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Thread: Pentastar 3.6 VVT Tables

  1. #21
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    I would like to clarify my understanding of the VVT tables when it comes to the DOHC setup of my pentastar engine. These tables are totally new to me, but I’ve read everything I can find on it. The problem is that there seems to be conflicting information because of different engine setups, like from the V8 engines who don’t have DOHCs. If I have anything wrong here, please correct me. I’ll supply my stock tables as reference. (2016 Dodge Challenger SXT 3.6L Pentastar)

    So first thing, because my engine is a pentastar with dual overhead cams, the VVT values for Intake and Exhaust can be modified independently of each other. This allows one to tune both for low-end torque and high-end horsepower independently as opposed to a single cam setup, where changes typically sacrifice one for the other.

    There are 4 main tables to modify.
    Airflow/Variable Camshaft - Intake Camshaft/Desired Angle and WOT Desired Angle
    Airflow/Variable Camshaft - Exhaust Camshaft/Desired Angle and WOT Desired Angle

    The Intake Cam Position table’s values represent RETARD values. (ie. value of 130 from 0 rpm to 3000 rpm is full RETARD of the cam. That would mean that a value in the table of say 126* in the last two columns represents a 4* advance?

    On the other hand, Exhaust Cam Position table’s values represent ADVANCE values. (ie. the 117 values along the lower limits are full ADVANCE) So a value of 101 in the last column would represent retarding the value 16* from full advance?

    Is that all correct so far?intakeVVT.PNGexhaustVVT.PNG
    2002 Silverado extended cab 5.3L.
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  2. #22
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    On the DOHC engines, the numbers represent actual lobe centre position of each cam.
    It will idle with exh fully advanced and intake fully retarded...Whether you want it advanced or retarded after that is up to you.
    Dont place much value in the stock numbers as they are veery emissions biased.
    Putting the cams where a 4v engine usually likes them for performance is a good start and then maybe even less overlap if it is supercharged.

  3. #23
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    exagerated cam overlap on Pentastar at PT 1700-2000 rpm

    I runned some numbers and see attached: I observe 40-57 Degrees cam overlap (calculated from VCM tables and proven practically driving) on the range of 1700-2000rpm on Partial Throat, what I think explains why the torque feels on those rpm like a bike on my pentastar....

    1. Can anybody propose to me / guide a direction on how to improve this? should I just change the VCM Exhaust Cam tables to not allow an smaller number than 90 degrees at partial throat? or what you guys recommend?

    I was thinking if asking for a 2018 wrangler 3.6 stock cam PT tables and copying them, as those have EGR so I would expect don?t make this Exhaust recirculation cam overlapping?

    2.- One other question: how possible that my 750mg aircharge/cylinder overlap looks so far from the WOT? I would expect WOT and 750mg/cyl aircharge to be scheduled very similar instead... but thats not what I observe. Suggestion?

    Thanks so much!CAM excessive overlap 3.6 pentastar at 1700 to 2200rpm rev1.pdf
    Last edited by Benjamin Lopez; 03-06-2022 at 04:08 AM.

  4. #24
    Quote Originally Posted by Benjamin Lopez View Post
    I ran some numbers and see attached: I observe 40-57 Degrees cam overlap (calculated from VCM tables and proven practically driving) on the range of 1700-2000rpm on Partial Throat, what I think explains why the torque feels on those rpm like a bike on my pentastar....

    1. Can anybody propose to me / guide a direction on how to improve this? should I just change the VCM Exhaust Cam tables to not allow an smaller number than 90 degrees at partial throat? or what you guys recommend?

    I was thinking if asking for a 2018 wrangler 3.6 stock cam PT tables and copying them, as those have EGR so I would expect don?t make this Exhaust recirculation cam overlapping?

    2.- One other question: how possible that my 750mg aircharge/cylinder overlap looks so far from the WOT? I would expect WOT and 750mg/cyl aircharge to be scheduled very similar instead... but that's not what I observe. Suggestion?

