500 V864 - is this even theoretically possible?
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500, 472, 425, 368 Discussion, 500 V864 - is this even theoretically possible? in Cadillac Engine Technical Discussion; This might be a crazy thought, but since the 368 V864 and the 500cu in Cadillac engines are of the ...
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    fleetwood96 is offline Cadillac Owners Member
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    500 V864 - is this even theoretically possible?

    This might be a crazy thought, but since the 368 V864 and the 500cu in Cadillac engines are of the same family, I wonder if it is even remotely possible to take a 500 block and use the 368 valve solenoids & covers, along with a throttle-body fuel injection system & '81 DFI computer and make a 500 V864? Would the main computer even notice a difference to make it not work? If this worked, I would think you would have plenty of power in an 80's Fleetwood or Deville and still get some gas mileage when all that power isn't needed. Heck, the thing might even have some power in 4cyl mode without having to switch back to 6cyl when encountering a slight breeze! Is this crazy or possible, and do you know of anyone who's tried it???

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    Imprl59 is offline Cadillac Owners Fanatic
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    Re: 500 V864 - is this even theoretically possible?

    Yes it is crazy, but it's that good kind of crazy!


    I have no idea if it would be possible but it sure would be fun to try. I hope you get some good input on this question because you have my curiosity raised now as well.

    Steve B.

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    Night Wolf's Avatar
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    Re: 500 V864 - is this even theoretically possible?

    yeah, that is definitly something to look into more... I can see it now:

    "yeah, not only does this 8.2L, 500 cubic inch big block Cadillac have 400hp and 500ft lbs of torque.... but with variable displacement, I get 30mpg on the highway with a 3-speed auto..... yeah, sucks that your hybrid gets only 10mpg more then this beast.... "

    those numbers are very easy to get on even a mild build from a 500 too

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    Shoehorn is offline Cadillac Owners Member
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    Re: 500 V864 - is this even theoretically possible?

    Firing order will be a problem.

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    Re: 500 V864 - is this even theoretically possible?

    It's just a solenoid that releases the pivot point of the rocker arms so the valves stay closed. The mechanics there aren't a problem. I don't know anything about the computer control of this system, so I can't comment there.

    In an article in a 80 Popular Science it says highway economy jumps from 16-18 to 24-27. That translates to 19-20mpg highway if a 500 was done the same way, which is pretty damn good.

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    kjc
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    Re: 500 V864 - is this even theoretically possible?


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    kjc
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    Re: 500 V864 - is this even theoretically possible?

    This subject came up on the mts board awhile back. That person was considering using a switch to control the solenoids. Also GM's new "displacement on demand" engines go directly from 8 to 4, they say it's much simpler, smoother and easier on the engine. One complaint that many owners had about the v8-6-4 was that the engine vibrated a lot in v-6 mode, so they eliminated it in their latest variable displacement system.
    I believe all 368s used stud-mounted rocker arms too, so that may be a problem. I don't know if the v-8-6-4s did this, but GM's new system closes both valves on the deactivated cylinders, so when the pistons rises with both valves closed, it compresses the air trapped in that cylinder, which pushes on the piston when it starts going back down, which helps turn the crank. Otherwise, the "extra" pistons and rods would just be along for the ride, making the other cylinders work harder. I don't mean to lecture, I just find this subject extremely interesting!

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    Re: 500 V864 - is this even theoretically possible?

    I have been looking into this for a while.

    Food for thought, maybe we can put our heads together and come up with something....

    1. You can open an exhaust valve full time in 4cyl mode and pump fresh intake air in the exhuast. (how much reversion will occur?)
    2. You can open an intake valve and keep the exhaust closed and pump air in the intake. Might be confusing pressures in the intake, but then again, a internal supercharger?? Hmmmmm
    3. You can keep them both closed. Pump vacuum...
    4. You can close only the intake valve (like GM does).
    5. You can create a bypass channel that vents the cyl through the head into the exhaust.
    6. Use the Sturman Digital Valve and electronically control the valves (my choice!), but lots of design work here! Fancy ECM, and you get bet you will be dealing with patent issues.

