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Double Dipping: Supercharged 5.0L Fords

Words and Photos: Richard Holdener 

What could possibly be better than a test where we add a supercharger to a 5.0L Ford? The obvious answer is adding boost to a pair of 5.0L Fords, one stock and one modified, of course! In fact, the great thing about boost from a supercharger is that it will improve the power output of any normally aspirated combination, from mild to wild. Boost is essentially a multiplier, meaning the more power your motor makes before adding boost, the more power it will make with each pound supplied by the supercharger. Running a pair of different 5.0L motors allowed us to demonstrate this multiplier effect, but just know that 10 psi of boost applied to a 250-hp motor is different than 10 psi of boost supplied to a 400-hp combination. We liked the test because the pair showed us what is possible once we modify our rebuilt 5.0L, but for now, we were content to simply add boost to our stock 5.0L motor. That the TorqStorm supercharger was so easy to install made a good test even better!

Our first test was run on a rebuilt 302 that featured stock internals in the short block. The 5.0L was sporting a late-model hydraulic-roller block, cast crank, rods and pistons, but fear not as there was plenty of strength for our intended power level. Having already pushed this combination over 350 hp and 400 lb-ft of torque with nitrous, we felt confident that the 302 could withstand a little boost. Cementing the confidence was 85,000-miles worth of abuse on a stock short block with a blower in the author’s personal 5.0L LX. The stock short block also featured a stock 5.0L cam and was topped with a set of stock iron heads. Completing the package was a dual-plane intake, 650 carb and long-tube headers. Run in this configuration, the rebuilder special produced 258 hp and 328 lb-ft of torque. It should be noted that it was necessary to upgrade the supplied valve springs with a package from COMP Cams. This allowed the motor to rev past 5,500 rpm without experiencing valve float. The spring package supplied with the rebuilt heads was seriously inadequate, so make sure to check.

After running the stock motor in normally aspirated trim, we installed the TorqStorm centrifugal supercharger. Installation was a snap, thanks in part to the self-contained oiling system, meaning it required no external oil feed or drain line to the oil pan. The blower mounting bracket installed to the cylinder head, then came the supercharger. The supercharger was supplied with a 3.25-inch blower pulley, which combined with an 8-inch crank pulley. The oversized crank pulley required us to replace our Meziere electric water pump with a mechanical version (and smaller pump pulley) to allow fitment of the crank pulley and blower belt. On the stock motor, the pulley combination produced nearly 11 psi at just 5,500 rpm. The TorqStorm supercharger was combined with a CSU blow-through carburetor and carb bonnet. After dialing in the air/fuel and timing (on 100-octane fuel), the combination produced 399 hp at 5,500 rpm and 449 lb-ft of torque at 4,000 rpm. What this motor needed now was a cam upgrade and a decent set of cylinder heads.

Since we didn’t have the components we wanted to modify our rebuilt motor, we did the next best thing. We ran the TorqStorm supercharger on a second test motor. Test motor number two was a junkyard 5.0L Explorer motor originally equipped with a set of GT-40 heads and Explorer intake. These were previously replaced with a set of TFS 11R 170 aluminum heads and a dual-plane intake. Completing the top-end upgrade on the 5.0L was a COMP XE274HR cam that offered .555/.565 lift split, a 224/232-degree duration split and 112-degree lsa.

The cam was a critical part of the success of the modified combination, as the stock cam was excessively restrictive, even under boost. The modified 302 was treated to the same CSU carb and TorqStorm supercharger, including the same blower and crank pulleys. Before adding boost, the modified motor was run in normally aspirated trim to the tune of 407 hp and 397 lb-ft of torque. After adding the TorqStorm supercharger, the power output jumped to 638 hp and 545 lb-ft of torque. The peak boost pressure registered was 10.1 psi at 6,500 rpm, but as expected, the boost was lower on this modified motor at the same engine speeds as the stock 302 (7.9 psi vs 10.6 psi at 5,500).

Power Data: Stock & Modified 302 Fords-NA vs TorqStorm