MORE ON TRACTION: VHT, DRY TRACK, & RACE TIRE HARDNESS

VHT & METHANOL: Regarding the use of racetrack surface treatments, methanol is a common thinning additive or carrier. It is used by many to spread the treatment out. Many racetracks developed recipes of track surface treatment and methanol mixtures for various racetrack conditions. Royce Miller, Maryland International Raceway, commonly uses 80% VHT and 20% methanol.

VHT AMOUNT & CONTAMINATION: Jim Weinert reports that heavier amounts of VHT are used on cooler track surfaces. Lighter amounts are used for hot days with racetrack temperatures over 100 deg. The supplier of VHT, P. J. Harvey, reports that the content of VHT has not changed in years. The racetrack surface does vary with location, temperature, and dew point. However Weinert also said that chemical studies did reveal a major problem in some cases when VHT was mixed with methanol. Methanol was often contaminated with water. Methanol contaminated with water also contaminates the VHT. That leaves a gooey surface not proper for traction. It was so prevalent that Jim now recommends in seminars to IHRA racetracks not to use methanol or any other solvent as a thinning agent. He recommends only straight VHT.

TRACK PREPARATION ENTITLEMENT: Keep in mind the variability of a racetrack surface from VHT recipes coupled with dew point & humidity, and the track preparation task can become complex. The staff members at IHRA and experienced sanctioned racetrack personnel now handle most of that and minimize the influence on the racetrack surface. Several racers have commented about the superior track surface at a national event compared to local events. Thank you IHRA and the track and keep up the hard work. I know from experience that racetrack preparation is a lot of work, and it is appreciated. We are now a long ways away from full track tire smoke from the 50’s and 60’s.

HIDDEN SOURCE OF WATER ON THE RACETRACK: Over the winter, I walked onto a racetrack surface right after a week of heavy rain. The weather that day was sunny and warm. Unfortunately, ground water had collected under this racetrack surface.

photo: wettrack.pdf

It was seeping out of cracks on the track surface and continued seeping out all day. If this were a racing event, water on the track from this source would have to be mopped up repeatedly to keep the track surface dry. This problem is more prevalent in some tracks than others. It is one reason to walk the racetrack during down time; to see idiosyncrasies such as this. It is caused by a lot of rainwater and the drainage characteristics of the racetrack. One racetrack worker reported that the staff dug up around the track and put appropriate drainage both under the track surface as well as along the sides of the track to eliminate this problem. Drainage is one of those characteristics that racers are unaware of. It is an important characteristic of any track with rainy weather.

RACE TIRE HARDNESS: Drag racers use two types of tires for drag racing traction. (1) Many local bracket and grudge racers use street tires. They are usually hard rubber for wear resistance. (2) Others, as well as most racecars in competition, use drag slicks. They are much softer for more stiction on the pavement surface. New racing tires that I used seem to work well for about 3 months. Then the traction seemed to be reduced. After about 6 months, they were worse. With reduced traction, my car was more prone to tire shake with older tires. I watched the Junior Dragsters measuring tire hardness, so I purchased a durometer and started measuring my tire hardness.

photo: durometer.pdf

THE DUROMETER has a small pointed end from the gage that is imbedded into the tire surface. Depending on the hardness of the rubber, the probe is deflected into the durometer housing. That amount of deflection is controlled by a calibrated spring and measured by a gage.

TIRE HARDNESS: I found that new tires from Goodyear and Hoosier, for my blown alcohol bracket car, measured a durometer reading of about 35 to 38. The variation was from the outside temperature. Hotter weather made softer tires and lower numbers. At this hardness range and a setup for one-second 60-foot times, the tires do not chuck or ball up. They hook up well and bracket & match racing is reliable with new tires. Beyond that time, tuning was more of a challenge. After about 3 months, the tires harden to a durometer reading of about 40 to 43. After one year, they are 45 to 50. After one year, they are a durometer reading of 50 to 54. New tires from Mickey Thompson, for a friend’s Top Alcohol racecar, had slightly higher durometer readings that were around 40 when they were new. However, they did not harden as fast. The racer reported that his setup with MT’s was a bit more “soft” on the launch, but he was happy with the life. Most new tires that I have measured were in the 30’s for durometer readings. Some of the softer tires for the bracket classes were in the low 30’s.

