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Thread: Tuning VVT cams for a lopey idle

  1. #41
    So after all this time, this topic may still bring up some questions even if it does not directly apply to the lope. Tonight I spent some time again looking over the cam profile of the 3.6 Pentastar engine and one thing I did notice; even though the tune is for a Challenger, it has the same profile as a FWD vehicle between 1696rpm- about 4500rpm. As mentioned before, the midrange is choked and more than likely its due to emissions. Now from 864rpm-1152rpm the cam is set for a 108.5 LSA and from 1312rpm to about 4352rpm the LSA drops then comes back up. This is obviously for emissions as the average user operated under these engine rpm's. At 512rpm the LSA is set for 122.5, at 6816rpm its set for 112.5....
    I've looked at many dyno results of the stock 3.6 and just about every one in the midrange has the intake centerline drop in the midrange then come back up which would explain the fluctuating Torque in the midrange, yet provides a steady HP increase.
    Anyways, back to the idle....
    Apparently with the 3.6 engine a 108.5 LSA is considered a tight LSA but with the 3.6 its not tight enough to create a lope....

  2. #42
    Senior Tuner mbray01's Avatar
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    Lsa is not what gives you the lope

    lope comes from valve overlap. At what point does the exhaust valve close vs the intake valve opening. Now essentially you are changing the lsa to get the valve events to cause an overlap. But don't make the mistake of believing the lsa is what creates lope.

    A 210/210 cam with an 108 lsa will be entirely different than a 240/250 with a 108 lsa

    you have to look at the specific valve events to determine what it is your trying to accomplish
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  3. #43
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    The pentastar idle cam timing doesn't change no matter how much you change the cam tables.
    The inlet cam is full retard and the exhaust is full advance (so minimum overlap) until the revs rise and speed is sensed.
    So no lope at idle.
    The PT and WOT cam timing is VERY emissions biased.
    There is performance and economy to be gained from modifying these tables.
    Cam timing and tune really wakes em up but then add a blower and they are transformed!!


    etard
    Quote Originally Posted by brr View Post
    So after all this time, this topic may still bring up some questions even if it does not directly apply to the lope. Tonight I spent some time again looking over the cam profile of the 3.6 Pentastar engine and one thing I did notice; even though the tune is for a Challenger, it has the same profile as a FWD vehicle between 1696rpm- about 4500rpm. As mentioned before, the midrange is choked and more than likely its due to emissions. Now from 864rpm-1152rpm the cam is set for a 108.5 LSA and from 1312rpm to about 4352rpm the LSA drops then comes back up. This is obviously for emissions as the average user operated under these engine rpm's. At 512rpm the LSA is set for 122.5, at 6816rpm its set for 112.5....
    I've looked at many dyno results of the stock 3.6 and just about every one in the midrange has the intake centerline drop in the midrange then come back up which would explain the fluctuating Torque in the midrange, yet provides a steady HP increase.
    Anyways, back to the idle....
    Apparently with the 3.6 engine a 108.5 LSA is considered a tight LSA but with the 3.6 its not tight enough to create a lope....

  4. #44
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    mbray01 is right and being a 4V emissions engine, the 3.6 cams are tiny.
    Mainly so they can swing them all over the place and not bump parts and keep a smooth 650rpm idle.
    But 4V's don't need much cam anyways, tuned with a PD blower these make peak power well past 7k.
    Rev limit of 7.6k has been totally reliable so far.



    Quote Originally Posted by mbray01 View Post
    Lsa is not what gives you the lope

    lope comes from valve overlap. At what point does the exhaust valve close vs the intake valve opening. Now essentially you are changing the lsa to get the valve events to cause an overlap. But don't make the mistake of believing the lsa is what creates lope.

    A 210/210 cam with an 108 lsa will be entirely different than a 240/250 with a 108 lsa

    you have to look at the specific valve events to determine what it is your trying to accomplish
    Last edited by Hemituna; 02-01-2017 at 07:59 PM.

