Tuning the 1.4t Cruze - A Mildly Scientific Approach

[Jordan927]

The seats suck...

I will do more testing when the weather clears up.

The 2013 Cruze has completely different cam tables. I haven't messed with vvt tuning yet so I really have no clue what I would be changing. The LSJ guys have their stuff figured out but it looks like our stuff works a little different.

Testing will be awesome. So far this has made me much happier with the performance of the car. I haven't yet maxed out anything, but I may max the overspeed limit...just to see. I would also like to add some timing right off the line to see if I can get better pick-up when I first crack the gas. I have found the key to quick take-offs with this car is to open the throttle halfway until the revs are above 3k...seems like that's the sweet spot for the turbo to start providing power.

On the cam topic, I think some low speed and high speed adjustments are whats needed. mid range seems to work nicely, but it seems like the engine runs out of power high in the rpm's I'm sure its due to the turbo used...but some better cam tuning might help.

This could yet be a car that doesn't drive me nuts every time I drive it.

Thank God I have a V8 Silverado too.

[rallycar2001]

haha! hey! im one of the lsj guys!
im in az, on a 100* day on 91 octane your tune works just fine...

[rallycar2001]

im in Jordan927, i wanna try that, unfortunately the cruze im tweaking is my girlfriends, and she isnt always at my disposal lol. i want to log exactly where the sweet spot for tps is and at what rpm then, make wot hit the sweet spot no matter what. isnt there a etc vs tps vs rpm?

[Gh0st]

Am I blind? Where is the torque management settings for the trans?

[snowvette]

I have tm turned off in my file if you want a copy. Give me a bit.

[rallycar2001]

... make sure your veiwing in advanced user? idk

[silverbullet08]

Played with mine for a bit today. Never really made any huge changes before cause of time, but I played with the cam timing a bit and am very impressed with the results. This thing revs out sooo much faster now up top. I found that about 18psi seems to be the magic boost for my car. Anything higher and it just wants to knock or doesn't allow for any timing. I have mine set up now to spike 18 and hold 17 to redline at 6300rpms. That shows 79% idc at spike a steady 72-73idc during the pull and right at 75% at redline holding a fairly steady 11.3-11.5 AFR. Only mod is a drop in K&N filter in the factory airbox.

For you all playing with these. Try pulling the advance on both cams closer to 0 from 4500 up. I pulled about 8* total from both cams so far and it seems to be loving it. I couldn't go much further cause I just ran out of time again. Let us know what your individual findings are.

On the factory tune set to MAF mode it was running low to mid 10AFR. Just a ref for others not using a WB.

[Gh0st]

Played with mine for a bit today. Never really made any huge changes before cause of time, but I played with the cam timing a bit and am very impressed with the results. This thing revs out sooo much faster now up top. I found that about 18psi seems to be the magic boost for my car. Anything higher and it just wants to knock or doesn't allow for any timing. I have mine set up now to spike 18 and hold 17 to redline at 6300rpms. That shows 79% idc at spike a steady 72-73idc during the pull and right at 75% at redline holding a fairly steady 11.3-11.5 AFR. Only mod is a drop in K&N filter in the factory airbox.

For you all playing with these. Try pulling the advance on both cams closer to 0 from 4500 up. I pulled about 8* total from both cams so far and it seems to be loving it. I couldn't go much further cause I just ran out of time again. Let us know what your individual findings are.

On the factory tune set to MAF mode it was running low to mid 10AFR. Just a ref for others not using a WB.

So the 0-32 range is advance of the cams? not retard for any of them? I know jack about the VVT stuff and it seems to vary based on the engine from what I've found.

Edit: Well, I guess lowering the numbers would technically be retarding the cam...Maybe this explains why GM retarded the cam for the 2013MY so much. Every complaint I hear is about how these things complete peter out above 5000rpm. I'll give it a shot once I figure out controlling the boost better at high RPM.

Hmmm...wonder if I can get the turbo to spool up faster by reducing overlap in the lower RPM and then at 4000rpm increase the overlap.

[rallycar2001]

yes i will try it today! i need a little help with intake maf scaling after getting a bigger intake...
yeah, i see what he is doing with the cam timing.. your effectively inducing more overlap with cam timing, so that means if the turbo exhaust side could breath a little better, you could utilize your active lower compression ratio you just created. i have a gt2052 turbo that has the same size internals/shaft diameter/ tip height/ and center housing rotating assembly. as the factory g1541t turbo that on it.
im gonna see if its possible to port out housings and effectively raise area/radius. on hotside . the garret i wanna try is a ball bearing that should clamp into the manifold with a bit bigger internals...
with the swept volume vs comp. vs lack of cid, it should still spool hard with exra 8-12 lbs per min/// EVERYWHERE!! should be fun.

