Limiting factor for RPMs?

[TC]

A lesson to TC I was giving in 2008! Hasn't learned yet.



2009.


I stopped looking after that. I'm sure there is an annual one for 2010 and 2011.

A quote from me from 2011 responding to a different type of physic's question, but sums up what I think about "gut feelings" and "expectations" on physics.

June 1st 2011


TC is loaded with what I call "Pot Logic". I coined that term way back in 2000 from a bunch of friends of mine that have the same problem as TC. They would get high, think the world HAS to operate a certain way, though with simple math, physics, etc it would prove them wrong, they would refuse to believe it because a long convoluted drawn out way they can make it "make sense in their mind". Reality be damned. I still have one friend that still operates on that logic. Fustrating as hell to debate or argue with him because he makes no valid points and insists they are valid. So now I just laugh at him, which pisses him off, but IMO it beats me getting pissed off instead.

See this is the problem your taking what I'm saying and skewing it to your liking...... I'm talking about the "engine" and only the engine and how the rate of the engines acceleration is effected by stroke.....

And when all of a sudden did stroke not have an effect on the speed at which an engine revs??..... It is a proven fact that a shorter stroke given the same HP pushing it as a longer stoke will rpm faster, this is do to the shorter stroke not having as much of a distance to travel during it's rotation........

So if you have two engines both with the same cubic inches and both making 500hp at 5000rpm with the only difference being one has a shorter stroke and the other having a longer stroke, tell me which one will go from idle to 5000rpm the quickest....... Which will get to 5000rpm first??.........

[squirrel]

See this is the problem your taking what I'm saying and skewing it to your liking...... I'm talking about the "engine" and only the engine and how the rate of the engines acceleration is effected by stroke.....

I think we understand that, but we also understand that it is not important. An engine is there to make a car move, and there are more important things about making a car move, than how fast the engine itself can rev.

[TheSilverBuick]

Pot Logic. You can't make 500HP with out a load on the engine, because there is no force to move. No free revving engine makes 500HP. HP is force moved a distance over time, so with no force to push against there is no horsepower.

[TC]

Or in other words....

3" stroke will travel 18.85 inches during one revolution....

4" stroke will travel 25.12 inches during one revolution.....

Then lets look at this at 1000rpm...

1000 x 18.85" = 18,850" or 1570' or 523 yards

1000 x 25.12" = 25,120" or 2093' or 697 yards

As you can see the shorter stroke travels way less distance than the longer stroke does.....

[TC]

Pot Logic. You can't make 500HP with out a load on the engine, because there is no force to move. No free revving engine makes 500HP. HP is force moved a distance over time, so with no force to push against there is no horsepower.

Ok so HP is irrelevant, which motor will get to 5000rpm first?? The one with the shorter or longer stroke.....

[TheSilverBuick]

Or in other words....

3" stroke will travel 18.85 inches during one revolution....

4" stroke will travel 25.12 inches during one revolution.....

Then lets look at this at 1000rpm...

1000 x 18.85" = 18,850" or 1570' or 523 yards

1000 x 25.12" = 25,120" or 2093' or 697 yards

As you can see the shorter stroke travels way less distance than the longer stroke does.....

So the longer stroke covers more distance in a shorter period of time...... So it's piston is faster!

[TC]

I think we understand that, but we also understand that it is not important. An engine is there to make a car move, and there are more important things about making a car move, than how fast the engine itself can rev.

I'm not debating that I know there are variables when it comes to the car, this is just about the motor and how stroke has an effect on how fast(quickly) an engine RPM's.....

[TC]

So the longer stroke covers more distance in a shorter period of time...... So it's piston is faster!

Here's a test, I'll run the 523 yards, you run the 697 yards, we both run at 5mph, who's going to be done first and at that what are you going to have to do to finish at the same time I do.........

[dieselgeek]

Here's a test, I'll run the 523 yards, you run the 697 yards, we both run at 5mph, who's going to be done first and at that what are you going to have to do to finish at the same time I do.........

Wow, horrible logic here. The longer stroke gives the air and fuel mix MORE LEVERAGE on the crankshaft, and more time to push the piston down. By your own logic that more torque is better, then the long stroke engine is clearly the winner.

[TC]

Wow, horrible logic here. The longer stroke gives the air and fuel mix MORE LEVERAGE on the crankshaft, and more time to push the piston down. By your own logic that more torque is better, then the long stroke engine is clearly the winner.

Not if the same force is being applied to both pistons.......And it's about "speed" at which an engine spins, has nothing to do with power output, though for Randal to cover his distance in the "time" that it would take for me to cover mine, he'll have to run faster and thus exert more energy..........

[dieselgeek]

Not if the same force is being applied to both pistons.......And it's about "speed" at which an engine spins, has nothing to do with power output, though for Randal to cover his distance in the "time" that it would take for me to cover mine, he'll have to run faster and thus exert more energy..........

This is stupid and makes zero sense. Same force pushing on both pistons yields higher torque potential in the long stroke engine. Your turbo combo is gonna be a weaksuck motor if were ever.going to get built. Especially if you are basing it on your own nonsensical stoner logic.

[TheSilverBuick]

More Pot Logic. Why do I have to run at 5mph? Because you say so? So of course if you make the piston with the longer arm move slower it will take longer, but the reality is it's going to move faster. To follow that up, using the same displacement, there will not be equal force on the pistons because they will have different surface area's to apply that force too. Same amount of fuel and air will push harder on the longer stroke, narrower bore (and why it can go faster...) than on a short stroke wide bore.

I won't necessarily have to exert more energy, it's more akin to if we both were on bicycles, and you had to run a lower gear than me (the longer arm to apply torque too). We can exert the same amount of energy and I cover more distance in the same amount of time.

[TC]

This is stupid and makes zero sense. Same force pushing on both pistons yields higher torque potential in the long stroke engine.

I'm not debating that, what you need to get through you thick ass skull is this is about "TIME", the TIME it takes the crank to make one revolution.......

The longer stroke will make more torque, yes that is a given, but it won't cover the distance in the same amount of TIME as a shorter stroke that has the same pressure pushing down on it.........

[TC]

More Pot Logic. Why do I have to run at 5mph? Because you say so? So of course if you make the piston with the longer arm move slower it will take longer, but the reality is it's going to move faster. To follow that up, using the same displacement, there will not be equal force on the pistons because they will have different surface area's to apply that force too. Same amount of fuel and air will push harder on the longer stroke, narrower bore (and why it can go faster...) than on a short stroke wide bore.

Again skewing what I say to fuel your argument??......

Ya cause I say so, 5 MPH represents the "force" being pushed down on the piston, and in my example we are talking about the same amount of power being pushed down on both the pistons..... We're not talking about more or less force just each piston being moved by the same amount of force, and in that case the shorter stroke will always complete its revolutions faster than the longer stroke, for the simple fact that it has less distance to travel..........

[dieselgeek]

I'm not debating that, what you need to get through you thick ass skull is this is about "TIME", the TIME it takes the crank to make one revolution.......

The longer stroke will make more torque, yes that is a given, but it won't cover the distance in the same amount of TIME as a shorter stroke that has the same pressure pushing down on it.........

My thick ass skill understands that you are making pointless, lame arguments and ruining some nice guy's thread again because, like always, you have to try make people think you are the "smartest guy in the room."

Unfortunately, that's not the case.

Why not just start a thread about your "Fantasy Engine" that is so much more awesome than anyone else's because only YOU understand your (nonsensical) reasoning for having to build it that way? I wonder if you made a poll asking if people believed you'll ever build a running engine - would even one single person besides yourself vote "yes" on that?

So, anyways, nobody here cares how fast an engine will rev in neutral with no load. No one. Good job ruining yet another tech post because you can't handle it when smarter people than you are having a good discussion. Dumbass.