Mistakes that weaken a supercharger’s performance

Mistakes that weaken a supercharger’s performance

Bertie S. Brown: Though they don’t cater to the Corvette market or late-model Ford Mustangs—none from 1994 to present due to congested engine bays—TorqStorm Superchargers’s product manager, Rick Lewis, has dealt with hundreds of incoming queries in the first eight years of the firm’s history. Here are five of the most common: 1) Compression ratios and intercoolers “The compression ratio for pump-gas engines is crucial,” says Rick Lewis. “TorqStorm recommends ratios of 9.1 to 9.5:1.” Higher ratios usually require an intercooler. “But if you are running less than 12psi of boost and under 10:1 compression ratio with a blow-through carburetor or venturi-style throttle body fuel injection,” insists Lewis, “ you can still achieve significant power increases without an intercooler, even on pump gas. Blow-through carburetors do a very good job of controlling intake charge temps.” 2) What increases in power can I expect? “Our single centrifugal supercharger, which supports 700+hp and generates boost of 6-8psi., increases engine power by about 40 percent over stock performance,” claims Lewis. “Add a second unit, which collectively generate 12-15psi., and the engine’s power output potentially doubles.” Note that the fuel pump must support 21psi of fuel pressure and it relies on a return line to the tank. 3) Carburetors and regulators The fuel delivered to a carburetor on a normally aspirated engine operates at 6 or 7psi. But the blow-through carburetor is designed to operate from 5psi to boosted pressures that can reach 18psi on a forced-induction engine. This task is achieved by the introduction of a boost-referenced fuel pressure regulator. Via a small-bore hose, the regulator is connected to a port on the...
Harmonic balancers: Free advice on selecting them

Harmonic balancers: Free advice on selecting them

By Archie Bosman:  It’s easy to underestimate the cost of a deficient harmonic balancer. But they can have a profound effect on the fortunes of the able race engine—a natural enemy of crank and bearings. With the engine running, camshafts and crankshafts vibrate torsionally (in twist) and, as the saying goes, for every action there’s a reaction. Camshafts are affected by the forces related to the opening and closing of the valves while crankshafts by the combustion events. Each time the cylinders fire, torque is imparted to the crank, causing deflections—twisting it as much as 2 degrees. All of this partially complicates the timing of the valve openings as well as the cam and ignition timing to say nothing of the oppressive conditions in which the crank operates. As a result of the vibrations and deflections in both shafts, a harmonic balancer or damper is connected to the crank to absorb them. Vibrations are at their highest when furthest from the flywheel. Hence dampers are mounted on the front of the crank. Yet, on historic and vintage race engines often there was no provision at the front of the crank to mount a damper. Consequently, they might use a custom elastomer or tunable pendulum damper at the rear of the crank near the clutch.   Resonance At certain engine speeds the torques imparted by the cylinders are in sync with the vibrations in the crankshaft, which results in a potentially destructive phenomenon known as resonance. This resonance can cause stress beyond what the crank can endure, resulting in crankshaft failure due to fatigue. Robert Bartlett of the noted historic...
How steering columns relate to ergonomics:

How steering columns relate to ergonomics:

Making hot rods a pleasure to live with. By Ben Mozart: If you aspire to own or build a great hot rod, especially a street rod, never take the positioning of a steering column for granted. Variations in cockpit and seat dimensions, particularly seat height, as well as steering wheel design and human proportions play an important role. However enticing the photographs of a machine may be, it is almost impossible to discover if it qualifies on all these counts unless you sit in the vehicle and test it for yourself. Exact steering column location is indispensable. Dave Cattalini of Roy Brizio Street Rods, a company based in South San Francisco that has built 300-plus street rods, reveals their formula. In the trade, they often speak of “drop”, which means the distance between the dash and the steering column. “Where will the seat be mounted?” asks Cattalini. “What is your height—are you 5 feet or are you 6 feet? Do you have short or long arms? Are you using a flat or a dished steering wheel? How much reach do you prefer—you don’t want the wheel to be placed too close or too far away, do you?” To answer these questions Cattalini urges the following: “Get a wooden dowel like a closet pole and to simulate the steering wheel, attach a pie plate to its upper end. Move the mock steering assembly about until you achieve the optimum layout. Then use a piece of 3/4in tape to hold it in place.” While the tape acts as your temporary drop link you can measure your column length, remembering to add...
Competition piston rings and what the OEMs taught us

