Spawne32

iTrader: (1)

While i understand exactly how VVT and cam timing works, I have never actually had any hands on experiencing with tuning VVT precisely. The thought occurred to me a while back that overlapping ignition spark tables using the same motor but different models of car's to fill in gaps in low RPM areas that were either difficult to tune, or really just helped improve cruising throttle response. This worked surprisingly well using a combination of the HHR and solstice 2.4 stock tunes of the same model year and engine type on the cobalt. As shown below... (these are compare file images, the numbers represent how much more vs the stock table)



The rest is all a matter of datalogging and recording and watching for KR. VVT on the otherhand is an entirely different story, as you have the relationship between the intake and exhaust cam to be concerned with. If I overlap the 3 tables using the maximums for each (intake and exhaust high baro tables) I come up with the following compared directly against my stock cobalt VVT tables.




Now i can test both of these against my stock tables at the track to see if there are results, but I can never truely know if im hurting or helping the airflow in and out of the engine by making these changes, and if these changes do wind up yielding crappy results, what if any changes should i be making to the VVT tables for better performance? Rumor has it around these forums that people have seen gains of up to .5 seconds depending on how aggressively they tuned the VVT.

noorj

iTrader: (17)

Basic VVT Tuning info

Help me understand cam timing (LNF))

LNF Cam adjustment

all give good NA cam tuning info

Spawne32

iTrader: (1)

Spawne32

iTrader: (1)

hmm, well it doesnt seem like anything that i did is all that extreme, i wonder what the reason is for leaving such a large gap out in the mid range on the cobalt. If it works as i think its going to work it might have a negative effect on the top end power and a more profound effect on my mid range.

noorj

iTrader: (17)

when I was playing with my cams NA I focused on two things:

advancing both cams down low, then retarding both up top

reducing overlap down low, then increasing overlap up top

Played around with the ramps of advance/retard/overlap as well as how much of each and what speeds to transition advance-->retard and no overlap--->lots of overlap.

I think I stopped on some tables that picked up .25-.5 seconds on 30-60 compared to stock. It is very hard to do this type of tuning without a dyno.

Spawne32

iTrader: (1)

wouldnt happen to still have that tune file would you?