by App Studios | Aug 14, 2013 | Induction, News, Tech How-To |
By Ben Mozart. Pictures by Moore Good Ink: It’s not inconceivable that the induction system of a four-cycle engine just might be its most complicated component. Keith Wilson made a career of manipulating air flow in racing engines. At 17-years old he was employed at a Florida company called Air Speed Engineering. There he spent ten years porting cylinder heads and intake manifolds. Then in 1985 he branched out on his own and formed Wilson Manifolds. Quickly he seized the opportunity to not only rework cast aluminum intake manifolds but also to explore his theories on cylinder filling in conjunction with induction designs constructed of aluminum sheet metal. As you might expect, these are the fundamentals around which Wilson Manifolds has evolved. Recently we sat down with Keith Wilson to hear his thoughts. He began by explaining the most basic: the carburetor spacer. Wilson maintains, “Good spacers are the least expensive form of tuning hardware known to the racer.” A spacer attaches to the intake manifold between the carburetor and the mounting pad, or more precisely the top of the manifold plenum. The charge (the fuel and air mixed together) exits the throttle body or the carburetor and flows through the spacer into the manifold plenum. From there it’s distributed to the individual runners and onward to the ports of the cylinder head. For the best engine performance, the charge distribution in the manifold needs to be even so that each cylinder not only receives the same mixture strength but also uniform volumetric efficiency. If the distribution is uniform but the emulsification of the fuel (the mixing with air) is uneven, performance...
by App Studios | 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 App Studios | Jul 12, 2013 | Carburetors, Tech How-To |
Text by Sam Logan. Pictures by Moore Good Ink. Engines produce vacuum, and over the past 130 years engineers have contrived ingenious ways to advance the carburetor’s powers to match engine developments. Aided by barometric pressure, ignition and compression, the carburetor creates the air-fuel mixture that promotes combustion. What’s more, it mixes gasoline with air in the correct ratio for combusting at varying engine loads, engine and air temperatures and altitudes. Carburetors work by pressure differential; high pressure flows toward areas of low pressure. Through a labyrinth of small-bore drillings in the 4150-style four-barrel carburetor, the vacuum draws a potent mixture of air and fuel. So formidable is the mixture, the carburetor has empowered naturally aspirated full-bodied 500 cubic inch drag racing cars to speeds in excess of 213mph in a distance no greater than 1,320 feet! On starting and at idle, the air speed is too slow to draw fuel from the carburetor’s main jets and through its boost venturii. So idle fuel is drawn from a low pressure area under the carburetor throttle plates, which at idle are almost closed (see illustration No. 3 below). As the engine gains speed, larger throttle openings provide sufficient air flow and the area of lowest pressure switches from the idle discharge ports to the boost venturii (see first illustration), which activates fuel flow through the carburetor’s main jets. On 4150-style carburetors, as displayed in these illustrations, the boost venturii reside within the main venturii and low pressure (partial vacuum) is created by the constricting shape of their bores—the bores’ narrowest part—which causes air speed to increase and, as a result,...
by App Studios | 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...
by App Studios | Jun 28, 2013 | Clutches, News, Tech How-To |
Installation Tips from Ram Clutches: Disengaging the quick-connect feed line when installing a new clutch system with an existing internal slave cylinder/bearing, ensures the bearing assembly remains partially filled with fluid. As a result the release bearing compresses against the clutch fingers as the transmission is being installed and requires more force to slide it in place than desirable. To avoid this hardship, alleviate the unwanted pressure by reconnecting the feed line before sliding the transmission fully into position. Thus the fluid trapped in the bearing can now return to the master cylinder. As the transmission is installed the bearing is preloaded into place. For further information contact: RAM Automotive Company 201 Business Park Blvd. Columbia, SC 29203 Telephone (803) 788-6034...
by App Studios | Apr 22, 2013 | Connecting Rods, News, Tech How-To |
Written by Moore Good Ink: When the crankshaft pulls the connecting rod downward on the induction stroke of a naturally aspirated engine, a stretching load is exerted on the con rod because the piston area is so much greater than the column of air being drawn into the cylinder. In contrast, when the inlet valve is open on a boosted engine, the rod is always under pressure, not a stretching load. Therefore the life of all rotating parts in the boosted engine is significantly prolonged. Of course, there is also a stretch on the rods when the throttles are closed and the engine is decelerating. It’s under these conditions where most con rods fail on oval track cars: when the throttles are closed as the car approaches the corner. Consider that situation for a moment: the piston is sealed to the bore by the rings and the crankshaft is pulling it down against huge resistance. Remember, the throttle plates are closed so there’s not much air pressure in the combustion chamber to assist. A streetable naturally aspirated engine producing 2,000hp doesn’t exist. But if it did you’d be lucky if the engine’s rotating parts survived for more than a few quarter-mile passes. There are, however, large displacement maximum-effort engines operating near this power range, but they are not streetable and only the most durable could complete 50 quarter-mile passes without a rebuild. In contrast, when you boost the engine, it will make this vast amount of power and you could run it on the street. Using lower engine speeds and with less radical valve train it will run for...
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