Muscle Mustangs & Fast FordsHow To Engine
Trick Flow Camshaft Install - Things That Go Bump In The Valve Cover, Part 1
Part 1: Trick Flow camshafts open and close the 4.6L SOHC valves much better than stock ones.
Over the course of hot rodding, one of the more debatable upgrades has been swapping camshafts--especially in modular engines. Given the Two-Valve's complexity and cost of buying two camshafts, the question posed isn't will it increase horsepower, but more appropriately, how much of an increase in horsepower?
We tossed that question to Mike Dezotell of Dez Racing, and he invited us to get a front row seat as he upgraded a '00 Mustang GT from a pair of OEM sticks to a set of Trick Flow camshafts. He first performed the test in naturally aspirated trim; next month we'll add and a ProCharger P1SC-2 supercharger system.
The Two-Valve engine uses a single overhead camshaft on each engine bank instead of the traditional in-block single camshaft that the small-block and big-block Ford engines employ. Each camshaft utilizes a long chain for its connection to the crankshaft, which keeps the valves opening and closing in sync. The intake and exhaust lobes (egg-shaped part of the camshaft) determine how much the valves are opened and closed, and it is traditionally measured in inches of lift and duration (the amount of time the valve is off the seat).
The actual amount of time each valve is opened is defined by the duration, which is measured in degrees of crankshaft rotation. The final popular piece of the camshaft puzzle is the lobe separation angle, also measured in degrees, but not crankshaft rotation. Rather the camshaft angle between maximum intake lift and maximum exhaust lift.
These statistics can certainly throw a curveball to the uninitiated, who almost always think bigger is better when it comes to cam selection. What could be wrong with opening the valves as much as possible and holding them open for the longest amount of time? After all, the engine is an air pump, so more air and fuel should equal more power, right? That, unfortunately, is incorrect.
"A lack of understanding the operation of a camshaft is probably the biggest problem in cam selection," says Greg Changet of Trick Flow Specialties. "You don't want a camshaft that puts the torque curve outside of the range of use for the vehicle. For example, you don't want a camshaft that makes torque on the high-rpm range as most street applications are typically not driven in a high-rpm range." The Trick Flow Stage 1 cam was designed for street use in regard to idle, driveability, and rpm.
Our test subject is a '00 Mustang GT out of the Dez Racing stable in Massachusetts. The car is powered by a mild street engine that benefits from a slight overbore (3.572-inches), bumping the cubes to 284ci. Compression is set to 10.5:1 thanks to the 38cc chambers of the Trick Flow Twisted Wedge cylinder heads.
The crank is a steel unit sourced from a Terminator Cobra engine, while the connecting rods are generic H-beam steel. Adam Secour built the short-block and the Dez Racing crew added the rest of the parts and pieces.
Moving topside, Dezotell and his head wrench, Brian Machie, bolted on Trick Flow Twisted Wedge heads. They selected the 38cc version because the smaller combustion chamber bumps compression to 10.5:1. The 10.5:1 static compression is fine in naturally aspirated applications, but some might raise an eyebrow next month when we supercharge the 4.6L.
Dezotell had some comments about the increased compression in a supercharged application. "The higher compression will make more power and torque at lower boost levels, which makes it more fun to drive. I wouldn't do this (Ed. note--10.5:1 compression) with stock P.I. heads or the engine would have detonation. The Trick Flow heads have more efficient combustion chambers, which allows the 10.5:1 compression without detonation under boost," he says.
The test began with the OEM sticks as Dezotell flogged it on the dyno. Then we took some joy rides to get a good feel for it on the street. Once we properly smoked the tires around town, the car was back in the shop for the addition of the Track Max cams (PN TFS-51802001), which are unofficially nicknamed Stage 1 cams.
Most retailers sell the cams only for approximately $499.99. The OEM camshafts in '99-'04 4.6L SOHC Mustang GT models come in at 0.505-inch intake lift, 0.534-inch on the exhaust side, and a duration of 186/194 at 0.050-inch, intake and exhaust respectively. The non-P.I. 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 P.I. camshafts given its '00 model year.
Dezotell strapped the Y2K Mustang to the DynoJet, and the results were an impressive 291 rwhp combined with 287 lb-ft of torque. Peak power came at 6,100 rpm, while the highest torque number was recorded at 5,000 rpm. On the street, the car pulled cleanly and drove like stock in around-town action. The idle was smooth even with the Ford Racing shorty-headers and Bassani X-style mid-pipe that's combined with a MagnaFlow after-cat exhaust.
We wouldn't think this engine benefits from larger, high-flowing Trick Flow heads and intake manifold--provided you didn't pop the hood. It's a real sleeper combination that could fool anyone into thinking the car has just bolt-ons.
Adding the Stage 1 camshafts was a quick task, and Dezotell had to make some adjustments in the ECU tune (using SCT software) for a clean and smooth idle. It doesn't take a trained ear to tell something more aggressive is under the valve covers, as the Stage 1 cams' tone goes with its specs--larger than stock, but not overly aggressive. The Stage 1 camshafts are designed for cars with OEM short-blocks, so piston-to-valve clearance is usually not an issue, but you should always check it to be certain.
The cam card supplied with the sticks shows these camshafts have a 0.550-inch valve lift for both intake and exhaust. Intake duration is 228 degrees, while 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.
On the street, the car drove nicely and there was no noticeable loss of low-end power. On the dyno, the story unfolded as the Trick Flow Stage 1 cams jumped output to 309 rwhp and 285 lb-ft of torque. Dezotell was confident the engine wanted more ignition timing and his suspicion proved true. The magic number was 34 degrees of total timing--3 more than the baseline runs.
"I tried adding more timing with the stock camshafts, but the engine pinged a little bit on the pump gas. It works best with 31 degrees total timing. The Trick Flow cams happily accept an extra three degrees without any hint of knock," injects Dezotell.
The peak rpm changed too, as the power climbed to 6,700 rpm before falling off. That's a gain of 28 rwhp just by swapping the camshafts and some additional ignition timing. Overlaying the stock camshaft graph with the Stage 1 curves reveals that the two profiles run similar in the horsepower department until 4,700 rpm. It's like a switch is flipped and the Stage 1 curve starts to put distance between itself and the OEM curve.
Those type of gains will show up in the drag racing world since the engine is rarely if ever below 4,700 rpm during a run. Torque was down a little below 4,000 rpm at WOT with the Stage 1 camshafts, but nothing that one would feel since it was only a few lb-ft at most. However, as the engine hits 4,000 and goes to redline, the torque output was above the stock camshafts--peak torque was 4 lb-ft better with the Stage 1 cams.
Pumping 319 rwhp isn't bad for a street-driven naturally aspirated Two-Valve combination. Next month, we add a ProCharger P1SC-2 intercooled supercharger system and run three pairs of camshafts (OEM, Trick Flow Stage 1, and Trick Flow Stage 2) on top of the heads to see if the abnormally aspirated gains are as significant as the naturally aspirated results.