Miller Cycle

[kleenair at ix.netcom.com]

ptimmerm at mashtun.JPL.NASA.GOV wrote:
> 
> I appreciate the knowledgable and friendly discussion
> of this rather arcane topic.  I was confident this
> would be THE place to discuss it.
> 
> My post started this thread, and it has moved to a
> discussion of high compression pistons, after
> the historical use was discussed.
> 
> In my case, I am only interested in supercharging,
> thus there is no internal modifications, save the
> camshaft, which seems easy compared to pistons.
> You see I was interested in superchargering 2.0 -2.5
> liter motors with standard compression ration.
> My dicovery of the Miller cycle at the LA atuo show
> this past monday, just adds a new wrinkle to this idea.
> 
> I am not sure how the following paragraph applies:
> 
> >The economy benefits of the Miller Cycle are certainly attractive in an
> >automobile, but a special cam is a big step that can be avoided.  Rather
> > than  modifying the cam and valvetrain, a servo system can control the
> >throttle advance so that the MAP is limited to safe value.  The whole
> >system can be designed, built, debugged and tested prior to tearing the
> >engine down to install the high compression pistons. The risk and cost
> >of >an incomplete project is quite low.
> 
> >MAP would provide the feedback and knock detection would determine the
> >maximum MAP.  This should be a quick and flexible home
> 
> Perhaps it is the use of the term "throttle advance" that is throwing me.
> Perhaps you mean to say that you can attenuate the efi flow electronically?
> Thanks again for the useful discussions.
> 
> paul timmerman


I don't see where you have gained anything without the Cam modification. 
 By raising compression and limiting throttle angle, you are basically 
running a high compression motor at less than full load.  Not very 
innovative!  Controlling the air flow is no problem, as you can do this 
with a drive by wire system relatively easily.  The above description is 
not a Miller Cycle engine.

I guess "throttle advance" means throttle openning angle.