There'* this guy that goes to my church and I showed him the new GXP last week. Buddy didn't believe me that it had a Northstar in it. So I ended up popping the hood and the guy almost lost his balance. Then he starts telling me that this engine has "...that feature that shuts off cylinders". I informed him that this was notably called discplacement on demand and then I just nodding waiting what else he would say. He then added as part of the cooling system for this engine that if the rad ever ran low on fluid, then, "...air could be taken into the system to cool the engine." OK, that is just ridiculous. How can you compare the properties of air and water when dealing with heat. They have such a great difference in heat capacity values that it'* not even funny. Plus the cooling system is basically sealed. I just nodded and listened to this guy sing his song. Should I have slapped him?

Normally yes..

But since you're @ church.. sigh .. you'll have to forgive his ignorance..

its not cylinder on demand, cadiallac hasn't done that since the 80'* with the v 8 6 4. what it is, is if your car starts to overheat, first it tells you its hot, shuts off the a-c if its on. then it shuts off 4 cylinders, and rotates which 4 are running, the 4 cylinders that arn't running it pumps air through them to help cool them. this isalso the reason it takes 8 quarts of oil in its HUGE oil pan, the excess amounts of oil are used not only to keep the engine cooler incase coolant is out or low, but to ensure that even if the car was being driven 90' sideways ( i know its impossible) it will always have oil, just like the indy race car version it was designed after. also, the reason northstars burn oil is because the cylinders are honed very aggresivly, not as smooth as most cars. this makes it so there'* a thicker coat of oil in the cylinder walls at all times, so that it can rev to RPM'* it'll never reach safely....


just a little FYI for ya

GM is and now has developed a cylinder shut down feature in there new Northstars powered cars, however they are not on the market yet. Essentially once a certain RPM has been reached, cylinders will stop generating power, spark is not generate before the power/exhaust stroke. Once the accelerator is depressed spark re-engages and power returns as fast as you can romp on the gas. GM tried this before and failed. My uncle who works on the new C6 engine line at GM St. Catharines explained this to me.

Now Mikey clearly explained Limp Home mode, which has been standard on the Aurora 4.0 and presumably all Northstar engines since 1995 (in the Aurora case). In case of engine cooling failure, the car will shut down 4 of 8 cylinders and redirect fuel to act as coolant. This Limp Home mode will allow 40mph for 60 miles (something like that) so that you can reach assistance.

2 different systems.

Thanks mikey. This is probably what the guy was talking about. The way he was talking though he sounded like he was talking about discplacement on demand like the new 300C utilizes. I know Cadillac hasn't used this system in a long time and that'* why I thought it was bogus. The limp home feature is proabably exactly what he was talking about.

Thanks for backing up Mikey'* argument Jim. I'm glad I didn't criticize the guy...especially at church. Anyway, thank'* for the lesson guys. I wish more of this technical stuff would be explained more elaborately in the manual.

DOD will be on pickup trucks (Vortecs) and the New C6 (LS2). Are those technically Gen III v8'* still?

DOD=kills hald the cylinders when you are cruising in OD, giving you a 4-banger. When you press the gas they all come back and plaster you to the seat. I think its cool...

ya, but when cadillac first did it in 79 i believe, they had a problem of people hitting the gas and being stuck in 4cyl mode, or taking to long to "activate" the other cylinders

they did a 8,6,4......are these new ones 8-or 4'*? or can they be 6'* too?

Isn't that exactly what BOOST does?

MUHAHHAHAHA

Boost is our 7th cylinder...