Looking for cam position info on LFX V6 when cams are parked at 0

[evolmotorsprt]

I've been looking over the LFX files for a friend with an ATS 3.6. I have an idea where I want to go with the majority of the tune, but I'd like some info on the cam positions relative to the numbers in the "Cam Position" tables. I'd really appreciate any knowledge you're willing to share.
Here's what I'd like to figure out:


Intake Cam Position at 0 in table = ? advance/retard

Exhaust Cam Position at 0 in table = ? advance/retard

If +1 in the table = +/- 1 whole deg of change for the relative cam


I've dealt with the LT1 VVT stuff and how everything relates for that motor, but I don't want to blindly make changes to this V6 without having a frame of reference. Thanks!

[DGS]

Your answer is 0 degrees TDC. What model year. Here's info on 2018. I assume you can determine specific commanded angles by plotting out between min and max degrees. 0-35 degrees. Post a tune, log, etc..

[evolmotorsprt]

Your answer is 0 degrees TDC. What model year. Here's info on 2018. I assume you can determine specific commanded angles by plotting out between min and max degrees. 0-35 degrees. Post a tune, log, etc..

Thanks for the reply. His car is a completely stock 2016 ATS 3.6. I have not had a chance to read his computer yet, but I downloaded the OEM file from the repository. We are currently planning CAI, catback, and a tune. After looking through the stock tune, it's pretty evident there is a lot of room for improvement, especially in part throttle drivability. Thank you for the attachment, it helps.

So just to clarify:
For the WOT table, The intake cam is +0deg TDC at idle, then it retards to -24deg by 1000RPM, and then moves to -10deg by redline. Correct?
Intake VVT.PNG

Here is the exhaust:
These numbers add instead of subtract, i.e. 0deg at idle and +3deg at redline, correct?
Exhaust VVT.PNG

Here's the tune from the repository:
2016 Cadiallac ATS V6.hpt

EDIT: It looks like I might have grabbed an ATS-V file that wasn't labeled correctly. I'd still like to know the answer to the above tables, but I'm going to wait and read his computer to get the correct file. I can't find anything for that ATS model in the repository.

[cobaltssoverbooster]

should be in reference to crankshaft degrees.
Intake cam Advances into overlap as numbers increase in value. (+)
Exhaust cam Retards into overlap as numbers increase in value. (+)
Cams are typically parked at idle in maximum allowed separation.

[2jzgte]

Now, I might be wrong, but the strategy makes sense from my logs of the vehicle in factory form.
Seems at low loads at any rpm there is a positive value.
LP9 Intake cam.PNG
If you look at all 4 strokes in degrees like on a time line, a positive value would retard the intake REDUCING overlap. Where as a negative value advances the cam in the number of crank degrees. Just like advancing ignition timing causes the coil to fire earlier in the Crank position. Doing this would increase overlap with the exhaust cam.
So you'll see the picture I attached this is from an LP9 2.8T. It only has VVT on the inlet for this year, but it's pretty strange.
Yours looks like it's parked at full retard as in with the least amount of overlap looking at the 4 strokes as a continual crank angle.
Engine Analyzer cam example.gif

But, if it means that it is advancing the cam by 20 degrees over base... This would have the complete reverse strategy for performance,. I mean almost literally.
Which do you think it is?

[cobaltssoverbooster]

gm has been known to use negative and positive values for cams in varying ecus.
i suggest you pull the ops like file from the tune repository. you will see that in his application there is not a table focusing shift based on negative values.
i am familiar with the changes in ecu models that shift using positive and negative values. for instance most of my work comes from the lnf, ldk, a20nht platform which has negative shift on one cam and positive on the other.
The best way to tell how its done is to analyze the idle and cruise cells. Think first that at full overlap at idle you will get chop, poor emissions, and excessive fuel use due to cylinder burn efficiency going down. So, from this you can expect idle to generally speaking be a cam lobe separation zone. at cruise the overlap can aid in efficiency and transitional zones based on application and cam profile.
so, for any new application to you i suggest that you analyze the idle zone as a separated state and the cruise/transition zone as a overlapped state. analyze and compare the values at both and now you know which way the cams are moving.
the applications i tuned in 2005 moved according to this description and so far everything up until current that i have seen from gm has moved this way.

bottom line, remember a stock application is all about maximizing burn efficiency in regards to emissions. from here you should be able to make some simple deductions and come up with the correct phase shift direction.

[DGS]

From the document I provided. The movement of the intake camshafts will advance (before TDC) the intake valve timing from TDC . The movement of the exhaust camshafts will retard (after TDC) the exhaust valve timing from TDC . The chart basically explains when and why camshafts are moved. At idle you would have least overlap for maximum compression ratio, idle quality, quick warm up of engine and cats, cold start emissions. Intake overlap scavenges cylinder of exhaust gases. Off idle, the exhaust overlap takes the place of an egr valve by pulling "inert" exhaust back in the cylinder, reducing the displacement of the cylinder (volumetric efficiency/airmass), reducing fuel, and reducing cylinder temps. for emission purposes and fuel economy. Less heat, less N0x emissions. High rpm and load will reduce overlap, increase displacement (volumetric efficiency/airmass) , add more fuel and increase performance.

[cobaltssoverbooster]

we are in agreement on the idea but after revisiting my responses i found i have worded my initial backwards and somehow convinced myself that was right.
movement should advance the intake cam which pushes it towards the exhaust cam causing more overlap.
im not sure why it took me so long to see why my initial response was worded backwards.

thanks for being consistent. all of my previous gm vvt tuning is consistent what we have preached in the last three comments. i fixed my original to prevent error for other readers.

[DGS]

Thanks for the comments. I'm still learning every day even thought I've worked on all kinds of engines over the years. A lot of what I do everyday is a combination of experience, intuition, and brain muscle memory. A lot of answers just arrive with no thought. Either the brain works without conscious effort or it comes from a higher being. The complicated part is when you have to explain it to someone else and hope it really is correct and if so then hope they understand it. I read a lot of your posts. They are some of the best put together write-ups in the forum. The difficult part is transitioning to some of the new tables in the new gen tunes and making sense of them. It gets more complicated every year. Thanks again for all of your information.

[cobaltssoverbooster]

Thank you.
I new the idea in my head was right because i have commented many of times on cam shift before. I just brain farted and slipped them up.
Nice to see someone else using the CA software. The complicated part is the fun part. Wish i could understand code to offer productive help in the user defined section; it is the hardest thing i have come across.