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Old 02-04-2010, 04:10 PM   #1
SCMC Member
Join Date: Nov 2004
Posts: 139
JLT's 2010 GT500 pulley pkgs and install

We got a hold of a well broken in 2010 GT500 with over 6000 miles on the clock already and got to work.

We have 3 pulley packages for the 2010 GT500.

JLTís SCT X-3 Pulley package $749

Diablosport Pulley package $699

JLT's Pulley Upgrade Package (no tuner) $335

Clink on links above for more info on these packages.

Both tuner packages include a free JLT T-shirt and have options for JLT CAI, double bearing idlers and pulley removal tools at discounted package prices.

Once it was strapped down to the DynoJet dyno we made a couple base line pulls. The car put down a 450 RWHP (SAE) average, we built a quick tune and picked up 20+HP, but stopped as this customer wanted the pulley changed.

We let the car cool down and pulled the intake and coil covers to change the spark plugs. The Coil covers come off with a simple 10mm deep socket on the passenger side and a Torx T-30 bit on the driverís side. Simply pull the covers off, pull a coil out one at a time and change the plugs using a 5/8Ē spark plug socket ratchet and extension. Gap your new plugs at .035 and put some antiseize on the new plugs threads to prevent them from sticking to the heads. Once this is done on all 8 plugs reinstall the coil covers and intake tube.

Next we need to attack the pulley and auxiliary idler kit. First we need to remove the belt from the stock pulley. A trick to doing this job much easier is to remove the stock radiator coolant tank. Donít remove any hoses, just remove the (2) 8mm bolts and move tank over to the side.

Now you have easy access to the belt tensioner. Using a 3/8 ratchet (breaker bar works even better) and a short 2-3Ē extension push clockwise to release the belt tension and remove the belt from the supercharger pulley only. I tuck it under the small coolant line on the passenger side.

With the belt off we used our Metco pulley removal tool to get the stock pulley off. The supercharger pulleys on the GT500ís are not bolted nor do they have a key way, they are a press fit and VERY tight. This is why no ordinary pulley removal tool from Snap on or Mac will work. Before you start, apply antiseize on the large bolt and washers being used. Put the horse shoe plate behind the pulley and mount the tool like this:

03, 04 Cobra shown here, but tool is the same.

Using 2 large wrenches or one wrench and a ratchet and socket on the end of the bolt, start to back off the nut to put pressure on the pulley. It will be very tight, but keep steady pressure on the wrenches as not to put force up, down or sideways and keep turning the nut slowly. You will hear a pop and then the nut will turn easier. Keep turning until the pulley is completely off.

Once you have it off, reconfigure the tool to install the new Metco pulley hub. Be sure to install the hub in the correction direction, with the larger side going toward the supercharger case. Put a little antiseize on the supercharger shaft to aid in the install.

Hold pressure against the tool bar and slowly tighten the bolt on tool to press the hub onto shaft until it is flush with the end.

Before you bolt the pulley ring on, letís install the Metco Auxiliary idler. Remove the 3 8mm bolts shown here.

Another tip, remove the pulley from the Metco idler bracket. This will give you more space to work with. Using the supplied bolts and spacers, attach the idler bracket and tighten it down.

Next install the supercharger pulley ring and belt. With the belt on the supercharger, push down on the belt tensioner and put idler pulley on bracket and release the belt. Bolt the pulley down and reinstall the coolant tank.

Once this was done, we were ready to make some power.

Diablosport just released the Predator U7141 tuner with pre loaded programs for the 2010 GT500, so we decided to check it out. Loading the tune with a Predator is easy. We selected ďPulley tuneĒ and it did the rest. As with all tuners it uploads your stock tune onto itself and stores it so you can return to stock at anytime, then loads the custom tune onto the car.

Once it was done, we set up the datalogger and brought the car up to operating temperature. Hammer down and power jumped nearly 60 RWHP over stock to 510. Not bad for only $699 and an couple hours time.

We knew we were here to do some custom tuning with SCT, so we loaded the stock tune back in the car and began to build our custom tune. A few runs later and power was up another 10 RWHP and 9 RWTQ for a total gain of close to 70 RWHP. At $749 thatís $10 per HP! We did this with an A/F of 11.7-12.0 and very little timing. A more aggressive tune will net even more power.

Here are some dyno graphs and info.

First is the stock dyno run vs. 2.6 pulley and Diablosport tune.

We use industry standard SAE corrected numbers, but not all dyno shops do. If these were uncorrected numbers it would look like this:

Some like this as the numbers look much better, but itís all in how you correct it. There is nothing wrong with either way, but SAE corrected numbers can be easily compared across the country in all climates.

Next are a few of the JLT SCT tuned runs.

And uncorrected:

With this huge power jump the car feel much better power wise, has great throttle response and the customer even reported heís getting better gas mileage. Win Win Win!

If you have any questions, please feel free to call me direct @ 757 335 1940 or email

Thanks for reading

757 335 1940

2011 Mustang GT 5.0
420 RWHP

JLT True CAI on board.
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