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Thread: Exhaust cam angle. Which direction is which?

  1. #1
    Tuner in Training
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    Nov 2016
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    Exhaust cam angle. Which direction is which?

    Exhaust cam angle. Which direction is which?

    The intake is obvious but not so much the exhaust.

    Is a higher value (or less negative) more or less overlap?

  2. #2
    Tuner in Training
    Join Date
    Nov 2016
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    Judging by how the exhaust cam timing is around idle, I'd assume the more negative numbers are earlier exhaust valve opening (less overlap) and more positive numbers are later exhaust valve opening (more overlap) but at full load, it's the reverse of what I've seen on other vehicles. On other vehicles, I've seen exhaust valve opening start late (with more overlap) and gradually decrease overlap as RPM increases. This is doing the opposite.

    I just want to get my head around what it's doing. Intake valve changes obviously makes WAY more difference but I'd still like to make a small theoretical change on the exhaust side to account for significantly less back pressure of replacing all 4 stock cats with 2 100cpsi cats.

  3. #3
    Tuner in Training
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    Nov 2016
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    I'd still really like to know the answer if anyone knows?

    I can't get my head around the exhaust cam timing map at all.