balbains324

Thats a very good idea, but I really like the idea of having a cogged pulley.

The tension that I put on the belt to stop it slipping has already killed my water pump bearings, so I am trying to get rid of excessive tensioning.

I agree with Denis, if I add another belt ~I will be adding to the problem.

I want to the machine shop today with all my pulleys, the guy has just said he would not be able to do it because the crank pulley is too bit for his machine.

Is there anyone in the US that could possibly get me some cogged pullleys made up?

Denis could you do something like this?

i8acobra

<div class='quotetop'>QUOTE (Bal @ Feb 16 2009, 08:29 AM) <{POST_SNAPBACK}></div><div class='quotemain'>The tension that I put on the belt to stop it slipping has already killed my water pump bearings, so I am trying to get rid of excessive tensioning.</div>

You won't be adding tension with an additional pulley. In fact, you'll be able to decrease the tension. To hold the belt on your supercharger pulley requires a certain amount of force (pounds per square inch of pulley surface). If the belt only contacts a small amount of pulley, all of your force is on very few square inches of pulley. This requires a large amount of tension (in pounds of pressure). This is what's killing your other bearings. If you increase the amount of pulley surface the belt rides on (more square inches), you can decrease the amount of tension. In other words, to get better traction on your pulley, you need more pounds per square inch exerted on the pulley. To do this, you either increase the force (pounds), which you already tried to no avail... or you increase the area of contact (square inches), by wrapping the belt farther around the pulley. An additional guide pulley (not tension pulley) will do this.

Here's a Mustang Cobra set-up to help demonstrate:



The silver pulley is not factory. It was added to wrap the belt farther around the S/C pulley. It adds no additional tension, just guides the belt.

ThisCelluloidDream

Option 3 is what i see a lot of high torque setups using, ie super diesels and whatnot. Cobra has it right with the guide pulley as your best option though, it you ask me. I'd say experiment with whatever you can afford and reasonably do.

Denisst99

indded,start by maximising belt traction like on the mustang
more surface means more grips

balbains324

Some very positive comments

I will start by maximising contact with the pulleys, this will require some custom fabrication!

Looks like I might have to invest in a welding kit!!

If this still does not work then I will look to get some cogged pulleys made up....my quote in the UK has been £550!!

Just wondering, would the Beta II pulleys fit the Beta 1 crank, water and alternator? If this is possible then I think I could ask NGM to price me for just the 6 rib pulleys? This would probably be the most viable solution to my problem along with guide pulleys

balbains324

Adding knowledge for the supercharged guys by keeping this thread up to date.

I have called various belt and pulley manufacturing technical departments and have had very good luck with responses.

The best solution to eliminate belt slip was from Goodyear belts, they advised after doing some technical calculations:

A 6-rib drive system using a J Section belt, we already use J section belts so it is a case of adding another 2 ribs onto our existing pulleys.

6.5" underdrive pulley
2.5" Steel supercharger pulley

Along with trying to get more contact with the belt using idler pulleys.

He also suggested increasing the diameter of the water and alternator pulleys to compensate for the fact that they will be over driven by the larger crank pulley.

I have got some getting CNC machined and they will be with me by next week. So I will take some pics.

They cost me £364.....!!! I did ask NGM for a set because they already do this but they are moving and said it would take a while.

balbains324

Resurect this post

I got the 6 rib pulleys, installed them but I still have the same problem with the belt riding off the water pulley!!

I tried everything...been 6 months and I have only driven the car 8 miles!!

The water pulley is way too far out away from the engine and does not line up with the alternator pulley or crank pulley

I need to figure out a way to get the water pump pulley pushed in towards the engine by 10mm....does anyone have any ideas?

Stocker

If you need a pulley with a custom offset, you have (at least) three choices:

Go to a pulley manufacturer and tell them how much offset you need, then leave with a pain in your wallet

Go to a machine shop and have them turn out a pulley from a piece of billet steel or aluminum to your specification, then drill mounting holes, again with the sticker shock

Go to your welder and have a spacer inserted in place of the current center section of your stock pulley, so it rides where you want it. Just be careful about warping and balance problems.

You might also look into an electric water pump, but it would have to be a generic unit or a one-off custom job.