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Old 10-26-2010, 05:13 PM   #1 (permalink)
t vago
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Variable displacement V8 - thoughts?

I got the bright idea today to see if I could retrofit a V8 engine (specifically, the 4.7L engine in my Dakota) with variable displacement. It would be beneficial to be able to recover between 8% and 20% of fuel economy in this manner.

Electronics is not a concern for me, since I have a BSEE and some experience with building and programming automotive engine electronics. It should be a simple matter to cut power from the necessary ignition coils and fuel injectors. Granted, the stock engine computer very likely would throw codes for multiple cylinder misfires and loss of continuity of said coils and fuel injectors, but this could be overcome in time with a standalone engine controller (like the Megasquirt).

It seems the big obstacle to this project would be shutting off airflow to the deactivated cylinders. The proposed solution came to me as I was reading ways on how this was done with engines that already had this capability.

I remember that there is a company out there who came up with an adapter kit to fit a Ford 4.6L intake manifold to the Chrysler 4.7L engine, and it was basically a pair of adapter plates that mated the intake manifold flanges of the Ford intake manifold to the intake flanges of the 4.7L heads.

It should be possible, then, to fabricate adapter plates to go between the stock 4.7L intake manifold flanges and the 4.7L head intake flanges. These plates would have butterfly valves to shut off airflow to the desired cylinders. This should work inasmuch as it would allow the O2 sensor to continue to correctly read the lambda of the exhaust gases, instead of trying to read exhaust gases excessively diluted with fresh air.


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