In previous issues of this magazine we have covered the efforts to break the EV land speed record for cars (Team Vesco, RET 139, May/June 2022) and motorcycles (Voxan, RET 128, December/ January 2021; and 137, February/March 2022; White in RET 135, November/ December 2021; and the outright wheel-driven record holder, with its IC engine, the Speed Demon in RET 134, September/October 2021). The courses over which they run are always long and flat, being several miles long to allow vehicles to accelerate, achieve their highest speeds through a measured mile and then brake to a standstill.
Jack Frost’s bike, with which he aims to break 300 mph from a standing start within a mile, looks surprisingly similar to the Suzuki it is based on (Images courtesy of Holeshot Racing/Harvey Brewster)
In England, Jarrod ‘Jack’ Frost is trying to set a record using a combination of high speed and rapid acceleration, using a machine based on a 2010 Suzuki Hayabusa; the eventual aim is to exceed 300 mph (482.8 kph) from a standing start in less than a mile (1.61 km). Frost uses Elvington Airfield, a former US Air Force and RAF base in the north of England, for his attempts.
The runway is more than 3 km long, and was laid over 60 years ago. A 3 km runway is not especially notable, but long runways tend to be at busy commercial airports or active military bases. Elvington is in neither, and is available for vehicle testing and breaking records. It is also the usual venue for breaking British speed records.
Compared to the much longer salt-flat courses, Elvington has a very favourable surface for any wheel-driven testing or record-breaking that requires high acceleration, owing to its high friction coefficient. The permanent surface is very consistent and can take a lot of abuse, whereas salt flat surfaces have a very variable consistency, the quality and usability of which owes much to the preceding weather. The salt flats also have a comparatively low coefficient of friction, which means that the rate of acceleration for wheel-driven vehicles is limited to lower values than is possible on permanent, paved courses such as Elvington.
Frost has been trying to raise the bar for this record for some time, and it currently stands at 274.926 mph, which Frost achieved recently at Elvington. He has two rivals in his quest to reach 300 mph from a standing start within a mile: Frenchman Philippe Le Peru and former Isle of Man TT racer and daredevil Guy Martin.
All three riders use machines of the same basic specification and all are built by Frost’s business Holeshot Racing. The main differences between the machines are aerodynamic, with each rider choosing and developing their own aerodynamic body kits.
Martin’s machine is notable for its large, blunt nose and conventional streamliner rear end. While that approach might be more aerodynamically efficient, with the aim of producing a lower product of front area and drag coefficient, the penalty is that it is more susceptible to cross-winds, given its much greater lateral area. It can thus be more difficult to control than Frost’s machine in similar conditions.
A happy Jack Frost clutching his time card recording 274.926 mph at one mile and 244.029 mph at the half mile from a standing start. With extremely high torque and very little help from electronics aids, accelerating to these speeds in such a short distance is not easy
Given that a key driver of performance in terms of acceleration and top speed is the confidence of the rider to keep the throttle as wide open as possible for as much of the run as possible, any of their concentration ‘bandwidth’ which has to be devoted to keeping the bike in a straight line in the middle of the runway has to be distracting.
Riding fast in a straight line is often denigrated as being an easy, straightforward exercise, but the number of racers seriously injured or killed doing just that is not insignificant, and Elvington has claimed the lives of experienced competitors. Frost himself notes, “For me, riding the bike is difficult as I have many previous injuries, and it can be hard fighting the wind as there are often side winds at Elvington.”
Frost has therefore sacrificed some possible aerodynamic advantage in order to make the bike easier to ride in a wider range of conditions. His bike is fairly unusual for a speed record-breaker: it does not run extreme streamlining, nor is it of the ‘long and low’ configuration as favoured by Voxan/ Venturi for their EV motorcycle speed-record machine in both streamlined and non-streamlined guises.
If you saw either the Voxan or White speed record bikes on the street, they would really stand out as something unusual. Frost’s bike is much less conspicuous: the bodywork is conventional, as is the rider’s position and chassis. Although longer than stock, the bike’s wheelbase is not really much longer than would be found on machines entered in road-bike classes in sprints and drag races.
