I've heard of GM setting up a few cars that with the push of a button the engine only uses 4 pistons for gas mileage. Was this done by tuning? How would one go about doing that since it would help mpg quite a bit?

 

Yes you can see this is achived with vvt or variable valve timing in the L99 auto Camaros. This is due to a specific type of valve train and tune in the ECU

 

It's called DOD.. Displacement on demand.
Caddy tried it some yrs ago with their 8-6-4 deal..NOT really a rousing success!

 

Have it on my new 2010 Sierra and with the new control strategies, it actually works pretty well - can't really tell when it's switching and the power's there when I need it.

Bird

 

I believe GM and CHrysler have this. Not sure about ford. It's been around for a while now, my boss has it on his Impala v6

 

yeah, you're not going to be able to do it on a car that's not made for it... you'd need to buy an engine that's built for that functionality

it requires special oil-pressure-controlled lifters, and many many other things in order for it to operate...

here's info about the DOD/AFM setup and operation:

https://ls1tech.com/forums/ls4-front...html?p=5322427


.

 

its not just cutting out fuel and spark to 4 cylinders lol

 

No, It will actually keep the valves from opening on those cyclinders. They are special lifters. There is a pin inside them that when these oil solenoids activate the pin moves and allows the pushrods to move down inside the lifter as the lifter moves up on the cam lobe. I believe this is correct..??

 

I dont know man...you gotta open those valves or else the cylinders that ARE firing will be fighting against a closed-off cylinder...kinda like trying to squash a 1 liter plastic bottle with the lid on...you aint gonna do it unless you pop that ****** lmao..

 

Nothing to fight against. If the valve dont open, theres nothing to compress. LOL

 

Since we are not operating in outer space there is air in the deactivated cylinders being compressed. According to GM Engineering the work used to compress the air is returned to the crank on decompression.

 

Minus any losses.

 

True. It's just an air spring. Nothing fancy about it.