How does it zoom? And, just the facts...
06-03-2005, 06:25 PM
#1
Don't you know I'm loco?
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How does it zoom? And, just the facts...
I've got a question for y'all. A couple questions, actually. I think I'm decently familiar with the rotary motion at this point (having made my avatar in MATLAB. My applet that lets you control the speed and housing shape is at here. Works with FireFox, anyway ).
Now somebody asked me, "Okay, so that's how it moves, but how does it speed up if there's no timing belt?" I was kind of at a loss.
Two smaller sibling questions are: (1) I can see how once moving, the spark plugs' timing keeps the motion going, but what about when you first turn on the car?
And, (2) what gets it going the VERY first time the car is used, before any gas is even in the engine?
Finally, I've been hearing a lot about how you should "keep it under 3000 for the first few minutes". Yeah, yeah. I realize that revving the heck out of it before its warmed up can't be good for the engine, but where is this 3000 number coming from? And where's the proof that, say, allowing it to go to 4000 is going to cause severe damage (okay, or just shorten the engine lifespan) down the line? I think there are far too many people parroting this piece of wisdom without understanding the reasoning behind it. So I'd appreciate some input by those who are convinced beyond mere conjecture.
Thanks! Rev on!
Now somebody asked me, "Okay, so that's how it moves, but how does it speed up if there's no timing belt?" I was kind of at a loss.
Two smaller sibling questions are: (1) I can see how once moving, the spark plugs' timing keeps the motion going, but what about when you first turn on the car?
And, (2) what gets it going the VERY first time the car is used, before any gas is even in the engine?
Finally, I've been hearing a lot about how you should "keep it under 3000 for the first few minutes". Yeah, yeah. I realize that revving the heck out of it before its warmed up can't be good for the engine, but where is this 3000 number coming from? And where's the proof that, say, allowing it to go to 4000 is going to cause severe damage (okay, or just shorten the engine lifespan) down the line? I think there are far too many people parroting this piece of wisdom without understanding the reasoning behind it. So I'd appreciate some input by those who are convinced beyond mere conjecture.
Thanks! Rev on!
06-03-2005, 06:37 PM
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hmm well the rotors spinning will make a vacumm which draws in air..and fuel...then ignited to make power..faster it goes more air can come in and etc etc.....so it'll speed up as long as there is enough air and fuel to push the rotors...the car times teh fuel/spark/air intake runners (ending at the ports)..to open at various rpm.'s to allow enough air and fuel to power the engine when it is revving..to keep it in reving steady the pcm will keep the throttle body only open a certain amount. i think that is the just of it.
a timing belt is only for timing the intake and exhaust valves on a piston engine (timing belt turns cams which push on vlaves etc.etc.).....we don't have those inplace of vlaves a rotary engine uses ports (which are opened and closed by the pcm)
so a rotary will speed up the same as a piston engine...gooo thermodynamics! it just does it in a slightly different way (i.e. ports vs valves. etc etc.)
to get it going the first time the car is on...would be the starter..the starter turns the flywheel which is attached to the e-shaft..then on this inital turn some fuel is added to get the ball rolling so to speak.
as for why you should keep it under 3000 rpm before it is warmed up...well i just let her idle until warm then i go to town.....most peopel keep it there b/c there won't be as much heat created by the engine as opposed to higher rev's......i keep her below 3750 rpm before whe is total warmed up (before the secondary ports open). i believe (don't quote me)..that the housing on the 13b-msp are alluminum and iron...which will expand at different rates based on temp (aluminum expands faster)..so until the engine is warmed up you dont' want her to ge tto hot or they will expand at different rates and thus could mess up your engine seals.
some one will probable come along and fix all my mess ups...but i think i did an okay job :D
not bad for 3 hours of sleep and typing at my government job computer.
p.s. sorry for bad typing :p
a timing belt is only for timing the intake and exhaust valves on a piston engine (timing belt turns cams which push on vlaves etc.etc.).....we don't have those inplace of vlaves a rotary engine uses ports (which are opened and closed by the pcm)
so a rotary will speed up the same as a piston engine...gooo thermodynamics! it just does it in a slightly different way (i.e. ports vs valves. etc etc.)
to get it going the first time the car is on...would be the starter..the starter turns the flywheel which is attached to the e-shaft..then on this inital turn some fuel is added to get the ball rolling so to speak.
as for why you should keep it under 3000 rpm before it is warmed up...well i just let her idle until warm then i go to town.....most peopel keep it there b/c there won't be as much heat created by the engine as opposed to higher rev's......i keep her below 3750 rpm before whe is total warmed up (before the secondary ports open). i believe (don't quote me)..that the housing on the 13b-msp are alluminum and iron...which will expand at different rates based on temp (aluminum expands faster)..so until the engine is warmed up you dont' want her to ge tto hot or they will expand at different rates and thus could mess up your engine seals.
some one will probable come along and fix all my mess ups...but i think i did an okay job :D
not bad for 3 hours of sleep and typing at my government job computer.
p.s. sorry for bad typing :p
Last edited by army_rx8; 06-03-2005 at 06:43 PM.
06-03-2005, 06:56 PM
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Originally Posted by unpocoloco
Now somebody asked me, "Okay, so that's how it moves, but how does it speed up if there's no timing belt?" I was kind of at a loss.
06-03-2005, 07:04 PM
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Originally Posted by Nubo
They're mistaken in thinking that the timing belt is what speeds up a piston engine. Speed is simply a function of how much air/fuel you're allowing into the engine. In a piston engine the timing belt keeps the valves opening at the right point in the combustion cycle. On the rotary that's simply handled by geometry of when the rotor passes over the ports.
a lill clearification though. the rotary handles when air is let it based on geometry of when the rotar passes over the ports..but all the ports (on our engine ) aren't open all the time......the pcm will control port opening (done in the intake manifold?) based on RPM. you can see teh ports opening on a dyno of the 8..when the power drops off sharply then recovers on the dyno that is the ports being opened up....the moment they first open there will be a pressure drop due to the fact that there is all of a sudden more passages for air to come into the engine...btu then power will shoot up. you can feel theis as well when you redline your baby...you will feel 2 times when power seems to pick up a lill more (you'll feel a push in the uppers revs)
hmm...okay i think that all made sense
Any pics or illustrations of this?
06-03-2005, 07:15 PM
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you can go to how stuff works and it has a nice diagram of a rotary engine in motion.
http://www.howstuffworks.com and type in rotary engine :D
http://www.howstuffworks.com and type in rotary engine :D
06-03-2005, 07:16 PM
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also for the port opening and closing i have a picture of the intake manifodl off the car and you can see how it opens and closes the port opening..unfortunatly i am at work (it's at home)..but i'll try and remember to post it up tonight or tomarrow for you.
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