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Thread: 6.4 Afternarket Cam VVT Tuning

  1. #1
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    6.4 Afternarket Cam VVT Tuning

    I've been dabbling with Mopar tuning lately, we just installed a Comp Phaser 274 in one of my employees 2012 SRT8 Charger. I'm going to tackle the tuning on it tomorrow. This will be my first cammed VVT Mopar.
    Car: 2012 SRT8 Charger 6.4, Automatic

    Parts are Comp Phaser 274 Cam
    Comp vvt phaser limiter kit
    PSI 1511 springs with proper cups, and shims for the Apache head install height.
    All new non-mds mopar lifters/trays
    New mopar head gaskets, bolts
    Mopar cold air intake
    Stock manifolds, exhaust, cats, etc

    Disabled the neural network, did some ve table finessing where I know it'll probably need it, made some other tune changes, loaded it. Aside from some new lifter noise, the car fired up on the first try and actually sounds really good.

    I know with the vvt limiter, I'm physically good mechanically, and no matter what the pcm says, there wont be piston/valve contact. I've installed the ford cams and with the vvt limiters, they actually give you some plug and play data on where to set the pcm tables to.

    I don't know where I should adjust these vvt tables to. Does anyone with more Mopar vvt experiance than I know what the max settings should be so it doesn't throw an error, also does anyone know if there are any other vvt settings that could/should be adjusted that this cam will "like" for part throttle, driveability, etc.

  2. #2
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    could you send me your stock file? I believe the vvt tables are under the >spark> advance tab.
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  3. #3
    Senior Tuner Mep_q8's Avatar
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    There are hardware switches that you'll have to change in order to take advantage of the VVT as well as the cam limiting settings. But I've picked up almost 40-50wtq on a VVT cam by adjusting them!

    Bader Norris
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    Quote Originally Posted by Trailblazin' View Post
    There are hardware switches that you'll have to change in order to take advantage of the VVT as well as the cam limiting settings. But I've picked up almost 40-50wtq on a VVT cam by adjusting them!
    Care to share more ? This car is done and gone, tuning actually went relatively easy. Turned off neural network, made some VE adjustments where I knew it would need them, did some logging and adjustments. First dyno pull was 12.8-12.9 full pull, even with more load added. Blended in a couple degrees of extra spark down low, blended an additional degree in up top. Logged on the Diablo logger, and the car made exactly the power I was expecting. Fires right up, hot or cold, settles to a steady low idle, doesnt hunt or surge. I left the stock VVT setting alone, I wasnt sure what to adjust in there (I know Ford and GM VVT) and figured I'd let the phaser limiter do it's job in there. I was expecting a cam position or phaser code, but 3 weeks now and no check lights, no complaints.

  5. #5
    Senior Tuner Mep_q8's Avatar
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    Sure! You'll need a dyno to see what your motor likes best. But basically stock cam timing values are based on smog, EGR and fuel efficiency.

    With the Phaser limter installed, you should have no problem not to run into piston to valve clearance as that is the point of the phaser limiter. So you should be safe experimenting to how far you want to retard or advance your cams.

    A cam rotates at half the speed of the crankshaft, so the cam timing values in HP Tuners are shown in Intake stroke degrees and Exhaust stroke degrees.

    Cam_angles.jpg

    Stock 6.4 VVT Base camshaft values are @ 0.050" :
    Intake: 236 / 360 (Crank Degrees) = [118 / 180 (Cam Degrees)]
    Exhaust: 238 / 360 (Crank Degrees) = [119 / 180 (Cam Degrees)]
    Valve Lift Intake: 0.591
    Valve Lift Exhaust: 0.559
    Lobe: 121

    The stock cam has around 45degrees overlap which would be expected from a factory camshaft. Lobe is very wide at 121 leading to a smooth mannered cam. Exhaust Valve lift is low as well.


    The 274 VVT Base camshaft values are @ 0.050" :
    Intake: 226 @ 720 (Crank Degrees) = [113 / 180 (Cam Degrees)]
    Exhaust: 234 @ 720 (Crank Degrees) = [117 / 180 (Cam Degrees)]
    Valve Lift Intake: 0.619
    Valve Lift Exhaust: 0.612
    Lobe: 116

    There are 48 degrees of overlap on the 274 cam, slightly higher but this would help with reversion and plumbing effects on the exhaust stroke. Higher valve lift too which would make more power with simply installing the cam and tuning for WOT.

    Some people will leave it there, but knowing the motor has VVT, tuning it for the new cam would make a hell of a difference!

    Stock Cam settings.jpg

    Here is an image of a 2014 Dodge Charger SRT8s Cam profile tables. You can clearly see the Exhaust Cam Position is highly retarded in lower RPMs and Intake Cam Position is advanced. For a stock cam this profile works great, as it does, but the reason being this is simply to create less overlap at lower RPMs for more low end power.

