Miller Cycle
Senior Member
True Car Nut
Joined: Feb 2003
Posts: 4,508
Likes: 2
From: Philly
I really don't understand the reasoning of doing this except for a single piston engine application where there aren't other pistons providing the inertia to allow the engine to utilize all the compression possible. And then you have to use a supercharger for it to work? Well then if you have to boost, wouldn't you want to make the most of it? The whole thing smacks of being different for no other reason to be different. Maybe Mazda should have sold the idea to Volvo. They like to do stuff just because.
The key here is pumping loss. It takes energy to compress the air. This alleviates some of this energy input and results in a boost in efficiency. Remember that efficiency doesn't equal power when it comes to mpgs.. at the cost of power, you get mpgs basically.
The compression ratio in a miller cycle engine is not the same as a typical engine. The 2.3l mazda engine is constructed as a 3.0 That .7l loss is a result of the swept volume that isn't compressed. (from intake valve open longer) A high static CR is limited to the intake valve opening timing and IMO much boost is better since you're loosing a third of your dynamic compression ratio to start with. Boost and direct injection is the way to go.
The concept is very sound, works, and used more often than you think. Hybrids use a similar cycle to boost mpgs. They just don't use forced induction.
Administratus Emeritus
Certified Car Nut
Joined: Jan 2006
Posts: 16,539
Likes: 18
From: Purgatory, Pennsylvania
Senior Member
True Car Nut
Joined: Feb 2003
Posts: 4,508
Likes: 2
From: Philly
I don't think 99% of us fall into the group association you're making.
Senior Member
True Car Nut
Joined: Feb 2003
Posts: 4,508
Likes: 2
From: Philly
I've definitely seen this not enforced even with myself before. Had I not, I wouldn't have linked.
For the OP and anyone interested, the link was to a non GM forum that talked about a newer 1.3l Mazda engine that used the Atkinson cycle with CVT to make up for the low end torque loss. It also had great info on the Miller and Atkinson cycles.
For the OP and anyone interested, the link was to a non GM forum that talked about a newer 1.3l Mazda engine that used the Atkinson cycle with CVT to make up for the low end torque loss. It also had great info on the Miller and Atkinson cycles.
Senior Member
Certified GM nut
Joined: Mar 2005
Posts: 2,284
Likes: 20
From: New Milford, CT
When I saw a new thread called "Miller Cycle" in the Lounge, I was expecting a beer joke.
But let'* see: 60% the displacement of a 3800, 40% better fuel economy (SSEi: 20 mpg, according to Edmunds), with only a 12% loss of horsepower. It'* not designed for performance, but by the numbers, that'* some efficient engineering.
Of course, the Miller engine falls flat on its face when the dealer explains to Joe Sixpack that the fuel-efficient car that will use less gas only runs on expensive gas.
Like a supercharged (Otto) engine, the Miller engine may catch on, but I don't see it becoming anything more than a niche.
But let'* see: 60% the displacement of a 3800, 40% better fuel economy (SSEi: 20 mpg, according to Edmunds), with only a 12% loss of horsepower. It'* not designed for performance, but by the numbers, that'* some efficient engineering.
Of course, the Miller engine falls flat on its face when the dealer explains to Joe Sixpack that the fuel-efficient car that will use less gas only runs on expensive gas.
Like a supercharged (Otto) engine, the Miller engine may catch on, but I don't see it becoming anything more than a niche.
Thread Starter
Senior Member
Posts like a Camaro
Joined: May 2010
Posts: 941
Likes: 0
From: Grant, Fl.