SCH General FAQ, Q&A

This is Supercharger Helps General Q&A or (FAQ) Frequently Asked Questions.
All experience and input and corrections are welcomed and not limited to what is posted in this thread. Some of my own personal experience is based on theory, and likewise this is not provided as fact or information derived from the manufacturers. This is purely a guide and intended to bring knowledge to the users of this forum in helping them solve or fix any problems they may have. None of the people who have contributed to this thread shall be held liable of consequences resulted from trying any of the direction or information provided in this thread.

How do I remove/swap a different pulley?
My belt is slipping, how do I fix this?
My belt is snapping, how do I fix this?
My belt is shredding, how do I fix this?
What kind of oil should I use with my blower?
Can I use a cog belt on the street?
Where can I get a replacement blower pulley key?

How do I remove/swap a different pulley?

When removing a pulley it is best to break the bolt loose while having the head unit still bolted up to the brackets and having the belt still tensioned on the pulley to keep it from rotating. When swapping on a new pulley that doesn't quite fit, use a heat gun and heat the pulley so that it expands, and makes it a little easier to slide on. WD40 or grease can also help. When you thread the bolt back in, it is recommended to use anti-seize on the threads. Lastly this seems like a nobrainer, but make sure the keys are installed in the keyway when you slide the pulley back on. If the pulley still does not want to go on after heating it up, DO NOT HAMMER IT ON. This will cause damage to other parts in the housing.

My belt is slipping, how do I fix this?

First lets start off by making it clear this ribbing design was made to slip to some degree but provide traction also. When brought to a very fast slowing or stop from high speed belt operation, the belt slips/slides instead of the drivetrain taking the brunt of the abuse, which in this case is the blower gears. Numerous ideas have been tried to gain traction in this ribbing design, from sandblasting the pulleys to spray on chemicals. The most common ways of providing more traction are making more belt surface available by stepping up to 10 and 12 rib belts and pulley from the common 8 rib. Also the easiest method is torqueing the belt down tighter. Though this has become an issue in tandem with extreme bearing wear on the #1 main because of added tension on the crank pulley which is being pulled toward the blower at a tighter degree now.

My belt is snapping, how do I fix this?

There could be a number of variables here. One thing to check is that your bypass valve is working and is sufficient for your application. If your bypass valve is too small, the remainding air that is not getting relieved will be forced back toward the compressor and the result is the impeller slamming to a halt causing something to give. Since the belt is the weakest link in terms of strength it will snap most likely. In reality you are also wearing the internal gears of the blower everytime this happens. In some race applications with transmissions using manual reverse valve bodies where the engine cannot be put into nuetral after making a quarter mile pass the abrupt slowing of the belt from getting off the gas can cause the belt to snap. You might look into getting a shield that covers the blower pulley to prevent hood damage.

My belt is shredding, how do I fix this?

Your alignment is probably off, whether you believe it or not. Using a straight edge, put it up against an edge where the belt rides and verify alignment. If they are not aligned, use spacers/washers from a hardware store to bring the blower pulley into alignment with the crank pulley. While harder to see with the naked eye sometimes, make sure the brackets are not tilted and are sitting flush against the block/head. A slight tilt would cause outer belt wear from the gated sides of pulleys or idlers at high belt rpm in the form of belt dust. With cog belts having ribs in the opposite direction as serpentine, the belt tends to walk around as rpm increases. If there is a gap between the belt and the lips(gates) of the idler, the belt could be shredding itself.

What kind of oil should I use with my blower?

See manufacturers recommendations.

Can I use a cog belt on the street?

There are pros and cons of using a cog belt and cog pulleys. Pros are it provides traction a serpentine belt cannot. The result is no belt slipping and no loss of boost during high rpm belt travel. The other Pro is cog belts do not require as much tension, therefore in race applications results in less bearing wear on the #1 main due to less tension on the crank pulley. Cons are because there is no slipping, the internal moving components of the blower take the rapid acceleration and deceleration stress much more often. This is why it is so critical to have a bypass valve(s) that is in working order and provides sufficient flow when the throttle body is closed rapidly. Cost, and warranty negation are also factors. Otherwise you can drive with cog belts on the street. The downside is increased wear which lessons the life of the blower. This is why most if not all manufacturers will not warranty a head unit which has used cog pulleys. For a weekend car it might be ok, but for any car that sees a lot of street duty where you are constantly stopping and going, a serpentine really should be your choice. You are gambling with stresses on the blower that it may or may not have been originally designed to handle reliably. Some head units were NEVER designed to be used with a cog kit and should never have a cog belt setup ever put on.

Where can I get a replacement blower pulley key?

Home Depot or Lowes has various sizes. You will need the hardened version.