As Cast-Still Fast: Twisted Wedge Head Test

By: Richard Holdener

Looking back, we can safely say that the original, as-cast, Twisted Wedge street head from Trick Flow Specialties had a major impact on the 5.0L Mustang market. It matters little that the Twisted Wedge heads were neither the first aftermarket performance heads available, nor were they the first aluminum head on the market for the 302 (and 351W). What the then-new offerings from TrickFlow Specialties did provide was an affordable, aluminum performance direct bolt-on head to the Mustang market when no such animal existed.

The as-cast port dimensions (170cc intake and 66cc exhaust) compared very favorably to the stock E7TE 5.0L head castings. The TFS heads generated peak flow numbers of 250 cfm (intake) and 193 cfm (exhaust). This compares to just 166 cfm and 112 cfm (from port volumes of 127cc and 44cc). In addition to the increased flow, the revised valve location (where the heads got their name) improved piston-to-valve clearance, allowing enthusiasts to combine wilder cam timing when performing a cylinder head upgrade on their 5.0L (or 5.8L). Yes, the Twisted Wedge heads had plenty to offer, but with so many heads now available, do they still deliver the goods?

To find out, we set up a test to compare a set of Twisted Wedge Heads (now called Twisted Wedge Track Heat 170 Cylinder Heads-Fast As-Cast) to the stock E7TE heads. While such a test seems straightforward enough, there was some prep work to be done prior to hitting the dyno.

First off, we needed a test motor. To take advantage of the airflow offered by the Track Heat heads, we needed something more than a stock 5.0L, both in terms of displacement and power potential. In the end, we selected a 331 stroker as our test mule. The 331 displacement came courtesy of a late-model, 5.0L block punched out to 4.030, combined with a 3.25-inch stroker crank. Sure, it was possible to step up to the larger 3.40-inch stroke and produce a common 347, but we liked the idea of the shorter stroke and reduced side loading. We selected a 9000-series cast crank from SCAT and combined it with a set of 4340 forged rods from Speedmaster and JE forged pistons. The JE flat-top pistons featured valve reliefs to accept the off-set TFS Twisted-Wedge valve locations. The pistons combined with the 61cc chambers to produce a static compression ratio of 10.1:1.

With displacement and compression out of the way, the test motor needed a camshaft. Having had such great success with the Xtreme Energy series from COMP Cams in the past, we decided to select one of our favorites from that lineup. The dual-pattern, XE274HR cam featured a .555/.565 lift split, a 224/232-degree duration split, and 112-degree lsa. The cam specs were sufficient to help test the merits of the Track Heat heads while still being used as a daily driver (especially in the stroker). The cam did require we make a valve spring change to the stock E7TE cylinder heads. It was necessary to upgrade the spring package to provide adequate spring rate and coil-bind clearance for the test, but COMP set us up with the 35200 spring package necessary for our test.

The cam was combined with an appropriate trio of carb, intake, and headers for the stroker. The induction system consisted of a Cross-Wind intake from Speedmaster topped with a Holley 750 HP carburetor. Exhaust chores were handled by a set of Hooker 1 ¾-inch, long-tube headers feeding 18-inch collector extensions. MSD supplied the necessary billet distributor, and Milodon came through with a complete Fox-chassis oiling system.

Before running the two sets of heads on our test motor, we took the liberty of testing them on the airflow bench. Run at 28 inches, the stock iron 5.0L heads managed 166 cfm from the 127cc intake ports. This paled in comparison to the 251 cfm offered by the 170cc TFS heads. Using a quick calculation, we see the stock heads might support something near 330 hp, while the TFS heads were capable of supporting over 500 hp on the right application. Having tested the horsepower “potential” on the flow bench, it was time to hit the dyno.

Airflow Data: Stock 5.0L (E7TE) vs TFW Track Heat

Intake Exhaust

E7TE TW E7TE TW

Lift

.100 54 63 40 53

.200 110 146 75 107

.300 142 205 100 144

.400 160 233 110 171

.500 157 251 112 187

.600 153 251 111 193

Stock 5.0L (E7TE) vs TFW Track Heat

Intake Exhaust

E7TE TW E7TE TW

Lift

.100 54 63 40 53

.200 110 146 75 107

.300 142 205 100 144

.400 160 233 110 171

.500 157 251 112 187

.600 153 251 111 193

Run on the 331, the stock 5.0L head produced 353 hp and 399 lb-ft of torque —pretty good given the lackluster flow numbers. After adding the TFS Track Heat heads, the power numbers soared to 439 hp and 437 lb-ft of torque. In addition to the peak power gains, the head swap netted improved torque production through the entire rev range.

5.0L Stroker Head Test-Stock vs TFS Track Heat (as cast):
The dyno results clearly show that the Trickflow Track Heat heads offered serious power gains on this 331 stroker. The power potential of the stroker was severely limited by the wimpy stock heads, but the combination woke right up after installation of the TFS heads. The peak numbers jumped from 353 hp and 399 lb-ft of torque to 439 hp and 437 lb-ft of torque. We liked the fact the power was up through the entire rev range and that the Track Heat heads lost no power to the stock heads, even down low. I guess the Twisted Wedge design still works, even after all these years.

The Twisted Wedge chamber design has always been a solid power producer and this test shows the as-cast Track Heat heads still deliver hefty power gains on a hot, little street stroker.