Difference between GM's performance CAI's for the 2019 6.2L- 2 PN's now

[L86 All Terrain]

Does the VVT system not adjust valve timing based on demand and adjust or change predetermined AF ratios from the ECM? If there is more air available and the octane is high, the VVT system will adjust along with the fuel tables and vice versa. This VVT system is why you can put 87 octane in a 6.2L and not melt a piston from knock. So if there is a change in added air or added fuel, would the system not adjust timing via the ECM relative to VVT system setting? Not trying to say your wrong, if you're tuners you surely would know more than me, I am just trying to grasp this as I am not a tuner by any means. In my eyes, the ignition timing should be variable and dependant on the VVT system's position at a given RPM. With more air/better fuel available, it should adjust ignition timing along with the VVT system changing position. Is this assumption correct or does ignition timing remain constant regardless of VVT position? 

[CamGTP]

VVT is mainly based on cylinder airmass and engine rpm. Then from what we are able to edit with tuning software there are three 3 sections of desired intake cam angle. Those being low/med/high barometric pressure. In the 2016 direct injection file I am using here the low/med tables only add timing at cylinder airmass values. The high table only adds in a few degrees of VVT above 3,200rpm.

 

The high table matches the WOT base VVT table as well, starts at 2 degrees from 3,200rpm and stops at 7-8 degrees above 6,000rpm. The computer doesn't care if there is more air or better fuel being used as these tables are not going to change on their own. It's not going to add in any more timing and it won't change the VVT angles based on more airflow.

 

So to say that the VVT is why this engine can run 87 octane is not really accurate. Because the timing/VVT tables don't change it's going to use the knock sensors to determine if knock is present and will dial back the ignition advanced to use a lesser amount until all the knock is gone. The high/low octane timing tables have a difference of about 10-15 degrees in just about all cells. When knock is present it interpolate the timing based on the knock learn factor. Basically a 0 to 1 type thing. If it's at a 0.40 KLF it will interpolate any given cell of the maps between the two tables.

 

 

Can't really melt pistons when closed loop fueling is good and timing is adjusted on the fly.

 

 

 

 

Edited November 20, 2019 by CamGTP

[CamGTP]

Other factors for timing are based on roughly the same concept. The high/low octane spark tables use cylinder airmass and engine rpm. The values are set in stone and do not change. There are spark corrections tables that are based on a few things.

 

The computer can add timing based on the commanded EQ ratio and engine rpm. It can add or remove timing based on coolant temp and air intake temps. Those two use the cylinder airmass and a temp axis that covers the range of the sensor(s). Cold air will add timing but anything over 86º will start removing timing.

 

 

As said before the MAF is one of the biggest pieces here. The more air going across the MAF, the more fuel the computer is going to give. If the tubing size around the MAF stays the same even with a new intake design, very little is going to change.

 

 

[L86 All Terrain]

So in your opinion the timing advance was caused by IAT's or coolant temperatures being different than others setups tested? Sounds like it was a rigged test, or accidental conditional factors than have manipulated the results. Maybe I am still interpreting your info wrong but its very interesting, thanks for the insightful post even if the tables are in a foreign language to me. 

[CamGTP]

Without data logs of the runs we can't say if timing changed at all. To me timing didn't really change because the graphs show everything is almost exactly the same for ambient temp and air density. If all the intakes are pulling air from the same location there shouldn't be that much of a change in air temp past the MAF sensor where the IAT is.

 

 

But this is also were things could get skewed because if for whatever reason the first run had really high intake temps from maybe idling or lack of dyno fans, well it would remove lots of timing and make less power. But then if the next few runs had way lower temps the computer wouldn't pull away power and there is your fancy new result of power.

[NemesisC5]

GM performance CAI likely comes with revised MAF tables to compensate for the lower restriction rather than a more aggressive performance tune just to keep things safe.  I'd be surprised if the GM tune includes any timing advance.

[TJay74]

In regards to the OP's question, the hard parts in both of the GM kits could be the same. The part # change could be due to a change in the calibration that GM developed for their CAI.

 

I have used HP Tuners since around 2005 or so, like CamGTP said there isnt much in the OEM tune that will change on its own on the timing side of things. All of the timing maps are static and fixed, there are modifier tables that depending on temps of things like the air and fluids can add/subtract timing. While what CamGTP said is true on the inlet tub size, the one thing that does change on most of the CAI kits is the filter is usually larger than the OEM filter and has less restriction since it changes from a pleated paper filter to a wet/dry foam gauze filter. The airbox also can tend to have larger openings making it easier for to flow into the airbox.

Wanna see how that works, take a large straw and put the end of it in your fist and close your fist down some and try and pull air thru the straw. Then open your fist and try it again, see the difference. The inlet tube stayed the same, all you changed was the opening (the air filter and airbox inlet opening to the outside) which made it easier to pull air thru the straw.

If the MAF can see more airflow from test 1 to test 2 with the only change being a CAI then it shifts the airflow at the same RPM's higher in the MAF table which then allows the ECM to add more fuel, again the timing side stays the same unless the new CAI is somehow able to reduce the inlet air temps (IAT's). The OEM IAT table is pretty aggressive, it starts removing timing once the IAT value hits 85° and it only gets worse the warmer the IAT value is coming into the engine. If the CAI can allow for some cooler air the IAT reduction will reduce some which will reduce the amount of timing that tables pulls for outside air temp increases.

I ran across a mod that I did to our 2016 Audi SQ5, this is a 3.0L supercharged engine that is rated at 354hp. An engineer owner modified the OEM airbox in several ways and changed the air filter from the paper pleated to a larger dry foam filter. The other changes included removing a snow guard in from of the OEM ram air inlet tube to the airbox, removing an internal splash shield inside of the airbox and opening up a hole in the lower part of the airbox that was filled in. Then he went after the data, he did all of these mods on the same day with the same conditions. His data logs showed that while the OEM airbox was still in place, the larger air filter and reducing the inlet restrictions allows the engine to build 1psi more boost than before which equated to around a 15-20 HP increase in power.

Personally I am not all that impressed with the GM CAI, there are better options out there that provide better results. At one point Blackbear had a test for the K2xx trucks, I would go with one of the better CAI from that test. I have the Airaid CAI kit on my 2016 Sierra 6.2 along with a ported throttle body, the power increase and throttle response is very noticeable and was well worth the investment for me.