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V&H’s new rider Gaige Herrera, on the 2023 Suzuki-inspired billet-engined Pro Stock Motorcycle drag bike, has received the primary three NHRA nationwide meets this 12 months.
I flew to Charlotte, North Carolina (web site of occasion 2), to speak with Andrew Hines and Eddie Krawiec, who’re each former PSM champions and are actually managing the group.
Krawiec started by saying that to him, there’s nothing too demanding or particular about using the bike. What fascinates him and attracts him ahead is the unrolling of the long run within the type of improvements devised by the persevering with dialog between the 2 of them.
He additionally made it clear that sheer efficiency can not win nationwide titles by itself. It is just one a part of an general racing course of, which, run after run, returns a constantly aggressive bike to the beginning line for the subsequent cross.
An instructive aspect in that is the clutch, which have to be inspected and presumably adjusted after each run. It comprises no springs; the stress that compresses the plate stack to ship torque from the engine into the V&H six-speed transmission comes solely from centrifugal weights that spin with the engine-driven a part of the clutch.
Krawiec described the motion of the clutch as feeling like a torque converter, as it’s flyweighted to maintain engine rpm in its vary of most torque.
Clutch entry requires the exhaust collector to be eliminated, adopted by the eight fasteners retaining the clutch cowl. The bike is angled a number of levels to the left on its stand to forestall oil loss from the open clutch cavity on the correct aspect. Subsequent 12 months’s design will get rid of having to drag the collector by offering a smaller “jockey cowl” above the collector.
I noticed that there aren’t any gaskets to trigger delays.
“We bought uninterested in gaskets,” Andrew stated. “There aren’t any gaskets on this engine; we O-ring all the pieces.”
Every bike carries a data collection system that presents the group with a steady file of engine rpm and different variables throughout every run. Skilled evaluation of the recorded knowledge can result in including or subtracting weight from the clutch arms, or to different adjustments. Every of the 4 stepped header pipes within the exhaust system carries its personal oxygen sensor, making it attainable to deal with the four-cylinder inline engine as 4 separate engines, every with its personal explicit wants.
The brand new engine may be very tall and its weight is packaged ahead—extra ahead than is feasible for the billet twins. That is doubtlessly necessary in a drag racing class restricted to a 70-inch wheelbase.
The Suzuki Engine’s Roots within the Previous
Though NHRA for product identification causes should name this bike “Gen III Hayabusa,” and regardless of its carrying bodywork “impressed by” that of the brand new Hayabusa, the all-billet engine stays a conceptual descendent of the unique GS750 and 1,000cc engines of 1976 and later. It retains that design household’s center cam drive and its pressed-together nine-piece curler crankshaft—regardless that the manufacturing Hayabusa’s cam drive is at one finish of a one-piece plain-bearing crank. This has been accomplished to protect elements interchangeability with the numerous engines for which V&H presently provide racing elements and providers (I realized they service 800 to 1,000 buyer cylinder heads annually).
The unique GS1000 engine’s bore and stroke have been 70 x 64.8mm, however NHRA’s actions taken to regulate parity inside PSM over time now permit 89.5 x 73.4, giving 113ci. For that displacement with 4 valves per cylinder, NHRA imposed a 630-pound minimal weight. Lightest within the class is the restrict for 2V or 4V Kawasaki fours, at 107 cubes and 575 kilos.
Efficiency
Energy? I used to be informed “greater than 400 hp at 14,000.” For all you folks who grew up being informed piston pace reaches a restrict at 4,500 ft per minute, that may be a piston pace of 6,740 ft per minute, or 50 % greater than that supposed “restrict.”
The result’s elapsed instances within the excessive sixes. An “incremental time report” offers extra knowledge than the straightforward “time slip”—telling us that the primary quarter of the strip (1,320 ÷ 4 = 330 ft) takes roughly 2.8 seconds for a PSM to cowl, then 1.5 seconds for the second 330, 1.3 seconds for the third, and simply over 1.1 second for the fourth.
