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LMAO.... You are absolutely correct... Here let me quote what I said, again....Originally Posted by djltoronto
This isn't my arguemnt, and you are both strangers to me, but you can't just mislead people. I would usually stay well away from these type of arguments, but this is just plain wrong.
NO and NO. What you have written here is 100% FLASE.
To set the record straight.
Draiter, not picking on you, but you did post pure falseness.
- Engine RPM is the RPM of the CRANK. (1 piston or 12 pistons, doesn't matter).
- actual piston speed (velocity) in an american V8 at 6000 RPM would be much faster than the actual piston speed (linear velocity) of an oversquare sportbike AT THE SAME RPM.
- An oversquare sportbike engine at 14,000 RPM does not necessarily have a greater piston speed (linear) than an Amercian V8 at 6000 rpm due to the exceptionally short throw of the crank (Anyone could easily do the math to see this) - see next point
- Who cares about actual linear piston speed?
"Are you crazy? You are trying to tell me that a 6k redlining engine is under the same forces as a 14k redling engine????? Not even close... Why do you think there has been so much research into the effects motorcycles have on oil? And why do you think there are motorcycle specific oils? Because the the two types of engines perform differently. As for piston speed, irregardless of stroke, a V8's pistons, at 6k RPM are going up and down at a rate of 750 times per minute... an inline 4 in a motorcycle, at 14k RPM, it's pistions are going up and down at a rate of 3500 times per minute, or rougly 5 times faster.... "
Let me go over it again... Here I am not talking about piston speed - which is a measure of distance over time... I am talking about the number of times a piston travels it's stroke at a given RPM, which is a measure of frequency... So what I am talking about, and what everyone else is talkinga bout are TWO completely different things... You are talking SPEED, I am talking FREQUENCY.... If a tachometer is mesuring crank speed then that crank rotates 1 time for each cylinder firing. So if you have a 1 cylinder engine at 6000RPM, that means that piston is going up, down, and back up, 6000 times per minute... if you go to a two cylinder, then each piston is going up, down, and back, up 3000 times per minute, 4 cylinder - each piston 1500 times per minute, 8 cylinder - each piston 750 times per minute. If you take a 4 cylinder engine running at 14000 RPM each piston is going up, down, up 3500 times per minute, or 600 times per second, compared to a 6000 RPM redlining V8, each piston - 750 times per minute, or 12.5 per second.... if you had a V8 redlining at 14000 each piston - 1750 times per minute, or 30 times per second....
So there it is, exactly what I was talking about a redlining v4 in which each piston is going, up, down, up 600 times per second is place FAR more of a load on components than a v8 redlining in which each pistion is going up, down, up 12.5 times per second...
Perhaps I should have changed this - "...or rougly 5 times faster..." to "...or rougly 5 times more for a given RPM..."
Any how, I am out of this.... bored now.... I am only seeing what I want to see, as is everyone else involved...
Thanks for the fun.
Last edited by Draiter; 02-12-2008 at 12:22 AM.
NO NO NO..
Come on man? Go open up and engine and look inside.
FOR every rotation of the crank, all the pistons move up and down once.
doesn't matter how many pistons there are, they are all directly connected to the crank.
I'll try to find an animation.
....Are you crazy? You are trying to tell me that a 6k redlining engine is under the same forces as a 14k redling engine?????
I never said anything of the sort, but I will now. A HEAVY BIG piston changing direction half as often as a super lightweight piston, may undergoe similar forces.
Not even close... Why do you think there has been so much research into the effects motorcycles have on oil?
Becasue they use wet clutches, that's the main reason.
And why do you think there are motorcycle specific oils? Because the the two types of engines perform differently. Yes, that's parts of it, but mostly cause of the wet clutches.
As for piston speed, irregardless of stroke, a V8's pistons, at 6k RPM are going up and down at a rate of 750 times per minute - NOPE, they are going up and down at a frequency of 100 hz (6000 times per minute) ... an inline 4 in a motorcycle, at 14k RPM, it's pistions are going up and down at a rate of 3500 times per minute, - NOPE, they are going up and down at a frequency of 233 hz (14000 times per minute) or rougly 5 times faster.... - exactly 2.33 times faster"
Any how, I am out of this.... bored now.... I am only seeing what I want to see, as is everyone else involved... - you probbably have not yet unsubscribed, which is good, these forums are here to help people, yourself, and myself included. A debate like this one is great, and the outcome should be that everyone gains a little something (knowledge).
Thanks for the fun.
doesn't matter who you decide to believe - change the oil after the first 500 kms. after that, ride normal.
where's the wind?!
UHHmmmmmm
DRAITER needs a little more experience with motors before he starts telling us which way is up.
Here is the way I see this;
There are too many variables involve to say one way is better than another in EVERY situation.
When I build a race motor I run it through a couple of heat cycles, take it easy on the first lap or two then give 'er.
When I break in a NEW motor I more or less follow the manual.
The difference being is when I build a race motor I am using used parts that have already been "bedded in". All I am really doing is seating the rings on pistons that I know have gas ports on the back of the rings.
When I am breaking in a new motor I am doing alot more than just seating the rings. All the rotating parts have to be "bedded in". ie: transmission gears and bearings, big and small end bearings, crank bearings, cam tower bearings, cam followers, etc etc etc.
The method of breaking in a bike that is pretty well the same in every manual, is designed to be generic enough that it will cover most engines, get the job done AND hopefully convince you to take it easy on the bike till it is OUT OF WARRANTY.
The truth be told, in the day of production machining that can be held to a tolerance of 0.0005" other than seating the rings there shouldn't be much to wear in.
Oh.... and piston speed matters. To an engine builder piston speed matters ALOT!!!. You find that out when you start collapsing pistons... or worse yet EXPLODING pistons.
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