SIDEWALL: In the higher-powered racecars, the condition of the sidewall is important in addition to hardness of the racing slick surface. Many race tires suffer reduced performance from sidewall weakening long before the surface gets too hard. A worn sidewall can result in (a) insufficient tire tread support and (b) more twist flex causing a reduction in reaction time during the launch.

DUROMETER RANGE AS WELL AS SIDEWALL: One national competitor commented that he has to change tires after a certain number of runs because of sidewall flex. He said reaction time is reduced in his 8-second bracket dragster after 30 to 40 runs. The durability of a drag slick sidewall varies for various tire manufacturers, power levels, and chassis & gearing. Some of the Pro Street cars run 10.5 inch wide tires in a racing class with that limit. Those that run in the 7’s and 8’s are reported to have tire sidewall life of about 10 runs. That is a narrow tire for that power level in a full bodied racecar. Top Fuelers report as little as one run up to about 5 runs on a set of race tires at the power levels that they are running. Other racecars that run 5, 6, and 7 second quarter mile times have sidewall as well as tire surface wear limits. Some racers record the number of runs with paint pencil, crayon, or chalk marks on each tire.

JR. DRAGSTERS: Junior dragster tuners use various methods for tire softening. Various tire treatments are on the market. Some need to be applied the day before. Others can be applied an hour before. Some teams use mineral spirits. Others use kerosene. A tire engineer once said that many solvents or light oils soften the rubber surface. Both the Junior Dragster teams and the Go Kart field often use methods to soften their tires. One owner said he softens the tires to a durometer reading of 22 that is very soft. He said that improved eighth mile times a tenth of a second over untreated tires.

The tire engineer did say that while you can soften tires with solvents, what is done to the rubber is untested and an unknown especially if a home brew is used. It may present a safety problem. As a result, he said that is why most tire manufacturers recommend extreme care and even avoidance in the use of solvents or any other fluids for tire hardness control or stickiness. For those who do use tire softeners, the use of a commercial brand from a reputable supplier with a history and application instructions is an alternative.

SPECIAL THANKS to the following contributors for information for this article:
P. J. Harvey, PJH Brands (Supplier of VHT)
Jim Weinert, IHRA Director of Field Operations and PJH Representative

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Top fuel dragster

Top-Fuel Racing refers to a class of drag racing in which the cars are run on a maximum of 85% nitromethane and about 15% methanol also known as racing alcohol, instead of gasoline. The nitromethane used to power the engines of top fuel dragsters costs about US$30 per U.S. gallon (US$8/L). Top Fuel dragsters use between 10 and 12 U.S. gallons (38 to 45 L) of fuel for a complete pass, including the burnout, backup to the starting line, and quarter-mile run. The engine generates about 3.4 times as much power as a similar displacement engine running gasoline.

These cars compete in a 1/4 mile (0.4 km) race and complete it in less than 4.5 seconds at upwards of 330 mph (530 km/h). A Top Fuel dragster accelerates from 0 to 100 mph (160 km/h) in less than 0.8 second, subjecting the driver to a force about 5.7 times his weight. This acceleration takes less than a tenth of the time needed by a production Porsche 911 Turbo to reach the same speed. A fuel dragster can exceed 280 mph (450 km/h) in just 660 feet (0.2 km). The full race distance is 1/4 of a mile, 1320 feet. For further information and standards for drag-racing, including safety requirements, see NHRA

The engine used to power a Top Fuel drag racing car has its roots in the second generation Chrysler Hemi 426 "Elephant Engine" made 1964-71. Although the Top Fuel engine is built exclusively of aftermarket parts, it retains the basic configuration with two valves per cylinder activated by pushrods from a centrally-placed camshaft. The engine has hemispherical combustion chambers, a 90 degree V angle; 4.8" bore pitch and a 5.4" camshaft height. The configuration is identical to the overhead valve, single camshaft-in-block "Hemi" V-8 engine which became available for sale to the public in selected Chrysler Corporation (Dodge, DeSoto, and Chrysler) automotive products in 1952.

