Dora Gets Twisted: 5.0L Ford Explorer Upgrades

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What better way to explore the power potential of these components from TFS than to install them on Dora our 5.0L Explorer?

Words and Photos By Richard Holdener

In the hierarchy of the late-model, 302 Ford motors, the 5.0L Explorer sits near the top of the heap, below only the limited edition Cobra. Thanks to the use of the GT40-style intake and high-flow GT40 heads (and GT40P in later versions), the Explorer actually offered more power than the previous Mustang GT mills, to say nothing of the more pedestrian 5.0L truck motors. Regardless of the chosen 5.0L Ford, the one thing they all have in common is they don’t make enough power. In today’s world, a 200-hp V8 just doesn’t get the job done, unless that job is strictly to get you from point A to point B. If that’s the case, better give that keyboard a click and browse on over to Cat Fancy or the Shopper’s Gazette. True blue Ford enthusiasts will want to stick around, as we are about to get serious on this Ford 5.0L, and since it was an Explorer motor, naturally we named it Dora!

Our good friend Mark Sanchez provided Dora, an early model 5.0L Explorer said to come from a running vehicle. The early model Explorers were equipped with the original GT40 heads, while later versions received the revised GT40P heads. We liked the spark plug access and use of conventional headers with the GT40 heads, but both will provide similar power numbers. Despite the fact TFS offered their excellent Track Heat EFI intakes to replace the already decent GT40-style used on the Explorer, we opted to run this test with a carburetor. The test involved the Twisted Wedge heads, Stage 2 cam, and 1.6-ratio roller rockers so either induction system would be able to demonstrate the gains offered by the upgrades.

To get things started, we first filled the motor with five quarts of COMP Cams 5W-30 oil, added a new K&N oil filter, and then plugged the motor into the dyno oil-pressure gauge. We just wanted to make sure the used motor had proper oil pressure before going to the trouble of installing it on the dyno and running our test. Everything checked out (including the later compression test), so it looked like Dora was all ready to explore.

Once installed on the dyno, we removed the factory EFI upper and lower intakes and replaced them with their carbureted counterparts. Given the rpm and intended power output of the stock (and modified) 5.0L, we chose a dual-plane Eliminator intake from Speedmaster. Designed to optimize power production up to 6,500 rpm, the dual-plane Eliminator was ideally suited to our small-block. We augmented the intake with a Holley 650 XP carburetor and MSD billet distributor, before completing Dora with a set of 1 ¾-inch Hooker (Fox-chassis) headers feeding collector extension (no mufflers).

The idea was to run the motor first with the stock components, prior to making the modifications from TFS. Once dialed in with 35 degrees of timing, Dora the 5.0L Explorer belted out 264 hp at 5,000 rpm and 316 lb-ft of torque at 3,800 rpm. Obviously, Ford designed the Explorer for low-speed torque, made all the more obvious by the use of the long-runner EFI intake manifold. With our baseline now established, it was time to grab Boots, get the map, and set off on our quest for mods.

In preparation for the upgrades, we drained the water, then removed the dual-plane Eliminator intake and carb, followed by the factory hydraulic roller lifters (which were reused), damper, and front cover. It was necessary to slightly lower the oil pan to facilitate removal of the front cover, but once removed, we had access to the timing chain, cam retaining plate, and finally, out came the stock cam.

After allowing Swiper to swipe the stock stuff, we replaced the wimpy stock stick with a Stage 2 grind from Trick Flow Specialties. One of our favorite grinds for a 5.0L, the Stage 2 cam offered a .542/.563 lift split, a 224/232-degree duration split, and 112-degree lsa. The cam received a liberal coating of oil prior to installation and was run after installation of the factory lifters. In addition to the cam, TFS also supplied a multi-index, double roller timing chain, 1.6-ratio, aluminum roller rockers, and a set of (6.70-inch) hardened pushrods designed to work with their Twisted Wedge heads. The kit also included a full gasket set (including Fel Pro 1011-2 head gaskets) and ARP head studs.

What really got Dora going was the set of Twisted Wedge heads. The 170cc heads featured lightweight aluminum construction, a 2.02/1.60 valve package, and the legendary Twisted Wedge combustion chambers and valve layout. A favorite among 5.0L fans since its introduction, the Twisted Wedge heads recently have been improved to keep pace with the competition. The castings have been redesigned to improve both exhaust strength and water jacket integrity. They also feature CNC-profiled combustion chambers with FastAsCast runners that are said to deliver near CNC-ported power numbers. We liked the fact the revised valve angles and orientation increased piston-to-valve clearance to allow more aggressive cam profiles with the stock pistons. There was more than enough clearance (.078) for our Stage 2 cam.

5.0L Explorer-Stock vs Twisted Wedge Top End What else can you say about a system that improved the power output of our Explorer motor (nicknamed Dora) by nearly 110 hp? Run in stock trim with a Speedmaster intake, Holley carb, and MSD distributor, Dora the 5.0L Explorer produced 264 hp at 5,000 rpm and 316 lb-ft of torque at 3,800 rpm. After installation of the TFS Twisted Wedge heads, Stage 2 cam, and aluminum roller rockers, the power output soared to 372 hp at a lofty 6,300 rpm and 356 lb-ft of torque at 4,200 rpm. Not only did the TFS components improve the peak power numbers substantially, but they also offered an extra 25 lb-ft of torque down at 3,100 rpm. Better power everywhere is the hallmark of a well-designed system.

5.0L Explorer-Stock vs Twisted Wedge Top End
What else can you say about a system that improved the power output of our Explorer motor (nicknamed Dora) by nearly 110 hp? Run in stock trim with a Speedmaster intake, Holley carb, and MSD distributor, Dora the 5.0L Explorer produced 264 hp at 5,000 rpm and 316 lb-ft of torque at 3,800 rpm. After installation of the TFS Twisted Wedge heads, Stage 2 cam, and aluminum roller rockers, the power output soared to 372 hp at a lofty 6,300 rpm and 356 lb-ft of torque at 4,200 rpm. Not only did the TFS components improve the peak power numbers substantially, but they also offered an extra 25 lb-ft of torque down at 3,100 rpm. Better power everywhere is the hallmark of a well-designed system.

Once installed and tuned, Dora was run one final time in twisted configuration. and boy did she perform. Equipped with the TFS heads, cam, and components, the carbureted Explorer motor produced 372 hp at 6,300 rpm and 356 lb-ft at 4,200 rpm. That represented a gain of nearly 110 hp (peak to peak) and even more power higher in the rev range. Hey Explorer, can you say Trick Flow? I knew you could!

Sources: ARP, Arp-bolts.com; California Pony Cars, Calponycars.com; Holley/Hooker/NOS, holley.com; MSD, Msdignition.com; Speedmaster, Speedmaster79.com; Trick Flow Specialties, trickflow.com.

 

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