I'm trying to understand how these numbers relate to timing and if advancing or retarding will help squeeze out a little extra power. Any help is much appreciated, couldn't find much searching.
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I'm trying to understand how these numbers relate to timing and if advancing or retarding will help squeeze out a little extra power. Any help is much appreciated, couldn't find much searching.
As far as I know the numbers are ICL and ECL and together make LSA.....I have a 2014 Wrangler and the stock WOT settings make for a race cam LSA number.....Seems strange.
I personally never understood why they even give you the option to advance and retard both the intake and exhaust, they move together no matter what, advancing one doesn't retard the other.
on a single cam you either advance or retard the whole cam....how do you figure advancing the intake retards the exhaust? if you are advancing the intake and the whole cam advances, how is that retarding the exhaust?
the tables are there for both ICL and ECL for the DOHC applications, same thing with the GM configs except GM goes by degrees rather than actual CL values.
LOL small word missing from my post "doesn't" but thanks for clarifying. I would agree with your statement on the DOHC purpose except that the various calibrations certainly have varying intake and exhaust advances, indicating they were originally programmed as though they can move independently. My thinking would tell me you should see the same exact overlap at all points in the rpm range, which is certainly not that case.
So then the question is, can the cam actually adjust during the overlap phase of the intake and exhaust lobes, so that theoretically it is barely changing the intake advance and adjusting the exhaust advance just prior to the valve opening and so it can act like a DOHC? I cant get my head around the rest of the motor and cam timing, as even though this makes sense for one cylinder, certainly there is another cylinder at the opposite phase (coming up on the intake valve opening vs another cylinder coming up on the exhaust valve opening) and therefore for one cylinder you are retarding the exhaust but on another cylinder are retarding the intake.
just think in terms of one cylinder, remember all the other cylinders have separate valves, they don't all open at the same time, which is why the cam(s) have independent lobes. cylinder to cylinder timing is ground into the cam so if you set one, you have set them all.
if you have one cam (OHV) then the whole cam moves together and overlap is fixed. DOHC applications can adjust overlap. however, I do think the viper has or had the ability to adjust intake and exhaust independently with an in block camshaft, but I've never tuned a viper.
the pentastar V6 is a small and low revving engine which is why it surprised me to have such aggressive values at WOT, like a 9000 RPM small block race motor....the values at part throttle make sense but seem to go backwards, maybe for emissions purposes.
the good thing is, the valve event info is googleable so you know where you are opening the intake and where you are closing the exhaust, which is what controls overlap and you also know where you are closing the intake, which is the most important valve event.
Thanks everyone for the explanations, is there anything to be gained from advancing this or retarding this on a stock cam hemi?
One thing I guess now I am understanding is the values are degrees from the CENTERLINE. if you are looking at the cam as a 360*, the centerline (spot exactly in the middle of the intake and exhaust lobe centerlines) as 0* then it makes sense for the tables to move opposite each other. So if the intake centerline is 110 and the exhaust centerline is 110, moving the intake to 112 would result in the exhaust being 108, but in both cases you are advancing both 2*, you moved the intake 2* further ahead of centerline but moved the exhaust 2* closer. I realize the centerline ALSO moves, but if you think of the centerline as a predefined location the PCM knows and measures back against regardless of where the cam is.
Is this correct?
For a fixed overlap OHV cam yes, that's true.
LSA is the average of ICL and ECL so let's get old school and say you have a stock cam that is @ .050 210/210 with a 118 LSA and no ground in advance meaning it is straight up and you install it straight up then:
IVO: 13 ATDC (-13)
IVC: 43 ABDC
EVO: 43 BBDC
EVC: 13 BTDC (-13)
So if Intake Opens 13 degrees After TDC and Exhaust Closes 13 degrees Before TDC then it's -26 degrees of overlap @ .050 lift.
