Low-RPM Performance
On paper, the efficiency advantages of a centrifugal blower look good, but roots-style blowers are still extremely popular in the hot rod market. "The advantage of a roots-style blower is that it is considered a positive displacement design," McFarland opines. "This design can move a much larger volume of air at a lower rpm than a centrifugal. Roots-style superchargers produce a very flat and wide torque curve and will begin to generate power as low as 1,000 rpm. No centrifugal supercharger can produce this same kick-in-the-pants feel."
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Belt Tension
Spring-loaded belt tensioners are idiot-proof, but don't fret if you must adjust the blower drive-belt manually. "On a cold engine, grasp the belt halfway between the upper and lower pulleys on the driver side of the engine and move it in and out," McFarland explains. "When it's properly tensioned, you should be able to move the belt approximately 1 inch total, or 1/2 inch inward and 1/2 inch outward. Check the belt again once the engine is warm and it should have approximately 1/4 to 1/2 inch of play. If it is less than that, then the belt is too tight and could damage the blower or crank snout."
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Induction Package
"People are so focused on the cfm a cylinder head flows, yet they often ignore the intake manifold. However, a cylinder head is only as good as the intake manifold it's attached to, so both are key components in an engine's overall inlet ducting. For both cylinder heads and intake manifolds, a focus on flow alone can lead to a poorly performing engine combination. Once again, having the correct charge-air velocity with the best flow coefficient, or least restrictive flow, will yield the best engine power. A poor intake manifold choice can limit the power gained by a good cylinder head, while a good intake manifold choice will maximize the performance potential of any cylinder head. The two components really work hand in hand." -Jim Dralle
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LS Intakes
Although Weiand is best known for its premium carbureted intakes and blower kits, the company is currently completing development on a new line of composite EFI intake manifolds for the LS-series engines. The new Weiand Street Warrior EFI intake was developed in conjunction with Starr Technologies of Australia to optimize the low- and mid-range power of LS1, LS2, LS3, LS6, L76, and L92 engines. "These intakes generate as much as 32 hp and 31 lb-ft over a factory LS6 intake on a mildly modified motor at 4,000 rpm," says Dralle. "They should hit the streets some time this summer."
Blower Long-Block
Supercharged motors have different needs than naturally aspirated motors, so Weiand has some tips for spec'ing one out. "If you are building an engine specifically for a blower, we recommend a 7.5:1 static compression ratio, four-bolt mains, steel rods, a steel harmonic damper, and a forged crank and pistons," says McFarland. "High-flow heads will get the most out of the blower, and wider valve seat widths will help cool the valves. In addition to longer duration specs, grinding the cam on a 112- to 114-degree LSA is preferable. Lastly, a high-output ignition will ensure adequate spark to light off the denser air/fuel mixture." CHP