When we last saw Project Retro 5.0, we had just wrapped up baseline testing with the factory E7 engine configuration. 260 horsepower and 327 lb-ft of torque from the 30-year-old mill is nothing to sneeze at, but at the end of the day, we want to see how much power we can squeeze out of this trusty little engine. Enter the Trick Flow Twisted Wedge 11R.
Back in the day, the go-to upgrade was a new top-end kit, consisting of new cylinder heads, a camshaft, and an intake manifold, or as it was commonly referred to on message boards of the time, H/C/I (Heads, Cam, Intake). Trick Flow Specialties (TFS) was a major player in the top-end game back in the day, with their revolutionary “Twisted Wedge” design. It eschewed the small-block Ford’s traditional 20-degree inline valve angles, instead, twisting things around with improved valve angles and a revised kidney-shaped wedge combustion chamber (hence the name).
The original complete top-end kit was advertised to make 350 horsepower with Trick Flow’s matched components. However, that was decades ago. We’re almost a quarter of the way through the 21st century. We have significantly more modern technology and understanding now than we did back in 1996 when the original Twisted Wedges first hit the market, and Trick Flow has embraced that.
Twisted Wedge 11R Cylinder Heads
The core of the Trick Flow 11R Top End Kit (P/N: TFS-K525-432-370) is the new Twisted Wedge 11R cylinder heads (P/N: TFS-52515301-C00). With decades of experience on the dyno and racetrack, along with tons of customer data and feedback, Trick Flow decided they were going to take their already successful design and push it further. Besides having tons of data on the original Twisted Wedge design, their design and development capabilities have increased exponentially as well, allowing them to easily and affordably go beyond what was possible back in 1996.
Cast from A356 aluminum, as the 11R name implies, one of the new features of the updated design is the valve angles. Where the original Windsor head has an inline design, with both the intake and exhaust valves sitting at a 20-degree angle, the original Twisted Wedge design stands up the valves, with the intake valve rotated 5 degrees to a 15-degree angle, and the exhaust moved 3 degrees for a 17-degree angle. The 11R goes even further away from stock with an 11-degree intake valve angle and a 13-degree exhaust valve angle.
Not only do the new valve angles improve flow characteristics around the valve head, but they also allow for a redesigned combustion chamber shape. Besides the new casting shape, the chambers come CNC-machined from the factory, not only providing an optimized shape, but also a perfect surface every time. Those chambers measure 53cc on our version of the cylinder head, which provides us with a 10.3:1 compression ratio when combined with the included .040-inch-thick head gasket and out flat-top pistons.
In the kit, the heads come completely assembled. The chambers are filled with a 2.02-inch stainless-steel intake valve and a 1.60-inch exhaust valve, both with a three-angle valve job from the factory. Feeding the intake valve is a CNC-machined intake port measuring 170cc in volume. While that is the same volume as previous versions of the Twisted Wedge design, it is a different, modern port design. On the exhaust side is a similarly refined 66cc CNC-ported exhaust runner, designed to efficiently remove the spent exhaust gasses.
The valves rest on ductile iron valve seats with bronze valve guides, and unlike factory-style cylinder heads, come fitted with 7/16-inch rocker arm studs installed. The installed valvesprings are good for a hydraulic roller cam up to .600-inch of lift, and are retained by a set of chromoly steel retainers with 7-degree locks.
The Top End Kit Valvetrain Components
One of the nice things about a top-end kit is not only getting everything you need, but that all of the components are designed to work together. The kit includes a set of 1.6:1 ratio aluminum rocker arms (P/N: TFS-51400520), designed for a 7/16 stud mount. The heat-treated aluminum bodies and CNC-machined to dimension — including reliefs for improved spring clearance — and then fitted with needle-bearing fulcrums and roller tips to reduce as much friction in the valvetrain as possible. The roller rockers come anodized blue and are retained with a set of polylocks.
Also included in the kit are a set of 5/16-inch diameter, .080-inch wall-thickness cold-formed 4130 chromoly steel pushrods that are 7.050 inches long with ball tips on both ends (P/N: TFS-21407050). The additional pushrod length is needed to achieve the correct valvetrain geometry with the new heads and stud-rocker setup. No measuring is needed, as Trick Flow has done that for us.
Track Max Stage 1 Camshaft
Included in the kit is a time-tested and proven component — the Trick Flow Track Max Stage 1 hydraulic-roller camshaft (P/N: TFS-51403001). Known on the message boards in the before times as the “TFS1”, the cam is a solid all-around performance grind, designed to do everything well. The lobes have .499-inch of lift with 221 degrees of duration on the intake, .510-inch of lift, and 225 degrees of duration — both at .050-inch of lift — on the exhaust. The cam features 112 degrees of lobe separation angle and is advertised with an operating range of 2,000-5,000 rpm, although it pulled much further than that, for us, as you’ll see.