    The higher you increase the overlap the higher power you will get on higher rpms, and this is something you need to experiment with on a dyno. Remember there are limiters that won't allow the cam to be advanced or retarded as much as you want, so you will also have to adjust them according.

    I really hope this helps, my brains about to explode.

    Bader Norris
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  6. #6
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    The overlap is a fixed value in the camshaft on the 6.4 VVT, since it is a single cam engine. Those tables will not change the overlap. All you can do is retard or advance the TOTAL cam events. A global change.

    Mustangs or multi-cam engines are a different story.
    Jaime

  7. #7
    Senior Tuner SultanHassanMasTuning's Avatar
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    since this camshaft is combines Int/Exh i do not thing you can individually adjust each. since there are camphaser limiters installed i suppose we can only advance or retard the profile in the same degrees.

    more testing is definately needed.
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  8. #8
    Senior Tuner Mep_q8's Avatar
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    True on both comments, I was up till 4:30am trying to redesign the wheel.

    The camshaft phasing from the stock files are pretty much the inverse of each other a shown in the image above. Flat line the cam profiles and start working from there, seeing where power/torque increases/decreases.

    Bader Norris
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  9. #9
    Senior Tuner SultanHassanMasTuning's Avatar
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    thats the thing though, how can someone build a new camprofile on a single camshaft. ideally we would zero advance exhaust and work on intake and vice versa with more traditional DOHC
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  10. #10
    Senior Tuner Mep_q8's Avatar
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    You got it.. I never found that much of an increase in top end power changing these settings, with or without cams. The VVT seems to be strictly towards creating more torque through mid-range.

    Bader Norris
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    So I am building A 5.7l non-mds W/vvt bases 392 stroker with springs 274 comp cam bbk headers, exhaust, 50lb injectors, port and polish heads and intake for my challenger. I’m a experienced Tech but new to PCM tuning. I’ve read every post for this cam and this seems to be the Cats Meow with brains and hands on. I would love to speak to you guys about this tune and see what’s my best option and if there is any extra knowledge I could pry out y’all heads. I’ll send pics of the my chick naked -Good ones. Lol. I’m kidding about that part. Unless I need too. Thanks looking forward to a reply

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    I have an issue I hope you can help me. I have. 2012 6.4 charger that has LT,90mm throttle body, ported intake,CAI. I just put a comp cam stage 1 HRT. With phase limiter. Car tuned fine runs and starts fine with good 12.7 WOT fueling and minimal knock. Now the issue is regarding the VVT tables. The car ranges from 134 degrees to 117 degrees exhaust cam degrees. Now the issue is i don’t understand this table. Stock exhaust wot tables have high degrees below 4000 and lower degrees above 4000 rpm. Now is the high numbers advance or retard? Because i tried lowering the numbers in the high rpm to gain more hp but i feel the car power drop. Doesnt make sense. Normally retarding the cam should gain hp up top. I hope you can help me out with this. Appreciate it a lot!

  13. #13
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    as the cam is advanced the exhaust center line gets further away from tdc firing for that cyl so the numbers increase

    that cam was ground with 113 lobe separation yeah?

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    Quote Originally Posted by Captain052 View Post
    I have an issue I hope you can help me. I have. 2012 6.4 charger that has LT,90mm throttle body, ported intake,CAI. I just put a comp cam stage 1 HRT. With phase limiter. Car tuned fine runs and starts fine with good 12.7 WOT fueling and minimal knock. Now the issue is regarding the VVT tables. The car ranges from 134 degrees to 117 degrees exhaust cam degrees. Now the issue is i don?t understand this table. Stock exhaust wot tables have high degrees below 4000 and lower degrees above 4000 rpm. Now is the high numbers advance or retard? Because i tried lowering the numbers in the high rpm to gain more hp but i feel the car power drop. Doesnt make sense. Normally retarding the cam should gain hp up top. I hope you can help me out with this. Appreciate it a lot!
    Advance, so numerically less will mean retard like you said. You really need a dyno to test that though. That or the manufacturer should be able to tell you what to set it at. I wouldn't be all confused if it doesn't make much of a difference though. I've tuned VVT cams in the past and saw very little actually. Not saying you won't gain power but they don't ALWAYS so don't be surprised if it doesn't.
    2018 Camaro SS, Maggie 2650, 103 TB, Big Gulp, E85

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    Let me add to the confusion.

    We are used to thinking in terms of Intake Lobe angles. After installing a cam we check the Installed Intake Cam (lobe) Centerline Angle to make sure it matches whats on the Cam Card. If the number is smaller, the cam is advanced, if bigger, the cam is retarded. On our tunes for VVT we are using the Exhaust Lobe Centerline, which makes everything backwards to what we are used to.