    Thanks so much!
    I calculated WOT overlap for a stock 2015 3.6 some time ago but got quite a bit different values than you show.

    Also recall target A/F of WOT is far more rich and Timing quite a bit different, than part throttle for the theoretical "Same" 750mg

    WOT Cam timing.JPG
    Last edited by duster360; 03-05-2022 at 05:03 PM.

  5. #25
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    Duster, you are totally right, I corrected my file in the original post to not confuse anybody reading it wrong. However the questions remain the same: 50Degr Overlap, even 67 in WOT? I understand you dedicated some time already to investigate and maybe test on this: can you share your conclusions?

    - I think in one end huge overlap will increase compression ratio on the next explosion by pushing a cylinder pre-filling with burned inert & hotter gas but on the other side this will reduce the amount of effective mixture that the cylinder will be able to swallow, right?

    - But if you observe the table... this huge overlap happens all after the TDC (except in WOT and over 3400rpm) so it is subject to the exhaust pipe restriction, meaning if you improve your exhaust system it will not get any benefit from the compression ratio increase, but it will just lose a considerable amount of effective air/fuel mixture, I would think if you improve your exhaust system, you prefer to reduce Exhaust cam retard from the stock values Thoughts?

    - On the other side, I dont see any sense for the 750mg aircharge to not align with the WOT in terms of overlap and cam timing: you see any sense to that? for what you write you also don?t see the sense on that right?
    Last edited by Benjamin Lopez; 03-06-2022 at 04:39 AM.

  6. #26
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    I got a JK 2018 stock file (EGR engine) and compared with the Challenger (No-EGR), and I see the following up front, (some conclusions/questions for comment):
    - 0. Iddle the JK has no overlap at all while challenger shows 8.5 degrees absolute minimum overlap
    - 1. Less overlap at low regime up to 2,752 (up to 27 degrees less): I interpreted this is the EGR area I would modify in the Chally for better drivability
    - 2. Specific at 1,152rpm and all over 355mg/cyl same exact high overlap for JK and Chally. This may be critical engine speed for some reason I don?t know but I would respect it as is
    - 3. high regime Chally has slightly more overlap at similar angles. I understand because its designed for slightly higher rpm and power... as Duster said different ignition, A/F etc
    - 4. Very different lock pins setting allowing this JK low regime smaller overlaps and in later angles. follows as this will become the difficulty to tune Chally for no-VVT-EGR.

    QUESTION: Is the lock pin set at the mechanical limit of my actual cam actuator? or can I variate it by how much, example: JK Intake Lock pin 147deg and max is 157deg while chally are 128deg - 140deg. Can I just overwrite these and it will just reach those angles? I would like to reach those 147deg.

    For info, Exhaust case for same subject as follows: Exhaust JK=132max/122lock while Chally=130max/117lock. If anybody interested I can show some excel comparing tabs.
    Last edited by Benjamin Lopez; 12-08-2022 at 03:21 AM.

  7. #27
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    So I will replay to myself after some time reading and investigating:

    - I found 2018JK has no EGR but... it has variable lift so definitively not a good reference for scheduling VVT of a 2011.

    - So I tried something that worked great: I entered in the int- & exh- VVT normal P/T tables the WOT angles for each and all of the air charges (just left the top left area unchanged to polish the chart. The car feels totally different.... more agile and specially 1500-2000 rpm where normally this model is more often driven in the street now it feels considerably more agile and strong. That is the only way I figured how to remove the EGR effect by using the highest pumping cam profile which Dodge defined at WOT, and ok... very sure if I would be smarter I could do something intermedium which would work probably better.... but with my poor knowledge this is like day and night better on my pentastar normal driving.

    I know most of you are professional tuners and advice on this can?t be for free, but anyway I keep updating and any advise received will be appreciated.

  8. #28
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    QUESTION: Is the lock pin set at the mechanical limit of my actual cam actuator? or can I variate it by how much, example: JK Intake Lock pin 147deg and max is 157deg while chally are 128deg - 140deg. Can I just overwrite these and it will just reach those angles? I would like to reach those 147deg."

