Muscle Mustangs & Fast Fords
Supercharged 427 Windsor Vs. ZEX 557 A460 Stroker - Goliath's Revenge
We Pit A Blown 427-Inch Windsor Against A Juice-Gulping 557-Inch Big-Block.
Call it what you will-David versus Goliath, brawn versus brains, or in our case, inches versus pounds-but regardless, it's the little guy taking on the insurmountable task of overwhelming the big guy.
In nature, bigger is usually better, meaning the big animals eat the little ones. In the horsepower game, more displacement is often better than having less. As the classic story goes, Goliath had free reign because there was no one big (or brave) enough to stand up to him-until he met little David. What David lacked in size, he more than made up for in weaponry.
When it comes to making power, bigger motors make more power than smaller ones because they can process more air and gas. While the Goliath-based logic seems sound, the statement does not take into account the automotive equivalent of David, his was a bag of smooth stones and fancy sling, ours is one you're familiar with-boost!
A Supercharged All-Aluminum 427 Windsor
Like its biblical brethren, our automotive David combines light and might. The light portion came from our choice of a Dart aluminum 351W Ford block. This block scores high on the cool and power-to-weight ratio scales.
Improvements on the other end of the power-to-weight scale came from a stroker version thereof. David was fortified with a 4.00-inch steel stroker crank courtesy of Pro Comp. Pro Comp also supplied a set of 4340 forged connecting rods, which were combined with a set of forged flat-top pistons from Probe Racing.
The aluminum 427 stroker short-block was machined by L&R Automotive and professionally assembled by Demon Engines. It is interesting to note that the use of flat-top pistons on a motor of this displacement usually means you have a static compression ratio exceeding 12.25:1, but we reduced static compression ratio to a street-friendly 10.3:1 using a rather large combustion chamber. The normal consideration is drivability versus power. Wilder cam timing (high-lift and long-duration) will result in higher peak power numbers, but these numbers generally occur higher in the rev range. Unfortunately for enthusiasts, the cost of all that wonderful top-end power is almost always a reduction in low-speed torque production.
But rather than go with the typical hydraulic roller, we chose a solid roller profile. To reach our goal of 1,000 hp, we wanted to maximize the output of the normally aspirated motor, then add as little boost as necessary to safely reach our goal. We selected a custom solid-roller profile from Cam Research Corp (www.camresearchcorp.com). After providing our specs and power needs, Cam Research Corp supplied us with an aggressive roller profile that offered a 0.692/0.684-lift split, a 254/252 duration split at 0.050 and a blower-friendly lobe separation angle of 112 degrees. The roller cam was combined with a set of PN 838-16 roller lifters from Comp Cams.
Once David had sufficient displacement and cam timing, we turned to head flow. Not surprisingly, head flow is one of the key ingredients in the power production of any motor, regardless of displacement. And the head flow must work in conjunction with the cam timing and intake design, as the combination helps dictate horsepower and torque peaks, as well as the shape of the overall curve.
With this in mind, we chose CNC-ported Trick Flow High-Port 225 cylinder heads. Impressive even in as-cast form, the High-Port 225 heads feature 2.08-inch intake valves and 1.60-inch exhaust valves, full CNC porting, and careful hand blending, which combine to produce impressive flow figures. The 225cc intake ports flowed 335 cfm at 0.700 lift, while the exhaust flow checked in at 258 cfm at the same valve lift. Though not relevant for most street motors, the 0.700-lift flow figures were important to us since our Cam Research roller cam offered right near 0.700 lift on both the intake and exhaust. The High-Port heads were set up with a suitable valve spring package to accommodate our near 0.700-lift roller cam and topped with titanium retainers.
The final component that all but determines the power output of the combination is the intake manifold. Knowing that our 1,000hp goal for David would come near 7,000 rpm, we chose an intake with high-rpm power in mind. Naturally, we chose a single-plane Super Victor from Edelbrock. Our version was massaged by the flow mongers over at Wilson Manifolds. The intake flow was optimized and the ports matched to the same 1262R intake gaskets used to size the entry of the Trick Flow High-Port heads. We also employed a Wilson carb spacer that adapted the 4150 carb flange on our ported Super Victor to the 1050 Holley Dominator carb we selected. While our supercharged combination would be run with a 1,000 cfm 4150 HP series Holley modified for boost by Carburetor Solutions Unlimited (CSU), we liked the look of the Dominator on the Super Victor.
