Testing first small-block Ford Hemi

Testing first small-block Ford Hemi

By Alfie Bilk: If you were seeking a guidebook on how not to carve out a career in motor sport, Greg Brown’s story might be a good starting place. Following two years of studying numerous concepts and with a prototype partially complete, he undertook the daunting task of pioneering production Hemi cylinder heads for the small-block Ford engine in a scant period of just under four and a half months. The processes for developing the rare Hemi included complex scanning to gather CAD data, mobilizing a casting company to create the tangible form and developing a CNC program that would sculpt its final shape. Then, a head was urgently dispatched to Jesel to develop crucial rocker development. With an intuitive grasp of the technical and an eye for future opportunities, what had shaped Brown’s decision? “If I failed to display it at the 2016 PRI exhibition in Indianapolis, I could potentially squander a year,” he said. The performance-minded public, particularly those based in the Northeast is large and active and languishing for a further 52 weeks in obscurity was obviously not an attractive proposition. Even more astounding, word of the unique cylinder head would be released without any convincing proof of a single dyno test. There was simply no time. When the inaugural dynamometer test of the new heads, which were attached to a 427ci World Products block, was eventually undertaken in January 2017, the results were astounding: 604hp and 601lb-ft torque. Astounding because the initial set up was meant to deliver 10.5:1 compression ratio. However, final valve changes were made, which entailed moving the intake valve seats to...
Racing valve springs: Sound rules to remember

Racing valve springs: Sound rules to remember

By Archie Bosman: Before starting this valve spring story, I thought I had a grasp of its mechanics, but then as it developed it became ever more complicated until it reached a point where I doubted if I had any intuitive understanding of how valve springs and their attendant valve gear function! Conveniently, the accumulated reams of research data were simplified when Dick Boyer entered the picture. Here, courtesy of Erson Cams, are several sound rules to remember. It’s a brief insight developed for those interested in high-performance engine technology that explains the severity of the environment in which the valve spring operates, and some of its relationships with the various functions of the valve train. Erson suggests that the primary factors considered when selecting valve springs in a racing engine are, first, the amount of valve lift and, second, engine speeds. As engine speed increases so does inertia, which refers to valve train resistance to changes in speed and direction.   With regard to the valve when fully open—at maximum valve lift—most engine builders desire the valve spring to be almost coil bound. Usually, the spring’s top and bottom coils will be touching with a few coils in the middle presenting a tiny gap that cumulatively amounts to 0.050in to 0.060in. This almost coil-bound condition returns the coil spring to a uniform, stable shape on every closing cycle. If not, the spring exhibits excessive space between the coils and it never relaxes—it constantly shakes and wiggles. Therefore, it could be argued that a valve spring operating at moderate lift that doesn’t close properly is more inclined to ail with...
Mistakes that weaken a supercharger’s performance

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...
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...
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...
Deck wave: What is it and how is it checked?

Deck wave: What is it and how is it checked?

By Titus Bloom: Research of racing parts invariably includes discussions with race engine builders and manufacturers. During their course, jewels of information can emerge, as was the case when we were developing a story following JE’s announcement of their advanced Pro Series head gaskets. Sometimes the gems are universally known sometimes not – still, these recent comments on surface flatness by Dick Boyer, designer of the latest engine blocks from World Products, seem noteworthy. “The profilometer is useful,” says Boyer, “but measuring the scratch depth in a deck surface is usually of less consequence than wave finish. What would be the point of having a beautifully smooth surface with a potentially threatening wave depth of 0.002in or 0.003in? Some builders probably put too much emphasis on profilometer readings and maybe not enough on surface flatness.” How do you check wave finish? “We lay a granite plate with 300-grit sandpaper on the deck of the block and stroke it five times front to rear—you’ll see the high spots, you’ll see the wave, which we measure with an indicator. We aim to limit variations in wave depth to 0.001in. It’s easy to control the prolifometer readings; it’s less easy to control the wave. I’ve seen waves measuring 0.002in which introduce sealing problems.” Boyer on torque-to-yield fasteners “When installed, torque-to-yield fasteners, which are common on road-going vehicles, are stretched to their maximum limit and discarded after use. If the bolts are not stretched to their full extent when the engine reaches normal operating temperature, they stretch a little more and the gasket gets loose. Torque-to-yield fasteners are not common in racing engines.”...