Supercharger Tensioner Bracket

And Strut Support

(Updated 7/9/04)

My design (below) did work but not as well as what you can buy from (  The work that Ian has done with his bracket system is amazing and the easy of use is nothing less than spectacular.  I left this page up as a reference for anyone wanting to design their own system or trying to run a large lower pulley.

Here is a link to some photos and a page for the SCH system

Here is a picture of the bracket installed


(picture of system I designed)

(click on images to enlarge them - any image on the page)

I am actually very proud of this little contraption - I never intended for it to get as complex but my final product is nothing less than amazing - let me explain.

I am pushing in the neighborhood of 1,000 horsepower in my Mustang.  This power is made by compressing air with my Vortech Supercharger and my ASP Cog Pulleys.  I have been told that for my YSi-Trim supercharger to compress maximum boost and flow 1,600 CFM of air it will draw over 100 horsepower.  This power is actually consumed by the supercharger to power the impellers to generate the boost.  Before all you turbo-people start the slobbering over how a turbo doesn't do that -  you loose power through exhaust restriction and I don't want to get into the debate over which consumes more power.

When you start spinning stuff this fast you also start to throw belts and rip cogs off the belt.  Last year I was running a 74 tooth crank pulley and a 28 or 27 tooth supercharger pulley.  When I would run the 27 tooth pulley I would throw the belt more often then when I was running the 28 tooth.  It makes sense, the smaller the pulley the smaller the arc the belt needs to move to slip of the head unit.  The only way to use a larger pulley is to also run a larger crank pulley.

Lucky for me I found a used ASP 80 tooth crankshaft cog pulley on eBay.  With the 80 tooth pulley I will be running either a 30 tooth or 32 tooth supercharger pulley.  The 30 tooth will spin it a little faster than last year and the 32 tooth a little slower.

Sounds great right?  Well the problem is with the 80 tooth pulley my belt hit the water pump pulley.  Not where the belt runs but where the pulley bolts to the pump.  I ordered a Meziere electric pump with idler to see if it would fit any better but the belt idler on the Meziere pump is actually larger in diameter than where the stock pump bolts to the water pump. 

The only solution I could come up with was to move the idler further away from the supercharger head unit and more toward the crank pulley.  Sounds simple right?  Well there are a number of things that change when you do this, you have clearance issues with the normal accessory drive belt, issues with strength with the pulley hanging so far down the bracket, and more problems I never expected. 

My final solution was to build a spacer bracket that bolts to the supercharger mounting plate (where it mounts to the engine) and install another slide adjuster at this location.  This solution provided serveral additional benefits I had not originally planned for.

  • The plate now acts as a strut support for the supercharger.  It creates two parallels at the head unit, both secured to the engine mounting location

  • It allows for easier tensioning of the pulley - the extra length provides more leverage (a cog pulley setup does not need to be as tight as a serpentine setup)

  • It moves the idler with its retaining supports closer to the crankshaft thereby holding the belt on the system more securely

  • It does not require the belt to arc in near as sever an angle as with the idler near the supercharger pulley

Well, I guess I won't know how well it works until I make it to the track.  I am positive it will work, if it doesn't I will be installing a stock set of pulleys as I ran last year.  I will post updates.


This is the inner bracket bolted to the standard supercharger bracket.  Two of the bolts are the same as those used to hold the bracket to the inner aluminum strut assembly that bolts to the block.  The other is tapped into the supercharger plate assembly.  Notice how close the standard serpentine belt is.


This is the extended outer idler bracket.  Notice the re-enforcement bar that is welded on the lower portion.  I don't know if it was needed but I figured it can't hurt. 


Here is the assembly as installed.  Notice how the idler assembly now creates another parallel mounting flange at the supercharger head unit.  This places two 1/4 inch thick mild steel flanges 1.5 inches apart in parallel.  This should work as well as any strut assembly other than the Vortech system that mounts the strut bar between the crank pulley and supercharger pulley.

All of the parts are out being zinc plated now.  I will update the pic when they are finished and installed.


This is hard to se but you can see how close the belt clearance is now with the new idler setup.  I have around 1/4 inch between the belt and the water pump.  I guess time will tell if this is enough clearance.


Return to main page