Hello everyone.
I want to leave some doubts about the VVT tuning.
How many degrees of advance and retard the cam can give to find the best performance?
How to know when to advance or retard the table of degrees from VVT?
I hope you can help me, thanks in advance
the correct way to tune vvt is using a dyno.
in general you advance the cam to increase torque and retard it to increase horsepower.
in the gm tunes advance is a value of 0 and every number above that is retard. you cannot advance past 0.
How many is the maximum retard that can be given to a stock engine?Originally Posted by Higgs Boson
VVT is a pretty sweet thing : http://www.hotrod.com/how-to/engine/...formance-test/
"The performance potential for VVT in a hot rod motor is huge, but relatively few enthusiasts have embraced it. To test the merits of VVT in a high-performance application, we strapped one of Mast Motorsports' 600hp L99 small-blocks to the company's dyno and phased the cam back and forth to see its effects in action. By simply advancing and retarding the cam, the VVT system swung the peak horsepower and torque curves by 18 and 10 numbers, respectively. Furthermore, in the case of the all-important power after peak metric, the difference was as large as 41 hp. The beauty of VVT is that an improvement in high-rpm power doesn't sacrifice bottom-end torque, and in the case of GM LS-series small-blocks, it's extremely easy to retrofit onto any non-VVT motor."
I just copied what was in a Gen5 factory tuneJasons 6 2 base 2014.hpt
The table had a much larger area of VVT numbers compared to my 09. So far I like the enhancement.
1997 Wrangler - LQ4 6.0 and 4L60e NP231C/J
2009 Saab 9-7X with a 6.0 swapped in, 4L65E from a 2009 Suburban, 2005 trailblazer selectable transfercase, and 3.42's from trailblazer as well
2015 Sierra 2500 Duramax with a fuel sucking emissions system
2009 G8 GT (wifes car)
please refer to my first sentence
Well not stock,but i retained the VVT set up when i swapped out cams,hoping to see some nice gains and broader tongue,but max power came with the high baro tables zeroed out. Even had two different tuners,two different dynos, try rolling in some retard only to lose power. When anything other than a stock cam is being used, comp cams sells a kit that limits the amount of travel within the mechanism, with a small metal block. i'm not sure actually how much travel is left,but there is plenty. I'm thinking you need a cam with a lot of advance ground into it so you can roll it back to find a sweet spot. I still have retard in the mid and lower baro tables, supposed to get better mileage by reducing pumping loses.
Do you ever hit the mid/low baro tables?
Most of the retard in the factory setup is for MPG and emissions, the most retard is at cruise loads and RPMs.
My vvt cam took very little retard up top, nothing even close to the stock cam.
the fact that the aftermarket cams are bigger they aren't going to require as much movement to make power since the GM stuff moves intake and exhaust equally and at the same time.....it doesn't really do that much, imo....
To tell you the truth i don't know if i hit those tables,i don't know that much about it, i'm doing my best to learn, i just see values in those tables and the high baro zeroed out like the tuners told me they did. How would i be able to tell if i am hitting them ? I don't think any configs i have contain any PIDS active for cam movement.
I just went back and looked at some logs and i do have an Intake Cam Angle PID and it looks like im seeing up to 8.4 degrees of retard at some places. Weather its hurting or helping,i have no idea.
When i put the new cam in i was thinking. this is going to to great. I thought i was going to be able to dial in a perfectly flat torque curve from 1500 to redline, nope didn't pan out that way. I guess GM engineers with all their resources are hard to out do for an optimized balance of power, drivabilitiy and fuel economy.
I wish there was something i could do to get more than 10 MPG.
Last edited by PDYoung; 12-02-2015 at 12:27 AM.
The tables on the left should tell you what barometric pressure when the tables are used. Where I live the low and mid would never be used anyways....
Just something to think about.
OK, I see what you are saying on the left, 75,84,94 kpa, for low,mid and high baro thanks for sharing that with me. I'm trying to learn and every little bit helps
now reading some older threads, it claim 0 in the high low med tables is actually 8.5* advanced
I'm I reading that incorrectly or have things changed
On most GM GEN4 that is correct....your map is in effect how many degrees you are retarding it from that point....so if you retard it 8.5...it will be at 0. It took me a while to get my head around it but if you just look at the map as the number of degrees of retard (or rather the number of degrees you are retarding it from its advanced park position) it helps.
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