The machine is certainly not standard in terms of chassis configuration though, nor is the rider position, although for a record-breaker it is fairly close in appearance to a road machine. The front forks are dropped through the yokes to lower the front of the machine, and its rear is similarly lowered.
This aids traction, as per the use of the ‘holeshot devices’ as developed in motocross and MotoGP, and critically also allows the motorcycle to present a slightly smaller frontal area. Frost has also replaced the bulky standard fuel tank with something much lower, allowing him to adopt a much more aerodynamic posture than would be possible with the standard fuel tank.
I asked Frost about the chassis modifications and their effect on performance. It is quite usual to extend the wheelbase of a motorcycle used at high speed because it improves its stability, making it more controllable and easier to ride.
However, by simply extending the swinging arm at the rear of the machine (the articulating fork to which the rear wheel is mounted), the centre of gravity of the machine moves forward, meaning that the rear wheel becomes less heavily loaded and therefore provides its own limit on traction.
The limiting torque at which tyre slip (wheelspin) occurs is proportional to the force acting downwards on the contact patch of the rear wheel (through which the motorcycle is driven). Frost says, “My chassis is 40 mm over stock length at the rear. Ideally it would be longer for stability but then there is a trade-off against grip.” The only way to offset that lack of grip is to try to put more weight on the rear, but that negates the positive effect of extra stability achieved through lengthening the swinging arm.
The engine Frost uses is based on the standard Suzuki Hayabusa. This engine, like some of its Suzuki forebears, is blessed with a very strong bottom end, which is why so many motorsport engines are based on Suzuki road bike engines. They are durable and can withstand a lot of tuning work without becoming unreliable, making them attractive in many racing disciplines.
Rather than taking the popular route of big bore and long stroke, Frost requires a fundamentally greater jump in output from his engine than is practical from stretching the standard 1340 cc engine to 1600 or 1700 cc. He has turbocharged it to produce an astounding 800 bhp (600 kW) and 385 lb-ft (522 Nm).
The standard 2010 Hayabusa had a reported 194 bhp and a top speed of 185 mph. Using a simple rule of thumb, and given a sufficiently long track, Frost’s engine should push the standard road bike to 295 mph. However, he has achieved 274.9 mph, which reflects the limited distance over which he has to run, despite the bike accelerating to 250 mph in a mere 13 seconds.
The very limited run duration allows Frost to use a small fuel tank. A single welded structure contains the tank at the front, and there is a pressurised plenum at the rear with the fuel rail exposed and mounted to the roof of the plenum. The engine is extensively modified, although it retains its standard 1340 cc displacement, and uses the original 81 x 65 mm bore and stroke. It uses a knife-edged crankshaft and aftermarket rods from CP-Carrillo. Pistons are CP-Carrillo, and need to cope with very high cylinder pressures and temperatures.
The engine assembly is held together by special heavy-duty fasteners to keep the cylinder head and main bearing caps in place under the much higher than normal loads. The heads are ported, the valves are 1 mm larger than standard and are made from Inconel, which is capable of dealing with the higher temperatures in the turbocharged engine.
The valvetrain features billet camshafts from Kent Cams, uprated valve springs and titanium spring retainers from APE Race Parts. Transmitting the power is taken care of by an MTC multi-stage lock-up clutch assembly that features a billet clutch centre and basket. Once engaged, lock-up clutches prevent any clutch slip, but that also removes an element of rider control in not being able to slip the clutch after engagement.
Compared to a single or dual-stage lock-up clutch, the multi-stage clutch allows a small degree of rider control as the clutch does not become fully locked as quickly (as would be the case with single or dual-stage lock-up options). This removes some of the risk of the bike flipping if all the torque is suddenly applied at launch.
Given such a short run, it is important to maintain drive for as long as possible, and this is the subject of a lot of effort on Frost’s part. The standard transmission for a road bike is 1-N-2-3-4-5-6 – that is, the rider presses the gear pedal down to select first gear from neutral and then each subsequent higher gear is selected by lifting the gear pedal up.