To properly prepare our David for battle against Goliath, we needed a weapon. Big D's was an impressive Paxton Novi 2000. Originally designed for use as a Renegade kit on an injected 351 Windsor, we modified it slightly for use on our carbureted combatant. Rather than go with the carb enclosure, we opted for a simple bonnet and the aforementioned carburetor from CSU.
Paxton supplied a few additional eight-rib blower pulleys, which allowed us to dial in sufficient boost to push to the magical 1,000hp mark. Truth be told, only an available belt length kept us from easily surpassing the 1,000hp mark. Minor components used to complete the 427 included ARP head studs and Fel Pro MLS gaskets, a Pro Comp billet distributor and plug wires and a Milodon oiling system. The Pro Comp distributor was run through an MSD Digital 7 ignition amplifier using Denso Irridium plugs, while Comp Cams supplied a set of 1.6-ratio Gold roller rockers and HiTech hardened pushrods.
Though designed for blower use, the aluminum 427 produced 628 hp and 565 lb-ft of torque. Credit the impressive TFS heads, Cam Research roller cam and Wilson ported Victor manifold for the lion's share of the power.
With our normally aspirated power established, it was time for the blower. The Paxton Novi 2000 was first run with an 8-inch crank pulley and 3.75-inch blower pulley. This netted an impressive 941 hp right off the bat at just 12.5 psi, though we did experience a bit of belt slippage. Unfortunately, we were only able to get a hold of one size belt for testing (at a local NAPA store) and that belt was a touch on the long side (basically our fault for not properly preparing for the test with different belt lengths). The belt would allow us to rev cleanly to 6,200 rpm before slipping.
In the end, we managed to produce right at 1,000 hp at 6,200 rpm using the 3.5-inch pulley and there was plenty left. Unless you had to run in the Renegade class, we strongly recommend a 10-rib or (better yet) a cog drive at this power and boost level to ensure a repeatable boost curve with no belt slippage. Despite the belt slippage, reaching our 1,000hp goal meant David had officially tossed the first stone.
A 557-Inch A460 Nitrous Stroker
To illustrate this age-old rivalry, our Dart David needed a rival, so Goliath took the form of a massive, normally aspirated stroker motor topped off with a little chemical weaponry in the form of nitrous oxide.
Like the 427, the goal for this motor was to exceed 1,000 hp. Paying full homage to the bigger-really-is-better theme, we started with the biggest production motor Ford had to offer and proceeded to add inches. By combining a 4.440-inch bore with a massive 4.50-inch stroke, the original 460 Ford was punched out to a massive 557 ci. The stock 460ci two-bolt block was retained, but filled with a forged reciprocating assembly consisting of a Pro Comp 4.50-inch (4340) forged steel crank, 6.70-inch (BBC) forged H-beam connecting rods, and forged flat-top pistons from Ross Racing pistons. The premium-forged pistons from Ross were designed to accept the valve orientation for the Trick Flow A460 aluminum race heads (they differ from the stock and Super Cobra-Jet valve orientation).
With maximum power production in mind, we selected a titan-sized camshaft. Comp Cams supplied one of its drag-race roller profiles that offered 0.806 intake lift, 0.763 exhaust lift, and a whopping 275/284 degree duration split (at 0.050). The sizable lift and duration specs were combined with a 110-degree LSA. To work with the healthy cam, Comp supplied solid-roller lifters (PN 836-16) and a matching double-roller timing chain.
Comp also supplied a set of pushrods (actually, two sets of eight) as the intake and exhaust required different lengths. The intakes required 9.20-inch pushrods, while the exhausts were slightly smaller at 8.90 inches. The final component from Comp Cams was a set of 1.70-ratio roller rockers. Ford fanatics may wonder why we chose 1.7:1 rather that the BBF standard ratio of 1.73:1, but the answer is easy. We originally tried a set of BBF Hi-Tech Stainless rockers (PN 1130-16), but they were a tad long from the pivot point to the center of the roller tip. The Trick Flow heads (and Pro Comp heads run on a similar motor) worked best with the 1.7:1 ratio set originally designed for the BBC (PN 1120-16).
Goliath also required a serious set of lungs, so we went for aluminum Power Port A460 race heads from Trick Flow Specialties. TFS offers the Power Port A460 heads in Fast-as-Cast configuration, but we elected to take the flow rate to the next level by stepping up to the CNC-ported version. Flowing 412 cfm at 0.800 lift, the Fast-as-Cast Power Port A460 versions could be hardly be considered a slouch.
