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Thread: cam valve tiiming

  1. #21
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    Quote Originally Posted by FstdodgeKY View Post
    Now my Tuning books state that both camshafts need to match total degrees of intake+exhaust=# for the factory cam. It uses the 5.7 which comes out at 128* (intake+exhaust=128*) Using your information of the stock 6.4 numbers we come up with 241* (106.5+134.5=241) and i see that when we use the demon cam it does not match (113+133=246)??? Am i missing something or am i just not interpreting what i've read right? Sorry if this seems like I'm beating a dead horse but just trying to understand this clearly..
    Forget the tuning school book added value, it used a 5.7 (LSA is ~114 & PCM treats full advance as ~125 deg) in their example, which is not the same as a 6.2/6.4 (LSA is ~120.5 & PCM treats full advance as ~134.5 deg). So that is why it should add up to 228.5 for a 5.7...for a 6.2/6.4 if you add them it should come out to 241. So on a 6.4 the PCM thinks full advance is 134.5 degs and you are running a 120.5 LSA cam with +14 degrees, therefore the PCM commands 134.5 degs for full advance (120.5+14=134.5) which is like Hemituna says in post #10. Knowing this and your cam specs (i.e. LSA, ground in advance, limiter) you work sort of backwards to find what the actual cam values.

  2. #22
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    Ok I understand that. My lsa is 123+10. So when I tell it to go to 134.5. The cam is at 133?? Correct?? And I just work backwards from there. Also this is on the exhaust side of thing to.

  3. #23
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    Also with the limiter installed I can only move the cam 14* instead of the factory 28* so the furthest I could move it would be to 119* correct??

  4. #24
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    Quote Originally Posted by FstdodgeKY View Post
    Ok I understand that. My lsa is 123+10. So when I tell it to go to Exh 134.5. The cam is at Exh 133?? Correct?? And I just work backwards from there. Also this is on the exhaust side of thing to.
    Exhaust numbers you have are correct. Do be aware that when you advance the cam, the intake numbers get smaller and the exhaust numbers bigger to either side of the 123.

    That is why I said to start out at Exh 124.5 (which is really straight up 123/123).

    You will find the PD blower engines dont like the cam moving much and the old skool thinking of advancing the cam at low rpm doesn't work so well here either.
    As you have boost on demand low down, more intake advance is not ideal and a later intake open & close keeps cyl pressures down some so you can get more (some) timing in them at low rpm.
    The exhaust cam timing works better when not too advanced also, hence my recommendation to start out straight up 123 everywhere.
    Have a look at an OE demon tune, they barely move the cam a degree or 2 from straight up and trust me that the factory engineers are not dumb.
    Last edited by Hemituna; 02-12-2020 at 02:20 PM.

  5. #25
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    Quote Originally Posted by FstdodgeKY View Post
    Also with the limiter installed I can only move the cam 14* instead of the factory 28* so the furthest I could move it would be to 119* correct??
    Correct

  6. #26
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    Quote Originally Posted by Hemituna View Post
    Exhaust numbers you have are correct. Do be aware that when you advance the cam, the intake numbers get smaller and the exhaust numbers bigger to either side of the 123.

    That is why I said to start out at Exh 124.5 (which is really straight up 123/123).

    You will find the PD blower engines dont like the cam moving much and the old skool thinking of advancing the cam at low rpm doesn't work so well here either.
    As you have boost on demand low down, more intake advance is not ideal and a later intake open & close keeps cyl pressures down some so you can get more (some) timing in them at low rpm.
    The exhaust cam timing works better when not too advanced also, hence my recommendation to start out straight up 123 everywhere.
    Have a look at an OE demon tune, they barely move the cam a degree or 2 from straight up and trust me that the factory engineers are not dumb.
    But at start up/idle VVT will default to 134.5 (133 actual) even though 124.5 is entered in the tables and the cam will only move when VSS hits a certain value (I think 3 MPH is default), correct?

  7. #27
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    Quote Originally Posted by Homer View Post
    But at start up/idle VVT will default to 134.5 (133 actual) even though 124.5 is entered in the tables and the cam will only move when VSS hits a certain value (I think 3 MPH is default), correct?

    Correct, it wont change idle cam timing from the full advance default setting until it sees a little speed from VSS

  8. #28
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    Quote Originally Posted by Hemituna View Post
    Correct, it wont change idle cam timing from the full advance default setting until it sees a little speed from VSS
    Does 36456 - ENABLE RPM allow you to adjust VVT at idle by turning down the numbers in that table?
    If in doubt, multiply everything by 1.1.

  9. #29
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    Quote Originally Posted by spoolboy View Post
    Does 36456 - ENABLE RPM allow you to adjust VVT at idle by turning down the numbers in that table?
    If I remember correctly that table also had mileage which I think is meant to limit VVT operation while the engine is breaking in.

    Yup, that's VVT enable based on oil temp & engine miles. I remember somewhere where idle can be defined by RPM and not VSS but it still won't let the cam move at idle...apparently nothing will allow it to move.
    table VVT.JPG
    Last edited by Homer; 02-13-2020 at 09:09 AM.

