: Does A Northstar Have Mds?



96CADDYDEVILLE
03-01-05, 04:26 PM
HELLO EVERYONE DOES A N* HAVE A MULTI DISPLACMENT SYSTEM? THE DEAL LIKE A HEMI 300 WHERE IT CUTS OFF FOUR CYLINDERS ON THE HIGHWAY. THE QUESTION WAS POSED TO ME AND I JUST DONT KNOW:bighead:

mcowden
03-01-05, 04:38 PM
No, it does not do anything like that. There used to be a Cadillac 4-6-8 system that would turn off cylinders, but it's not the Northstar.

96CADDYDEVILLE
03-01-05, 04:42 PM
Thanks

starfox86
03-03-05, 10:31 PM
I read on this site that is what the Northstar system does. shuts off 4 to get u some place safe at a max speed of 50mph::::::::LOOK AT THIS!!! .............................................
Camel Mode - Loss of Coolant Protection (check this discussion for references): (back to the top)

The Northstar engine has a loss of coolant protection mode where four cylinders are shut down (the injectors are turned off) so they can cool themselves by pumping only air... Once that set of four cylinders is cooler, they're turned back on and then the other four cylinders are shut down to cool. The two groups of cylinders continue to shut down alternately so as to protect the engine during a severe overheating situation and allow the driver to reach a safe place rather than be stranded on the side of the road.

It has been nick named "camel mode" since the engine can run without water in it.

Camel mode is VERY effective on the Northstar for several reasons...

mcowden
03-03-05, 11:13 PM
You are correct, Starfox86, but 96CaddyDeville was asking whether the Northstar turns off cylinders during cruising speed for purposes of fuel savings and then turns them back on when acceleration is demanded. The Northstar doesn't do that, which is to say it doesn't technically have a Multi Displacement System, but you are absolutely correct about the "camel mode." GM calls it "Limp Home Mode," and it's intended to cool cylinders during an overheating emergency by letting them pump just air. Half of them are shut down at a time. They are not turned off and on to save fuel and increase power, though, as they are on the DaimlerChrysler engines. Limp Home Mode is just for short distance emergency cooling. That's the difference between Limp Home Mode and a Multi Displacement System. Good catch, and thanks for posting!

BeelzeBob
03-03-05, 11:17 PM
I read on this site that is what the Northstar system does. shuts off 4 to get u some place safe at a max speed of 50mph::::::::LOOK AT THIS!!! .............................................
Camel Mode - Loss of Coolant Protection (check this discussion for references): (back to the top)

The Northstar engine has a loss of coolant protection mode where four cylinders are shut down (the injectors are turned off) so they can cool themselves by pumping only air... Once that set of four cylinders is cooler, they're turned back on and then the other four cylinders are shut down to cool. The two groups of cylinders continue to shut down alternately so as to protect the engine during a severe overheating situation and allow the driver to reach a safe place rather than be stranded on the side of the road.

It has been nick named "camel mode" since the engine can run without water in it.

Camel mode is VERY effective on the Northstar for several reasons...



The Northstar does indeed turn off the fuel to 4 cylinders if it detects and overheat condition so as to protect the engine from damage. This is called the "camel mode" but this feature is NOT the same as the variable displacement systems on some of the GM small block engines and the Chrysler hemi.

The variable displacement systems disable the valve train operation to the disabled cylinders so that the valves stay closed all the time. This is completely different to the camel protection mode where the valves continue to operate normally and the cylinders continue to pump air even though they are not "running".

If the valves are kept closed the cylinder acts like an air spring and returns the energy used to compress the material. In the camel mode , with the valves open, the dead cylinders impart a huge pumping loss.

Do NOT confuse the loss of coolant protection scheme with the variable displacement systems...they are absolutely not the same thing and do not operate on the same principles.

Aurora40
03-04-05, 01:24 PM
In the camel mode , with the valves open, the dead cylinders impart a huge pumping loss.

This is intentional, though, right? Doesn't it transfer heat to that air it is pumping out to help cool down the engine? Or was it more just because this was a simpler solution?

BeelzeBob
03-04-05, 02:47 PM
This is intentional, though, right? Doesn't it transfer heat to that air it is pumping out to help cool down the engine? Or was it more just because this was a simpler solution?



uh....yea....it was intentional. We wouldn't have done it that way otherwise. A disabled cylinder running in the modulated displacement mode wouldn't reject any heat as the valves would be closed and the gases trapped in the cylinder wouldn't circulate.

The modulated displacement systems and the camel mode limp home system are completely different systems from a design, purpose, function standpoint.