The NHRA competition rules limit the displacement to 500 cubic inch (8193.5 cc). A 4.19" (106.4 mm) bore with a 4.5" (114.3 mm) stroke are customary dimensions. Larger bores have been shown to weaken the cylinder block. Compression ratio is about 6.5:1, as is common on engines with overdriven (the supercharger is driven faster than the crankshaft speed) superchargers.

The block is CNC machined from a piece of forged aluminium. It has press-fitted ductile iron liners. There are no water passages in the block which adds considerable strength and stiffness. Like the original Hemi, the racing cylinder block has a long skirt (to reduce piston "rocking" at the lower limit of piston travel); there are five main bearing caps which are fastened with aircraft-standard-rated steel studs; with additional reinforcing main studs and side bolts. There are three approved suppliers of these custom-made after-market blocks, from which the teams may choose.

The cylinder heads are CNC-machined from aluminum billets. As such, they have no water jackets and rely entirely on the incoming air/fuel mixture for their cooling. The original Chrysler design of two large valves per cylinder is used. The intake valve is made from solid titanium and the exhaust from solid Nimonic 80A or similar. Seats are of ductile iron, beryllium-copper have been tried but its use is limited due to cost. Valve sizes are around 2.45" (62.2 mm) for the intake and 1.925" (48.9 mm) for the exhaust. In the ports there are integral tubes for the push rods. The heads are sealed to the block by copper gaskets and stainless steel o-rings. Securing the heads to the block is done with aircraft-rated steel bolts.
 

The camshaft is billet steel, made from 8620 carbon steel or similar. It runs in five oil pressure lubricated bearing shells and is driven by gears in the front of the engine. Mechanical roller lifters, steel push rods and steel rockers are used to actuate the cams. The rockers are of roller type on the intake side, high pressures on the exhaust limits its use to the intake side only. The steel roller rotates on a steel roller bearing and the steel rocker arms rotates on a titanium shaft within bronze bushings. Intake rockers are billet while the exhausts are investment cast. The dual valve springs are of coaxial type and made out of titanium. Valve retainers are also made of titanium, as are the rocker covers.

Billet steel crankshafts are used; they all have a cross plane a.k.a. 90 degree configuration and runs in five conventional bearing shells. 180 degree crankshafts have been tried and they can offer increased power, even though the exhaust is of open type. A 180 degree crankshaft is also about 10 kg lighter than 90 degree crankshaft, but they create a lot of vibration. Such is the strength of a top fuel crankshaft that in one incident, the entire engine block was split open and blown off the car during an engine failure, and the crank, with all eight connecting rods and pistons, was left still bolted to the clutch.

Pistons are of forged aluminium, 2618 alloy. They have three rings and aluminium buttons retain the 1.156" x 3.300" steel pin. The piston is anodized and Teflon coated to prevent galling during high temperature operation. The top ring is an L-shaped Dykes ring that provides a good seal during combustion but a second ring must be used to prevent oil from entering the combustion chamber during intake strokes as the Dykes-style ring offers less than optimal combustion gas sealing. The third ring is an oil scraper ring whose function is helped by the second ring. The connecting rods are of forged aluminium and do provide some shock damping, which is why aluminum is used in place of titanium, because titanium connecting rods transmit too much of the combustion impulse to the big-end rod bearings, endangering the bearings and thus the crankshaft and block. Each con rod has two bolts, shell bearings for the big end while the pin runs directly in the rod.
 

The supercharger is a 14-71 type roots blower. It has twisted lobes and is driven by a toothed belt. The supercharger is slightly offset to the rear to provide an even distribution of air. Absolute manifold pressure is usually 3.8-4.5 bar, but up to 5.0 bar is possible. The manifold is fitted with a 200 psi burst plate. Air is fed to the compressor from throttle butterflies with a maximum area of 65 sq. in. 45.5 Maximum boost, in PSI, produced by the supercharger at wide-open throttle.

