displacement on demand

[novaz06]

Just for kicks, anyone enabled this in their LS7? HP Tuners appears to allow for this. I wonder what kind of gas milage improvement, if any? I am taking a long road trip in April and I was thinking of enabling it just for that. Any thoughts? Does it even actually work?

[Jim Lembo]

Originally Posted by novaz06

Just for kicks, anyone enabled this in their LS7? HP Tuners appears to allow for this. I wonder what kind of gas milage improvement, if any? I am taking a long road trip in April and I was thinking of enabling it just for that. Any thoughts? Does it even actually work?

IIRC, DOD requires a different sprocket that has a "cam phaser" built into it.
As far as I know the LS7 doesn't have this installed from the factory.
I'm sure someone more knowledgeable than me will chime in on this soon.
I bet DJ Worm has the correct info about this.

Jimbo

[No Doubt]

It requires much more than that. Thus, quoting from an article at Superchevy.com....

DOD-specific hardware includes two-stage switching lifters, a lifter oil manifold assembly (located in the valley of the engine), a redesigned lube circuit and oil pump, electronic throttle-by-wire operation, a pressure-activated muffler valve, and an improved E40 engine controller running DOD-specific software.

"In order to eliminate the pumping losses, you need to disable both the intake and exhaust valve." This results in a completely sealed, deactivated cylinder, which is essentially an air spring being acted upon by a piston. Virtually all the work put into it during compression is returned to the crank during decompression.

"Currently, we could disable just the fuel delivery, but the valves would still be opening and closing and each cylinder would still be doing work pumping air in and out. So there would be no net gain in efficiency--you wouldn't have eliminated the pumping losses at all."

[AZZ061]

my 2006 SRT8 had the MDS on the motor made great for long trips as long as there were no inclines!

[seamus2154]

I'm getting 19-20 MPG w/ my new GMC w/ this feature and I'm thrilled. 5.3 motor. I had an 01 w/ the 5.3 and got 13-14 nice improvement.