by admin | Jul 23, 2013 | News, Press Releases |
Race Tech Magazine, July 23, 2013 Life is never easy for the valves in a racing engine. The pounding they received from the rocker arms is merciless, particularly in high revving applications or those where heavy duty valve springs are used. The situation is bad enough with steel or stainless steel valves, but things can reach breaking point when a comparatively soft material like titanium is used. One solution is to beef up the valves with hardened tips, but that only solves part of the problem – you still have a very limited contact area between the valve stem and the rocker arm. Click here to read the entire story online at RaceTechMag.com...
by admin | Jul 12, 2013 | Clutches, Tech How-To |
Ram’s single- and dual-disc assemblies for the Mustang 3.7 V6. By Ro McGonegal: It wasn’t that long ago (2008) when Ford’s 3-valve 4.6 Modular V8 produced 315 horsepower. Now, the 24-valve 3.7 liter V6 in the (2011-13) Mustang generates more than 305hp and 280 lb-ft of torque. To us, that indicates a very sturdy platform for safely increasing output. Concurrently, the ever-rising cost of fuel will likely be a natural promotion for the smaller displacement engine. Invigorate it with a supercharger or some other type of aggressive power enhancement and you’ll be experiencing nearly twice the engine’s original output. Since it is highly unlikely that the OE pressure plates and clutch cover could handle such largesse reliably and repeatedly, Ram offers seven new clutch sets (see chart), each with progressively increased clamping loads that facilitate torque increases from 450 to an amazing 1200 lb-ft. Three are single-disc designs and another four that maintain dual friction discs. All are engineered as direct fitments and each is paired with a billet Ram flywheel. Note that none of them require modifications to the factory release mechanism. Ram’s 10.5-inch single-disc clutch sets are offered as HDX, Powergrip and Powergrip HD and accommodate as much as 650 lb-ft of torque. All Ram flywheels are available in billet, either steel or aluminium. By nature, billet material weighs less than cast iron, so replacing the heavy factory dual-mass flywheel with a Ram billet unit reflects substantial weight savings: 10 lbs for the steel and 22 lbs for the aluminium version. And as everybody knows, a lighter rotating mass invites quicker acceleration. To facilitate even greater increases...
by admin | Jul 12, 2013 | Carburetors, Tech How-To |
Text by Sam Logan. Pictures by Moore Good Ink. Download text and hi-res images here. Engines produce vacuum, and over the past 130 years engineers have contrived ingenious ways to harness its power to the engine’s induction system. Aided by barometric pressure, ignition and compression, the carburetor creates the air-fuel mixture that promotes combustion. Through a labyrinth of small-bore drillings in the carburetor, the vacuum draws a potent mixture of air and fuel. So formidable is the mixture, the carburetor has empowered naturally aspirated full-bodied 500cu in drag racing cars to speeds in excess of 213mph in a distance no greater than 1,320 feet! It works by pressure differential; high pressure flows toward an area of low pressure. On starting and at idle, the area of lowest pressure on a carburetor is under the almost closed throttle plates (see second illustration below) and as the engine gains speed, the area of lowest pressure switches to the boost venturii https://www.glass.net (see first illustration). On 4150-style carburetors, the boost venturii reside within the main venturii and low pressure is created by the constricting shape of their bores, which causes air speed to increase and, as a result, a siphoning effect is introduced at a boost venturi’s tiny air-fuel discharge orifice and through the air-fuel metering circuits back to the fuel bowls. (The faster the air speed passes through the venturii the more fuel is withdrawn from the fuel bowls and thus unleashing optimum engine power.) As the fuel bowls are vented to barometric pressure—an area of greater positive pressure than that of the discharge orifice in the venturii—the air-fuel mixture is...
by admin | Jul 11, 2013 | Engine Builds, Tech How-To |
By Sam Logan, Photography by Moore Good Ink: The world’s first aftermarket Cleveland crate engine was unveiled recently by the Waldorf, Maryland, firm McKeown Motorsport & Engineering (MME). They call it Titus. Though MME’s Titus crate engine distinguishes itself from its mighty predecessor of the 70’s and 80’s in many ways—internally balanced forged crankshaft, deck-plate bored and honed, priority mains wet- or dry-sump lubrication systems and so on—it is the multiple choices of induction systems that set it apart from the conventional crate engine. To this end MME offers five different cylinder heads for five different duties, and they require specific information to select the correct cylinder heads and induction system for every engine. The most important element in building a high performance engine—an engine that accelerates quickly—is to know the crucial rpm range in which it will operate. It’s also helpful to understand that high average power output prevails over peak power output—always—at least in a muscle car if not a dynamometer. In addition to stating the engine’s operating range, which influences the runner lengths of the induction system, MME needs to know the car’s weight. The induction system of a Titus engine powering a 2,000lb Cobra is obviously different to that of a 3,800lb Mustang. Gearing also has an effect on induction choice. For example, a Titus engine powering a gear ratio of 3.25:1, used predominately to propel the car at 1,500rpm along the street, dictates a different cam and induction system to that of one empowering a 4.11:1 gearing, operating at 3,000rpm. Hood clearance is a further consideration, although the Titus’s 9.2in deck height usually provides...
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