    To make matters worse, if we change to a cam with a different Lobe Seperatin Angle or Intake Centerline angle, the VVT Exhaust angles become totally bogus! On a 5.7, a VVT Exh Angle of 125 simply means that the cam is fully advanced, and a VVT Exh Angle of 117 simply means that the cam is retarded 8 degrees.

    I set the VVT Exh Angles for the mild cam I'm using by making "power runs" on a engine simulation computer program (EngineAnalyzer 3.2) I bought 20 years ago. It was run fully advanced, and then retarded 2 degrees over several runs. Based on these results, the VVT Exh angles are set at 125 up to 3800 rpm and tapers to 117 at 5800. I have no idea what the actual Exh Centerline numbers are, just that 125 is full advanced and 117 is retarded 8 degrees.
    2010 Jeep Grand Cherokee / 5.7 Eagle

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    Other - 180 T-stat, Catch Can

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    Quote Originally Posted by FLandy
    if we change to a cam with a different Lobe Seperatin Angle or Intake Centerline angle, the VVT Exhaust angles become totally bogus!

    I have no idea what the actual Exh Centerline numbers are, just that 125 is full advanced and 117 is retarded 8 degrees.
    they mighta been bogus to begin with...

    have yet to find a man that checked

  17. #17
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    Quote Originally Posted by LilSick View Post
    they mighta been bogus to begin with...

    have yet to find a man that checked
    He is right about that. No one to date has stepped forward and said that they have compared/verified using a degree wheel the cam's exhaust cam position and checked them against the cam card. Next time I find myself involved in a cam swap; I plan on going through this check process myself to see where the cam is actually at versus where the cam card claims it to be. Now as far as saying 125 degrees being a cam thats fully advanced on a 5.7L hemi and retarding from there, are you saying that a cam fully advanced with no advance ground into the cam should be at 125 degrees for the exhaust cam angle? The reason that I am asking, and to clarify and understand this correctly for myself, is that my cam on my 5.7L hemi has 3 degrees advance ground into it, and it shows to be at 128 degrees for exhaust cam position. My cam is locked so it's always reading 128 degrees. is it the ground in advance that allows my cam to be above the 125 degrees fully advanced position?
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  18. #18
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    first of all this is a thread about a 6.4 so this 5.7 stuff is gonna mess the 6.4 guy up. close yer ears el capiton

    according to your sig your cam was ground with 113.5 degrees of lobe separation

    according to what you just said it has 3 degrees of adv ground into it (that means they moved the dowel pin back 3 degree, pushing the cam forward 3)

    3 from where tho???

    113.5 is tighter lobe separation than stock 5.7

    arent they 115?

    either way, 3 degree adv from 113.5 is 116.5 - but that would be in relation to where straight up would be

    when you locked your phaser, you locked it full adv right?

    so if it is really at 128 then it is 11.5 degree adv from their +3 straight up number of 116.5

    and the only way that math works is if your phaser had 23 degree of swing before you locked it

    did it??????

  19. #19
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    Quote Originally Posted by Spray-Cam Hell-Ram View Post
    He is right about that. No one to date has stepped forward and said that they have compared/verified using a degree wheel the cam's exhaust cam position and checked them against the cam card. Next time I find myself involved in a cam swap; I plan on going through this check process myself to see where the cam is actually at versus where the cam card claims it to be. Now as far as saying 125 degrees being a cam thats fully advanced on a 5.7L hemi and retarding from there, are you saying that a cam fully advanced with no advance ground into the cam should be at 125 degrees for the exhaust cam angle? The reason that I am asking, and to clarify and understand this correctly for myself, is that my cam on my 5.7L hemi has 3 degrees advance ground into it, and it shows to be at 128 degrees for exhaust cam position. My cam is locked so it's always reading 128 degrees. is it the ground in advance that allows my cam to be above the 125 degrees fully advanced position?
    The fact that your cam sensor is reading the same at all rpm shows that the Lock is doing its job. Since the lock holds the timing gear firmly in the advanced popsition, the number you are seeing is the "true" fully advanced position for your engine.

    As to why the number you are seeing is different than the full advance numbers on the VVT tables, it may be due to production variances in timing gears. Or it may be that Chrysler (er... I mean....Stellantis) sets the VVT tables to a slightly retarded point so that the cam can adjust to the same position regardless of production variances.

    If with the Timing Gear locked, your installed intake centerline matches what the cam grinder specifies, your all set!
    2010 Jeep Grand Cherokee / 5.7 Eagle

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    Other - 180 T-stat, Catch Can

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    Quote Originally Posted by FLandy View Post
    If with the Timing Gear locked, your installed intake centerline matches what the cam grinder specifies, your all set!
    how do you check that?

    with a wheel and indicator or in the log?