  5. #45
    Hemituna,
    Your info has been really appreciated!
    Last night I played around with my cam settings on my tune and you are not joking! I've still got to fine tune the fuel and spark maps, but today I drove it easy to get the fuel trims in check before I floored it. No I did not disable the Neural Network........
    My tune seems like it has been for the past few weeks in normal city driving, but when I floor it...OMG this little 3.6 pulls hard straight to 7000rpm(my set limiter and this is where I stopped the cam profile). Before it would start to seem like its running out of breath around 5000rpm but now its like it took a big inhale and just keeps going...lol
    HemiT and Mbray01, I understand what you mean about comparing the duration and lsa...
    Thanks again for all your support

  6. #46
    This is what i have achieved....Spark, AF and ex cam.
    4wd and 33 wheels.

    https://www.facebook.com/53453960007...type=3&theater

  7. #47
    Quote Originally Posted by Javier Wilde View Post
    This is what i have achieved....Spark, AF and ex cam.
    4wd and 33 wheels.

    https://www.facebook.com/53453960007...type=3&theater
    Javier,
    Those dyno posts are for what?
    Now this topic has gone 3 pages already, I've since held off on any lopey cam tunes as the vehicle is my daily driver. I'm still interested in the lope at an idle personally still since I have a cutout (long story short) and would like it to sound better. Over the past few months it's priceless on how many "Mustangs" more than any other vehicle have sat next to me revving there engines and I just fly by them. Heck, one day with a few passengers I ran against a late model WRX and it was just a joke because I kept letting off the throttle at 10mph over the speed limit and they were still catching up...lol
    If there are any new updates on this, please let me know

  8. #48
    Senior Tuner SultanHassanMasTuning's Avatar
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    there must be a weight factor to enable the cams to move at zero throttle/vehicle speed
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  9. #49
    Quote Originally Posted by SultanHassanMasTuning View Post
    there must be a weight factor to enable the cams to move at zero throttle/vehicle speed
    Sultan,
    I have a Chrysler 3.6 with VVT. There are various adjustments that can be done to adjust the cams to whatever position I want them to be. The lift can't change, but the position of the intake and exhaust cam's I can adjust for a wide range of options. I currently have my cams tuned to the 3.6 Dodge Challenger cam's with a slight adjustment at a couple areas where the factory sweeps them for emissions. My current tune hit 263hp at the wheels or 328.75bhp.

    Note: The engine HP was calculated by using WHP divided by 0.80 which is what the factory rating is at:
    226hp/0.80 = 282.5bhp (advertised as 283bhp)

    Currently I'm still waiting for posted information on what the cams can be safely tuned at because it's an interference engine. Once I know what the safe range of the cams are, then I'm going to look into going back to play with trying to get the "Ghost Cam" tune again.

  10. #50
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    Who said you cant lope on VVT? Heres a video of my caliber srt4 on 272/272 cams

    08 Caliber SRT-4 E85 Tuned on HPT. 483WHP 507WTRQ 24psi

  11. #51
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    On the hemi's (at least with the GPEC2A controller) one way you can get a "lopey" idle by bumping up the torque in the idle torque spark proportionality but to me it sounds choppy and not lopey.

  12. #52
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    Quote Originally Posted by Homer View Post
    On the hemi's (at least with the GPEC2A controller) one way you can get a "lopey" idle by bumping up the torque in the idle torque spark proportionality but to me it sounds choppy and not lopey.

    mine is not choppy thats for sure
    08 Caliber SRT-4 E85 Tuned on HPT. 483WHP 507WTRQ 24psi

  13. #53
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    Quote Originally Posted by mmrodriguezjr2012 View Post
    mine is not choppy thats for sure
    Glad it works for you but on my 5.7, stock cam it, making changes to the idle torque table, does not make it sound like a cammed motor.