While this grind would typically require a calibrated mass airflow meter back in the day, our Holley EFI Terminator X made short work of giving it all the fuel it needed. No lifters are included in the kit, but since we are running brand new stock replacements from Melling already, we had no qualms about reusing those hydraulic-roller lifters. Keeping that in time is the included billet-steel timing set from Trick Flow (P/N: TFS-52578520). It’s a nine-way adjustable design allowing up to eight degrees of crankshaft (4 degrees camshaft) advance or retard
Bolting It All On
Another nice part of the top-end kit, is that Trick Flow includes a gasket kit with all of the needed new sealing pieces (P/N: TFS-51400904). The head gaskets are a very nice steel-core design with the fluoroelastomer coating to prevent leaks, a set of composite intake gaskets, steel-core exhaust gaskets, and a nice set of valve cover gaskets (which were absolutely taxed, considering how much we had to cut out of the valve cover flange to get header clearance with our early Mustang shorty headers that were never designed to be used on aluminum heads).
The real trick component in the kit are the head bolts (P/N: TFS-92005). As we mentioned earlier, the heads have provisions for 1/2-inch cylinder head bolts found on stock 351W and aftermarket 302 blocks. Now, usually, you would use centering shoulder spacers to work with the 302’s 7/16 bolts, but the Trick Flow bolts included in the kit have the shoulder spacers machined right into the bolt itself. This led to an embarrassing search around the dyno room for the spacers we thought we had misplaced.
Topping Off The Combination
When it comes to an intake manifold, we wanted to stick with the retro vibe, while still getting decent performance. Nothing screams early ‘90s like a Holley SysteMAX intake manifold (P/N: 300-72S). Funny story; when we originally brought the idea up to Holley, we asked if they maybe still had a SysteMAX we could use in a back room somewhere. We got a funny look along with the reply, “They are still in production. We just got in another shipment recently.” We were too excited to be embarrassed. Besides being in continuous production since the early ‘90s, the intake manifold actually holds a C.A.R.B. Exemption (E.O. D-115-11) making it emissions legal in all 50 states. Designed with a healthy plenum volume and large, long runners, the two-piece design has been a staple of the Fox Body market for a long time, and for good reason.
It bolts right onto the engine, accepting all of our other parts — throttle body/EGR spacer, fuel injectors, fuel rails, sensors, thermostat housing, etc. — without a hiccup, making it a true bolt-on unit. However, just like our stock intake manifold, our fuel rails were a little on the tall side and we had to space the upper plenum out a bit from the lower intake. That was an easy task, thanks to the NOS Big Shot SysteMAX plate system (P/N: 02119NOS).
While we didn’t hook up the entire nitrous kit (yet), the Big Shot plate uses a thick aluminum plate with two full-length spray bars to inject fuel and nitrous oxide into each individual runner, without the need to drill and tap a single hole. Simply mount the Cheater fuel solenoid and the Super ProShot nitrous solenoid with the included brackets, plumb them up, and you’re good to go. The kit comes with jetting for as little as 150 horsepower and as much as 275 horsepower, but for now, we just slipped some vacuum caps over the inlet ports for some naturally aspirated numbers.
Hitting The Dyno With The 11R Heads
With everything back together, getting the engine fired up was just a matter of adding fuel, and pressing the start button on KPE Racing‘s dyno. We were once again running straight 93-octane E10 pump gas from Sunoco, and the engine was purring like a kitten. No surprise considering we have the smallest cam offered in the lineup, designed to be a great street cam.
According to Trick Flow’s advertised power chart, a 306 with 11.0:1 compression, Quick Fuel carburetor, and 1-3/4-inch long tube headers (none of which we have), the top-end kit made 432 horsepower at 6,500 rpm, and 370 lb-ft of torque at 5,500 rpm. Stout numbers to chase for sure. So when we were able to tickle 400 lb-ft of torque and break the 410 horsepower threshold, we called it good. The final numbers were 411.1 horsepower at 5,800 rpm and 399.0 lb-ft at 4,900 rpm. Not bad at all for 10.3:1 compression, a long-runner EFI manifold, and a set of 1-5/8-inch shorty headers that we had to beat with a sledgehammer to get enough clearance.
The real measure though, in our eyes, is how much the modern 170cc Twisted Wedge 11R heads were worth over the previous iteration of the 170cc Twisted wedge heads. With the previous kit being advertised at 350 horsepower, that’s a 61 horsepower increase over what you could expect from a similar kit, 25 years ago. Now, imagine if we had a modern intake manifold and a more aggressive modern camshaft. However, we’re trying to keep this as apples-to-apples as possible and not stack the deck against the previous generation.
Stay tuned, because in the next installment, we add boost in the same fashion as this test – using a tried and true Vortech Fox-Body non-intercooled centrifugal supercharger kit. But, instead of the infamous S-trim supercharger that led countless Foxes to victory over their Brand-X foes, we’ll be running the modern Si-trim head unit. We promise, you don’t want to miss that!