Hammerhead Hemi peaks 928hp: 427ci SB Ford

By Freddie Heaney: The sound of the dyno approaching 8,000rpm was almost ear splitting. It was the first Friday of June and sitting in an open wooden-framed space at Charlie Pepper’s engine shop in Auburn, near Atlanta, Greg Brown’s innovative Hemi heads on a Man O’ War 427ci small-block Ford peaked at 928hp at 7,700rpm and generated a maximum torque figure of 674.0lb ft at 6,000rpm. Watch the video. When first tested in mild street form with around 9.5:1 compression ratio the combination yielded 602hp. Quite the accomplishment for unique and previously untested cylinder head designs. But it was not the main event nor might this be. Now, around six months later and using ported heads and intake manifold, higher compression ratio and bigger carburetor, but still employing the same stock-size valves (2.200-inch intake and 1.650-inch exhaust) the engine began the afternoon tests by generating peak power figures in the 850hp range. But with incremental timing and carburetion adjustments it eventually made its way up to a mighty 928 horsepower. Inevitable, I asked? “No, not at all, replied Brown. “Though we increased the flow in the ports from 382cfm / 260cfm to 435cfm / 290 (inlet and exhaust respectively), I would have been happy with peak horsepower numbers of around 850. Remember, ninety percent of all high performance wedge-style cylinder heads rarely exceed 800hp.” Of even greater significance, perhaps the 1250cfm Dominator-style carburetor had proved to be too small during the tests and will be replaced by another that’s capable of generating air flow of around 1450cfm. Was the 1250 carb an ill-advised choice perhaps? “No,” said Brown, “this... read more

Comparison: Testing a TorqStorm

But the best part was the TorqStorm’s ability to generate 400lb ft torque at 2000rpm; its rival reached 400lb ft at 2500rpm. At 3000rpm the ‘Storm generated 484lb ft compared to the Vortech at 436.

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Unique buttons: piston pin retention designs for Pro Mod and big turbos

By Freddie Heaney: Denver Colorado: Gibtec Pistons has announced unique piston pin retention buttons. Their latest design for Pro Mod and big turbo racing engines incorporate a radial locking feature. The advent of the piston button and its subsequent popularity came about because of the convenience it offers. Changing pistons with buttons not only reduces the time taken to replace pistons at the race track but also ends the frustration of fiddling about with round wire locks or the double spiral types. “Some years ago when we were developing the original concept,” says Gibtec Piston’s Robbie Giebas, “the button seemed to offer a further advantage. Where the piston pin bore breaks into the oil control ring groove, we thought the button would prevent the expander in the oil control ring from distorting around the half-moon opening, a deficiency particularly prevalent in power adder engines.” Though partially true, they later discovered the button could, in fact, damage the oil control ring by pushing upward or rotating against it or a combination of both. Now  with an innovative radial locking mechanism, Gibtec has filed a patent to protect the design. The patent, apparently, is more extensive than a utility patent but also includes concept coverage.   Rob Giebas and Gibtec’s ascension by agility and intellect It was a decisive moment when in 2013 the then 40-year-old Detroit native founded his piston-making venture in Denver, Colorado. The formation of any new business is almost always a protracted struggle, and Gibtec Pistons’ prospects were no less challenging; how could it survive in a diminished market? In fact all markets were dealing with vast cultural changes but... read more

The anatomy of the supercharger or what makes it tick

By Titus Bloom: Superchargers are magical devices. They increase the oxygen supply to the engine by compressing the air, thus increasing its density. Accordingly, the engine burns more air-fuel mixture and produces more power. In a centrifugal supercharger, the air is propelled through the compressor wheel and compressed in the diffuser—the thin passage formed between the compressor cover and the bearing housing—and in the volute or scroll where its kinetic energy is converted to pressure. All of the dimensions, including the diameter of the diffuser, diffuser gap distance, size and diameter of the volute, contribute to the degree of compression. In a turbocharger—exhaust-driven forced induction—the compressor wheel is powered by exhaust flow, but in the supercharger the compressor wheel is driven via a gearbox that takes its power from a crankshaft pulley by way of a drive belt. The gearbox accelerates the compressor wheel from engine speed to a point where the compressor operates efficiently. Here below is the assembly process:                                         Source: TorqStorm Superchargers Rick Lewis (616) 706-5580 Sales@TorqStorm.com... read more

Mistakes that weaken a supercharger’s performance

Bertie S. Brown: TorqStorm Superchargers’s product manager, Chris Beardsley, has dealt with thousands of incoming queries in the first decade 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 Chris Beardsley. “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 aluminum cylinder heads, and a blow-through carburetor or venturi-style throttle body fuel injection,” insists Beardsley, “ 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 temperatures.” 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 Beardsley. “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 intake manifold below the carburetor throttle plates. In this way it reads boost and increases the... read more

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... read more

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... read more

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... read more

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... read more