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Thread: Cam exhaust max position

  1. #1
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    Cam exhaust max position

    Can someone tell me how to find the camshaft exhaust maximum degree and minimum degree of at 218/228 @.50 CAM? duration .571(i)/.545 (e)

    Thanks
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  2. #2
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    Are you asking where should you run this cam??

    If it is a 6.4, full advance will be at 134degs exhaust and 107.5 intake.(you can log it at idle to see the numbers)

    The new cam is a 114LSA with +6 degs adv ground in (114 - 6 = 108 intake LC at full advance)
    The stock cam is 120.5LSA with +14degs of advance ground in (120.5 - 14 = 107.5 intake LC at full advance)

    So to run the new cam at the LSA number (straight up in old skool speak) you will need to retard it 6 degs.
    As the hemi's use the exhaust number to move the cam, that will be 134 - 6 so 128 exhaust degs.....this will put it at 114 intake LC and 114 exhaust LC in reality even though we are commanding and logging 128 degs.
    If you have a 10deg limiter in it, it wont retard past 124 (134-10 = 124) but doubt it will want that much retard anyways.

    Reason we have to skew the numbers is because no-one has told the PCM firmware that you have a new cam in it with different advance ground in and different LSA.
    So the numbers we see when logging assume we are running the stock cam and we have to translate those numbers to suit the new cam.

    Start off with all the numbers in all the exhaust tables at 128 and you can try a little more adv/retard once you get it dialled in a bit.
    It will probably like a few of degrees of advance (130-133 exh) especially at lower/mid rpm.

    It will like advance as the cam is bigger and you will only need to retard it a small amount unlike the stock cam as the extra duration carries the power up further.
    Last edited by Hemituna; 01-20-2021 at 01:43 AM.

  3. #3
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    This is awesome... Thank you so much for explaining.

  4. #4
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    CAM Numbers


  5. #5
    Tkemp I think that you have the exhaust cam timing backwards in regards to RPM. You need to be at 134 in the lower rpm range and start lowering the values after 4200 rpm or so down to 124 ish at redline.
    Last edited by Party340; 01-19-2021 at 07:25 PM.

  6. #6
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    Party340, thank for the advice.. here's the new numbers im dialing in. does this look better??
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  7. #7
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    NN enabled or disabled? Having issue figuring that one out.

  8. #8
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    Try something like this.
    Stay with NN enabled for now and see how it dials in.
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  9. #9
    Quote Originally Posted by Hemituna View Post
    Try something like this.
    Stay with NN enabled for now and see how it dials in.
    tKemp what he said!
    Hemituna I saw that dodge retards the cam at low rpm's and I saw that you did that as well. Is this to lower cylinder pressure at the bottom of the rev range reduce knock? I also see that you never went to full advance on the cam at WOT. Is this because it's installed at 108 ICL or are you trying to stay away from the lockpin timing settings? Still learning this VVT stuff as well.

  10. #10
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    Tracking, thanks again Hemituna, I definitely appreciate you helping us amateurs out. I will load the tune in the morning and see how it performs.

  11. #11
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    This is GOOD information which is really going to help me when I get into this. Thanks to ALL!
    ( I don't want to take over tkemps thread, but here's the cam I installed, not that it's all that different)
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    Last edited by Viperdude1; 01-21-2021 at 09:56 AM.