The 5.0L Still Responds

Ford introduced serious modern muscle with the four-valve Coyote, but the original 5.0L fuel-injected small block started the performance revolution in 1986. Stock for stock, the 225-horsepower 5.0L cannot match its 400-plus-horsepower successor - but the platform earned its reputation by responding well to aftermarket upgrades. That characteristic has not changed.

To demonstrate just how well these motors respond, we ran a 5.0L through a series of dyno tests: first in near-stock configuration, then after a heads, cam, and intake upgrade, and finally with a 100-horsepower nitrous shot.

Building the Short Block for What Comes Next

With nitrous on the build sheet, the bottom end needed to handle more than a set of bolt-ons. Starting with a factory 5.0L hydraulic roller block, the rotating assembly combined a forged steel crank from RPM, a set of forged rods from Speedmaster, and flat-top forged pistons from Probe Racing. The stock block remained the limiting factor for absolute power, but this forged assembly provided the strength margin required for nitrous use.

The bottom end was fortified with a 4340 forged-steel crank and a set of 4340 forged-steel 5.4-inch rods from Speedmaster - built to handle the planned nitrous application.

Probe Racing supplied the forged-aluminum flat-top pistons. The .040-over pistons featured generous valve reliefs to accommodate the high-lift Xtreme Energy cam.

COMP Cams supplied a new set of hydraulic roller lifters, used with the production spider retainer assembly.

Baseline: Stock Heads, Stock Cam, GT-40 Intake

The stock E7TE heads were modified to accept screw-in rocker studs. For baseline testing, the stock rockers were replaced with 1.6-ratio guided roller rockers.

The flat-top pistons yielded a 9.35:1 static compression ratio with the 64cc chambers in the stock heads. The baseline configuration included stock E7TE Ford heads, the stock cam, a GT-40 intake, and an Accufab throttle body. Supporting components: Hooker 1 3/4-inch Fox chassis headers, a Meziere electric water pump, FAST XFI management system, MSD billet distributor and ignition amplifier, Lucas 5W-30 oil, and FAST 36-pound injectors. Other than the screw-in studs and a spring upgrade, the head ports, chambers, and valve job were completely stock - flow and power output reflected factory-level head performance.

The GT-40 was one of the most common intake upgrades for the 5.0L platform - a known quantity for baseline testing.

Feeding the GT-40 was an AccuFab 65mm throttle body and ProM 77mm mass air meter, used only as a radiused air entry.

Testing showed the GT-40 intake was worth nearly 20 horsepower over the stock 5.0L H.O. intake, with a slight trade-off in low-speed torque. Tuned through the FAST XFI system, the forged 5.0L produced 279 hp at 5,300 rpm and 323 lb-ft of torque at 3,400 rpm. Torque exceeded 300 lb-ft from 2,800 rpm to 4,700 rpm - consistent with the H.O. 302's torque-biased character.

The Top-End Upgrade: RHS Heads, COMP Cam, Holley SysteMax Intake

The head, cam, and intake upgrade consisted of CNC-ported RHS Pro Elite 205 heads, a COMP XE274HR cam, and an Extrude Hone-ported Holley SysteMax intake. The Pro Elite heads featured 205cc intake ports, a 2.055/1.60 valve package, and 62cc combustion chambers - capable of supporting close to 600 horsepower. The XE274HR cam (part number 35-518-8) offered a .555/.565 lift split, a 224/232-degree duration split, and a 112-degree lobe separation angle suited to EFI, blower, and turbo applications. The Extrude Hone process forced abrasive media through the SysteMax runners - an effective approach for long-runner intakes where conventional porting access is limited. ARP head studs and Fel-Pro head (1011-2) and intake (1262) gaskets completed the assembly.

The stock heads were replaced with CNC-ported RHS Pro Elite heads - aluminum construction, CNC porting, and flow capacity well beyond the factory castings.

COMP also supplied new lifters, hardened pushrods, and a double roller timing chain for the upgraded valvetrain.

The XE274HR cam from COMP Cams: .555/.565 lift split, 224/232 duration split, 112-degree lobe separation angle.

The guided rockers were replaced with 1.6-ratio aluminum roller rockers from COMP Cams.

After installation, the peak numbers jumped to 395 hp at 6,200 rpm and 380 lb-ft of torque at 5,000 rpm. The modifications shifted the torque curve higher in the rev range, with the modified 302 exceeding 350 lb-ft from 3,900 rpm to 5,900 rpm and never dipping below 300 lb-ft. Both the heads and intake had capacity for considerably more power; the relatively mild 274 cam provided a balance of output and drivability. A larger cam profile would trade low-speed power at this stage, but there was a way to add power without that compromise.

The upper intake received porting and a larger 75mm throttle body.

Adding the ZEX Wet EFI Nitrous Kit

With 395 hp from the modified 302, a 100-hp nitrous shot was the direct path to the 500 hp target.

The top-end package brought the 302 close to 400 horsepower - still short of the 500 hp target. Nitrous oxide offered the most straightforward path to close that gap. The ZEX Wet EFI kit combined nitrous and fuel into a single fogger nozzle, mounted in the air intake ahead of the Holley throttle body. The adjustable kit supported 75 hp to 125 hp on any injected application; we installed 100 hp jetting. The ZEX controller learned the TPS voltage curve to ensure nitrous activation only occurred at wide-open throttle - though the system did not prevent activation at low engine speeds, which must be managed separately to avoid engine damage.

With nitrous engaged, the 5.0L produced 506 hp and 547 lb-ft of torque - up from 395 hp and 380 lb-ft on the normally aspirated combination. The additional power came with no penalty to idle quality or drivability.

Dyno Results Summary

Stock heads, stock cam, GT-40 intake: 279 hp at 5,300 rpm / 323 lb-ft at 3,400 rpm

RHS Pro Elite heads, COMP XE274HR cam, Holley SysteMax intake: 395 hp at 6,200 rpm / 380 lb-ft at 5,000 rpm

Top-end package plus ZEX 100 hp nitrous: 506 hp / 547 lb-ft of torque

The top-end upgrade extended the usable engine speed to 6,500 rpm while adding 116 hp. The nitrous kit added another 111 hp with no change to the base calibration or drivability. Three stages, one short block, and the 5.0L platform proved it still has room to deliver.