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Location:
Perth, WA
Registered:
October 2002
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mad scientist seeks sensible people to tell him not to try this idea.
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Wed, 13 November 2002 01:46
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ok... i'm certain there is going to be a flaw somewhere in this idea, and i want someone to tell me what it is so i can stop thinking about how it might work. What i was contemplating was taking a 4agze, and converting it to what you might call a 4agmze
what's the m stand for? miller cycle.
i'm sure plenty of you will know what miller cycle engines are, but for those who don't i'll try and fill you in with what little i know about them. (and if i get anything wrong, feel free to correct me)
it's basically a regular 4 stroke engine (otto cycle) with a supercharger, and with the valve timing set up to leave the valves open for part of the compression stroke, so rather than compressing against the cylinder walls, it's compressing against the supercharger. I don't fully understand how it works beyond that (i never claimed to be an automotive engineer of any description) so i'm very open to being shut down on this idea.
mazda have used a v6 miller cycle engine on one of the eunos' and word has it it's a very effective setup. miller cycle engines are supposed to (according to mazda) provide about an ~ 15% increase in efficiency over a similar otto cycle engine, and a reasonable increase in torque too... now i'm not certain of the truth of this, (mazda might just be blowing their own horns so to speak) but i'd be very interested to see how this could work with a 4agze... at the very least you'd need an aftermarket ecu and at least one new cam (and someone mad enough to grind an inlet cam to suit an application like this). You'd also probably need an extended amount of time fiddling to get it running at all, much less in any sort of efficient configuration...
so... what's the word? Any ideas on why this wouldn't work?
EDIT: this idea is brought to you by the brain that tried to work out a way of setting up a 'ground effect' style undercarriage for a friend's track car, the 'you're fucked' dashboard indicator (to let you know when you're upside down) and other such fabulous brain-farts. your abuse is welcome.
[Updated on: Wed, 13 November 2002 01:50]
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Registered:
May 2002
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Re: mad scientist seeks sensible people to tell him not to try this idea.
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Wed, 13 November 2002 02:38
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i'd think it'd blow the ass out of your supercharger, I mean, with the charger pumping what, 10 PSI? and a compression test usually yieldind 150-200 PSI, I think you're gonna have probs!!.
On another note, can I pleast order Item 2 in your catalogue (the "your fucked" warning light)?? I think I could do with one of those. I often find myself upside-down and not know it!!
Tim.
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Location:
Perth, WA
Registered:
October 2002
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Location:
Montrose, VIC
Registered:
May 2002
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Re: mad scientist seeks sensible people to tell him not to try this idea.
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Wed, 13 November 2002 04:12
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No, the idea is not completely stupid... Also on a slightly different note, have you ever studied the principle of the GM diesel engine? The 4/71, 6/71, etc. etc. - where the traditional blowers came from.
I actually wanted one of the blowers off of the Mazda engine to put on a 4AGZE, but couldn't find one at a reasonable price. Pity, because they're a nice little lysholm unit too.
If set up carefully with sequential injection, it could be made to work quite well, although for maximum benefit direct injection and then using the supercharger to scavenge the cylinder (like a 2 stroke) would be even better.
Also I'd imagine that such an idea would work best with a variable valve system to vary volumetric efficiency, rather than a throttle - I reckon it'd have advantages for light load thermal efficiency.
Take some time to get the cam timing worked out properly though, but I'd love to hear more about it. Talk to me on MSN sometime, they say great minds work well together 
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Location:
Brisbane
Registered:
May 2002
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Re: mad scientist seeks sensible people to tell him not to try this idea.
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Wed, 13 November 2002 05:03
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I'd have to ask why you'd want to do this. You want more performance? You won't get it - a Miller cycle engine will actually have less power than a conventional supercharged engine due to decreased volumetric effeciency. You want better fuel efficiency? With lots of development work, you will get it (thanks better thermal efficiency, which is the whole point of the Miller cycle).
Is it worth the trouble? I'd say no, but maybe I'm not on the "mad scientist" wavelength at the moment. 
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Location:
Perth, WA
Registered:
October 2002
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Re: mad scientist seeks sensible people to tell him not to try this idea.