The Six-Velocity Gearbox
Though the unique GS Suzukis have been five-speeds, the narrower vary of this engine—robust from 11,800 to 13,800—requires a six-speed. V&H machine gear blanks together with the canines. Then items requiring inner splines are despatched for broaching and the gear tooth are lower by one other specialist. The completed elements are then heat-treated. To make six gear pairs match right into a five-speed house, the peak of the participating canines has been decreased.
In keeping with the idea of minimizing turnaround time at occasions, this six-speed seamless-shift gearbox is constructed as a “cassette” which may be extracted from the engine case with each shafts and their shift drum on a “door” in 10 minutes. As a subsequent step they plan to make a brand new “door” that can accommodate six speeds with full-height participating canines.
Seamless Shifting
To keep away from the “interruption of service” that happens as a traditional gearbox first disengages the gear pair which can be driving the bike, then engages the next-higher ratio, drag bike gearboxes are in-built so-called “seamless” trend. In a seamless field, the subsequent gear is engaged with out first disengaging the ratio that had simply been driving. Usually, this might lead to a double engagement and a transmission lockup, however modifications are made to forestall this.
The non-driving faces of the engaging dogs are lower as angled ramps, in order that because the gear pair that had been driving rotates backward, the ramped dogs kick it out of engagement. An altered shift drum is required to allow this.
First and high gear lack the disengaging ramps. Small springs guarantee that the gearbox will “reset” for the subsequent run.
Hines invited me into the truck, the place he was making adjustments to a six-speed, and I used to be capable of see the main points of its building. The V&H truck is like all such automobiles, being supplied with lighted workbench house on either side, under that are drawers containing elements and gear. Once I requested if I would see a piston or different inner elements, the reply was that as a result of nobody has time for engine service at occasions, solely full spare engines are carried.
Gear altering is pneumatic by way of a button on the left bar, sending air stress to a cylinder beneath the left aspect of the engine, working the shift lever.
The Cylinder Head
The cylinder head now has 16 valves, consumption diameter being “within the excessive 30s” and the exhausts “within the low 30s.” All are operated by F1-style light-weight finger followers slightly than by the cylindrical tappets used previously.
Billet drag engines don’t have any cooling system—no fins, no water jacket. Warmth generated throughout every run is absorbed by engine mass, and is then cooled within the work space by blowers. Throughout every run, cylinder head temperature rises, however sufficient materials is offered to forestall its rising excessive sufficient to impress detonation.
The current curler crankshaft can be made by V&H, assembled and trued on gear designed and constructed in-house. Andrew Hines stated the “flywheel wedging instrument” on this setup, created in 2009, was his first CAD challenge, using a brake caliper piston to exert the crank truing power.
Accepted Gasoline
Hines referred to a collection of NHRA-approved racing gasolines they’ve run in PSM engines. Gasolines are tailor-made to the appliance: Pump fuel, for instance, is given higher volatility in winter to supply fast beginning, however much less volatility in summer season to keep away from vapor lock.
In racing, use of high compression ratios will increase torque, but additionally makes damaging detonation extra probably. The protection towards that is to lift the fuel’s octane number (ON, a measure of detonation resistance). However this in flip turns into an issue as a result of probably the most detonation-resistant gasoline elements are bigger molecules which lack volatility (the boiling level of toluene, which has a excessive ON, is up at 231 levels Fahrenheit, and that of octane is 258 levels). What this implies is that if you happen to single-mindedly design a gasoline to have the best attainable ON, it could evaporate poorly, leading to a slower-burning lean combination.
So a compromise is made: boosting ON with pretty heavy gasoline elements, however taking care to keep up volatility by including mild fractions like butane (ON ~ 92).
So necessary to efficiency are these variables that V&H have studied combustion utilizing combustion chamber stress transducers from Austrian growth, simulation, and testing agency AVL to file simply how briskly or gradual combustion is with totally different fuels.
Let’s evaluate the volatilities of two kinds of gasolines—Sunoco’s SR18, used within the unsupercharged Professional Inventory Bike class, and VP’s C16, blended to be used in turbocharged racing courses.
SR18 may be very unstable, with an preliminary boiling level of 99 levels Fahrenheit and a closing boiling level of 223 levels.
C16 is way much less unstable, with an preliminary boiling level of 193 levels Fahrenheit and a closing BP of 351.5 levels.
