How to Build a Budget 637hp 385ci Small-Block Engine

Budget-Based, Blown & Bad! - Building a 637hp small-block on 91-octane

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Mighty Demon Blow Through 2/36

Our carburetor for this build is Demon’s latest Mighty Demon blow-through carburetors. We used a 650-cfm carb; however, Demon also offers optional 750- and 850-cfm versions.

385ci Small Block Install Performance 3/36

For spark, we installed a Performance Distributors street/strip DUI distributor. This setup has a simple one-wire hookup, is hand built, and comes with a 50,000-volt coil and Dyna Module. We also ordered ours with a melonized gear for the hydraulic-roller camshaft.

385ci Small Block Performance Distributor Spark Plug 4/36

Performance Distributors also has a line of spark plug wires called Livewires; these are direct-fit 8mm diameter wires with RFI noise suppression. We opted for the under headers with 90-degree boots. These are also offered in black, blue, purple, red, silver, or yellow.

385ci Small Block Dyno 5/36

To get the final numbers, we headed over to The Carb Shop, where the Vrbancic brothers pushed our mill to the limits on 91-octane pump gas, and—drum roll please—our baseline all-motor pull made 428/434 hp/lb-ft. With the 3.25-inch pulley, it made 604/575 hp/lb-ft at 8 psi. On the smaller 2.98-inch pulley, it made 637/628 hp/lb-ft at 9.8 psi.

Last thoughts

All said and done, we were only limited by the factory block and 91-octane pump gas. While the carburetor did an excellent job of cooling the fuel prior to entering the intake, we're willing to bet we could have further improved the numbers with the addition of an intercooler and higher-octane fuel. Would the block have lasted? Maybe, but it certainly would have been a time bomb. At the end of the day, we're looking at a 600-plus-horsepower supercharged mill that's completely reliable and can be had from blower to pan for around $7,400. Note: machining and assembly charges will vary; our build added an additional $2,000, making it a total of $9,400 from start to finish.


Mena, AR 71953
Comp Cams
Memphis, TN 38118
Performance Distributors
Memphis, TN 38132
The Carb Shop
Ontario, CA
Speedway Motors
Lincoln, ME 68528
A.R.E. Performance & Machine
Simi Valley, CA 93065
Demon Fuel Systems
Wyoming, MI 49548


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