Installing an Oversized SC Crank Pulley

Compiled from email from Tommy Guttmann, Mike Gruber, Steve Hoult and Tass Hamstra


I've just installed an E,L.P. Crank SC pulley which is a Cusco clone machined from billet aluminum. This replaces the Cusco SC Crank Pulley (13.5 psi)., which replaced my Blitz Pulley (11.5 psi) which replaced my stock pulley (8 psi). My observations on the differences are here 

Before you start, you should read the BGB and have a fair idea of what you're up against before you try this. Plan on spending between 2 and 4 hours depending on your skill and determination. Please read this warning! Here is an english translation of the instruction sheet

The Stock Pulley is on the right, Blitz on the leftcusco2.jpg (56175 bytes)

E. L. P. Prototyes aluminum Cusco clone installed

Unfortunately I don't have a picture of the four pulleys together. The left picture has the Stock and Blitz pulleys. The right picture has the Cusco pulley kit. The bottom is the ELP.

Available Crank Pulleys

Stock        8 PSI      145 mm                             Fits perfectly with no mods ;-)

HKS         10 PSI       12 mm Oversize               Fits with no mods

Blitz        12PSI         15 mm Oversize               Must bend timing pointer 30 degrees out of way

Cusco       14 PSI        17 mm Oversize               Must remove timing pointer and replace with theirs. Also replaces idler pulley

ELP          14 PSI        17mm Oversize                You'll need a smaller idler pulley. I used the one that came with my Cusco

Minimum Recommended Tools

(2) heavy duty jack stands

10mm, 14mm, 17mm Sockets, 14mm combination wrench.

Raising the Car

Use the rear tranny support bracket just between the engine and muffler as the central jacking point. Place the stands along the side jack points on BOTH sides of the car. Leave the jack (remove the jack handle of course!) underneath the transmission to provide 3 points of support. If you only raise the passenger side you'll have difficulty getting at some of the 10mm bolts holding the rear bellypan on the opposite side.

Also, you need the whole rear to be in the air so as to be able to use the "Mike Gruber technique" of immobilizing the crank by removing the clutch access cover and jamming your screwdriver into the ring gear. I wouldn't do it any other way after knowing this...

Start off by first pulling off the rear belly pan (10mm bolts)

Next, the get the tension close when re-installing later on, it will help to have felt the old ones (across their longest sections) before loosening them...just to feel how tight to tension them. After you have the feel, release set nut(s) 14mm on both idler pulleys. To release the pulleys you need to first loosen the 14mm nut on each idler pulley and the rachet it down. The pulley for the Alternator/AC belt is reachable from above and is located in front of the passenger side engine mount and about 4 inchs down. The SC pulley is reachable from underneath the car and is located to the rear of the crank pulley. Once thes are loose you can back out their tension length adjusters (14mm) as far as possible without them falling completely out. The one for the SC belt is accessed from the top, beside the dipstick base. You need a very long extension (approx 24"). The adjuster for the AC/Alt is in front of the crank pulley.

I found it easiest to completely remove the idler wheel on the SC belt until after you thread the belt back on. Then bolt the idler wheel back on. (Steve Hoult)

"The Mike Gruber technique"

Remove the clutch inspection plate, and jam a big screwdriver in the flywheel teeth to hold the crank from turning. Apply 110 ft-lbs torque to break pulley bolt loose (more if it's been on there 10 years). If you use this method you won't need to undo the passenger side engine mount, nor will you need the special SST's (Steve Hoult)

Tommy Guttmann on removing the pulley:

After that...a little wiggling and "gentle" prying with a large screwdriver (pulley against oil pan's flange) helped dislodge it. Again a pulley puller (SST) would have been helpful. (Careful not to pry against the plastic timing cover!)

Steve Hoult on removing the pulley:

Spraying  some penetrating lube onto the crank shaft after removing the crank pulley bolt may help wiggle the pulley off, putting some oil on the new pulley will REALLY help put it on (and shave about an hour off your time, hint, hint)

Tass Hamstra on removing the pulley:

If you use a narrow and long puller you can take the pulley off without lowering the engine. I didn't use the kind that screws in the holes, just the kind with the hooks on the end.

Mike Gruber on removing the pulley:

I didn't need a puller to get the old pulley off, just rocked it back and forth and pulled gently. It comes off in about 15 seconds when I remove it now to do timing belt R&R and other stuff on the front of the engine.

Installing the New Pulley

For the Blitz pulley, you'll have to bend the timing pointer up about 30 degrees. I used a Vise-Grip from the bottom once the old pulley was off. The even larger 17mm O/S Cusco 14psi pulley has a new pointer and smaller diameter idler pulley for additional clearance (See picture above). To install the Cusco pointer, you remove two bolts from the oil pan and using the supplied bolts and spacers bolt the pointer there. The Timing mark on the Cusco pulley will align with this new pointer. You must now use the timing light from underneath the car. Before you attempt to install the new Cusco pulley, you need to remove the old pointer completely. (I simply snapped mine off).

