: explain the V-8-6-4 please!

10-18-04, 07:46 PM
I was just wondering how this thing works...never actually seen one either.

10-18-04, 10:08 PM
I'm not a 100% sure on it but I believe the computer would shut off two cylinders or or for cylinders when at highway speeds depending on speed and throttle position. The way it would do this is with some solenoids on the valve covers. I think they would disengage the rockers somehow...

10-19-04, 12:03 AM
I did a quick search and found a quick little explanatino in Popular Hot Rodding, http://www.popularhotrodding.com/features/0408phr_worst/index.html

A search of V8-6-4 will find a number of hits on the site.

In 1981, engineers at Cadillac made an attempt at producing better gas mileage for its line of heavy luxo-liners. Dubbed the V8-6-4 (or, Displacement On Demand), the engine changed cylinder modes, eliminating two cylinders at a time as power demands decreased. The idea was right on the money, but the available technology to implement it was not. Measuring 368 cubic inches, oil pressure to specially-designed hydraulic lifters was shut off by solenoids, which caused the lifter to collapse, and effectively prevented the cam lobe from opening the related valve. The biggest rap with the V8-6-4 was a distinct hesitation when cylinders were deactivated, which commonly became known as a "driveability" problem. The same engine resurfaced in 1982, without its cylinder deactivation feature, and as a result, was generally considered to be a good engine.


10-19-04, 01:20 AM

10-23-04, 12:52 PM
I could have sworn it had nothing to do with the lifters, instead using solenoids to remove the fulcrum from the rockers, and leeping the lifters seated with a dummy spring. Also, I thought in '82 they went with another gem, the HT4100, in cars meant for public consumption (commercial chassis cars are the exception)

10-24-04, 11:25 PM
I had one of these cars that had this engine. It has nothing to do with the lifters. It has a solenoid which would make the rocker arm piviot at a different way so that it didnt actuate the valve. it could work as a four six or eight cylinder.