These superchargers are in fact derivatives of General Motors scavenging-air blowers for their two-cycle diesel engines, which were adapted for automotive use in the early days of the sport. The model name of these superchargers delineates their size; i.e. the once commonly used 6-71 and 4-71 blowers were designed for General Motors diesels having six cylinders of 71 cubic inches each, and four cylinders of 71 cubic inches each, respectively. Thus, the currently used 14-71 design can be seen to be a huge increase in power delivery over the early designs.

Mandatory safety rules require a secured Kevlar-style blanket over the supercharger assembly as "blower explosions" are not uncommon. The absence of a protective blanket exposes the driver, team and spectators to shrapnel in the event that nearly any irregularity in the induction of the air/fuel mixture, the conversion of combustion into rotating crankshaft movements, or in the exhausting of spent gasses is encountered.

The oil system has a wet sump which contains 16 quarts of SAE 70 mineral or synthetic racing oil. The pan is made of titanium or aluminium. Titanium can be used to prevent oil spills in the event of a blown rod. Oil pressure is somewhere around 160/170 lb during the run, 200 lb at start up, but actual figures differs between teams.

Fuel is injected by a constant flow injection system. There is an engine driven mechanical fuel pump and about 42 fuel nozzles. The pump can flow 92 gallons/minute at 8000 rpm and 500 PSI fuel pressure. In general 10 injectors are placed in the throttle horn above the supercharger, 16 in the intake manifold and two per cylinder in the cylinder head. Usually a race is started with a leaner mixture, then as the clutch begins to tighten as the engine speed builds, the air/fuel mixture is enriched. As engine speed builds pump pressure the mixture is made leaner to maintain a predetermined ratio that is based on many factors, one of which is primary one of race track surface friction. The stoichiometry of both methanol and nitromethane is considerably greater than that of racing gasoline, as they have oxygen atoms attached to their carbon chains and gasoline does not. This means that a "fueler" engine will provide power over a very broad range from very lean to very rich mixtures. Thus, to attain maximum performance, before each race, by varying the level of fuel supplied to the engine, the mechanical crew may select power outputs barely below the limits of tire traction. Power outputs which create tire slippage will "smoke the tires" and the race is often lost. However, as a testament to never giving up, Cruz Pedregon, a Funny Car driver has won two races, years apart, when his car spun the tires during the run, when the OTHER driver also smoked his tires, and they both proceeded down the track, smoking the tires side by side. It was an amazing spectacle to see once, let alone twice. (This is not to be confused with pre-race tire-spinning which heats that tires and smokily lays down molten rubber, which cools slightly, allowing a maximum traction "run" just moments later.)

The air/fuel mixture is ignited by two 14 mm spark plugs per cylinder. These plugs are fired by two 44-amp magnetos. Normal ignition timing is 58-65 degrees BTDC. (This is dramatically greater spark advance than in a gasoline engine as "nitro" and alcohol burn far slower.) Directly after launch the timing is typically decreased by about 25 degrees for a short time as this gives the tires time to reach their correct shape. The ignition system limits the engine speed to 8400 rpm. The ignition system provides initial 50,000 volts and 1.2 amps. The long duration spark (up to 26 degrees) provides energy of 950 millijoules. The plugs are placed in such a way that they are cooled by the incoming charge. The ignition system is not allowed to respond to real time information (no computer-based spark lead adjustments), so instead a timer-based retard system is used.
 

The engine is fitted with open exhaust pipes, 2.75" in diameter and 18" long. These are made of steel and fitted with thermocouples for measuring of the exhaust temperature. They are called "zoomies" and exhaust gases are directed upward and backwards. Exhaust temperature is about 260 °C at idle and 980 °C by the end of a run. A night run provides visual excitement with slow-burning nitromethane flames many feet above this screaming spectacle of acceleration. A "good run" is over in just 4.5 seconds, the noise ends, and braking parachutes are seen in the distance, after a speed of over 325 miles per hour has been reached.