Competition piston rings and what the OEMs taught us

By Sam Logan:   In our racing world we tend to think of ourselves as the elite corps. But in pistons and more particularly piston ring design, it is not our racing brains that are the driving force but those of the Original Equipment Manufacturers. It would be a glum glimpse of the US racing industry if nothing changed. But it has and nothing could be more illustrative of change than ring development. In fact, if we’re not careful our tow vehicles will operate with 1 x 1 x 2mm ring packs before our race cars. And it’s not just skinny rings that’s been pioneered by the OEMs, the enduring cast iron top and second rings have been replaced by stronger and lighter steel types. Furthermore, thermal face coatings are being applied to top rings by high-velocity oxygen-fueled spray guns at supersonic speed. The force of the collision causes the face coating to become embedded in the rings. What are they seeking? Well, with regard to the thermal face coating, they are pursuing bond-integrity. Second, they are also constantly looking for improvements in overall strength and toughness of the top ring. And third they seek to lower the ring’s coefficient of friction; that is the ratio between the force necessary to move one surface over another and the pressure between the two surfaces. The high-velocity oxygen-fuel technique that applies the thermal face coatings allows the OEMs to run high-tech rings in their latest turbo applications. These are subjected to countless detonation incidents. Tod Richards, a ring specialist at MAHLE, a racer and a race engine builder marveled, “The rings...
Tough NMRA classes beg the question: What is a good clutch?

Tough NMRA classes beg the question: What is a good clutch?

By Fergus Ogilvy:   There are several schools of thought on the question of what constitutes a good clutch. But first there are two separate strands to this narrative that need to be addressed: street or track. It’s key to distinguish whether the car will be used mostly for high-performance street-travel or for track use and its purpose needs to be decided. In either case the clutch has to transmit the car’s horsepower and torque and a stock clutch assembly will flounder in thermal shock and abuse, even in a slightly modified car.   Let’s focus our attention for a moment on selecting a good clutch for a high-performance street car that visits the drag strip occasionally. In this pursuit, the first consideration is usually vehicle weight. Accurate information about the vehicle’s poundage not only guides to the proper selection of an adequate clutch but also has relevance in the selection of the most effective flywheel. Another necessary statistic is the amount of power being transmitted through the clutch. And third, let’s not overlook the gearing. Lastly, pay attention to the size and type of tire conveying the rotational energy to the road or track.   Flywheels and a simple gearing formula Lighter flywheels provoke engine speeds to accelerate and decelerate quicker while the opposite is true of heavier flywheels. Heavier street cars usually benefit from a heavier flywheel, which maintains its advantageous momentum—it inhibits engine speeds from descending too quickly. However, shedding 10 to 15lbs of mass from the rotating assembly of a properly geared vehicle has a pronounced effect on its responses. Hence, lightweight, high-revving race cars...
Remedy for Jeep’s steering ailments:

Remedy for Jeep’s steering ailments:

Solutions all hot rodders should know. By Archie Bosman: Many consider type CJ Jeeps, those in production from 1976 to ’86 susceptible to internal steering column ailments, particularly the open-top models where the column could be exposed to rain, snow, dirt and dust which hastens wear. The wear is not reflected in the steering column’s ability to turn the wheels—instead it’s conspicuous by looseness in up-and-down movement and also back-and-forth within the steering column. Many Jeeps from this era feature a steering tilt mechanism. The significance of efficient steering tilt was brought to prominence by Michigan steering specialists ididit whose history began in the mid-nineteen-eighties. At that time Street Rods were the foundation of their customer base and their multi-angle steering tilt was born of necessity. The chief annoyance among hot rodders was the awkward positioning of the steering column that was installed at a near vertical angle and never conducive to comfortable driving. This inconvenience spawned a succession of multi-angle steering tilt arrangements that increased the angle of articulation of the steering wheel and corrected the impediment. But for Jeep CJ owners, over time the tilt shaft assembly, which was offered originally as an option, became sloppy at the head of the column. The arrangement incorporates two aluminum castings and two shafts, an upper and a lower, both with forked ends. The ends are positioned 90-degrees apart and the assembly is completed with a grooved metal ball that is manufactured in two halves. Of course, the advantage of having access to a replacement steering column with efficient tilt mechanism not only rectifies potential wear troubles but also allows...
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