Cam timing. Not LNF motors

[KLUG'S SS]

I know that dead horse has been beaten over and over and over again but I am talking about the newer lineup of the ecotec motors like the 1.4t in the Cruze and Sonic or the 2.0t in the Malibu, ATS, Regal. Has anyone gone in depth with cam timing on these? With just the basic knowledge that most guys know by now where on setups with small/smaller OEM turbos will see an improvement with reduced valve overlap, on my personal Cruze this approach hasn't seemed to yield very good results yet or at least results I was expecting. This should hold very true on a Cruze like mine where the exhaust gases are stacking up pretty good against the tiny turbine housing creating like damn near 3:1 boost differential or even higher from what I've read. Just for a sanity check in the screen shots here of the stock cam timing maps for a Cruze like mine looks like GM has the exhaust cam heavily retarded in the cruising areas for the egr effect for mileage and it would appear the intake cam is also heavily retarded in the cruise areas also for mileage and then both advanced in the higher loads. Am I correct or am I the one that's retarded? Lol.

[KLUG'S SS]

No going back to the LNFs the negative numbers in the cruising load region was heavily intake cam advance and then exhaust was of course retarded heavily in the same load region and between the two created the natural egr effect for good mileage. So the big positive numbers in like the E78 pcm have got to mean advance not retard. That's just crazy to me though because looking at the intake "wot" cam timing table GM actually progressively advanced the intake cam as the rpms got higher. Very counterproductive for a turbo motor!!! I guess with the low boost levels these cars run in stock form it would appear that the engineers were then trying to use some overlap to help the motor rev out a little easier.

[TownDrunk]

On the 2011-15 Chevy Volt 1.4l (n/a), we had our best results by copying the intake over to exhaust and tweaking (advancing) from there. Bear in mind, we were looking for fuel economy, not power and with a motor generator, had to start out with a high compression, FFV, V8 pickup tune to get a good flex-fuel base tune.

A few of our Volt owners expressed interest in slapping a Cruze turbo on their Volts with the only reason being, "because I can".

Volterado_exhaust_cam.PNGVolterado_intake_cam.PNG

[KLUG'S SS]

I would love to see that. Hell what does a Volt weigh??

[KLUG'S SS]

Can you confirm my logic that GM did indeed have intake cam advanced in the cruise low load areas? The reason I keep questioning this is just because with my car in search of power playing with the valve timing the turd isn't responding how I think it should. Now granted I am not expecting any miracles, their isn't that much hidden power here playing with the VVT but everything I try and based on consistent repeatable timed logged runs stuff isn't adding up!

[TownDrunk]

About 3800 lbs. Take a Cruze and slap a lot of heavy batteries on it. It doesn't idle much either since it uses that time to recharge the battery (not fully, but like a hybrid). FWIW, it failed horribly when Laz adapted a Cruze tune to it. Does great with the Silverado V8 tune.

Lovely piece of engineering.

[TownDrunk]

I'm not much of a tuner, I just work with guys smarter than me.

I know Laz spent a lot of time comparing other stock tunes and implementing their stock timing to stock Volt to see how that worked out, then adapting what worked and didn't into our current (not ready for production) tune. He played with Equinox, Cruze, Silverado, Buick Regal and a bunch of other tunes, avoiding the V6 ones, and always keeping everything else stock. Once cam timing is done, we'll merge our other changes into the tune again.

[Giambals]

You need to be careful with the new Ecotec engines. Positive numbers in the new 1.4T mean retard on the intake and exhaust. It depends on the engine though. I believe LE2 and LFV both retard on intake and exhaust, and L3A advances on intake.

[Vasquezz1228]

I was trying to figure out the cam timing o my 2.2 LAP and read a lot on the LNF but i dont think it applied very well since on my car i would add to the intake and it would retard the cam and adding to exhaust would advance it. My tables dont have negative numbers though. Sounds like they are setup like these new ecotecs

[KLUG'S SS]

Yea I mean the same concept of reducing overlap on turbo motors well should say small turbos that create a ridiculous amount of back pressure should apply the same as all the LNF cam timing threads that all went very well in depth. A big kudos to codename Bill, MikeM173 among others for all of the info, testing and insight they provided.

But yea the "language" and philosophy of how the cam timing tables are done in the newer ecotec motors appears to be quite different compared to the LNF platforms. Like I had mentioned earlier in this thread I am still not 100% positive if it's larger numbers on the intake cam that represents advance or retard? From my testing I am quite certain that on the exhaust cam at least that larger numbers represent advance and smaller numbers are retard. I am still hoping someone someone can chime in on this thread maybe that has some knowledge and give some clarification. Haha

Actually I should backtrack a bit on that statement about them being quite different than the LNF. The small exhaust cam numbers in the cruise areas would indeed indicate heavy retard for that natural egr effect just like the LNF.

[lt1z350]

When I was doing my 2.0t ats I had found a link that talked about the intake cam could only be advanced and exhaust cam only retarded. So bigger numbers on exhaust away from zero is more retard and why they didn't have - numbers in the tune. Now this is on the early e39a tcm maybe different on others. When I used that logic tuning the car for the track it got faster with larger numbers on exhaust cam up top and had just left intake alone for most part.
On my new vsport with e92 it has some crazy advance down low. 24 degrees off idle on intake cam. Soon as get my base tune better going to start playing with this more as sweep is much larger then e39a allowed.