custom ud pulley

[sam c.]

The other thing I'd be interested in is how much cavitation is occurring in the stock pulley driven WP.

Right now, it's known conclusively that a stock 6" pulley can be swapped with a 4" pulley with no negative effect on cooling despite the WP turning a third or so slower. There's a number of variables in the cooling system including (but not limited to) the radiators heat xfer coefficient, the fluid friction through the system and engine coolant channels, the heat xfer of the block, the thermostat, ambient cooling, oil cooling, etc. All together though, the one thing we know for certain is that the WP is currently being turned a lot faster than necessary.

[sam c.]

I'm with you RK... I'd guess the alt. is really the bigger question here.

[Topless]

Originally Posted by sam c.

The other thing I'd be interested in is how much cavitation is occurring in the stock pulley driven WP.

Right now, it's known conclusively that a stock 6" pulley can be swapped with a 4" pulley with no negative effect on cooling despite the WP turning a third or so slower. There's a number of variables in the cooling system including (but not limited to) the radiators heat xfer coefficient, the fluid friction through the system and engine coolant channels, the heat xfer of the block, the thermostat, ambient cooling, oil cooling, etc. All together though, the one thing we know for certain is that the WP is currently being turned a lot faster than necessary.

Math and experimentation time then! Let us know what you find.

I grew up around scientists and engineers so I understand your burning curiosity very well. One of my friends used to be a model rocket hobbyist and always wanted to build bigger and better. He was building liquid fueled rockets in his garage until a man with money and vision offered him a partnership. The company is now called Space-X Technologies.

[sam c.]

Originally Posted by Topless

Space-X Technologies.

Wow! Maybe I'm a bit of a dreamer, but I believe SpaceX is one of a small handful of companies that are currently in the process of changing the course of human history right before our eyes. Very nice!

[Topless]

Originally Posted by sam c.

Wow! Maybe I'm a bit of a dreamer, but I believe SpaceX is one of a small handful of companies that are currently in the process of changing the course of human history right before our eyes. Very nice!

I absolutely agree. Man on Mars in our lifetime I think. These guys are very focused and determined and currently have a $2Bil satellite launch schedule on the calendar... And Tom owns a Boxster.

[sam c.]

Originally Posted by Topless

Man on Mars in our lifetime I think. These guys are very focused and determined and currently have a $2Bil satellite launch schedule on the calendar

...and who says capitalism and free enterprise don't work?

[Jake Raby]

I have not tried a 3" pulley. My hypothesis is it would be great on the track, but would suffer greatly in highway scenarios. I say this because 4" seems to be on the ragged edge.
Have fun.

Send it to me and I'll dyno it back to back and test some other dynamics of it and how they impact the engine, too.

Just like bigger is seldom better with an engine displacement and "just right" is the hardest sweet spot to find, there becomes a point where smaller is not better with something like these pulleys.

[sam c.]

Awesome! Will do.. yeah, that sweet spot is what I'm curious about. I plan on cutting a 3" to start with and monitor the real world impact on cooling, charging, and drivability. Getting some dyno numbers would be great data. If the 3" turns out to be crap, I'll step back and do a 3.5". If the 3" is good to go, I'll have a 2.5" cut just to see what happens.