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Old 03-03-2013, 08:38 AM   #17 (permalink)
pete c
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Quote:
Originally Posted by payne171 View Post
Boy, maybe I am missing something on the variable displacement, but why not have a couple (or few) of v-twins connected by a clutch? It can't imagine balancing issues could be any worse than the current crop of cylinder deactivation autos. Valve shutoff is moot. The clutch should last quite a while. You could even make one of the engines a lot simpler than the other because it wouldn't have a very big affect on emissions because it would only run during acceleration.
I've wondered this as well. A pair of 90 degree V twins connected by clutch.

Such a system would undoubtedly be more efficient, but, I do see a few potential issues.

1. It's more expensive. It needs two separate ignition systems, and ECUs. Probably two exhaust systems as well.

2. Possible NVH issues. Even though 90 degree twins are inherently balanced, two of them running right next to one another might sound like crap when out of phase with each other. Perhaps this could be dealt with with some engine control wizardry.

3. Emissions. I suspect these would need separate exhaust systems which means one of them kicking in and running cold/dirty frequently.
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