    Wait...you have an SRT4...I was talking about a V8...apples and oranges.
    Last edited by Homer; 12-30-2018 at 09:32 PM.

  14. #54
    This topic is a few months old now with no updates....
    I'm currently tuned with the stability program disabled (No ABS, Traction Control, Stability control). Unlike other models my Avenger and possible other FWD vehicles this is hard to do without throwing a CEL. I currently have my limiter set to 7500rpm and the motor pulls hard to 7000 without a problem. This was handy at Carlisle this year especially since I was focused on setting the car up for the AutoX (real street challenge).
    I'm still looking into doing the Ghost Cam tune, I had offered a tuner $ to do this and was notified they don't work with the 3.6 anymore. Has anyone else figured out how to do the Ghost Cam tune on the Pentastar V6?
    I'm also reading on how to tune for E85 lately as its almost $1 cheaper per gallon in my area and my 3.6 loves it.....

  15. #55
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    Quote Originally Posted by Hemituna View Post
    The Hemi's and Pentastar are same, I have had HPt support look to see if we can change idle vvt but no luck so far.

    Sucks cos when loading it up and launching, you are stuck at base settings till it senses some speed.

    At idle, the pentastar at least has the intake cam fully retarded, but the Hemis have the cam fully advanced.

    Not so good when holding on the converter and building boost with full cam advance...they want to knock a LOT!!
    Has anybody solved the cams not moving until it sees speed problem? Any band aids?
    On a n/a car would limiting how far the cam swings at idle help?

  16. #56
    Tuner in Training guru1oftal's Avatar
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    I'm not sure that this is something that can be overcome. The cam phasers use oil pressure and my guess is that oil pressure at idle isn't enough to bring them off their default position.

  17. #57
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    Quote Originally Posted by guru1oftal View Post
    I'm not sure that this is something that can be overcome. The cam phasers use oil pressure and my guess is that oil pressure at idle isn't enough to bring them off their default position.
    That could be the case , but even if I brake tourqe at 2500 RPM and launch, the RPM stays at 2500 RPM until it sees speed .

  18. #58
    Advanced Tuner PurpleRam's Avatar
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    Quote Originally Posted by guru1oftal View Post
    I'm not sure that this is something that can be overcome. The cam phasers use oil pressure and my guess is that oil pressure at idle isn't enough to bring them off their default position.
    Correct, the clock spring is what keeps the phaser full advance ,the solenoid bleeds off oil pressure at idle, as pressure builds the solenoid redirects it to one of 2 passages, I'm not sure exactly which passage does what, have not take the time to get that deep in to it yet. but it's on my to do list in the next few weeks.
    Last edited by PurpleRam; 10-30-2019 at 01:59 PM. Reason: mistakenly wrote 3 instead of 2 passages
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  19. #59
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    Quote Originally Posted by PurpleRam View Post
    Correct, the clock spring is what keeps the phaser full advance ,the solenoid bleeds off oil pressure at idle, as pressure builds the solenoid redirects it to one of 2 passages, I'm not sure exactly which passage does what, have not take the time to get that deep in to it yet. but it's on my to do list in the next few weeks.
    Do you know what table keeps them there until it sees speed? If I brake tq up to 2500 , that should be enough oil pressure to move them right ?
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  20. #60
    Advanced Tuner PurpleRam's Avatar
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    Quote Originally Posted by PurpleRam View Post
    Correct, the clock spring is what keeps the phaser full advance ,the solenoid bleeds off oil pressure at idle, as pressure builds the solenoid redirects it to one of 2 passages, I'm not sure exactly which passage does what, have not take the time to get that deep in to it yet. but it's on my to do list in the next few weeks.
    Spent a few hours yesterday going through the physical part of the VVT system, I want to correct the earlier post but I don't want to edit it, it's VOLUME not Pressure that moves the cam back in fourth.
    04 GTX........ 8.91@151mph 392Ci G3Hemi NA 3600lbs 2.6HP/CI Naturally Aspirated
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