  10. #30
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    Quote Originally Posted by Homer View Post
    If I remember correctly that table also had mileage which I think is meant to limit VVT operation while the engine is breaking in.

    Yup, that's VVT enable based on oil temp & engine miles. I remember somewhere where idle can be defined by RPM and not VSS but it still won't let the cam move at idle...apparently nothing will allow it to move.
    table VVT.JPG
    So if you made that whole table 100rpm, it still wouldn't do the trick at idle?
    If in doubt, multiply everything by 1.1.

  11. #31
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    Well considering the last column is mostly 600rpm...probably not. I thought it moves during cold start but my logs show it does not budge.

  12. #32
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    Quote Originally Posted by Hemituna View Post
    If it is the TSP cam in your sig then LSA is 117 with 4 degs max advance ground in and I'm guessing also uses a retard limiter (prob 10degs total).
    So straight up is 117/117 and at full advance (+4) will be 113/121...used with limiter fitted, max mechanical retard will be 123/111.
    As the lobes are bigger it will like more advance than the 6.4 cam so will probably like 114ish intake & 120ish exhaust low down and maybe 117/118ish intake & 117/116ish exhaust up top.
    So that is 1 deg retarded from full adv (113+1 = 114int & 121-1 = 120exh) to 4/5 degs retarded (113+5 =118int & 121-5 = 116) at high rpm. These are the ACTUAL (real) cam numbers.
    As usual the PCM has no idea you have changed the cam....so you will need to use numbers that are derived from the fully advanced numbers the PCM uses.
    Log the stock at idle cam numbers. On 6.4 & 6.2 Hellcat/TH they will be about 106.5 intake and 134 exhaust (+14 adv from 120.5 LSA )
    I cant recall what numbers 5.7 idles at with its 114.5 LSA cam but same rules apply.
    So using 6.4/6.2 as example with your new TSP cam you just need to concentrate on how much retard you are telling it to use.
    We decided above that we wanted 1deg at low rpm and 4/5 at high rpm.
    These engines use the exhaust table to move the cam so we will make the changes there.
    134 is full advance so 1 deg retard is 133 exh.....4 degs retard is 130 exhaust.....5 degs retard is 129 exhaust and so on till you hit the 10deg retard limiter at 124degs
    (You can command more but there is no point as it will be mechanically limited and can sometimes also pull up a CEL)
    Hope that all makes sense LOL.
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  13. #33
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    Hi friends, we have a HHP/BES wich is COMP cam with the COMP cam phaser limiter on our 2015 hellcat some one recomend to lock the cam wich is loggical because is Positive Displament SC and dont require to move so much,
    so the question is

    As a Hemituna says 134 fully advanced - 7 degrees on exhaust cam(maxed by the face limiter) would made 127 Aprox is that straight to be locked the cam)?
    All the comp cams limiters are made to stop at 7 degrees ?
    Is recomended 127 on this HHP custom camp hellcat good ?
    should i set all the tables values to 127 ?

    by the way great explain the Hemituna do to understand this values Thanks

    Thanks for any advice

  14. #34
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    I'd start at 133exh ...the comp cams generally like to be run quite advanced.

    Quote Originally Posted by toxicperformance View Post
    Hi friends, we have a HHP/BES wich is COMP cam with the COMP cam phaser limiter on our 2015 hellcat some one recomend to lock the cam wich is loggical because is Positive Displament SC and dont require to move so much,
    so the question is

    As a Hemituna says 134 fully advanced - 7 degrees on exhaust cam(maxed by the face limiter) would made 127 Aprox is that straight to be locked the cam)?
    All the comp cams limiters are made to stop at 7 degrees ?
    Is recomended 127 on this HHP custom camp hellcat good ?
    should i set all the tables values to 127 ?

    by the way great explain the Hemituna do to understand this values Thanks

    Thanks for any advice

  15. #35
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    What a dumb is 14 degree not 7 sorry
    So 134- 14 is 120 degrees on all the table ? this should work great on our setup ?

  16. #36
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    Quote Originally Posted by Hemituna View Post
    I'd start at 133exh ...the comp cams generally like to be run quite advanced.
    Great thats sound good
    dont know to much about this cams setups

    Thanks a lot

  17. #37
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    If it's a 123 LSA or something like that with less overlap I've found it won't like to be as advanced but most seem to do something like a 117 LSA and those I run at 133 usually. Do you have the cam specs?

  18. #38
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    Quote Originally Posted by tbrtuning View Post
    If it's a 123 LSA or something like that with less overlap I've found it won't like to be as advanced but most seem to do something like a 117 LSA and those I run at 133 usually. Do you have the cam specs?
    Oks Oks dont have it here but i should post them tomorrow

    it looks like these Comp cams like 133

    Thanks

  19. #39
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    unfortunately due is a custom cam for HHP/BES do not come with scheduling specs so we gone to go to the dyno soon and test in wich position works better, for sure going to start at 133 as you recommend

    Thanks Hemituna and Thanks tbrtuning for the info

    Cheers