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Neil,  The Mazda Millenia used a Miller cycle ( late iv closing) with a screw supercharger to keep power up when required. Atkinson and Miller have some resemblance so supercharging might be an option when power is needed. Late iv closing is aimed at mpg not power.

Peter

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19 minutes ago, PeterC said:

Neil,  The Mazda Millenia used a Miller cycle ( late iv closing) with a screw supercharger to keep power up when required. Atkinson and Miller have some resemblance so supercharging might be an option when power is needed. Late iv closing is aimed at mpg not power.

Peter

In the Miller cycle the blower acts as a valve to trap the mixture expelled form the cylinder by the late iv closure in the intake manifold, so raising the manifold pressure a bit and not wasting energy put into the early compression stroke

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Here's a blown Miller cycle engine from Nissan. Dont know if it was in production.

https://www.greencarcongress.com/2012/05/hr12ddr-20120530.html#more

I was at one time very interested in Miller cycle and pushing the mpg of the TR6. I have a Miller cam for the 2,5 6-pot going free if anyone offers to do the experiment. Without the blower it might be a bit soft on power but it would be interesting to see how far mpg can be pushed.......

Peter

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1 hour ago, Neil T said:

Thank you Peter

I find this very interesting,got my thinking head on and I might give this a go just to see what happens. I have a 2.5 four pot from Toyota with the Atkinson system  so will keep you informed.

Neil, I would suggest you start by finding the effective comp rat when unboosted and operating on the AC. Very roughly speaking 3 to 4 psi of boost will raise the eff comp rat by one ratio. If you try to take it above about 10.5:1 detonation might occur on 97 RON. However detonation cannot be accurately predicted, these are mere ball park numbers. An intercooler will allow more boost before knocking. If you can source the screw compressor off a Millenia that would be good start, better than an Eaton blower. They turn up on ebay sometimes. Indeed the spec for the Millenia might be worth copying: look for comp rat, boost, cooling, acceptable fuel and does the ignition use a knock-sensor to kill detonation.

An interesting project !

Peter

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