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Wed, 13 November 2002 05:17
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norbie: that's a very fair response... and i probably should've mentioned this in the original post... i'm the sort of person who is sometimes less interested in the ends than the means if you know what i mean... (pun intended)
i just thought it'd be really interesting to try and work out the logistics of converting from a conventional s/charger setup to a miller cycle setup...
the idea very much reqires the 'mad scientist mindset', and is not something i'd go through with unless i had a seriously absurd amount of money to throw around to get new cams reground every other day during development, etc etc. like i say, it's just something of a 'mental experiment' to see if we can think of any reason why it shouldn't work. If i wanted better performance i'd go for something tried and tested, i.e. forced induction, aggressive cams, etc etc etc...
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I supported Toymods
Location:
Berowra-Sydney
Registered:
July 2002
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Re: mad scientist seeks sensible people to tell him not to try this idea.
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Wed, 13 November 2002 07:09
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don't worry i've had worse idea's, i'll mention it although i'll probably get some weird looks from people 
a device that meassure's the weight and volume of your #2's and have all the toilets in the house networked together so it has ranking of who in the house has done the biggest/ most heavy/ and a reading of weight/time reading just like the power to weight ratio done on a car
i might have a weird or disgusting idea but honestly you have to think it would be a little bit funny to sit down and hang a #2 to find to your satisfaction that you just broke the household record
anyway i'll go back into my physco ward now 
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I supported Toymods
Location:
Brisbane, QLD
Registered:
May 2002
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Re: mad scientist seeks sensible people to tell him not to try this idea.
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Wed, 13 November 2002 10:07
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Well, this is not exactly the miller cycle, but might be interesting to a great degree in its own right (and must say, this is practiced explicitly and implicitly in the motor world, but more or less). It will still be an otto cycle engine, but with better volumetric efficiency.
The intertia in the intake charge and in the case of the supercharged engine, the additional pressure you see in the intake manifold can be harnessed. The idea is to keep the valves open during the inital part of the compression cycle to the point where the airflow would almost stop (before reversal and putting pressure on the supercharger). This is not as simple as saying "until the manifold pressure equals the in cylinder pressure" because of the intake air velocity of the incoming air would allow it to be kept open longer. Faster the airflow, the better. So this would indeed help you increase the volumetric efficiency at higher RPMs (where it is a nice thing to have). However, the problem is without truly variable valve duration what would be "just where the airflow would almost halt" at a higher would be creating a reverse wave at a lower RPM (due to reduced air velocity). However given your configuraion you might be able to establish a set of operational parameters that would give you your desired effect while keeping within a safe range from the undesired effects. Would be interesting to try never the less.
My 2 cents... As for crazy ideas, mate I am all about crazy ideas  Just tend to keep most of my crazy ideas close to home, thats all...
Cheers and good luck! And yes, I'd like to hear more about progress (no not just the outcome) of you experimentation.
Cheers
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Location:
cambo
Registered:
May 2002
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Re: mad scientist seeks sensible people to tell him not to try this idea.
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Wed, 13 November 2002 10:45
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ok i dont know much but after reading this ill comment anyway.
ive never heard of this 'miller' thingo, but to me it just sounds like what an engine does anyway. dont all engines have overlap? like no engine has the inlet opening at TDC and closing at precisely BDC (and similarily for exhaust). so what is the miller thingo? does it only apply to supercharged engines? or is it just a tech term for cam overlap cause from what i understand overlap can start at around 15 degrees before one valve has opened and 15 after the other closed meanging around 30 degrees overlap? do people understand what im saying in my spastic terminology?
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Location:
Perth, WA
Registered:
October 2002
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Re: mad scientist seeks sensible people to tell him not to try this idea.
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Wed, 13 November 2002 12:32
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evo: well, you're sort of right. it IS like a normal otto cycle, only not. and only applies to supercharged engines.
a miller cycle engine (by its very definition) must have a supercharger, and (also by definition) leaves the inlet valves open for more of the compression stroke than any otto cycle engine would. when they first came out they were sometimes (incorrectly) referred to as five stroke engines.
on this note, has anyone seen the 6 stroke engines that one aussie bloke is working on? very interesting stuff...
for those who still don't really understand all this 'miller' stuff:
http://www.mazda.co.nz/technology/1022.html
is an excellent page explaining how it works, and
http://link.sandiego.com/scripts/wheelbase/message .idc?passin=301
is an indication that at one stage mazda were considering a 'miller-wankel' rotary miller-cycle engine.
v. interesting stuff.
p.s. i am not a rotor-head, nor am i a big mazda fan. just so happens that mazda are the company who embrace the most interesting different engine technologies...
p.p.s. regarding 'truly variable valve timing', desmodromic (sp?) valve gear is another thing which i'm madly interested in. makes so much sense. can't work out why ducati are the only people who still use it... would mean instead of regrinding cams, you could tune valve timing just like ignition and fuel... all with a computer... mmmmm.... nice.
