Supercharged Crate Engine - A Crate Start

Jegs And Vortech Join Forces To Sell A Supercharged Small-Block Crate Engine

Richard Holdener Nov 27, 2007 0 Comment(s)
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The kit included dedicated fuel lines for the dual-feed carburetor.

While Jegs offers these upgrades with their standard GM crate motors, there were a few changes necessary to suit the needs of the supercharged combination. The Edelbrock Performer intake manifold was retained, as were the necessary intake gaskets, but the carburetor was upgraded to a 650-cfm unit from Quick Fuel designed to meet the fuel flow requirements under boost. When combined with the boost-referenced fuel pump, the combination ensured adequate fuel pressure to the carb under boost. The carb jetting in the 650 was naturally optimized for the boosted application.

The power producer of the new blown crate motor was, of course, the supercharger system itself. Designed by Vortech, this V-2 S-trim centrifugal supercharger was designed to provide roughly 7 psi of non-intercooled boost to the 350. Naturally, a great deal more boost, and therefore power, are available from the Vortech (we've easily exceeded 600 hp with this kit on wilder combinations); but for this application, the pulley ratios were kept purposely conservative to keep boost down.

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A manual (marine) fuel pump was employed on the blower motor. Note the vacuum/boost reference fitting designed to always provide 7 psi of fuel pressure on top of the existing boost pressure.

To establish a baseline for this story, we first ran the combination in normally aspirated trim. This allowed us to demonstrate the merits of the supercharger, as the power gains will always be a percentage of the original power output. After installing a small 4-barrel carb (the Quick Fuel 650-cfm carb was jetted for boosted applications) and headers, the 260hp crate motor responded by thumping out 264 hp at 4400 rpm and 353 lb-ft of torque at just 3500 rpm. No surprises here, as the mild cam, compression and head flow limited the power output of the 350 small-block.

Adding the Vortech blower to the mix increased the power output of the 350 to 383 hp at 5500 rpm and 431 lb-ft of torque at 4200 rpm. The Vortech improved the power output of the motor by 45 percent with just over 7 psi of boost.

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Upgrades to the basic crate engine also included an HEI distributor. If we could ask Jegs for one thing, we'd like to see a small cap distributor to improve clearance with the carb enclosure.

Blower and crate engine fans alike should rejoice in this new offering from Jegs, as the combination is both affordable and strong, with plenty of power left in reserve. Every bit as important is the fact that the new combination comes complete and ready to install. We liked the look of the combination, but, being enthusiasts, we can't wait to ditch the wimpy hydraulic flat-tappet cam and factory iron heads in favor of more performance-oriented pieces.

Given the way small-blocks respond to improvements in breathing, we look for some serious power gains from the proposed head and cam upgrade. What makes the heads and cam even more appealing is that the power gains offered by the additional breathing will actually be multiplied by the boost pressure. If we got a 45 percent gain from 7 psi of boost with the 264hp combination, we expect to see a similar gain once we get the normally aspirated motor up closer to 350 hp. Remember, every good supercharged powerplant starts with an equally good normally aspirated one.

Priced at under $5,500, this Jegs supercharged crate motor combination is almost like buying a Vortech supercharger kit and getting the long-block for free.




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