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Twisted Wedge Two-Valve Heads - Two-Cam Cylinder-Head Jam
Trick Flow Specialties Two-Valve Heads Turn The SOHC Market Upside Down-We Gain 34 RWHP Over Ported Stock Heads.
We headed to Steve LaPointe Race Engines to see what the Twisted Wedge Two-Valve heads would do on a flow bench. LaPointe used the same bore size as our test engine (3.552-inches) to ensure accurate results. The heads peaked at 0.600-inch lift with 253 cfm for the intake side and 189 cfm for the exhaust. That compares to 219 cfm (intake) and 200 cfm (exhaust) for the CNC-ported stock heads, but the head is more than just a set of healthy flowing ports and a nice combustion chamber; Trick Flow addressed many issues.
The new Twisted Wedge modular heads accept both Windsor and Romeo style valve covers, which makes ordering them easier as enthusiasts sometimes mix up the names and styles. The spark plug holes accept a traditional style plug with a full 3/4-inch reach to eliminate blowouts and the need for inserts. We used NGK TR6 4177 spark plugs (one range colder than stock) with a 0.035-inch gap for this test. The deck of the head is also 3/4-inch thick, to help prevent the cylinder head from lifting in high-boost and high-compression applications.
"The Twisted Wedge Two-Valve heads are the only 1.840-inch intake valve heads on the market that you can bolt onto a stock bore/piston short-block. All other 1.840-valve heads require a 0.020-inch overbore so the valves clear," notes Noe.
"We talked to NMRA racers and shops and kept hearing complaints about the cam journal oiling at high rpm," said Noe. TFS addressed the concerns with a new oiling system that better feeds the cam journals at high rpm levels. The journals are removable and the four-bolt pieces are made from a powered metal. Noe notes, "There is a specific reason we use a proprietary powered metal for the cam journals." It centers on durability and manufacturing but that is all he would say on the patented setup.
Putting the Twisted Wedge Heads to the Test
Our test vehicle is a '00 Mustang GT out of the Dez Racing shop (Seekonk, Massachusetts), and the Two-Valve combination starts with a stock engine block that was bored 0.020 to 3.552 inches. A new cast-steel crank with a stock 3.550-inch stroke swings eight H-beam steel connecting rods and forged pistons. The stock cylinder heads feature a Stage 2 CNC port job from Total Engine Airflow, and are topped off with a pair of F-42 camshafts from Anderson Ford Motorsport. ATI's P-1SC centrifugal supercharger pumps 11-12 psi of boost into the Fox Lake P-51 intake manifold.
The exhaust is rather small with a set of Ford Racing shorty headers connected to a Bassani 2.5-inch x-style midpipe and after-cat exhaust. Without methanol injection, the '00 Stang made 466 rwhp and 429 rwtq with 17 degrees of ignition timing and 93-octane pump gas. Our baseline pull with the Snow Performance water/methanol kit spraying down the intake charge showed 486 rwhp and 447 rwtq-the increase due to the 23 degrees of timing that the meth injection allowed. All dyno testing was performed on a DynoJet chassis dyno and the car features a Tremec T45 five-speed manual transmission.
The engine uses a set of ARP head studs, making a head swap with the engine in the car difficult, if not impossible. Brian Machie of Dez Racing yanked the mod motor to make things easier-as crazy as that might sound. He had the engine out in less than two hours, and took off the top-end shortly after that. The heads bolted on just fine and we used a set of Fel-Pro Multi-Layer gaskets (0.036-inch thick). Our compression ratio increased from 9.1:1 to 10.4:1, thanks to the 38cc chamber of the Twisted Wedge Street/Strip head. Our stock CNC-ported heads had a 44cc chamber and Ford delivers stock P.I. heads with a 38cc chamber. Moving down to the non-P.I. heads, the combustion chamber goes to 52 cc.