Once the wiring harness, blower...
Once the wiring harness, blower tubes, and fuel components were moved out of the way, the passenger-side valve cover slid off easily.
We secured a supercharged Two-Valve combination as our test subject and baselined it on the chassis dyno at JPC Racing. Proprietor Justin Burcham had backed down the timing as a safety precaution for our barrage of dyno pulls. Everything we did was backed up within 1 percent-on both the baseline and subsequent testing. The '02 Mustang GT spun the dyno to an impressive 655 rwhp and 605 rwtq. This GT isn't considered ordinary due to the stout engine package under the carbon-fiber hood. A VT Racing-built Two-Valve modular engine has a fortified bottom end, ported Two-Valve heads, and custom VT Stage 3 camshafts. On top of the 302ci stroker engine is a Fox Lake P-51 intake manifold. Also, there is a ProCharger D1SC blower with larger blower tubes done in-house at JPC Racing. Backing the muscular modular is a T-56 six-speed transmission. Burcham has made 710 rwhp with higher timing, but he backed it down for the testing to the 655-rwhp baseline we achieved the morning of the install.
The Jesel cam followers went in easily, to say the least. In fact, it was one of our easiest install stories in recent memory. JPC has a tool from Ford that is required to swap out the cam followers. Other than that, we used the usual assortment of tools required to remove the valve covers. Installation took only a few hours, including us stopping JPC technician Adam Humm multiple times for photographic purposes.
The final results are interesting. We picked up 42 peak rear-wheel horsepower, a number that doesn't tell the whole story-more on that later. Burcham made three straight runs within a few horsepower of the new peak of 705 rwhp and torque sat at a lofty 633 lb-ft-some 33 lb-ft better than the baseline. Our gains were repeatable, showing the cam followers helped this engine tremendously.
 The fuel-pressure regulator...  The fuel-pressure regulator sensor had to be removed for us to remove the driver-side valve cover. |  The driver-side valve cover...  The driver-side valve cover is taken off. |  The Two-Valve modular engine's...  The Two-Valve modular engine's valvetrain is exposed. Under the cages and camshafts sit the cam followers. Everything remains in place, and a special tool from Ford is used to remove and install them. |
As impressive as those gains are, we felt the story behind them was that this particular engine was suffering from valve float thanks to 20 psi of boost and 6,500-rpm dyno pulls (7,000 rpm on the racetrack). According to Scott Cushman of VT Racing Engines, this engine was built to make around 550 hp with about 14 psi of boost and 6,000-rpm shift points. The larger supercharger and increased rpm range are well out of the realm for the valvesprings and stock-cam followers.
We feel the test bullet had such impressive gains because the Jesel cam followers brought stability to the valvetrain. "The stock cam followers were most likely flexing badly under the load," Jesel's Bob McDonald says. The deflection most likely caused valve float. That's not to say the Jesel pieces won't pick up power in every engine; they will increase horsepower, and the gains-in our case-are on the high side. Some sources we spoke with have said they've generally seen 25- to 35-rwhp gains with the Jesel cam followers in similar combinations.
Here is the special wrench...
Here is the special wrench attachment that allows easy removal of cam followers. Once fastened to the valvespring top and cam lobe, the user pulls back on the handle and the cam follower pops out.
We performed another test, one on a naturally aspirated Two-Valve engine that's slated for use in NMRA Factory Stock. The stock short-block has ported stock heads, custom Rich Groh Racing camshafts, and runs mid-11s on drag radials with no power adder. This combo is mild when compared to most other naturally aspirated Two-Valve combinations, due to class restrictions. In this test, Burcham reported a 10hp gain, shooting up from 321 to 331.5 at the rear wheels. The torque curve also experienced similar increases throughout.
Pushrod or modular, reducing friction and adding rigidity to valvetrain components yields greater horsepower in mild and wild combinations.