HPI Tires

[designed2survive]

Lol... You guys made my day with the back and forth.

Ice is right though. With 2 pulleys of the same diameter (doesn't matter how big or small) the rpm stays the same at both pulleys. That's the concept of 1:1 ratio.

The rotational mass will dictate how high or low the rpm will be but it will stay the same at both pulleys.

 

[Bulldogger]

Lol... You guys made my day with the back and forth. I've is right though. With 2 pulleys of the same diameter (doesn't matter how big or small) the rpm stay the same at both pulleys. That's the concept of 1:1 ratio.

The rotational mass will dictate how high or low the rpm from will be but it will stay the same at both pulleys.

I understand that but a larger pulley has a faster outside speed then a smaller pulley.

 

[Ice_2k]

HPI Tires

Bad post, ignore

 

[Ice_2k]

I understand that but a larger pulley has a faster outside speed then a smaller pulley.

That just means with larger pulleys the belt itself will move faster. Everything else stays the same.

 

[Bulldogger]

At a fixed 17,000 rpm a 1" propeller has a tip speed of 51mph.

At a fixed 17,000 rpm a 1.5" propeller has a tip speed of 76mph

both are using a 1:1 ratio.

A larger pulley is turning the belt faster at the same rpm.

 

[Ice_2k]

That's what I said. And all of that has no effect on the speed of the tires

 

[Bulldogger]

That just means with larger pulleys the belt itself will move faster. Everything else stays the same.

So a faster moving belt vs a slower moving belt at the same rpm won't change the speed.

 

[designed2survive]

I understand that but a larger pulley has a faster outside speed then a smaller pulley.

Correct if you only increase the size of the pulley on the engine side. The engine will have to work harder though. Too hard and problems will arise.

Incorrect if you also increase the second pulley to the same diameter.

True, on the pulley attached to the clutch you will have faster outside speed with a bigger diameter pulley, but on the second pulley (same diameter) it's actually the opposite effect that will happen. So the effect of the first pulley is cancelled by the effect of the second one.

Worse, unless you have lighten the weight on those pulley, you would have just added more rotational mass, therefore increasing stress on the engine.

 

[Ice_2k]

HPI Tires

So a faster moving belt vs a slower moving belt at the same rpm won't change the speed.

Exactly. Because it moves faster on the first pulley and then the larger second pulley means the belt will rotate it at a lower rpm then it would if it was a small pulley, cancelling the difference out.

Edit: I see d2s beat me to it

 

[Bulldogger]

Exactly. Because it moves faster on the first pulley and then the larger second pulley means the belt will rotate it at a lower rpm then it would if it was a small pulley, cancelling the difference out.Edit: I see d2s beat me to it

Sadly that makes sense

 

[RampageHopUps]

Holy Redneck Engineering.