[Updated on: Wed, 13 November 2002 13:06]
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I supported Toymods
Location:
Brisbane, QLD
Registered:
May 2002
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Re: mad scientist seeks sensible people to tell him not to try this idea.
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Wed, 13 November 2002 18:40
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There are a number of companies that are developing/have developed and has patents on cam-less electronically controlled valve technology. However, from a production car point of view, royalties and increased production expense plus reliability testing requirements maybe a few reasons why most manufacturers are still not using it.
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I supported Toymods
Location:
Berowra-Sydney
Registered:
July 2002
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Re: mad scientist seeks sensible people to tell him not to try this idea.
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Wed, 13 November 2002 23:13
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Isn't there a way of improving engine performance by adjusting the intake and exhaust length? i read it somewhere and they do it in Formula One where you adjust the intake and exhaust lengths to a point where as the sonic wave gets to the end of the exhaust pipe another sonic wave begins at the front of the intake pipe, resulting in more power and efficiency, i'm sure someone knows more about this process then i do.
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Location:
Perth, WA
Registered:
October 2002
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Re: mad scientist seeks sensible people to tell him not to try this idea.
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Thu, 14 November 2002 00:47
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gin51e: yep, they have sort of 'telescopic' lengths of tube which adjust themselves, controlled by the ecu. pure feckin genius.
i've always been the sort of idiot who wants to apply this sort of technology to road cars, and guts himself trying to work out ways to do it legally. the only reason i gave up on the 'mental experiment' of how to set up 'ground effect' undercarriage gear on a road car modified for track work was because i realised that there's no point unless you're working with rather higher speeds than any of the cars i have access to tinker with...
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I supported Toymods
Location:
Brisbane, QLD
Registered:
May 2002
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Re: mad scientist seeks sensible people to tell him not to try this idea.
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Thu, 14 November 2002 01:01
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Errr... This technology is available (apart from the continuosly variable form) in many multiple intake geometry intake manifold
(such as Toyota ACIS for example) schemes in production cars.
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Location:
Perth, WA
Registered:
October 2002
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Re: mad scientist seeks sensible people to tell him not to try this idea.
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Thu, 14 November 2002 01:34
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| humble wrote on Thu, 14 November 2002 09:01 |
Errr... This technology is available (apart from the continuosly variable form) in many multiple intake geometry intake manifold
(such as Toyota ACIS for example) schemes in production cars.
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yeah, i was more referring to the 'continuously variable' part. there's something that makes rather more sense about having a full range of motion rather than a few 'presets' to switch between. it's like the difference between a throttle position meter with the ability to tell the difference between 'WOT, POT, and absolutely nothing' and one that is just a potentiometer...
continuously variable is almost always going to be better and more flexible than 2 or three fixed options.
that's why i love the idea of desmo valves, 'cause that way you can have constantly variable valve timing. none of this vvti/vtec/mivec crap... true variable induction timing. mmmm...
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Location:
Ulladulla
Registered:
October 2002
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Re: mad scientist seeks sensible people to tell him not to try this idea.
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Thu, 14 November 2002 02:37
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Hiyup
I belive BMW were working on a solinoid operated valvetrain using magnets in the flywheel as a freeking huge alternator and starter motor. This would be sooooo cool, you could use a stepper motor type setup on the valves and have the computer control the lot to give you the most aggressive "cam" profile for any given RPM...
As for the Miller Cycle stuff, I wouldnt have a clue...
But I say go for it!
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Registered:
May 2002
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Re: mad scientist seeks sensible people to tell him not to try this idea.
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Thu, 14 November 2002 14:19
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You wonder why the desmo valves aren't more widespread? Anyone tried to get their ducati serviced lately?? It's freakin expensive...
As for the "unfortunately difficult methods of extracting horse power" discussion. I was thinking(only for about 10 minutes - I realised a 2jz would be cheaper and easier...) about trying to convert a standard engine into a 2-stroke (after my NSR I'm hooked on the damn things!!) Like Orbital in Perth do. using a sealed, wet sump and having a supercharger do all the work...
you could modify the head to better force out the waste gasses and have the cam ground to suit...
tim.