    Is 'lock pin' just what they are labelling the 'ground in' lobe center? That's how i saw it when looking at my tune. I am no pro... straight out newb at hpt. 120 deg is advertised centerline for a 6.4 tho yeah? Its also 'lock pin'. The cam is moved by oil pressure (and maybe something centrifugal?) so i do not believe changing those numbers moves it at all... more like the numbers represent where the cam should be. Thats how i see it but like i said im new
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  9. #29
    Quote Originally Posted by LilSick View Post
    QUESTION: Is the lock pin set at the mechanical limit of my actual cam actuator? or can I variate it by how much, example: JK Intake Lock pin 147deg and max is 157deg while chally are 128deg - 140deg. Can I just overwrite these and it will just reach those angles? I would like to reach those 147deg."

    Is 'lock pin' just what they are labelling the 'ground in' lobe center? That's how i saw it when looking at my tune. I am no pro... straight out newb at hpt. 120 deg is advertised centerline for a 6.4 tho yeah? Its also 'lock pin'. The cam is moved by oil pressure (and maybe something centrifugal?) so i do not believe changing those numbers moves it at all... more like the numbers represent where the cam should be. Thats how i see it but like i said im new
    The phaser Lock pin is a physical pin that quite literally locks the phaser together, thus disabling it until the PCM decides to turn "on" the VVT(starting, too cold, idle, ect).

    Here's an example. The "Lock pin" slips over that spring and will lock the inter shell to an outer plate(removed: see upper left of pic) Oil pressure will depress the pin to "unlock" the phaser.
    variable-valve-timing-5.jpg

  10. #30
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  11. #31
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    Quote Originally Posted by Benjamin Lopez View Post
    QUESTION: Is the lock pin set at the mechanical limit of my actual cam actuator? or can I variate it by how much, example: JK Intake Lock pin 147deg and max is 157deg while chally are 128deg - 140deg. Can I just overwrite these and it will just reach those angles? I would like to reach those 147deg.
    Do you see it now? Now that there are pics? They are just numbers in the pcm. The actual position of the cam in relation to the crank is determined by oil pressure. If you change cams or lock one out (or restrict movement) make the numbers in pcm match what is happening in the engine.
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  12. #32
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    Yes I had a good idea on how the lock pin works but I was confused as of why there is a lock pin constant in the program if it is mechanically fixed (it is where it mechanically is). But with your explanation I think I understand that the constant is there for in case I modify the hardware to lock in different angle... then I have to change that setting to be match the mechanical pin angle, right?

    I am now refining my tune for the cam P/T change I mentioned: I needed to also modify the max-tip tables to match the PT new table because it jumps to it over 50 or 60KPa MAP so it needs to be aligned to the P/T tablet... but I am really amazed on the improvement. Mine is 2.63 gear and I did feel the engine too small on normal driving (1500-2000rpm) while on WOT over 3,500rpm I did feel it very progressive and quite strong. Now feels all way through as the 300HP engine it is... I don?t understand why Dodge offset the cams for emissions instead of just adding an EGR: this thing now drives nicely in the street and mountain road. I wonder what my emissions are now in this configuration.

  13. #33
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    Quote Originally Posted by Benjamin Lopez View Post
    - I found 2018JK has no EGR but...

    - So I tried something that worked great: I entered in the int- & exh- VVT normal P/T tables the WOT angles for each and all of the air charges (just left the top left area unchanged to polish the chart.

    That is the only way I figured how to remove the EGR effect by using the highest pumping cam profile which Dodge defined at WOT...
    Nope, they dont need egr because of the amount of overlap ground into the cam

    What? What did you do? Switched pt and wot numbers? What?

