Miller or Otto ??

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Sat 2 Jun 2007 18:53
Miller or Otto ?? - Pendlebury
Mazda will be introducing a Miller cycle engine with the new Mazda 2 to increase mpg.
With the emphasis turning more towards green issues can we expect to see more of this in new cars - especially as there are also some increased emmissions targets for diesels on the way that will add circa £300 to the price of each diesel engine.


www.channel4.com/4car/news/news-story.jsp?news_id=...6
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Sat 2 Jun 2007 21:17
Miller or Otto ?? - Roly93
Mazda have been playing with Miller Cycle tecnology for a while now, but it isn't all 'beer and skittles'. Granted Miller cycle engines are intrinsically more efficient than OTTO cycle, BUT, Miller cycle engines usually dont work at all well without a Supercharger to bump up the intake manifold pressure. So what you gain in efficiency you lose in cost and complexity of manufacture. It is interesting stuff from an engineering point of view, but I dont think Miller cycle engines willrapidly take the market by storm.
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Sat 2 Jun 2007 22:13
Miller or Otto ?? - mike hannon
Somebody had to ask - what's the difference, then?
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Sat 2 Jun 2007 23:33
Miller or Otto ?? - dxp55
I hope Mazda 2 is more economical than my Xedos 9 Miller 20-22mpg round town and 26 if lucky on run - one thing though it rev's so freely and best engine I have ever had - very complex - plugs are 2 1/2 hr job -rocker cover gaskets 5 1/2hr for both but it does howl when you floor it. :-))

Dave
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Sun 3 Jun 2007 00:07
Miller or Otto ?? - Vin {P}
auto.howstuffworks.com/question132.htm

V
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Sun 3 Jun 2007 00:09
Miller or Otto ?? - Vin {P}
And en.wikipedia.org/wiki/Miller_cycle

V
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Sun 3 Jun 2007 08:42
Miller or Otto ?? - Vin {P}
dxp55,

From Mazda's explanation of the Miller Cycle at: www.mazda.com.au/articleZone5.aspx?articleZoneID=3...7

"An engine that has a lower compression ratio will also naturally produce smaller amounts of friction, particularly on the compression stroke. Since the Miler engine is targeted at a vehicle that would normally use an engine over 3.0L, the reduction in size to 2.3L provides an improvement in fuel efficiency of around 13 percent. "

From that quote and others on that page, it looks like their aim is to produce an engine that performs like a 3L engine but uses less fuel than the 3L engine would do. The power reduction resulting from the drop to 2.3L is overcome by the supercharger, but the Miller cycle means that the power loss doesn't happen. They would argue that you're getting 3L performance on the cheap (fuel, not maintenance-wise!)

My interest comes from the fact that I had an Otto cycle Xedos9 which I loved, and reading up on it led me to the wonders of Miller.

V

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Sun 3 Jun 2007 16:48
Miller or Otto ?? - mike hannon
Thanks for the informative links. Seems like a lot of dubious extra complication to me. Why has no other manufacturer taken it up?
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