Michael Galimi
February 6, 2012

Last month you read about a naturally aspirated Two-Valve engine that gained 28 rwhp without sacrificing any of the car's street manners. The Trick Flow Specialties camshafts made the idle sound healthy but not overly aggressive, and there wasn't any bucking at low rpm. We return this issue to chart the gains while the same engine is exposed to boost.

Our original goal was to add 14 psi, but the ProCharger P1SC-2 actually pumped up the 284ci bullet with 16-17 psi. The engine handled it without any hassle, thanks to the 93-octane fuel, 18 degrees total timing, and the big front-mounted ProCharger air-to-air intercooler.

The goals for this test are to start with the stock sticks, change to the TFS Stage 1 cams (PN TFS-51802001), and then make one more step up to the larger valve-bumpers (PN TFS-51802002), which we're unofficially calling Stage 2 cams.

The foundation is the 284ci engine that Adam Secour built for the Dez Racing crew. It is a rather basic combination with 0.020-inch-over pistons combined with a Terminator crankshaft and no-name H-beam rods. Topping off the short-block is a pair of Trick Flow Twisted Wedge 4.6L cylinder heads. The 38cc combustion chambers create a static compression ratio of 10.5:1.

Some might think it is high for a supercharged combination, but Mike Dezotell of Dez Racing thinks otherwise. "The efficient combustion chamber lets us get away with more compression, more ignition timing, and more boost than the ported stock heads," he proclaims. He was right because the engine saw between 16 and 17 psi with 18 degrees of total timing and no trouble on the 93- octane pump gas.

Last month's adventure ended with the Two-Valve runner cranking out 319 rwhp with the small Trick Flow cams and 34 degrees total timing. Dez Racing's head wrench Brian Machie then reverted to the stock cams and bolted on the ProCharger.

The '99-'04 4.6L SOHC Mustang GT models utilize the Performance Improvement (PI) heads, cams, and intake. The heads and intake are Trick Flow units, but the base camshafts are of the PI variety. The PI camshafts have 0.505-inch intake lift, 0.534-inch on the exhaust side, and duration of 186/194 degrees at 0.050-inchuintake and exhaust respectively. The non-PI 4.6L SOHC engines ('96-'98 Mustang GT) utilize smaller camshafts, which carry intake/exhaust lifts of 0.461/0.466 inches and intake/exhaust durations of 200/209 degrees. Our test engine was equipped with the larger PI camshafts given its '00 model year.

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The stock PI camshafts performed nicely as the 16-17 psi of boost pushed output from 319 rwhp naturally aspirated to an impressive 540 rwhp. That is a gain of 221 rwhp from the ProCharger intercooled supercharger system. The idle was smooth as expected and the supercharger made minimal noise. We were impressed with the mid-500 power levels as it is more than enough to push a New Edge into the 10suprovided the trans and suspension is up to snuff. Ignition timing was set at 18 degrees total; Dezotell relies on SCT tuning software to accomplish the task.

Most people would be happy with 540 rwhp, but we knew there was serious potential on tap given the naturally aspirated gains with the Trick Flow camshafts upgrade. The Stage 1 cams added nearly 30 rwhp in naturally aspirated testing, but last month's test didn't prepare us for what we got with boost. The Trick Flow Stage 1 camshafts pumped output to 602 rwhp and the calculator shows that is a 62 rwhp increase over the stock bumpsticks. The torque matches or is above the stock camshaft curve, with the peak showing an increase of 9 lb-ft of torque, bringing the total to 478.

The first chassis dyno test netted us a 540 rwhp and 469 lb-ft of torque result--impressive for a simple combination. A Tremec 3650 transmission with a Ram clutch sits behind the supercharged mill.

We already know the street manners of the Stage 1 cams. Just like the naturally aspirated setup, the car exhibited smooth idle and no bucking down low. They feature a healthy 0.550-inch lift on both valves. Intake duration is 228 degrees and the exhaust lobes carry duration of 230 degrees, both are measured at 0.050-inch of lift. The lobe separation angle is listed as a tight 112 degrees.

With 602 rwhp verified at the wheels, it was time to swap in the Stage 2 set. The Stage 2 cams offer 0.580-inch lift for intake and exhaust valves. The duration is also larger than Stage 1 with the specs showing Stage 2 cams carrying 234 degrees of duration as measured at 0.050-inch lift.

Please note that the cam numbers don't quite relate as they do in pushrod engines. Two of the biggest differences are that the overhead camshaft designs don't run into the same deflection issues that are associated with pushrod engines because the cam follower is right on the rocker. In the non-modular engine the cam is connected to valve through lifters, pushrods, and finally the rocker arms, which are prone to deflecting under load. "The cams are rated differently as wellupushrod camshafts are rated at the lifter and almost all of the modular camshafts are rated at the valve. The numbers are not an apples to apples comparison," explains Greg Changet of Trick Flow.

The Stage 2 camshafts performed excellently on the chassis dyno, as well as around town. The idle was more aggressive but not excessive, and the GT displayed smooth driving characteristics. The gains were immediately noticed on the dyno as this time the rwhp topped out at 616, while the torque jumped to 485 lb-ft peak. Compared to stock, the Stage 2 camshafts are worth 76 rwhp and 16 lb-ft of torque.

A quick comparison to the Stage 1 camshafts reveals a difference of 14 rwhp and 7 lb-ft of torque. The maximum rpm changed too, as peak power went from 6,400 rpm with the PI cams to almost 7,000 with either of the Trick Flow camshafts.

The ProCharger-blown 284ci engine was impressive as 616 rwhp is a serious number on real pump gas. Dezotell said that it could make more, as he wasn't using the Snow Performance methanol injection kit. That would put the car in the mid-600 range.

Naturally, we could add a larger supercharger and go right into the 700-rwhp realm, but that is another story for another day. For now, Dezotell is going to enjoy the 616 rwhp before the winter months put an end to the street fun.

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