LSA is 118 and ICL is 118 (no advance) so then ECL must also be 118....since (ICL+ECL)/2 = LSA
So with a cam that controls both intake and exhaust (like a pushrod motor or SOHC motor) advancing the cam 4 degrees will move ICL to 114 but LSA is ground into the cam profile so it is still 118.
So (114 + X)/2 = 118
then X = 122 ECL
So then when you advance the whole cam 4 degrees IVO moves to 9 ATDC and EVC moves to 17 BTDC and 17+9 is still of course 26 (-26 technically).
The cool thing about DOHC is that you can move the cams separately and depending on the application and range, go from -26 overlap at idle for fresh smells and smoothness to say, 20 degrees of lumpy overlap at WOT for power, and anything in between, because now you can advance the intake and retard the exhaust at the same time.
Check this out:
Cam Timing and LSA Change Effects
So in the case of these mopars, where is camshaft zero or parked?
It appears at full retard based on what it says in the tune.
Hopefully someone who has had a motor apart or degreed the cams can confirm or deny.
So what I'm missing looking at the tune for my 392 is where you guys make WOT adjustments? I see all kinds of part throttle tables but nothing for WOT.
^ no power gains, change your cam to a after market and then you will see some gains
all you can technically do it exhaust advance/retard thats it.
i have done testing on both 5.7 and 6.4 with no gains
^never touched those engines
I've swept the cams on hellcats and 6.4's with little to no gains. Have not tried a 5.7 but I assume it is similar.
The WOT settings are on the money for an NA.
If S/C, they can use some tweaking.
The PT settings however are purposely lame for emissions.
Bringing these closer to WOT settings will liven the engine up lots and go a ways to
eliminating the slow and then GO throttle response as you lean on the pedal.
Attachment 64814
So I'm guessing If I smooth out my WOT cam profiles to the average WOT settings it should help with the midrange dip?
Attachment 64815
If I keep the cam within the Base and Max centerlines would I be safe to prevent PV issues?
How can I get the pt settings closer to the wot numbers? On my tune the pt table is 3D with 100? across the board. Would I take the ramp from the wot table and spread it across the x axis.... While adjusting the Y axis for the aircharge? As in using the WoT x axis at .08grams but making it milder... While in the .70grams x axis making it the same as the WOT table.
Attachment 74860
This is how I am understanding the PT cam setting. Am I way off base or somewhere close to where I should be?
For the NA V8's with stock cams I can confirm that there are no gains to be had by moving the cam at WOT. We have tried this on many 5.7's and 6.4's
For aftermarket cams in the NA V8's there are some performance gains to be had by modifying the WOT cam table.
For aftermarket cams in the forced induction V8's there are significant gains in modifying the WOT cam table (unless of course a locker kit is used).
When I say cam table I mean the exhaust WOT table. As previously stated there is no sense in changing both tables since there is only one cam.
Interesting, The Tuning School recently posted some WOT gain on a stock 6.4L but did not mention what they changed in the VVT tables. Any ideas what they did?Quote:
https://thetuningschool.com/blogs/news/vvt-in-123
If I remember correctly the intake was set at 109 degrees until around 4,000 rpm at which point it transitioned to 112 degrees.
if i do like photos here, its better for performance and safe ?
Attachment 95153Attachment 95154
@Hemituna @Higgs Boson appreciate your feedback guys :)
You cant crash the valves, it is physically impossible in a stock engine.
Do try the changes you have made, but it will drive worse than std....well now you will know to maybe try another direction :)
Read up on (google) cam timing and LC numbers.
Then you will get an idea of what most engines like...the pentastar is like most engines hint, hint.
You will see the that the stock numbers have waaaaay tooooo much overlap, but that is for an egr effect (emissions) not performance or even economy.
good to know that valves cant hit pistons, thanks :)
i have read in many posts your comment about the overlap and its from factory for EGR , but its not yet clear for me how to calculate the overlap and maybe then i will be able to reduce it
will be great if you can point a direction :confused: