Pulley Direction and RPM

[GRNOVA]

I am trying to figure out what RPM my vacuum pump will spin. How do I do this. I am thinking about running a pulley on the front of an idler pulley but can't figure out the speed? Vacuum pump cannot spin more than 50 to 80% of the crank or more than 6000 RPM's. Here is my set up.

[GRNOVA]

Here is a close up

[CanyonKiller]

First, you have to figure the ratio at which the idler pulley will spin. To do this divide the circumference of the crank pulley by the idler pulley. Then, do the same with the add on drive pulley and the vacuum pump pulley.

[GRNOVA]

here is what i came up with

[CanyonKiller]

Without knowing the exact diameters I cant check, but the ratios seem to be correct and it looks like you'll need a larger vacuum pump pulley.

[GRNOVA]

Without knowing the exact diameters I cant check, but the ratios seem to be correct and it looks like you'll need a larger vacuum pump pulley.

This is what I came up with.

[Bryce]

In the model posted I see you are directly connected to the crank pulley so your ratio is 3.5 divided by 5.5, or 63.6% of the crank pulley speed. That is within the given range of 50% to 80%.

[GRNOVA]

Thanks Bryce,
Yea I could not run a pulley off the lower left idler pulley because I would need a 13" pulley to get it to the right RPM. Now I need to figure out how to mount a pulley on the front of the crank. I also added another pulley on the right side of the crank to get me more wrap on the crank! I wish someone would have made a set up for this I am starting to second guess myself and my capabilities. HA HA HA (in a sinister DR. Doom voice)