    On the valve idea of #4, look at a rev kit, and then create something to move out of the pushrod path so the valve doesn't open, but the rev kit will keep the lifter in the bore.

    Maybe some sort of way to "unscrew" the rocker arm nut like you were taking the rocker off. Again, need to hold the pushrod in place and keep the lifter in the bore, using some modified rev kit or something.

    A channel bypass valve with a solenoid control to open and close the bypass port when going into 4cyl mode. Still need to cut fuel to those cyls. So either EFI or butterfly valves in the intake would be needed. Don't need anything big, just something to be able to withstand normal combustion temps and pressures when driving normal, and then to open and bypass the air as the piston comes up. Head mods here, but this may have some benefit too in being more standalone and not mess with the pushrods/valve/lifters.

    Thoughts?

    Tom

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    Re: 500 V864 - is this even theoretically possible?

    864's work by having the solenoid release the fulcrum of the rocker arm, and the valves stay closed. With a 500, you'll probably have enough power even in 4cyl mode that it would be more possible to drop 6cyl mode.

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    Re: 500 V864 - is this even theoretically possible?

    Quote Originally Posted by davesdeville
    864's work by having the solenoid release the fulcrum of the rocker arm, and the valves stay closed. With a 500, you'll probably have enough power even in 4cyl mode that it would be more possible to drop 6cyl mode.
    i think that would be very fun to build this type of engine
    and put it in some kind of street rod or classic truck.
    but insted of going with the dfi use a carberuator !,
    and find a carberated 368 and swap heads, and make some kind of switch set up to activate the solenids,
    that might work. :lightbulb

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    kjc
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    Re: 500 V864 - is this even theoretically possible?

    I think it would be better for both valves on the deactivated cylinders to be closed at all times. That way, the compression action would overcome the enertia generated by the weight of the rising piston and rod, then the compressed air will push the piston back down, rather than the crank having to pull it back down. The effect of all these things combined would be that the engine would not "know" that it has four "extra" pistons and rods hanging on the crank, it would not "feel" their weight, therefore, even greater highway fuel efficiency.

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    davesdeville's Avatar
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    Re: 500 V864 - is this even theoretically possible?

    The problem with building an engine like this is that the solenoid actuated rocker arms are on 368 heads. I've never seen the heads up close, and have no idea if it would be possible to run the rocker arms on a 500 head, another idea would be to run a 368 head on top of a 500, 368s only have a 4.057" bore, but 425 heads (4.082" bore) have been run on 500s before, the valves are smaller than stock 500 valves, so high end performance would be diminished. Not to mention I don't know the volume of the combustion chambers, so compression will be affected.

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    kjc
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    Re: 500 V864 - is this even theoretically possible?

    Maybe the valvetrain could use something similar to Potter's stud mounted rocker system.
    Everything on a 368 head is tiny compared to a 500 or 472 head. I think the chambers are 66cc but I'm not sure.

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    Re: 500 V864 - is this even theoretically possible?

    I have seen these heads up close at the junk yard on a 1981 eldo
    and i took the solonoids off they are only held on with 2 bolts ,
    i wish i had pics to post but i dont,
    the push rods appear to be the same length and size as the non solonoid valves .
    i dont think it will be possible to mount the rocker arms from the 368 on the 500 heads(no bolt holes cast on the heads)

    hope that info helps,

  16. #15
    Fleetwood472 is offline Cadillac Owners Fanatic
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    Re: 500 V864 - is this even theoretically possible?

    I found an idea to address the mounting problem for these rockers on Al's site here is what he said:

    "I just took a quick glance at both style heads. My first thought would be to start with a set of castings with no A.I.R. hump down them. #552 or #950.
    Then I would look at machining down the height of the stock rocker mount pads. I would install a moly bar straight across all the lowered rocker pads.
    Drill and tap new bar to accept the original V4-6-8 rocker assemblies.
    Mount sytems styled like this have worked for many aftermarket Cad rockers. They work well."

    Has anyone been successful in mounting this system yet? - Justin

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