To install the belts I find putting the SC belt on with the idler pulley removed and then installing the pulley is easiest for me.

Installing the Belts

Running the belts is a little more involved with the new pulley, because the clearance is so tight between the idler on the S/C belt and the new pulley itself. Last time, I just removed the idler wheel, ran the belt, and then replaced the wheel, which was easy, and didn't require me to force the new belt over the pulley. Tensioning the belts is a reverse of removing them, but if you're installing new ones (great idea!!!), then run the car on the stands for about 15 to 20 minutes to allow them to stretch before buttoning it all up again. They WILL loosen and stretch!

I ran my car for about 15 minutes up on the stands as suggested. Five days later my SC belt was squealing. These belts had already been on the car for about a month so they had one chance to stretch. It's not real hard to tighen the SC belt,  just cranked it down from above. (Steve Hoult)

Now go to the ABV Page to reroute those pesky vacuum lines or find out how to add a Boost Gauge

My observations on the differences in pulleys.

    When I purchased my SC it came with the standard SC crank pulley. The power of the stock SC motor is well suited to the stock suspension. There is enough power to break the rear end free or to snap the rear end back into snap should it start to come around. Once I had upgraded to 15" wheels and tires, I no longer had enough power to break the rear end free. In my mind, I had to upgrade the power to match the suspension. At the time my choices were the HKS (10 psi for about $250) or the Blitz (about 12 psi for $400). At the time the Cusco was not available in the US (or I couldn't find it). Knowing how I am, I immediately decided on the Blitz.

    After installing the Blitz, there was a world of subtle difference. I was expecting to feel a hammer in my back. At first, I was less then impressed. On my second trip out I looked closer at my speedo. YEEEEOOOWWW! There was a huge difference, Since I don't have access to a dyno or a G-Tech, I used a stretch of road that has definite landmarks to measure my max speed. This doesn't give real results, rather it just gives relative results. At the end of the run with the stock pulley my speed was 58 mph. With the Blitz I reached 67 mph. Quite a difference. Repeating the runs with the Blitz had it loosing a mph or two. I suspected that it was heat soaking the intercooler.

    After about 8 months I found a Cusco pulley in Canada. I ordered it right away. After mounting it I was expecting another large subtle difference, I was wrong again. There was the hammer in the back. There was the V-8 type grunt. This thing made a huge difference compared to the Blitz (in more ways then one). Not only was there a big difference in power, the difference in mileage was huge as well. I haven't done real testing on mileage, but I have to fill my tank more often during the week (used to be about 1 and 1/2 tanks a week, now 2+ tanks). Do I care? Not in the least! The grin factor more then makes up for it. BTW, the speed for the Cusco runwas 76 mph. That's almost 20 mph faster then the stock pulley. On the downside, you can really tell the difference after the IC starts heat soaking. Repeated runs ended up loosing about 4-5 mph which you can feel. You can also feel the difference in power between early morning and late afternoon first runs. I think the Cusco would make good use of a upgraded intercooler.

    After having the Cusco pulley on for many months, the crank snout sheared . When I got the engine replaced with a j-spec engine I also replaced the pulley with ELP's lightweight aluminum pulley. The first thing I noticed was that the throttle response was better then the Cusco. I don't notice any problems related to the lack of the rubber dampner ring. I like the pulley. The power is the same as the Cusco because it's the exact same size. 

Return to the top


  I want to warn all of you about the one weak spot I've found in the design of the Supercharged engine. The SC crank pulley shares a very small key with the crank timing belt pulley. This is an extremely critical fact. The Timing belt pulley is about 2.5" thick, but only about 1/3" is held by the key. The other side of the key is holding the SC crank pulley (also only about 1/3"). Each time you hit the throttle both gears want to retard on the crank. Each time you let off the gas both pulleys want to advance on the crank shaft. If their is any slop this causes accelerating wear which will not only ruins the pulleys, but will also wear the snout of the crank. Also, if left unrepaired, the vibration will accelerate the wear on the front main bearing. All of this wear is accelerated with larger (more weight) SC crank pullies.

How do you avoid these EXPENSIVE problems?

I don't have the answer, just some suggestions. Before you install a larger SC crank pulley make sure you clean any brown, powdery substance completely. This substance is actually a sign that wear is already occuring. REPLACE the key with a brand new one. This will minimixe any slop that already exists. Even with a new key, check to see if there is slop in the keyway with the new key. You really should use a micrometer and check the crank snout and pulley to see what the slop will be. I can't give you a good figure for acceptable slop, none is best. Less is better. 

Another thing is to make sure you tighten the crank pulley bolt to the proper torque spec.

 Return to the top