Why the large variations? The gasoline utilized in unsupercharged PSM engines has solely the engine’s pure warmth and consumption turbulence to evaporate it. However in a turbo engine, with its compressor spinning at a zillion rpm, producing further warmth and turbulence, a heavier and fewer unstable gasoline, its composition extra tightly targeted on highest attainable ON, may be evaporated to type a fast-burning fuel-air combination. With all that “assist” a turbo gasoline doesn’t want to spice up its evaporation with elements having excessive volatility however missing 10–20 factors in ON.
Tubular Metal Chassis
As per NHRA regulation the Gen III Hayabusa’s chassis is 0.058-inch wall chromoly welded metal tubing. It’s a twin loop design with its two higher tubes arching up over the engine. A light-weight telescopic fork with twin discs completes the entrance finish, and the rear is inflexible, supporting the 10-inch-wide slick with out suspension. To deliver the chain line far sufficient to the left to clear the tire, the transmission’s output shaft is made extra-long, nicely supported by an outrigger bearing within the body itself.
Between the engine and rear wheel is an open bay within the chassis occupied by two batteries, a crankcase evacuation pump, and an oil separator. One battery serves the engine and its programs. The opposite drives the fairly loud pump (Hines demonstrated it!). Crankcase evacuation reduces friction loss by making it attainable to run lower-pressure oil scraper rings (as used on late Honda RC45 World Superbike, Yamaha’s M1 MotoGP engine, and so forth).
The Mickey Thompson slick is mounted on a sheet metallic disc wheel. Hines commented that there’s various air quantity within the wheel itself, and that if the quantity of inflation air have been decreased it might change the tire’s spring fixed.
What Does “Inventory” Imply?
Eddie Krawiec described the method by which NHRA maintains the visible connection between the drag bike’s bodywork, which is essentially longer and decrease, and that of the inventory bike. Two apparent options of the brand new manufacturing bike—the “aspect gills” and cobra’s head seat again—are preserved within the race bodywork, as is the ever-greater diploma to which the fairing is coming ahead to “eat” the entrance wheel. The windscreen on this bike is a inventory Hayabusa half!
Making a Bike Go Straight at 200 MPH
He additionally famous, “It’s very easy to make a good condition unhealthy in a rush.” To forestall this, V&H digitized the bodywork’s form in an effort to make its two sides similar. Increasingly more typically now, PSM bikes are reaching 200 mph, at which Hines notes the ram stress of air is 7/10 of 1 psi. If that stress acted over a 5 sq. foot (= 720 sq. inches) bike frontal space, the drag power could be 720 x 0.7 = 504 kilos. Streamlining reduces this power significantly, however you’ll be able to see how a scarcity of “drag symmetry” may exert a power giant sufficient to make a motorbike onerous to steer at pace.
The Consumption System
Digital gasoline injection is authorized in PSM, so precise carburetors have change into uncommon (though on some engines, flat-slide Lectron carburetors are used as gasoline injection throttle our bodies). This bike has immediate throttle response, producing a brain-drilling sound depth. Though butterfly throttles are the current bike trade norm, this bike has pivoted-gate throttles that cross air round solely a single edge, not the 2 edges of a butterfly. In an engine combining giant bore (over 3-1/2 inches) and excessive rpm it’s important to attain the very best mixing of gasoline and air as far upstream as attainable. Any gasoline that fails to evaporate by the moment of ignition can have the impact of leaning out the combination.
I requested Hines about intake port downdraft angle: Is it close to zero like that of the unique GS engines (to make their carbs match beneath a conventional fuel tank), or is it steeply downdraft as in current Japanese sportbike design?
“It’s neither the one nor the opposite, however someplace between,” was his response.
In an earlier dialog final 12 months I had requested if he’s contemplating the adoption of a one-piece plain-bearing crankshaft.
“I give it some thought on a regular basis,” was his response.
It could arrive as quickly as subsequent season.
Many times in these conversations I may see that the foremost asset V&H brings to Professional Inventory Bike will not be an enormous truck backed up by machining facilities and superior tooling. It’s the gathered expertise of those folks, their curiosity about each outcome, and persevering with examine of trigger and impact which have made their work profitable.
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