to be aware of the required injector size and shape before you make the selection. Finally, injector wiring plugs also vary; however, it's usually not much drama to wire in new plugs - assuming that you can get them!

    -500cc per minute is approximately equal to 49lbs per hour which is equal to approximately 100hp.
    -lbs/hour = cc per minute / 10.2
    -lbs per hour = HP / 2.04
    -cc per minute = lbs per hour x 10.2
    -cc per minute = HP x 5
    -HP = cc per minute / 5
    -HP = lbs per hour x 2.04

    Fuel Injector Flow Rates
    Injectors listed by flow rate, from lowest to highest

    Link to Site with Chart of TESTED injectors ... larArticle

    Terrible idea putting those wheels on...