The CNC porting transformed the already impressive heads into phenomenal performers. The porting improved the peak intake flow to 465 cfm (at 0.800 lift), with a corresponding exhaust flow of 330 cfm. Every bit as important as the big peak numbers was the fact that the porting improved the flow rate of the A460 heads through the entire lift range. These amazing flow numbers came with an increase in intake port volume of just 20 cc over the as-cast heads (340 cc versus 360 cc). Big flow gains are one thing, but when they come with a minimal change in port volume, you know you have the makings of a winner. In addition to the porting, the A460 heads also featured a stainless 2.30/1.88-inch valve package, 83cc combustion chambers (for a 12.5:1 compression), and a complete valve spring package, including titanium retainers that support up to 0.850 lift. In short, the Trick Flow CNC-ported Power Port A460s were some serious headgear.
Massive displacement, aggressive cam timing and hellacious head flow are all well and good, but they are meaningless if you strangle them with a stock four-barrel intake. Lucky for us, TFS recognized this fact and designed not one, but two different intake manifolds dedicated to the A460 port configuration.
First up was the single-plane R-series A460 intake manifold designed for use with a Holley Dominator carburetor. This intake features high-flowing, extended runners, a raised plenum floor and additional material for custom port work. The R-series intake also features dedicated bosses for direct-port nitrous or fuel injection. TFS also offers an R-series A460 tunnel ram designed to accept either a single or dual Dominator carbs. Naturally, we opted for the dual-carb top and proceeded to call Holley for a pair of new 1,050-cfm Ultra Dominators.
Like the R-series single-plane intake, the Trick Flow tunnel ram was designed for large-displacement, high-rpm Ford motors, and included bosses for nitrous and/or fuel injection. As much as we like a good fuelie motor, there is something wildly impressive about a big-block Ford sporting a tunnel ram and a pair of shiny new Ultra Dominator carbs.
Our plan was to run the single four with the Zex perimeter plate nitrous system; then follow up with the tunnel ram, but the dual-carb intake also required use of an offset distributor or crank trigger. We had neither at testing. In the end, Goliath was forced into battle using only the single four-barrel R-series intake.
Our nitrous-injected, 557 stroker also included a billet distributor, plug wires, and polished aluminum valve covers (to clear our roller rockers) from Pro Comp. Since we planned on spinning it to 7,000 rpm, a good oiling system was a must. Moroso supplied a deep-sump oil pan, windage tray, and high-volume oil-pump combo to ensure constant lubrication.
One area that needed to be addressed was the roller lifters. Our first attempt with roller lifters resulted in the oiling hole intersecting the main oil galley-a situation which literally pumped all the oil to the top of the motor at the expense of the main bearings. The cure came from the Ford experts at Cam Research in the form of roller lifters with a revised oiling hole location. This ensured all the Lucas synthetic oil was distributed properly to the thirsty rod and main bearings, as well as the cam, lifters, and rocker arms. The final touches on the 557 included ARP head and main studs; a Fel Pro head, intake, and oil pan gaskets; and an ATI damper.
The ATI Race damper was critical since we were pushing the stock block well past its original power limit. Vibration dampening becomes ultra-critical with elevated power and rpm levels. Keeping things cool was a Meziere electric water pump, another critical element when pushing the limits on this 12.5:1 race motor. Goliath was also sporting some chemical weaponry in the form of an adjustable perimeter-plate nitrous system from Zex.
Like the belt slippage issue with David, we cursed the gods for not allowing us to run the Tunnel Ram on our Goliath. Truth be told, the gods were less to blame than the author, but we curse them nonetheless. Goliath still impressed everyone by belting out 895 hp at 6,900 rpm, and an equally impressive 757 lb-ft of torque at 5,800 rpm with the single four-barrel intake. Torque production from the behemoth exceeded 700 lb-ft from our roll-in point of 4,500 rpm to 6,600 rpm. Having recently tested tunnel rams on a 540-inch Chevy, we can safely say that Goliath would have easily exceeded 900 hp with the dual Dominators, but reaching 1,000 hp required some juice.
Using the single four-barrel R-series intake and single 1050 Dominator, we added a Zex perimeter-plate nitrous kit, adding over 150 hp with 150hp jetting. Equipped with the Zex system, Goliath produce peak numbers of 1,135 hp and 962 lb-ft of torque. Even if we ignore the spike (see dyno results), the 557 still produced 1,070 hp. Had we been able to run the 427 with a cog belt and the 557 with a tunnel ram (and more nitrous), who knows what the outcome would be. But on this day, hindered as he was by the belt issue, Goliath managed to turn the tide and exacted his revenge on little David. All hail Goliath!