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post #1 of 16 (permalink) Old 06-08-2013, 03:53 AM Thread Starter
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VVT Engines Explained

This is for the members who don't have any idea of what Variable Valve Timing is in the 08-10 cobalts. Its more of today's emissions control than horsepower, since we don't use Secondary Air Injection/EGR Valve OBD-II systems.

He may not cover in this video, but VVT at cruising speeds will close the exhaust valve sooner so less NOx is produced for smog. This closes sooner than normal operation so less fuel will be needed for the next cycle of combustion, giving the exhaust more dilution and reducing the combustion heat (also reducing NOx).

I figured this will be a good visual aide for those who also want to look at upgrading/performance modification ideas and to understand what components to look at when modifying. This is valvetrain parts to pay close attention too. You cannot just slap an intake, header, and exhaust and expect horsepower/torque increase when your car is nothing more than an air pump. The PCM already has it set for amount of air going in and out, with them bolt ons, your PCM will go to what is known as "adaptive strategy" or last known good voltage. There is more to it than you normally know and coby7, bankerbalt, leevecius and a few other techy's know what I am talking about.


2009 Cobalt LS XFE U74
Mods: K&N Typhoon Intake, Option Cat-Back Exhaust, Cosmo Short shifter, Maxxim Ahead 17X7's, MPx shorty antenna, FE5 Strut/shocks, Tein S Techs, Moog endlinks, Moog spring seaters, ZZP shorty header, LSJ downpipe, LNF front grille
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post #2 of 16 (permalink) Old 06-08-2013, 09:03 AM
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So adding an bolt ons will give you the same performance basically?

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post #3 of 16 (permalink) Old 06-08-2013, 09:23 AM Thread Starter
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on some applications, it varies between engine design. I was told by a few techy's on here that the LAP motors that carry the VVT are already equipped with oversized valves to compensate for the bolt ons. Otherwise, if built by engineers to factory setup, your intake and header when during valve overlap, will just simply bypass during that phase and exit through the exhaust causing your cold air intake and header to just stream unburnt fuel and air, thus resulting in a rich fuel smell out the exhaust pipe.

adding a bit more of info:

Its very hard to explain, but shown is a good way of knowing. All engines are in compliance with 50 state legal emissions onboard. Therefore, you get a volumetric efficiency table (ive talked about this before), but that is the standard numbers they use to adapt to any environment, altitude, and air barometric pressure. When you get your tune, say for instance Vince from Trifecta, he establishes your VE table and re-calculates a generic table that is higher based upon your region of residence. This will allow for better air/fuel ratio and expand your valves for horsepower and torque. This is what is known as a tune. He takes what performance parts you have and re-learns a data table that is permanently stored in your PCM. So when you floor the gas pedal, his data table will kick in out of the 12 that are pre-established already in your PCM's learn mode or adaptive strategy. This is your common tune. A dynotune will enhance that power even more based upon where you reside and drive your vehicle. A dynotune will measure BARO for your MAP sensor, MAF sensor input, 02 bank 1 sensor, and other conditions in the local environment.

2009 Cobalt LS XFE U74
Mods: K&N Typhoon Intake, Option Cat-Back Exhaust, Cosmo Short shifter, Maxxim Ahead 17X7's, MPx shorty antenna, FE5 Strut/shocks, Tein S Techs, Moog endlinks, Moog spring seaters, ZZP shorty header, LSJ downpipe, LNF front grille

Last edited by 5t3alth; 06-08-2013 at 10:40 AM.
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post #4 of 16 (permalink) Old 06-08-2013, 09:15 PM
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Quote:
Originally Posted by 5t3alth View Post
on some applications, it varies between engine design. I was told by a few techy's on here that the LAP motors that carry the VVT are already equipped with oversized valves to compensate for the bolt ons. Otherwise, if built by engineers to factory setup, your intake and header when during valve overlap, will just simply bypass during that phase and exit through the exhaust causing your cold air intake and header to just stream unburnt fuel and air, thus resulting in a rich fuel smell out the exhaust pipe.

adding a bit more of info:

Its very hard to explain, but shown is a good way of knowing. All engines are in compliance with 50 state legal emissions onboard. Therefore, you get a volumetric efficiency table (ive talked about this before), but that is the standard numbers they use to adapt to any environment, altitude, and air barometric pressure. When you get your tune, say for instance Vince from Trifecta, he establishes your VE table and re-calculates a generic table that is higher based upon your region of residence. This will allow for better air/fuel ratio and expand your valves for horsepower and torque. This is what is known as a tune. He takes what performance parts you have and re-learns a data table that is permanently stored in your PCM. So when you floor the gas pedal, his data table will kick in out of the 12 that are pre-established already in your PCM's learn mode or adaptive strategy. This is your common tune. A dynotune will enhance that power even more based upon where you reside and drive your vehicle. A dynotune will measure BARO for your MAP sensor, MAF sensor input, 02 bank 1 sensor, and other conditions in the local environment.
Nice right up for the newbies ,.........VVT for the win as always " F##k yo vtec".... GO CHEESE BURGER GO!!!

0-60....tooloonggg......Someone Wanna tune me =)

Last edited by cobaltune; 06-08-2013 at 09:27 PM.
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post #5 of 16 (permalink) Old 06-08-2013, 10:25 PM
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I think ill put one on just to upgrade the look of my engine compartment

Future mods:
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post #6 of 16 (permalink) Old 06-25-2013, 09:41 PM
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Then what is Ecotec? I remember reading it had something to do with exhaust valve timing for cleaner emissions, is this true? And does that count as VVT? I have an L61 engine with a CAI, and I've noticed a fair bump in mid to high end power, but a loss at low RPM, and it occasionally throws a P0171 code. Is that the PCM 'adaptively strategizing'? Would love to know.

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post #7 of 16 (permalink) Old 06-26-2013, 06:59 AM
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Ecotec (capitalized ECOTEC, from 'Emissions Control Optimisation TEChnology') is a General Motors (GM) trademark that refers to a series of emissions technologies that were implemented throughout a range of GM engines.

That's what Ecotec is. Just a crap load more of emissions crap that I remove on every car I've owned lol.

P0171 System too Lean (Bank 1) - Read Our Article On Oxygen Sensor Codes For Help With This Generic Check Engine Light Code

That is your code, it's basically saying when you open her wide open your 02 sensor isn't adjusting your fuel quick enough. Not that big of a deal unless it STAYS on lol.


And you will lose a little low end torque when adding a CAI. Torque is built off restriction on 4 cylinder cars. If you have a tiny intake (lets say 1in in diameter for example), you will have LOADS of torque but not much high end power, but since you put on a bigger one, you lose that torque, but you gain good amounts on the top end of your spectrum. Make sense?

'09 SS/TC - Stolen
Mods - Injen CAI, CIA MAF Relocate CP's, Dejon FMIC,
Custom 3" DP, 3" Exhaust, GT3076R, Pioneer AVH-4100DVD, Hurst STS, ZZP triple pod, Autometer Cobalt boost/DPIC/WB gauges, Nitto NT05 245/40/18's, H&R Springs, 80:20 Meth Spray
Future - KSport Kontrol Pro Coilovers, 10% Tint, FMIC spray
538whp/501wtq @38 psi on meth and 93 oct on stock ish motor


06 EVO IX MR/SE - Sold
Mods - *Updated 10/6/13* AEM TRUboost EBC, 4in custom TBE, SD dual 93/e85 tune, ETS 4in Race Core FMIC, Dual Aeromotive 400lph Fuel Pumps, T4 Tubular Manifold w/ dual WG's, FP Super99HTZ DBB Turbo, GSC 274 mivec cams, ARP headstuds/rod studs, FIC 2150cc Injectors, Aeromotive FPR, Aeromotive Fuel Rail, catch can, Mini Battery Kit, Slim Coolant Fan, Kiggly Racing high pressure valve Springs/Titanium Retainers, Supertech Stainless Steel Valves, Dual VTA Tial 44mm WG's, 4g64 Stroker Manley Pistons, 155mm 2.4 LR Manley Turbo Plus I Beam Rods with ARP 625 Studs, 100mm forged non-billet Manley Crankshaft, Full H/E PNP with Port Matching, Kiggly Racing Girdle, Dual Tial 50mm BOV's, Excedy Triple Disc Carbon HD Clutch, AEM EMS

'95 Ram 2500 Diesel
Mods - 5in TBE, Boost Elbow set to 28psi, Adjusted fuel pump, Open Turbo.