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I supported Toymods
Location:
Brisbane, QLD
Registered:
May 2002
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Re: mad scientist seeks sensible people to tell him not to try this idea.
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Thu, 14 November 2002 15:04
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Someone mentioned truly variable valve lift and desmodromic valves. To my understanding, this valve actuation system was developed in the early 20th century to address issues related to high RPM operation. As opposed to using one camshaft lobe and valve spring, where the valve openning is powered by the camlobe whike the valve closing is powered by the valve spring, the desmodromic valve system uses two cam lobes and two rocker arms where one lobe powers the valve opening and the other, the closing totally eliminating the need for valve springs. In a nutshell, desmodromic valve systems address a lot of issues that are related to valve springs, specially in high RPM operation. My question is, how is the continuosly variable valve lift achieved? it'd be really interesting to see how that is done as the system is mechanically more complex than the standard valve spring approach.
Cheers
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Location:
Rocky Mountains, Canada
Registered:
May 2002
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Re: mad scientist seeks sensible people to tell him not to try this idea.
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Thu, 14 November 2002 16:49
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Very interesting stuff.
A good place to start looking for manufacturer secrets is the american patents archive. Lots of good info for DIY can be found in there.
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Location:
Perth, WA
Registered:
October 2002
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Re: mad scientist seeks sensible people to tell him not to try this idea.
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Thu, 14 November 2002 22:49
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when people claim 'continuously variable valve lift' or some such system, it has (in the past) been done through the use of little pneumatic/servo type things, rather than cams. what this means is you not only get the resistance to valve spring bouncing at high revs that ducatis 'one lobe to open one lobe to close) system offers, but (with a suitable computer to control the valves opening and shutting) you can get 100% variable valve TIMING as well. this means no more cams. at all. 
this means instead of getting someone to grind you a cam, valve timing would be dealt as just another part of tuning your ecu...
nuts. 
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I supported Toymods
Location:
Brisbane, QLD
Registered:
May 2002
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Re: mad scientist seeks sensible people to tell him not to try this idea.
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Fri, 15 November 2002 01:35
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Yeah I know this. I was just curious since you mentioned desmodromic valve systems and continuosly variable valve lift since I wasn't aware of any aspect of the said design offering variable valve lift. Anyways, there has been much progress with desmodromic valve systems as well, for example take a look at the 2001 patent offered to Delphi Automotive Technologies (yeah, the guys who design/manufacture the GM Delco ECUs).
There are multiple systems that offer complete valvetrain control (needless to say camless) and of these, the pnuematic approach was used in the F1 racing arena for quite a while. If I am not mistaken, BMW is introducing or has introduced a production engine with electronic valve actuation. This is not new, if you look at the infrastructure development that has taken place for the last decade or so. For example, Motorola had demonstrated 100% electronic valve actuation systems applying their microcontroller and semiconductor products almost a decade ago. But one has to understand, unlike in say software development where there is a relatively small research to production time span (say a year at most), in the Automotive industry, the turnaround times can even be a decade or more even.
The main factors that affect the turnaround time is more than everything, production readiness cost (a prototype technology verified to work is far from production stage, where the technology has to mature through multiple generations of reliability testing, safety testing, production infrastructure development, technical skill propogation and finally, the manufacturing resource allocation) and above all, the need for it. Desmodromic valve systems have been around from 1910 and frankly, was not being used as it wasn't needed in production cars. As for Ducati, they have always been racing oriented and high RPM engines are the norm than a nifty feature.
If you are into the technology angle of automotive industry, have a look at SAE (Society for Automotive Engineer - http://www.sae.org) and go through the tons of reserach work that has been and is being done and you would realise where the R&D and production is relative to eachother. Having said everything that is being said, when it comes to many interesting technologies, with a reasonable budget you can experiment on your own and wihtout restriction (with respect to patents) if you are a hobbyist experimenter (non-commercial basically).
Good luck with you explorations.
"Any technology sufficiently advanced would be instinguishable from magic" -Arthur C. Clarke.
However, the flip side is, it's not magic, just advanced technology and at the end of the day, it's just application of science. Therefore, there is no magic that is beyond your grasp!
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Location:
Perth, WA
Registered:
October 2002
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Re: mad scientist seeks sensible people to tell him not to try this idea.
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Fri, 15 November 2002 03:53
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the other flipside to this (which i'm quite fond of) is the idea that any technology that is distinguishable from magic is insufficiently advanced.
love it.
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