research proposal on variable displacement engines "interview" help

[N10]

hello ,i am currently writing a theoretical research proposal for the technical writing course i'm taking and i need to do an interview(the teacher said we could do interviews on email) i havent's found no one "knowledgeble" of my subject which is "variable displacement engines(like found on HEMI V8 or honda accord V6,the thing shuts off the some of the engine's cylinders when lower power is needed and thus better fuel economy can be achieved.)so i thought maybe someone here would be able to provide me with some information even if it's something "general" about this technology..like the advantages..weaknesses or how it works...and i would need to use your name for referencing only....it would be great if anyone could help asap...

thanks alot!

 

[dano]

GM tried it in the early '80's (for Cadillac, known as the L62 or V8-6-4 Engine), and it failed miserably. There were lots of issues with the ECU (the computer which controlled the system).

Chrysler/Mercedes renewed the technology in 2004. Mitsubishi also tried in in the late 90's(?).

Honda probably has the most successful VDE, with the J-series engines, which use VTEC technology to turn a bank of cylinders off, depending on the load to the engine.

 

[raggie33]

i think the best way to make it work is solenoid controlled valves. when they kill a cylinder kill spark to the cylinder and fuel and close intake valve and open exhaust to the killed cylinders

 

[N10]

thanks for the replies guys

 

[Steve K]

in the late 90's, I was working on a "dual fuel" project that also included the ability to shut down cylinders when the load was light. The dual fuel engine was a modified Caterpillar diesel engine. The engine was modified to add injectors for natural gas. The engine would start on diesel fuel, and switch over to primarily natural gas once the engine was warmed up. A small injection of diesel acted as the ignition source for the natural gas.

I think the advantage of shutting down some of the cylinders is that simply reducing the fuel per cylinder becomes inefficient after a certain point. Better to maintain some minimum fuel delivery into the cylinder, but reduce the number of cylinders being used.

This strategy gets easier to implement if the ECU is already controlling the fuel delivered per cylinder. It might be easier on a diesel, since the ECU is regulating the engine speed based on accelerator pedal position. I'm not sure how it would work out for a typical gasoline engine.

One interesting tidbit was that our software would vary which cylinders were being used. i.e. if you were only running two out of the six cylinders, it would run cylinders 1 & 4 for a short while, then switch to cylinders 2 & 5, then switch to cylinders 3 & 6, and then back to 1 & 4. This kept the cylinders from cooling off, which would affect emissions when the engine did start to use the cylinders again.

regards,
Steve K.

 

[FRANKVZ]

Chevy uses that technology now: http://alternativefuels.about.com/o...rolet-Silverado-FFV/08-Silverado-V-4-mode.htm Maybe you can try e-mailing Chevrolet and try doing an online interview with one of their engineers.