Page 7 of 7 FirstFirst ... 34567
Results 121 to 129 of 129

Thread: LNF Cam adjustment

  1. #121
    Advanced Tuner
    Join Date
    Feb 2008
    Posts
    665
    Sorry guys to bring this one back from the dead but just had a few questions to double check myself on changing the cam timing tables. Someone please feel free to rip me a new one if you would like because I feel like a moron! I've read thru every thread involving cam timing a few times and I just want to confirm a few things. Slightly different application I am messing with in regards to my 09 CTS but same E69 pcm. So as to my understanding the more the numbers are negative on the intake table the more advance and thus more overlap, correct? As far as the exhaust table goes the more positive the numbers the more the exhaust cam gets retarded or is it reducing the numbers retard the exhaust? Now using the formula for figuring out the actual overlap in the editor those final numbers the smaller they are the more overlap their is or less overlap? For example in my CTS which of course is NA I would assume the smaller numbers do mean more overlap because in the highest load region where I would be going WOT the numbers are all negative which for naturally aspirated the overlap is a good thing, well for the most part anyways.

    Been successfully modding and tuning LS cars and trucks for almost 10 years but just trying to wrap my head around this style pcm/operating system. I understand the technical side of cams pretty darn well just trying to make sure that I am on the right track with how GM interprets the advance, retard, cam overlap etc... within the tune. Right now I feel a little bit like an idiot! Lol.
    I am just wanting to see if I can improve mileage in the cruise areas and in the higher loads see if I can squeeze a little more out of my car.

    Thanks.
    Last edited by KLUG'S SS; 01-02-2016 at 03:20 PM.
    2017 Silverado LTZ

  2. #122
    Tuner
    Join Date
    Sep 2014
    Location
    Utah
    Posts
    68
    10-17-2013 #114
    codename Bil Doe codename Bil Doe is offline
    Advanced Tuner

    Join Date
    Jan 2007
    Posts
    480
    Simple table to help you visualize, only, since pos and neg numbers with advance and retard can get confusing. This is only visualization for what you're doing with overlap irregardless of how much total advance you have. Just a comparator.

    Repeating previous info, the minimum overlap occurs with both cams in park position (intake at +10 in the editor, exhaust at -6) . The maximum overlap occurs with intake fully advanced (-40 in the editor) and the exhaust fully retarded (+44 in the editor)

    1. Treat the MIN overlap you can create thru the editor tables as a value of 0:

    MIN overlap available = (MIN intake advance - intake park position) + (MIN exhaust retard + exhaust park position)

    MIN overlap available = (+10 -10) + (-6 + 6)
    MIN overlap available = 0 + 0
    MIN overlap available = 0

    2. Treat the MAX you can create thru the editor tables as a value of 100:

    MAX overlap available = ABS(MAX intake advance - intake park position) + (MAX exhaust retard + exhaust park position)

    MAX overlap available = ABS(-40 - 10) + (44 + 6)
    MAX overlap available = ABS(-50) + 50
    MAX overlap available = 50 + 50
    MAX overlap available = 100

    Why take the absolute value? Because of the park position being zero and the intake cam only advancing, the values will always be negative. Taking the absolute value and adding to the exhaust gives you an easier visualization of whether you're creating more overlap or less based on a scale of 0-100. Easier for people to visualize. Also easy to compare to stock and other people's tables.

    This does not take into account actual cam positions. This is to help visualize overlap - cam positions relative to each other. With that explanation, here's the equation:

    ABS[INTAKE -10] + [EXHAUST + 6]


    This means that a value of 0 is the least amount of overlap you can have, and a value of 100 is the greatest amount.
    Quick reply to this message Reply Reply With Quote Reply With Quote Multi-Quote This Message
    Last edited by powermizer; 01-02-2016 at 06:31 PM.

  3. #123
    Tuner
    Join Date
    Sep 2014
    Location
    Utah
    Posts
    68
    Bill helped me clear it up by this^^^^

  4. #124
    Advanced Tuner
    Join Date
    Feb 2008
    Posts
    665
    Quote Originally Posted by powermizer View Post
    Bill helped me clear it up by this^^^^

    Ok, thanks! I mean I read that before I just started second guessing what I thought based on some testing done on my car. I don't know maybe I'm going crazy! LOL. I always seem to be on the forum here late at night more than any other time, probably was pretty damn tired and half out of it so it wasn't clicking for me. Haha
    2017 Silverado LTZ

  5. #125
    I wouldn't trust that Bill dude.

    You can get significant gains without changing anything else boost wise by eliminating most (not all) of the mid-range cruise speed overlap of the cams.

    GM has a lot of overlap to let the car freewheel more at freeway speeds. Loses a lot of torque, but you don't need it when cruising. More overlap = less engine braking = better mpg. Get rid of the humps mid-range.

    I found consistent gains of 0.3sec from 60-80mph over 50+ pulls (to verify data vs more overlap).

    http://www.hptuners.com/forum/showth...uot-cam-timing

  6. #126
    Tuner
    Join Date
    Sep 2014
    Location
    Utah
    Posts
    68
    Bill is that you? lol I never thought I would see the day!!! Its good to see your back. hope you hang around!!!! Somehow I missed your work on those cam tables. Thanks for bringing those back.
    Last edited by powermizer; 01-05-2016 at 06:08 PM.

  7. #127
    You haven't seen the day. =p

    I randomly popped on. Been helping some people with LFX, LF4, LT1 because they asked. Very few people understand torque based ecu's and try tuning them like LS engines. It's like reading the stone ages of LNF understanding.

    Otherwise, I've written off the internet. I still get suckered into helping when people ask because I still care. You can find me at the track. Or by text

  8. #128
    Typical LNF writeups I've done can be found by searching google for "hptuners lnf [cam/optimum spark/kr]" or by adding "codename Bil Doe"

  9. #129
    Advanced Tuner
    Join Date
    Feb 2008
    Posts
    665
    Quote Originally Posted by codename Bil Doe View Post
    I wouldn't trust that Bill dude.

    You can get significant gains without changing anything else boost wise by eliminating most (not all) of the mid-range cruise speed overlap of the cams.

    GM has a lot of overlap to let the car freewheel more at freeway speeds. Loses a lot of torque, but you don't need it when cruising. More overlap = less engine braking = better mpg. Get rid of the humps mid-range.

    I found consistent gains of 0.3sec from 60-80mph over 50+ pulls (to verify data vs more overlap).

    http://www.hptuners.com/forum/showth...uot-cam-timing
    I am currently in the middle of my own testing lately but have you ever experimented with adding more overlap in the cruise areas than what GM already has in there for mileage gains?? Because of so many variables always difficult to get a good bead on any mileage gains or losses with tuning changes....

    In the higher load (WOT) region of the cam timing tables I've already had very good success as far as performance gains goes. In fact almost could not believe the gains going by my timed runs in the scanner. However was just looking for some mileage gains as well when I'm cruising. I know I know I want the best of both worlds, I'm asking a lot. Lol.
    Last edited by KLUG'S SS; 01-07-2016 at 09:01 PM.
    2017 Silverado LTZ