Switching From V4 To V8 Mode

flyboyron · April 19, 2010

I was telling a friend all about how my truck switches from V4 to V8 mode and he asked me how it did it.

I had no idea....

Where do I go to find out what exactly this engine does and how?

gmtech4 · April 19, 2010

you go to the dealer and see the shop foreman and ask him to print out the description and operation of the system,poof,its in your hand

Silverado4x4 · April 20, 2010

The E40 ECM measures load conditions based on inputs from vehicle sensors and processes that data to manage dozens of engine operations, from fuel injection to spark control to electronic throttle control. DOD adds an algorithm to the engine control software to manage cylinder deactivation and reactivation.

When loads are light, the E40 automatically closes both intake and exhaust valves for half of the cylinders and cuts fuel delivery to those four. The valves reopen to activate all cylinders when the driver demands brisk acceleration or full torque to move a load.

In conventional engines, valve lifters are operated by the engine’s camshaft, and lift a pushrod that operates the valves in the cylinder head. In the DOD V8 engines, the special de-ac lifters are installed in cylinders 1, 4, 6 and 7, while the remaining cylinders use conventional lifters.

The special hydraulically-activated de-ac lifters that enable GM’s Displacement on Demand.

The hydraulically operated de-ac lifters have a spring-loaded locking pin actuated by oil pressure.

For deactivation, hydraulic pressure dislodges the locking pin, collapsing the top portion of the lifter into the bottom and removing contact with the pushrod. The result is that the bottom of each de-ac lifter rides up and down on the cam lobe but the top does not move the push rod.

Without the lifting, the valves do not operate and combustion in that cylinder stops. During reactivation, the oil pressure is removed, and the lifter locks at full length. The pushrods, and therefore the valves, operate normally.

The final Displacement on Demand component is the LOMA. This assembly is a cast aluminum plate, installed in place of a conventional engine block cover. The LOMA holds four solenoids, control wiring and cast-in oil passages. The solenoids are managed by the ECM, and each one controls oil flow to a de-ac lifter, activating and de-activating the valves at one cylinder as required for Displacement on Demand.

Because the vibration and acoustic dynamics of the engine under V-8 and V-4 modes differ, the exhaust system of DOD-equipped vehicles is tuned to compensate for the changes.

The 3-stage Honda VTEC valve switching capabilities are enabled by three hydraulic circuits in the rocker arm, which enable a cylinder deactivation mode (VCM).

On a comparative note, Chrysler uses similar hydraulically-activated special lifters in its implementation of cylinder deactivation (MDS). Honda takes a different approach from GM and Chrysler in using a squirt of hydraulic fluid to deactivate half of the rocker arms for what it calls Variable Cylinder Management (VCM).

The Honda approach is a variation of its VTEC (variable valve timing electronic control) cam lobe switching scheme used for more than a decade. Instead of skipping between high- and low-lift cam lobes, VCM selects a rocker-arm alignment that delivers no valve lift at all.

flyboyron · April 20, 2010

That is pretty ingenious. I will have to let my friend know now. Thanks.

My 06 Honda Civic had the VTEC engine where when idling or under very light loads it would adjust the valve timing and leave the intake valves open a little longer and what would happens is the piston would push some of the mixture back into the intake manifold so it would burn less fuel. They say it got 3% better mileage than the previous versions.

TRCM · April 25, 2010

The E40 ECM measures load conditions based on inputs from vehicle sensors and processes that data to manage dozens of engine operations, from fuel injection to spark control to electronic throttle control. DOD adds an algorithm to the engine control software to manage cylinder deactivation and reactivation.

When loads are light, the E40 automatically closes both intake and exhaust valves for half of the cylinders and cuts fuel delivery to those four. The valves reopen to activate all cylinders when the driver demands brisk acceleration or full torque to move a load.

In conventional engines, valve lifters are operated by the engine’s camshaft, and lift a pushrod that operates the valves in the cylinder head. In the DOD V8 engines, the special de-ac lifters are installed in cylinders 1, 4, 6 and 7, while the remaining cylinders use conventional lifters.

The special hydraulically-activated de-ac lifters that enable GM’s Displacement on Demand.

The hydraulically operated de-ac lifters have a spring-loaded locking pin actuated by oil pressure.

For deactivation, hydraulic pressure dislodges the locking pin, collapsing the top portion of the lifter into the bottom and removing contact with the pushrod. The result is that the bottom of each de-ac lifter rides up and down on the cam lobe but the top does not move the push rod.

Without the lifting, the valves do not operate and combustion in that cylinder stops. During reactivation, the oil pressure is removed, and the lifter locks at full length. The pushrods, and therefore the valves, operate normally.

The final Displacement on Demand component is the LOMA. This assembly is a cast aluminum plate, installed in place of a conventional engine block cover. The LOMA holds four solenoids, control wiring and cast-in oil passages. The solenoids are managed by the ECM, and each one controls oil flow to a de-ac lifter, activating and de-activating the valves at one cylinder as required for Displacement on Demand.

Because the vibration and acoustic dynamics of the engine under V-8 and V-4 modes differ, the exhaust system of DOD-equipped vehicles is tuned to compensate for the changes.

The 3-stage Honda VTEC valve switching capabilities are enabled by three hydraulic circuits in the rocker arm, which enable a cylinder deactivation mode (VCM).

On a comparative note, Chrysler uses similar hydraulically-activated special lifters in its implementation of cylinder deactivation (MDS). Honda takes a different approach from GM and Chrysler in using a squirt of hydraulic fluid to deactivate half of the rocker arms for what it calls Variable Cylinder Management (VCM).

The Honda approach is a variation of its VTEC (variable valve timing electronic control) cam lobe switching scheme used for more than a decade. Instead of skipping between high- and low-lift cam lobes, VCM selects a rocker-arm alignment that delivers no valve lift at all.