Sequential transmissions like this risk selecting neutral between first and second gears, so Frost has commissioned Nova Racing to produce a transmission cluster and reconfigured selector so that neutral is only next to first and not between first and second gears, although he has chosen to maintain the standard Suzuki gear ratios.
The selection of gear ratios is by an air shifter. Pressurised air is stored in the swinging arm, and the air shifter helps to keep gear change durations to the absolute minimum. This is important not only for maintaining drive but to maintain boost pressure.
In order to change gear with a sequential gearbox, it is necessary to reduce the loads on the gear selector mechanism, and this involves reducing engine torque by fully or partially closing the throttles or through an ignition cut. For the period where the engine load is reduced, there is also a reduced flow of mass or energy through the turbine, so the turbocharger loses speed, and boost is temporarily reduced at the point where load is reinstated.
In addition to minimising the gear change durations during a run, Frost must try to keep the bike accelerating at the limit of traction. With the huge torque available to Frost, there is the added risk of the bike over-rotating – flipping over – about the rear axle.
Many modern bikes have a degree of anti-wheelie control, but Frost is effectively relying on rider ‘feel’ to get the best out of his machine. The relatively early generation of Suzuki Hayabusa he uses does not benefit from drive-by-wire electronic throttles, so one of the main controls over output torque is not available.
Frost has a lot to think about in keeping control of the bike during a run. Even though there remains a lot of reliance on the rider to control the engine during a run, some of the work is done electronically. Frost uses a Syvecs/Life Racing ECU.
Life Racing has a very capable set of engine control tools, and the Syvecs ECU is perfect for the Hayabusa as it does not require the larger number of inputs and outputs required for a twin-turbo V8 with multi-point injection the full Life Racing F88 is capable of.
Frost uses closed-loop lambda control and boost control per gear against engine speed, manifold air pressure and throttle position. The closed-loop knock control developed by Life benefited from sister company AER’s turbocharged endurance engines being tested in the same building. In order to wring the maximum performance from these engines, a very capable knock control system was required to allow the engines to run continuously right on the very edge of knock.
The bike has front and rear wheel speed sensors and a four-axis g-sensor, allowing the control system to know the attitude of the bike and the degree of wheel slip. In an ideal world, these could be used for traction control, launch control and anti-wheelie.
However, Frost notes, “The track at Elvington is too inconsistent, so I have these turned off and just ride the bike on feel.”
Frost’s day at the track is also relatively easy in terms of machine adjustment. “I change the gearing to suit the conditions but that’s usually only one rear sprocket tooth change.” His running costs are also relatively modest. “I usually have to run two rear tyres so I use two rear wheels,” he says.
Within two hours, Frost had six runs between 267.957 mph and 274.926mph, significantly faster than most people will travel in their lifetime on land. Small adjustments to the motorcycle, engine boost and controls take place between runs
Other than gearing, there are only minor machine adjustments “I also make suspension and height adjustments on the day,” he says. “Engine control is done through the electronics. We don’t adjust much other than slight changes to boost on the day.”
The costs of entering a motorcycle for a complete weekend-long organised event are similar to those for a motorcycle race at ‘club’ level.
Considering that Frost’s engine is producing performance several times in excess of the standard specification, I asked him about durability. “My engine is very reliable, the bike has done all last year and this year and also a few drag races, so at least 100 runs. It has been stripped once during this time to give it a check over.” However, he says he would strip the engine for internal inspection if there was any serious knock detected or a change in oil pressure.
Summary
Jack Frost is trying to raise the bar for a relatively unusual record. The aim of achieving the maximum velocity at the end of a measured mile requires not only high performance from the engine but for the rider to be confident and able to accelerate at the maximum rate throughout.
The end of a successful day, with another record achieved. Frost and others, among whom Frost is the fastest, aim to reach 300 mph from a standing start within one mile
In this respect, the record is a different discipline to conventional speed record-breaking. There is an emphasis on being able to maintain the maximum acceleration from the moment the bike leaves the line to the end of the timed section of the course. Although the ECU Frost uses allows a large degree of engine control, many of the features aren’t enabled because the inconsistencies of the course surface would require a lot of set-up and constant tuning.