Budget Supercharged Small-Block Chevy Engine Build - 445HP For $3,995

Dyno Numbers
The following dyno curves show the progression of our boneyard motor from a normally aspirated baseline (Test 1) through bolting on the out-of-the-box Weiand 142 supercharger (Test 2). The test also included using a set of 151/48-inch headers through a pair of Flowmaster 211/42-inch mufflers.

Note that the boost level on this engine is very conservative, only reaching 5 psi at the very peak rpm point. This is with the stock pulley supplied with the kit. A smaller blower pulley would spin the blower faster, making more boost and perhaps more low- and mid-range power. But this also would heat up the air and probably cost some top-end power. More importantly, extra boost would be a very bad idea with our stock cast pistons.

The Scoggin-Dickey modified heads widen the spring pads for larger-diameter valvesprings (which weren't used on these heads) and also cut down both the valveguide diameter and the guide height for more spring clearance.

Note how the blower torque gains tend to be greater below and above the normally aspirated engine's peak torque of 4,200 rpm. Since peak torque is where peak volumetric efficiency (VE) occurs, the blower helps make the most power in the rpm ranges where the engine needs the most help-on either side of peak VE.

Track Times
We plugged this power curve into the Quarter Pro drag racing simulator from Racing Systems Analysis (quarterjr.com) to simulate a 3,500-pound street car with a TH-350 trans, a 2,600-rpm converter with 3.31:1 rear gears, and sticky M/T DOT tires to help it hook. Shifting at 6,500 rpm, the simulator spit out a 11.97/113.5-mph pass. Subtract a couple of tenths on general principles and you're still looking at a 3.31-geared street car that can run low 12s on pump gas with an engine that costs less than $4,000. And this baby will do it all day long 'cause that blower never needs a bottle refill. It doesn't get much better than that. END

Carb Swap
We began with a used Holley 650 double-pumper for $60 that we found on eBay. We then swapped in one of Holley's new HP main bodies for a mere $125. (The details on this are outlined in "Holley HP Main Body Swap" in the Feb. '06 issue.) The key point is that a mechanical-secondary 650 uses the same throttle-blade size as a 750 carb. So we converted a small carb into a bigger one for less than $200 including new gaskets. A new, Holley non-HP 750 double-pumper is $400.

Vortec heads use interesting deep-thread engagement spark plugs with the tapered seat-sealing surfaces. We used Autolite spark plugs for our test but closed the gap down to 0.30 inch to ensure arc-over.	The Weiand 142 is a two-lobe-rotor, 142ci blower. It is sealed to the intake manifold with a simple rubber O-ring, but it is critical that the four attachment bolts be torqued only to 10-12 ft-lb. More torque than this will distort the blower case and cause damage to the case and rotors.
With the blower in place on the engine, we set up a complete accessory drive, including a water pump and an alternator, to simulate the way the engine would run in a car. This might cost a few horsepower, but it's also a more realistic way to test the engine.