IMSA 2017 Prototype Tech Profile: Riley/Multimatic Mk 30

IMSA 2017 Prototype Tech Profile: Riley/Multimatic Mk 30

IMSA

IMSA 2017 Prototype Tech Profile: Riley/Multimatic Mk 30

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Take a look inside each of the brand-new cars that will comprise IMSA’s WeatherTech SportsCar Championship Prototype class in RACER’s six-part technical preview leading into the Rolex 24 at Daytona.

Tech Profile #1: ORECA 07
Tech Profile #2: Ligier JS P217

ORIGINS AND PERFORMANCE:

The North American combination of Riley Technologies and Multimatic have come together to produce the only P2-based 2017 model built in a collaboration between two manufacturers.

With Multimatic’s large-scale composites capabilities in Canada, the firm took responsibility for the Mk 30’s carbon fiber tub, bodywork and aerodynamics. From its base in North Carolina, Riley Technologies designed and manufactured the majority of the mechanical components on the WEC P2 Mk 30 chassis. From the Mk 30, the partners also produce the RT24-P Daytona Prototype international variant for Mazda.

With one team using the Mk 30 in IMSA, the primary development for the WEC-spec P2 is taking place in with Visit Florida Racing. Although the Mazda Racing team is able to help with feedback on the non-DPi aspects of the car, that leaves VFR to explore the Mk 30’s WEC aerodynamics and learn how its impacts the car’s overall performance with the spec Gibson V8 motor in the back of the car. Together, Mazda and VFR have kept each other abreast of any chassis-related problems, which proved to be valuable when a right-front suspension control arm failure on the Mazda at Daytona led to sharing the information and the immediate stoppage of testing. New, fortified pieces were then sent by the manufacturer for both teams to use and testing resumed.

One development issue – gearbox cooling – hampered the Mk 30 and RT24-Ps in testing, but those issues were reported to be resolved before the end of the Roar.

Of the three WEC P2 models and the three DPis, the Mk 30 stands out for its highly conventional shape among 2017 cars. Riley’s cars have always placed a higher value on straightforward, user-friendly designs, than pushing the outer conceptual limits, and with that core philosophy in mind, almost everything about the Mk 30 appears to adhere to that standard.

Like many IMSA Prototype teams, the late arrival of 2017 cars has left entrants like VFR with a significant learning curve to overcome and very little time to reach the peak before the green flag waves at Daytona. The Mk 30’s performance at the mid-December Daytona test and again at the three-day Roar Before the 24 test spoke to the new-car discovery process taking place, and while the car has yet to demonstrate class-leading speed, valuable gains were made by the end of the Roar.

Of the six prototype models, the Mk 30 ranked fifth among fastest laps at the test (only Nissan, with its newborn DPi, was slower). Although being the fifth-fastest chassis is far from optimal, the gap to the class-leading model, ORECA’s 07, was reduced to 0.579s by VFR on Day 3 at the Roar. Prior to that session, the margin ranged from 0.9 s to 2.4s.

What remains unclear is how much faster the Mk 30 can run at a unique track like Daytona, where the ability to make extreme drag and downforce reductions plays a major role in saving time on the long banking sections.

One commonly held belief in the paddock is the car’s base downforce and drag levels are higher than the other models, meaning it could be a challenge for the Mk 30 to reach down to the same level of slipperiness the other cars can achieve.

An interesting example of this was temporarily seen with IMSA’s initial Balance of Performance tables for the Roar. The Mk 30, in that first BoP document, was granted a few aerodynamic options that spoke to improving its straightline and top speed performance against the other WEC P2s. Owing to an agreement with the ACO/FIA to perform zero performance balancing among WEC P2s, a second BoP document soon followed with the Mk 30’s special aero allowances removed.

With the revised BoP in place, the Mk 30 recorded the slowest top speed of any model at the Roar. In an interesting twist, the Mk 30-based Mazda, with its custom DPi bodywork, was fastest.

Considering the overall lap time achieved by the car, the Mk 30’s performance on the infield road course – where higher downforce helps – allowed the VFR car to shine. Under braking, and while cornering, the Mk 30 is hard to match. Once the season moves from the missile-like aero needs of Daytona to circuits like Sebring, Monterey, Detroit, and other venues where higher downforce is a benefit, the VFR team should have a car contends for wins.

DAYTONA TEST PERFORMANCE NUMBERS

The aforementioned six prototype models were represented by 12 cars entered at the Roar (3 x ORECA 03, 3 x Cadillac DPi.V-R, 2x Mazda RT24-P, 2 x Nissan Onroak DPi, 1 x Ligier JS P217 and 1 x Riley/Multimatic Mk30).

MK 30’s Fastest Roar Lap: 1m38. 922s (P5 among the six models, P7 of the 12 cars, -0.579s to the fastest lap set by the ORECA 07)

MK 30’s Best Roar Top Speed: P12, 188.3 mph (-8.8 mph to the top 197.1 mph set by Mazda’s RT24-P)

NAMES AND SPECIFIC VEHICLE DATA

Lead Chassis Designer(s): Bob and Bill Riley

Lead Aerodynamicist(s): Mark Handford

Transmission Vendor: Xtrac

Brake Package Vendor: Brembo Calipers with carbon Hitco discs and pads

Data and ECU Electronics Package Vendor: Cosworth (spec)

Engine displacement and cylinder count: 4.2-liter V8 by Gibson Technology (spec)

Engine air induction system: Naturally-aspirated

SPEC 2017 P2-BASED DATA FOR EVERY PROTOTYPE MODEL

Minimum Weight: All WEC P2s and DPis have a minimum of 930 kilos (2050 pounds) with no fuel or driver for the Rolex 24. 930 kg is also the minimum in the WEC.