    Can't remove overlap that is ground into the cam. "Highest pumping cam profile as defined by dodge" - Which angle is that???: My intake cam (eng > airflow > variable camshaft > intake camshaft > wot desired angle > max airflow) numbers look at to be expected, starting off very advanced and retarding as rpm increases but my ex numbers say the exhaust valve flows best at 115 degree centerline no matter the rpm:
    Attached Images Attached Images
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  14. #34
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    Quote Originally Posted by Benjamin Lopez View Post
    Yes I had a good idea on how the lock pin works but I was confused as of why there is a lock pin constant in the program if it is mechanically fixed (it is where it mechanically is). But with your explanation I think I understand that the constant is there for in case I modify the hardware to lock in different angle... then I have to change that setting to be match the mechanical pin angle, right?
    I believe its there because they use this system on more than one engine and on engines that come with different cam profiles.

    Quote Originally Posted by Benjamin Lopez View Post
    I am now refining my tune for the cam P/T change I mentioned: I needed to also modify the max-tip tables to match the PT new table because it jumps to it over 50 or 60KPa MAP so it needs to be aligned to the P/T tablet... but I am really amazed on the improvement. Mine is 2.63 gear and I did feel the engine too small on normal driving (1500-2000rpm) while on WOT over 3,500rpm I did feel it very progressive and quite strong. Now feels all way through as the 300HP engine it is... I don?t understand why Dodge offset the cams for emissions instead of just adding an EGR: this thing now drives nicely in the street and mountain road. I wonder what my emissions are now in this configuration.
    Would be great if you included some pix or the before and after tune
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  15. #35
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    CAMTRY02 BenL rev01.png

    Lilsick did you try those WOT tables on a dyno?

    These attached are the cams I have now, on WOT i only touched 2degrees at high rpm and I am trying to determine if improved or not trending on the scanner because I don?t have a dyno available to check it. Mine is pentastar challenger 2011: yours?

  16. #36
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    Lol no. Those are my stock numbers. Dyno great starting point but just cuz it makes good number on dyno (if it does) that does not mean it will go quicker. Time slips do not lie. Mine is a '16 scat (392). A motor is just a air pump with some fuel and spark tho so same diff. Now i am really trippin on why the 6.4 has 115 in every ex lobe wot cell
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    ok yours is 392 I understand has 2 cams and you can not variate overlap (right?), but mine has 4 cams (2 for inlet and 2 for exhaust) so I can variate overlap.

    I did "read" R/T and SRT cam charts are not improvable from factory. I also did read they have tables for INLET and also for OUTLET although they only use one of the two (obviously because they are in the same shaft). Maybe that is why the outlet cam table does not have sense, because they use only the inlet?. But I don?t know I just did read that around the forum.

  18. #38
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    Mine only has 1 cam so nope can not change the overlap. I am not so sure you can either short of going in to the motor and doing so mechanically. Have you put desired angle and the actual angle parameters up towards top of the list and given them a short polling interval and changed the table in the tune and logged and seen that the cams actually moved?

  19. #39
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    yes Sir, I entered the new desired cam angle values in the PT table per the screen shot, loaded them in the car, and then I did trend with the scan and it does what I tell him to do. I can show you trends. and I am on NN just for clarification.

    In fact when I did that I discovered unstable rpms at mid pedal, and looking at the trend I discovered that the cam was swapping from reading on the PT table to reading on the max TIP table with MAP passing over 70-80KPa and I needed to also put same numbers on the max TIP table to resolve that. If yours doesn?t react to changing the PT table it may be probably because you are doing it in the one the V8 is not using as I mentioned... they have both IN and EXH tables but apparently they only use one of the two.

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    yeah mine only uses ex centerline numbers. I just did what you did (my TIP is disabled stock but i changed all the other tables, except wot) and you are correct: According the the log the cam went exactly where i told it to. Which means that where ever i read that you can not change the starting point on here that info is wrong as well as what i wrote up there ^^^. I wish someone woulda corrected dude and called bullshit cuz i woulda been changing these tables from the gate.

    Does anyone know how this actually works? That vid ^^^ shows the cambers with the vanes and the oil holes in the cam/fat ass front cam bearing but where are the solenoids that control the oil flow??????? theres gotta be one on ea side of the vane so that is 2 for ea phaser. your car has 4 phasers correct???? where are these 8 electric valves????
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