The engine is warmed up for about 80 seconds. After the warm up the valve covers are taken off, oil is changed and the car is refueled. The run including tire warming is about 100 seconds which results in a "lap" of about three minutes. After each lap, the whole engine is taken apart and gone through, and much of it is replaced.


Performance
Power output of these engines is most likely somewhere between 6000 and 8000 horsepower (approximately 4500-6000 kilowatts). This is calculated from performance as these engines aren't tested on a dynamometer. This would suggest a torque output of 5100-6750 Nm (3760-4980 lb-ft) and also a brake mean effective pressure of 80-100 bar.


Engine weight
Block with liners 85 kg 
Heads 18 kg each 
Crankshaft 37 kg 
Complete engine 225 kg.

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Motocross History

istory of Motocross
In 1924, the first known British off-road event known as the Scrambles was held at Camberley in Surrey. This would become the earliest known origin of freestyle motocross as we know it today.
Over the years, the event would evolve, largely through the efforts of riders from Europe who shortened the tracks while adding laps and various obstacles through the course such as jumps.
The sport's popularity would increase during the 1930s, particularly in Britain where events involving teams from various districts and companies would be held regularly. Bikes used in those competitions at the time would be barely distinguishable from those used on the streets.
1950s to 1970s
As the competition intensified and the terrain increased in difficulty, the technology used for the design of competition and special-event motorcycles would improve, particularly with the introduction of the swinging arm suspension during the early 1950s.
The international motorcycling governing body held the 500cc displacement formula European Championship in 1952 that was subsequently upgraded to World Championship status in 1957 followed by a 250cc equivalent in 1962 where two-stroke motorcycles began to make their mark in the industry.
Various companies throughout Europe from countries such as Sweden, Czechoslovakia and Britain thrived by creating models that became renowned for their lightness and maneuverability. The introduced improvements in motorcycles during the 1960s would relegate the older and heavier four-stroke machines to smaller, niche events.
In the late 1960s, companies from Japan would rival their European counterparts in the manufacture and production of high-quality motorcycles for motocross enthusiasts. In fact, in 1970, Suzuki would claim the first world championship for its motherland after being victorious in the 250cc event.
1975 would see the introduction of the 125cc world championship and the sport experienced significant growth due in no small part to the increase in popularity of motocross in the United States. While European riders would continue to excel in events held during the 1970s, the Americans would gradually improve before winning international competitions during the 1980s.
1980s to 1990s
It was during the 1980s that rapid technological enhancements in motocross would take place thanks to the innovation of companies from Japan. These included the creation of water-cooled machines as well as the monoshock rear suspension device.
During the 1990s, new laws were introduced to ensure that the production of four-stroke motorcycles would adhere to environmentally conscious standards.
Motocross Today
Recently, motocross has gradually developed new forms of riding and disciplines ranging from indoor stadium arena events such as Supercross and Arenacross to Freestyle Motocross where riders display an array of skills while performing thrilling jumps and stunt

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NHRA history: Drag racing's fast start

NHRA history: Drag racing's fast start

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Born on the backroads of America in the post World War II years, drag racing's roots were planted on dry lake beds like Muroc in California's Mojave Desert, where hot rodders had congregated since the early 1930s and speeds first topped 100 mph.

Wally Parks

One could even argue that drag racing was born in Goltry, Okla., in 1913, with the birth of Wally Parks, who nearly four decades later would found drag racing's most successful and influential sanctioning body.

Parks' family moved to California in the early 1920s, and Parks had an early interest in cars. He attended his first dry lake speed trials event in the 1930s, which whetted his fascination for performance. In 1937, Parks was one of the founders of the Road Runners Club.

Organized drag racing
In 1947, Parks, a military tank test-driver for General Motors who served in the army in the South Pacific in World War II, helped organize the Southern California Timing Association and later became its general manager.

