Mention the name Harrop to pretty much anyone in the global Speedhunters community and the word supercharging usually follows.
But forced induction is a relatively recent addition to the Australia-based outfit’s incredible history.
Harrop has been helping make our cars stronger and faster for a whopping 64 years (read more here in Richard’s story of the company started by Len Harrop in 1955), and during that time it has been involved with the top levels of motorsport, too.
From engineering the Holden Racing Team’s Commodores in the 1990s, to supplying 5-litre GM and Ford V8 engine hardware for Australia’s Supercar series in the mid-2000s, featuring Harrop’s own-design cranks and intakes.
More recently, Harrop has competed at the World Time Attack Challenge in Sydney with their own 700hp, normally-aspirated, LS7-powered GM Holden Monaro.
For the record, the Monaro finished 10th in class – the only rear-wheel drive V8 in a field of Evos and RX-7s.
But all that hard-won knowledge and experience is largely directed to the aftermarket and road cars in particular, and supercharging is at the forefront of that.
“Back in 2004 we saw an opportunity for a power adder that would work as an extension of our existing intake products,” explains Harrop’s Heath Moore. “Turbocharging was gaining momentum at that point, but supercharging was more in-line with our philosophy of producing OEM levels of quality.”
With that in mind, Harrop began working with Eaton, utilising and developing their Roots-type TVS (Twin Vortices Series) positive-displacement superchargers, which provide much more linear power delivery compared with centrifugal superchargers.
The first kit Harrop produced was for the GM LS1 V8 engine based around the TVS1900 supercharger (the numbers refer to the volume of air measured in cubic centimetres that the pump moves per pulley revolution), and the LS platform remains their most popular engine for supercharger kits to this day.
More kits and upgrades followed — for the 4.2-litre V8 engines found in the B7 Audi S5 and RS4 to working with Toyota Racing Development (TRD) on the 2GR-FE 3.5-litre V6 engine (and later the Lotus Exige). Harrop was also the first to develop a positive displacement supercharger kit for the E9X BMW M3’s S65 engine. “This gave us massive challenges,” says Heath, “not least the insane amount of time developing the electronic bypass actuation control. But ultimately it was worth it, as the kit gives this engine the mid-range boost it was crying out for.”
More recently, Harrop has turned its attention to the FA20 – the 197hp, 2-litre boxer engine in the Toyota 86 and Subaru BRZ. “This is a popular kit using the TVS1320,” says Heath. “The standard car has a great chassis, but with the positive displacement kit removing the infamous torque dip, the car now performs brilliantly.”The Pony Club
Walking into the Harrop Performance Centre (HPC) workshops (used for fitting upgrades and kits to customer cars as well as for R&D), though, and despite the presence of the GM Holden machinery that Harrop still have a deep interest in, we come across the team’s current focus — the sixth-generation S550 Mustang GT.
Harrop has already developed a kit as part of its Stage 3 package, which pushes the peak power of the GT’s Coyote V8 up to 550kW (738hp), but this 2016 example is helping to validate the performance potential of a new kit for both the port and new 2018 direct-injection 5-litre, capable of 820+kW (1,100+hp)…
Based on the TVS2650 supercharger (350cc larger than their current range-topper for the Coyote), as found in the new GT500, the kit is currently being signed off ready for mid-year release, and of course, will remain fully streetable. The standard engine wouldn’t last long at this kind of sustained power level though, so a comprehensive supporting upgrade of the Coyote’s internals and fuel system is essential. “We’ve retained the factory crank,” says Heath, “but there are new rods and lower-compression pistons to cope with the 18-20 psi of boost, along with a stronger valvetrain plus upgraded high-flow fuel system for E85.”
With a comprehensive range of suspension and brake packages available for this model, the GT’s chassis can easily be made to cope with that kind of power. The upgrades include larger, fully-floating bobbin-drive, two-piece rotors for the front and rear, along with upgraded lines and pad material, while the suspension is now based around Shockworks coilovers developed by an ex-Ford ride and handing engineer.
With the previous supercharger kit and tuned for E85, Harrop’s S550 ran a 10.5-second quarter-mile pass at 139mph (223km/h) at Regional Victoria’s Heathcote drag strip — in full street trim, of course — so we’re looking forward to seeing what the new engine package can do. Harrop might even lend Matt the keys if he promises to behave…
Despite all the CAD and 3D prototyping machines on the main factory floor, Harrop still heavily relies on the knowledge and hands-on experience of its 60 staff — some of whom have been working here for over 30 years.
I bet they never imagined they’d be working on a 1,000hp street-driven Mustang, though…
Photography by Matthew Everingham