Future Mods- Super Street Clutch (rated @1400ftlbs tq), 67mm turbo, 160lb valve springs, added timing, tubular exhaust manifold, larger injectors, possible 6 spd swap.


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post #8 of 16 (permalink) Old 06-26-2013, 09:23 AM
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Praise Ceaser! I always knew ECOTEC wasn't anything to brag about, I like to tell friends it's the anti-VTEC.

Regarding the code, then it's a simple case of upgrading the 02 sensors to something a little faster? I hear the term 'Wideband' thrown around here alot. I'm going to do a little research on the subject.

The torque thing makes sense. Then by the same logic, adding things like a header, downpipe, free-flow cat, cat-back etc will have a similar effect on low end engine torque? Thanks for sharing another glimpse of enlightenment, we really appreciate it.

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post #9 of 16 (permalink) Old 06-26-2013, 10:32 AM
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Quote:
Originally Posted by Plain Jane View Post
Praise Ceaser! I always knew ECOTEC wasn't anything to brag about, I like to tell friends it's the anti-VTEC.

Regarding the code, then it's a simple case of upgrading the 02 sensors to something a little faster? I hear the term 'Wideband' thrown around here alot. I'm going to do a little research on the subject.

The torque thing makes sense. Then by the same logic, adding things like a header, downpipe, free-flow cat, cat-back etc will have a similar effect on low end engine torque? Thanks for sharing another glimpse of enlightenment, we really appreciate it.
No, a wideband sensor will not help you here, but they are nice to have. The WB sensor will give you an actual ratio readout on a gauge to help you while tuning, where as a narrowband will just say rich, lean, ok. Honestly, if you want to get that fixed, you need to re-tune your car to re-calibrate the MAF in your new intake to allow it to adjust the values correctly so that it will add fuel faster.

And yes, adding more bolt ons that will allow for better flow in your engine will do the same effect.

'09 SS/TC - Stolen
Mods - Injen CAI, CIA MAF Relocate CP's, Dejon FMIC,
Custom 3" DP, 3" Exhaust, GT3076R, Pioneer AVH-4100DVD, Hurst STS, ZZP triple pod, Autometer Cobalt boost/DPIC/WB gauges, Nitto NT05 245/40/18's, H&R Springs, 80:20 Meth Spray
Future - KSport Kontrol Pro Coilovers, 10% Tint, FMIC spray
538whp/501wtq @38 psi on meth and 93 oct on stock ish motor


06 EVO IX MR/SE - Sold
Mods - *Updated 10/6/13* AEM TRUboost EBC, 4in custom TBE, SD dual 93/e85 tune, ETS 4in Race Core FMIC, Dual Aeromotive 400lph Fuel Pumps, T4 Tubular Manifold w/ dual WG's, FP Super99HTZ DBB Turbo, GSC 274 mivec cams, ARP headstuds/rod studs, FIC 2150cc Injectors, Aeromotive FPR, Aeromotive Fuel Rail, catch can, Mini Battery Kit, Slim Coolant Fan, Kiggly Racing high pressure valve Springs/Titanium Retainers, Supertech Stainless Steel Valves, Dual VTA Tial 44mm WG's, 4g64 Stroker Manley Pistons, 155mm 2.4 LR Manley Turbo Plus I Beam Rods with ARP 625 Studs, 100mm forged non-billet Manley Crankshaft, Full H/E PNP with Port Matching, Kiggly Racing Girdle, Dual Tial 50mm BOV's, Excedy Triple Disc Carbon HD Clutch, AEM EMS

'95 Ram 2500 Diesel
Mods - 5in TBE, Boost Elbow set to 28psi, Adjusted fuel pump, Open Turbo.

Future Mods- Super Street Clutch (rated @1400ftlbs tq), 67mm turbo, 160lb valve springs, added timing, tubular exhaust manifold, larger injectors, possible 6 spd swap.


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post #10 of 16 (permalink) Old 06-26-2013, 04:10 PM
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So the exhaust valve closes sooner, trapping some of the exhaust in the cylinder? And if this is the case, how does that use less fuel?
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