The first SCTA "Speed Week," held at the famed Bonneville Salt Flats in 1949, was the result of a diligent effort of Parks, then its executive secretary. It was here that racers first began running "against the clock" - actually, a stopwatch - coaxing their vehicles to accelerate quicker rather than simply to attain high top speeds.

The first drag strip, the Santa Ana Drags, began running on an airfield in Southern California in 1950, and quickly gained popularity among the Muroc crowd because of its revolutionary computerized speed clocks.

When Parks became editor of the monthly enthusiast magazine Hot Rod, he had the forum and the power to form the National Hot Rod Association in 1951 to "create order from chaos" by instituting safety rules and performance standards that helped legitimize the sport. He was its first president.

NHRA's first races
NHRA held its first official race in April 1953, on a slice of the Los Angeles County Fairgrounds parking lot in Pomona, Calif. Four decades later, that track has undergone a $6-million expansion and renovation and hosts the NHRA season-opening Winternationals and the season finale, the Automobile Club of Southern California NHRA Finals. The aggressive upgrading of facilities to 'stadium' quality, with fan amenities, VIP towers, and tall grandstands, was the passion of NHRA President Dallas Gardner, who took the reins in 1984 when Parks became Board Chairman. In 2000, Tom Compton became just the third president in NHRA history as Gardner ascended to the role of broad chairman and Parks became chairman of the NHRA Motorsports Museum.

In 1955, NHRA staged its first national event, called simply "the Nationals" in Great Bend, Kan. Six years later, as the Nationals hop-scotched around the country to showcase the growing sport before settling in Indianapolis in 1961, the Winternationals became NHRA's second event.

Incredible success
 Now in its fifth decade, NHRA is the world's largest motorsports sanctioning body with 80,000 members, 140 member tracks, more than 35,000 licensed competitors, and more than 5,000 member-track events.

"No one could have conceived what has happened," Parks said of the NHRA's tremendous growth and success. "But we did have ambitions of its becoming a national sports entity. We weren't planning or marketing geniuses or anything like that. Things happened and we went with our instincts.

"We just had an idea and a strong desire to be self-sustaining ... to control our own destiny and be our own masters. We wanted to build the organization on its own merit. We saw a need -- that being an avenue for safe drag racing -- and with the help of a lot of good people and a little luck we seem to have had some success."

About the term "drag racing"
Although the tiretracks of its history are clear, the origin of the term "drag racing" is not. The theories are almost as many and varied as the machines that have populated its ranks for five decades. Explanations range from a simple challenge ("Drag your car out of the garage and race me!") to geographical locale (the "main drag" was a city's main street, often the only one wide enough to accommodate two vehicles), to the mechanical (to "drag" the gears meant to hold the transmission in gear longer than normal).

The first "dragsters" were little more than street cars with lightly warmed-over engines and bodies chopped down to reduce weight. Eventually, professional chassis builders constructed purpose-built cars, bending and welding together tubing and planting the engine in the traditional spot, just in front of the driver; the engines, and the fuels they burned, became more exotic, more powerful, and, naturally, more temperamental.

Like almost all racing cars, they have undergone tremendous evolution as racers upgraded, experimented, theorized, and tested their equipment.

Safety and innovation paved the way to rear-engined Top Fuel cars in the early 1970s, and once drag racing legend Don Garlits - himself a victim of the front-engined configuration when his transmission, which was nestled between his feet, exploded in 1970, severing half of his right foot - perfected the design, the sport never looked back. Today's Top Fuel dragsters are computer-designed wonders with sleek profiles and wind-tunnel-tested rear airfoils that exert 5,000 pounds of downforce on the rear tires with minimal aerodynamic drag.

As racers became smarter, the speed barriers fell: 260 mph toppled in 1984; 270 in 1986; 280 in 1987; 290 in 1989: and the magic 300 mph barrier fell before the wheels of former Funny Car champion Kenny Bernstein on March 20, 1992. Just seven years later, Tony Schumacher became the first to top 330 mph in February 1999, in Phoenix, Ariz