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Thread: Engine firing order?

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    Engine firing order?

    What the cylinder firing order, is it as simple as 1-2-3 or does it do 2 at a time then 1?



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    On most 3-cylinder engines it is 1-3-2.

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    word, so that's that, now i know how i want to make my header

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    According to Mitsubishi manual it is 1-3-2: http://www.manualslib.com/manual/988....html?page=291

    So they fire in reverse order last to first on 120deg? crank?

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        click to view fuel log View my fuel log 2015 Mirage DE 1.2 manual: 46.4 mpg (US) ... 19.7 km/L ... 5.1 L/100 km ... 55.7 mpg (Imp)


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    Administrator Daox's Avatar
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    Why would you need to know firing order to make a header?

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        click to view fuel log View my fuel log 2015 Mirage ES 1.2 automatic: 49.0 mpg (US) ... 20.8 km/L ... 4.8 L/100 km ... 58.8 mpg (Imp)


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    Quote Originally Posted by Daox View Post
    Why would you need to know firing order to make a header?
    it wouldn't matter on 2-3cyl, but on engines with more cylinders you can have adjoin cylinders share runners.

    It also depends if you have 180deg or 120deg crank. 120deg crank will have cylinders fire every 240deg, but 180 (basically 4cyl with missing 4th cyl) will have 180/180/360deg spacing. So on 180 crank you could potentially design 3->2->1 exhaust, instead 3->1.

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        click to view fuel log View my fuel log 2015 Mirage DE 1.2 manual: 46.4 mpg (US) ... 19.7 km/L ... 5.1 L/100 km ... 55.7 mpg (Imp)


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    What cyclopathic said. Also thinking how a turbo setup would do if each pipe to the turbo got shorter and short, so say cylinder 1 is the longest, 2 medium, and 3 short, wondering how it would effect overall boost and power band.

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    Administrator Daox's Avatar
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    Equal length runners are always most desirable. If you have different length runners you have the pressure pulses from the exhaust hitting the exhaust turbine in an uneven frequency which reduces efficiency and thus power.

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        click to view fuel log View my fuel log 2015 Mirage ES 1.2 automatic: 49.0 mpg (US) ... 20.8 km/L ... 4.8 L/100 km ... 58.8 mpg (Imp)


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    depends on the type of turbo, subaru's in the US come factory with unequal length headers to the up-pipe to turbo, and it works great. granted, some people swap to equal length with a proper turbo to match and get more power, there are many ways to build everything.

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    I have noticed when at highway speeds there is a slight but regular "hiccup". Like a momentary power loss. Is this because of the 3-cylinder 4-stroke firing order?



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