[rallycar2001]

Played with mine for a bit today. Never really made any huge changes before cause of time, but I played with the cam timing a bit and am very impressed with the results. This thing revs out sooo much faster now up top. I found that about 18psi seems to be the magic boost for my car. Anything higher and it just wants to knock or doesn't allow for any timing. I have mine set up now to spike 18 and hold 17 to redline at 6300rpms. That shows 79% idc at spike a steady 72-73idc during the pull and right at 75% at redline holding a fairly steady 11.3-11.5 AFR. Only mod is a drop in K&N filter in the factory airbox.

For you all playing with these. Try pulling the advance on both cams closer to 0 from 4500 up. I pulled about 8* total from both cams so far and it seems to be loving it. I
couldn't go much further cause I just ran out of time again. Let us know what your individual findings are.

On the factory tune set to MAF mode it was running low to mid 10AFR. Just a ref for others not using a WB.

please show us your cam tune!! im so excited but too scared to start guessing!!

[Gh0st]

yes i will try it today! i need a little help with intake maf scaling after getting a bigger intake...
yeah, i see what he is doing with the cam timing.. your effectively inducing more overlap with cam timing, so that means if the turbo exhaust side could breath a little better, you could utilize your active lower compression ratio you just created. i have a gt2052 turbo that has the same size internals/shaft diameter/ tip height/ and center housing rotating assembly. as the factory g1541t turbo that on it.
im gonna see if its possible to port out housings and effectively raise area/radius. on hotside . the garret i wanna try is a ball bearing that should clamp into the manifold with a bit bigger internals...
with the swept volume vs comp. vs lack of cid, it should still spool hard with exra 8-12 lbs per min/// EVERYWHERE!! should be fun.

If both cams are retarded the same amount, wouldn't the amount of overlap stay the same?

From the VVT Tuning thread -

Simple cam tuning rules for BOOSTED engines:
Advance intake and exhaust => more low-RPM power, less high-RPM power
Retard intake and exhaust => more high-RPM power, less low-RPM power
Less overlap => lower EGTs, faster turbo spool, less fuel
More overlap => higher EGTs, slower turbo spool, more fuel

To increase overlap, you have to RETARD the EXHAUST, and/or ADVANCE the INTAKE.
To reduce overlap, you have to ADVANCE the EXHAUST, and/or RETARD the INTAKE.

Boosted engines don’t like overlap. The incoming cold air and fuel cools down the outgoing exhaust charge, condensing the exhaust gasses. This is VERY counter-productive in a turbo application since the engine needs no help from scavenging to fill the cylinder. I've heard this being called "turbo chill".

Cool, condensed gasses in the same space push less hard on the turbo, causing lag. HOT gasses are better at spooling the turbo, thus the advanced exhaust timing to open the valve sooner in the power stroke. This steals some of those hot, expanding exhaust gasses to help spin the turbo a little faster. When the piston is near the bottom of the bore, hardly any energy is going into rotating the crank anyway, so stealing expanding gasses won’t hurt anything. The retarded intake just helps cut down the overlap further.

With that said, looking at the stock tune, it looks like GM retards the exhaust a little from 3000 to 3600rpm. That also seems to be where I see lag in the turbo spooling. Perhaps advancing the exhaust cam and retarding the intake there may help with that dead spot.

[rallycar2001]

cruze log.hplcruze log13.hplcruzelog12.hplwhat table are you guys looking at??
a couple of logs i ran just now

[rallycar2001]

So the 0-32 range is advance of the cams? not retard for any of them? I know jack about the VVT stuff and it seems to vary based on the engine from what I've found.

Edit: Well, I guess lowering the numbers would technically be retarding the cam...Maybe this explains why GM retarded the cam for the 2013MY so much. Every complaint I hear is about how these things complete peter out above 5000rpm. I'll give it a shot once I figure out controlling the boost better at high RPM.

Hmmm...wonder if I can get the turbo to spool up faster by reducing overlap in the lower RPM and then at 4000rpm increase the overlap.

that would make sense..
what are you guys adjusting close to 0*... intake cam base angle? i cant seem to follow you guys on this

[rallycar2001]

ok, got it. awesome.

[Gh0st]

ok, got it. awesome.

Yeah, the WOT table. It doesn't look like the stock tables can really be adjusted much down low to reduce overlap. I'm tempted to just try the 2013 tables(and corresponding spark timing table for the VVT) to see how the car feels.

[Gh0st]

Rest of the week is supposed to be rainy so I won't be doing anything soon

[rallycar2001]

im gonna

[rallycar2001]

well, i pulled 3 out of exhaust and interpolated 4000 rpm and up, i dont wanna retard it anymore becuase i dont wanna burn a valve. as for intake, i added a total of 7 at redline and interpolated 4000 and up. i honestly cant tell if it pulls harder or not. some pulls it felt better and others it didnt.
here someone look...

[rallycar2001]

Rest of the week is supposed to be rainy so I won't be doing anything soon

did you ever figure out how to tune past .75 airmass?

[rallycar2001]

my logs read 29 psi of boost, and dont display things after i change gauges. is there some kind of special correction factor?