Maximum Length: 4750 mm (187 in.), which is 100 mm/4 in. longer than the previous LMP2 max length.

Maximum/Minimum Width: 1900 mm max (approx. 75 in.) to 1800 mm min (approx. 71 in.), which is narrower than the previous maximum of 2000 mm/75-3/4 in.

Maximum Height: 1050 mm (approx. 41.5 in.), slightly up from the previous 1030 mm (40.5 in.) standard.

Wheel Size: 18×12.5 in. fronts and 18×13 in. rears.

Tires: All supplied by Continental. Unique use of DP-derived Daytona specification for the Rolex 24, only. Brand-new 2017-spec Continental tires will be used from Round 2 at Sebring onward.

Transmissions: Six-speeds are required for every car. In the WEC, P2 teams are severely limited on the number of gear ratios that may be used (three sets), which will compromise the ability to perfect power and torque curves at some tracks. IMSA has removed the restriction for WEC P2s running in the WeatherTech Championship, and there are no limitations for DPis.


FRONT SUSPENSION

Riley’s front and rear suspension is unlike anything in sports car racing. While every other constructor went with a torsion bar arrangement, the Rileys reached back to a successful concept employed with its World Sports Car and Indy Racing League designs in the 1990s.

The front suspension system, which sits nicely atop the front of the chassis on a shelf designed into the tub, uses pushrods and massive rocker arms to compress individual dampers, springs, third springs/dampers, and interacts with an anti-roll bar affixed to the front of the bulkhead. The separation of the primary springs from the dampers provides a wider range of suspension adjustments, motion ratios, and increases the speed of spring changes which decreases chassis setup time.

Below: Rocker arms (purple), dampers (orange), springs (yellow), anti-roll bar (cyan), third spring/damper (green).

REAR SUSPENSION

The Mk 30 and RT24-P use the same split spring/damper-with-giant rocker arrangement at the rear. Hidden from sight is the anti-roll bar that sits low in the chassis and is mounted through the bellhousing.

Below: Rocker arms (purple), dampers (orange), rocker-to-anti-roll bar links (cyan), third spring/damper (green).

Compare the Mk 30 to the extremely conventional layout used on the ORECA 07 (below) and the other P2-based cars.

Below: Rocker arms (purple), dampers with coilover springs (orange), rocker-to-anti-roll bar links (cyan), anti-roll bar (yellow), third spring/damper (green).

AERODYNAMICS

Like every 2017 P2-based chassis, the MK 30 was constructed using a raised forward section of the tub to flow air through the keel. The elevated section allows air to flow in from the front below the tip of the nose (green) and on both sides (orange) in the space above the splitter.

Air also flows into the keel beneath the splitter (cyan), and with wing profiles on the underside of the splitter, there’s plenty of activity taking place while shoveling air into and past the splitter and out to the sidepods. The front brakes are fed by ducts (red) at the leading edge of the beam.

In light of the rumored excess downforce and drag, the Mk 30 was routinely seen without downforce-adding dive planes at Daytona. Additional drag-reducing efforts were made by adding a small piece (red) to smooth the airflow leaving the base of the fender/splitter/foot section.

The Mk 30’s fenders are fairly pronounced at the front and smooth and progressive at the rear. Brake ducting is built into leading edge of the fenders.

The front fenders terminate in an abrupt manner (yellow).

The Mk 30 is somewhat slab-sided in the sidepod area (orange), but like the ORECA 07, a narrow waist section (yellow) is used below to route air leaving the keel via turning vanes (red), and from the sides (green), on the way past the exhaust outlets.

A horizontal piece that runs the length of the sidepod (green) was seen on the Mk 30 and RT24-P at times. It curves the exiting keel air upward.


Below: A look at the extremely different sidepod and vane treatments on the Mk 30 and RT24-P. The rounded Mazda sidepods have different philosophies on rear fender profiles, sport air conditioning condenser cooling vents, and use a duct on the side (below the “P”) for cooling rear componentry.

In another comparison to the plunging ORECA 07 tail section (top), the Mk 30’s engine cover and engine bay exit terminates in a flat/rectangular shape (bottom).

MISCELLANEOUS

The Mk 30 is the only 2017 car to use a split engine cover (above, below). Both sides attach to the mandatory tail fin, which is hard mounted to the chassis (green). It’s a smart, quick solution that prevents the need that other cars have to pull the rear wing assembly before having enough room to remove the engine cover.

Thanks to the fin being a fixture that stays in place, the Mk 30 and RT24-Ps have rear cameras build into the fin that feed the cockpit traffic monitor.

The Mk 30 incorporates the new and standard swinging center head support (green) that is hinged at the back and can be freed up front by pulling a quick-disconnect pin to allow rapid access to the driver from the passenger side of the cockpit, if necessary.

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