MAZDA MILLER at the wrecker.

"Dash-doorhandle-6 cyl none the richer" (dash-doorhandle-and-bondo) 01/18/2016 at 12:19 • Filed to: None

5

17

I see these from time to time, but not often. I remember reading about them at the time and boiling the long story down to: it’s a 3 stroke with no compression stroke, requiring the forced induction to fill the cylinders. It trades off the parasitic loss of a supercharger for the thermal efficiency of not having to do it’s own compression and somehow comes out ahead because Japan is magic.

That kind of sums up my understanding of these engines, that and by common logic this set up would probably be easier on the rings/bearings etc. Any Mazda guys or girls care to elaborate?

Party-vi > Dash-doorhandle-6 cyl none the richer 01/18/2016 at 12:24

3

Jake - Has Bad Luck So You Don't Have To > Dash-doorhandle-6 cyl none the richer 01/18/2016 at 12:26

1

That is some straight magic

gin-san - shitpost specialist > Dash-doorhandle-6 cyl none the richer 01/18/2016 at 12:28

0

The Wikipedia entry makes it sound like a 5-stroke, where the compression stroke has two phases. Weirdly interesting.

https://en.wikipedia.org/wiki/Miller_cy…

Dash-doorhandle-6 cyl none the richer > Party-vi 01/18/2016 at 12:29

0

DOUG!

He was actually one of three famous people who went to my elementary school. The others were Monty Hall and Burton Cummings. No recent celebs though, none whatsoever.

bob and john > Dash-doorhandle-6 cyl none the richer 01/18/2016 at 12:30

5

noo....miller cycle is a 4 stroke cycle.

“In the Miller cycle, the intake valve is left open longer than it would be in an Otto cycle engine. In effect, the compression stroke is two discrete cycles: the initial portion when the intake valve is open and final portion when the intake valve is closed. This two-stage intake stroke creates the so called ‘fifth’ cycle that the Miller cycle introduces. As the piston initially moves upwards in what is traditionally the compression stroke, the charge is being pushed back out the still-open valve. Typically this loss of charge air would result in a loss of power. However, in the Miller cycle, the piston is over-fed with charge air from a supercharger, so pushing some of the charge air back out into the intake manifold is entirely planned. The supercharger typically will need to be of the positive displacement type due its ability to produce boost at relatively low engine speeds. Otherwise, low-rpm torque will suffer.”

if anything, you could count it as a 5-stroke

Manwich - now Keto-Friendly > Dash-doorhandle-6 cyl none the richer 01/18/2016 at 12:34

0

Actually, the miller cycle engine has 5 strokes. The extra stroke is from having a 2 stage intake stroke.

DrJohannVegas > Dash-doorhandle-6 cyl none the richer 01/18/2016 at 12:36

1

Bask in the 90s Mazda greatness.

Also, the magic is in the pumping losses.

Dash-doorhandle-6 cyl none the richer > bob and john 01/18/2016 at 12:43

0

Guess I could have read up, Was going to call it a 3 and a half stroke but that looked weirder in type than it seemed in my car-filled brain.

What is the Japanese analog Of the leprechaun? I think it also has some of that going on.

Dash-doorhandle-6 cyl none the richer > DrJohannVegas 01/18/2016 at 12:51

1

PUMPING LOSSES was the word I was looking for. Brain is mostly full of Mopars that I no longer even care about.

mazda616 > Dash-doorhandle-6 cyl none the richer 01/18/2016 at 13:02

0

My stepmom had a ‘99 Millenia S with the Miller Cycle and a supercharger. It was awesome. But, it blew up. Which was fine by me, because my stepmom was a massive evil bitch. I figure the car did me a favor by causing her inconvenience and such. So, I always admired it.

Spoon II > DrJohannVegas 01/18/2016 at 13:44

0

Ermagerd, that music. This video is awesome!

DrJohannVegas > Dash-doorhandle-6 cyl none the richer 01/18/2016 at 13:45

0

Pumping losses (or the lack thereof) when at part-load is also what makes the Diesel cycle so magical. Because there is (usually) no restriction on intake pressure (or flow, if you want to think of it that way), Diesel engines are a good bit more efficient than Otto-cycle engines at part load. Hooray for throttling with fuel!

KusabiSensei - Captain of the Toronto Maple Leafs > Dash-doorhandle-6 cyl none the richer 01/18/2016 at 13:46

0

Ah the good old Mazda KJ-ZEM Miller cycle V6.

The point of the supercharger providing positive boost pressure was that you start the compression stroke with the intake valve open, and close it when the piston has gotten 20% of the way up (or so. I don’t remember the exact number), but because you have positive pressure from the supercharger, you get the same charge at intake valve closure as you would in an N/A engine at the bottom of the stroke.

So you get 100% of the compression for about 80% of the work of the piston (since it doesn’t have to push against anything until the valve closes).

It’s an interesting concept. If you remove the supercharger, you get an Atkinson cycle engine.

Dash-doorhandle-6 cyl none the richer > DrJohannVegas 01/18/2016 at 14:01

1

Double edged sword though, Most of the big Diesel stuff I have to joy of working on (BIG like 2 steering axles big) Require something called a roda valve, which closes the intake tight. The reason being that natural gas, sour gas or other combustibles floating around in the oil and gas industry can go up your intake, removing the injector pump from the equation, causing it to rev to the moon and grenade spectacularly. This almost never happens, but I always make sure they work if I’m the last guy that messed with the electrics.

Dash-doorhandle-6 cyl none the richer > KusabiSensei - Captain of the Toronto Maple Leafs 01/18/2016 at 14:06

0

They sound different too. This one was perfectly good too. This wrecker is right next door to a steel mill, so cars are literally thrown over the fence at the six week mark. This one is well on it’s way to becoming a guard rail or a Kia Rio.

DrJohannVegas > Dash-doorhandle-6 cyl none the richer 01/18/2016 at 14:26

0

Yep. Runaway is scary enough on something like a 4BT, I can’t imagine the forces (and danger!) in something fully-industrial-sized.

HammerheadFistpunch > bob and john 01/18/2016 at 14:58

1

yup, basically its an extreme modified atkinson cycle. The basic principle is that the expansion stroke is greater than the compression stroke so a great portion of the energy gained from combustion is used to turn the crank.