3 cyl cruising

[95SleeperAcheiva]

that DoD comes in the 3900 right?
Thats why I wanted to know if the 3400 lifters still fit in them. If they do grab a 3900, punch it to 4.0L, pitch the DoD crap, put on a 3.5 intakes (because I hear the 3900 intakes have some kind of variable legth intake system on it too) and we should be making some good power.

I've tried bringing this up in various threads before.

Also, when is this damn OBD 3 coming out? When is the 42 volt cars coming out? I'm not looking forward to buying all new diagnostic equipment!

[IsaacHayes]

not all 3900 have DoD. I'd keep the intake on the 3900 and use a window switch or something to activate it. The VVT may or may not cause a problem if disconnected. The 3500 VVT also has a varible intake IIRC, and you can't use the non-vvt 3500 intakes (did they discontinue the non-vvt 3500?). Also if using the 3900 you'll need some sort of 7x trigger rigged up and run odbI car or aftermarket computer, as a SFI car would also need a 24x trigger (I guess you could rig one of those up too)..

I didn't see any v8 for the malibu. Maybe monte carlo/impala though.. I wonder how the exhaust sounds when it goees to 4 cyl if you have loud exhaust. If it all of a sudden sounds like a honda... hehe.

[prophiseer]

Also, when is this damn OBD 3 coming out? When is the 42 volt cars coming out? I'm not looking forward to buying all new diagnostic equipment

"OBDIII" is technically already out, it's called CAN (Controlled Area Network), and is already implemented in many newer european and some asian cars. Federal regulations are requiring it mandatory by 2010 (I think) for domestics.

42V I think is close behind, but I'm not sure.

[sharkey]

42 volt is already in place on the gm hybrid trucks.

[billy wood]

I still dont get it. Pull a couple of spark plug wires & see how well your engine runs...

[Fedaykin]

well if you isolate the intake on the 3 cylinders, (dual blade or dual throttle bodies) with modified intake manifold, you could stop the other 3 cylinders from pulling air... MAF would read the amount of air coming to the 3 running cylinders, and with standalone fuel management you could tune for necessary fuel.

[Calvin]

It can be a bit more complicated than that. I saw where someone attempted this very same thing with a Dodge Intrepid, but shutting off three injectors doesn't work very well when you don't do something to account for the O2 sensor that will now be in the disabled cylinder bank reading very very lean.

You would have to get a standalone or set the factory unit up to run open loop when you triggered the cutting of three injectors. Using a wideband in only the live cylinder bank, you could pull that off. BTW, on a 60 degree V6 you really can have pretty even (smooth) running with one bank shut off since the firing order goes bank1-bank2-bank1, etc.

You would also have to reconfigure your transmission parameters. Running on only three cylinders means you are going to have the throttle farther open (which is good since it reduces pumping losses) but you will have to adjust your computer since most cars unlock the TCC pretty quick when they see the throttle open more than is necessary for cruise with the full # of cylinders.

The dual TB setup of the intrepids makes shutting off a bank a little easier than what we've got.