So with a ported factory blower, we're again getting more power than expected. As Lauzardo mentioned, there have been several instances where other people have made over 500 rwhp from the identical setup, but with the stock exhaust manifolds, throttle body, and inlet pipe, we would not see the big five-double-0. In reality, it doesn't bother us because the car is just plain nasty on the street with First gear being literally useless with so much torque and traction being a huge issue in Second. Hooray for neck-snapping grunt. The problem is, now it has us wanting more.
Pulleyed For Max Grip
On all '03-'04 Cobras, adding an underdrive supercharger pulley increases boost. That's fine and dandy, and yes you get more power. However, one of the biggest issues with this simple mod is the lack of adequate belt wrap with the reduced diameter pulley. It can cause slippage, especially when you're powershifting. The best way to tackle this is to use an auxiliary idler pulley right next to the supercharger's snout to provide the additional belt wrap. What does this do? Well, it makes the belt have more contact area with the pulley and it greatly prevents slippage to make sure that you get the most amount of boost possible with your setup.
For our car, we went with Steeda's billet aluminum setup, which not only looks the part, but also plays the part with a 100mm idler pulley diameter. It bolts right to the factory supercharger "bridge" and installs in mere minutes. Because the belt now has a new route, it will require a longer belt, typically one-half to a full inch longer. If you are using a stock crank pulley and a 3.0 upper, you'll need a Gates PN K080745. If you are going to a four-pound pulley like we did with the ported Eaton, then you will need Gates PN K080850. With your belt tensioner nice and tight, before you know it, you'll be rewarded with slip-free fun.
Since the Cobra's crank bolt...
Since the Cobra's crank bolt fought us every step of the way, we had to call in the reinforcements and use a long piece of square tubing while the car was in gear, with the brake pedal to the floor and a prybar in the driveshaft. It finally broke free after Lauzardo made fun of its mother.
With the lower idler pulley...
With the lower idler pulley bracket in place, we positioned the steel brace that goes underneath and below the factory crank pulley. Once all together, we then tightened everything down as an assembly with the included hardware.
Next up, we bolted up the...
Next up, we bolted up the crank hub directly to the crankshaft and then the Metco 90mm idler pulley to the idler bracket.
The drive pulley goes on last...
The drive pulley goes on last and uses six Grade-8 bolts. The quality and workmanship of Metco's components always impresses us. Mike D'Orta, who installed our pulley system, tightens up the last bolt and routes our new drive belt in place.
With the pulleys in place,...
With the pulleys in place, we lowered the car down from Mustang Magic's lift and headed back over to the DynoJet. With Lauzardo back in the saddle, he put in more fuel in the mid range where we would see the most gains from the pulley and blower. As he mentioned, the car would be full of torque from 2,500 to 5,000, which is where the extra fuel is needed most.
On the dyno, we saw 16 psi...
On the dyno, we saw 16 psi of immediate boost and watched it carry it all the way to about 5,000 rpm. Unfortunately, we started to lose boost after that and the gauge dwindled down to 12 psi by redline. Our factory throttle body and inlet manifold simply became a restriction at that point and we reached our limits of airflow.
On the dyno, our newest round...
On the dyno, our newest round of modifications upped power to a final of 471 rwhp and 506 rwtq. This represents a gain of 18 hp and 53 lb-ft of twist. But the peak numbers are neglecting how much more power was picked up across the board, and in particular, at 3,500 rpm, where we saw a gain of 38 hp because of the huge torque gains. Around town, the car was simply wild and almost unmanageable on street tires.