HOLDEN'S FORGOTTEN GO-FAST 6-CYLINDER HISTORY
The engine choice for Marty's Monaro has certainly drawn plenty of comment online (you can see what he's doing for yourself HERE, if you haven't already). If you haven't watched it and don't want any more spoilers than the title of this post gave you, maybe go make a cuppa tea, sit down with a tasty snack, and clap your vision-orbs onto that episode, so we're all on the same page.
Okay Pookie? (It is ok if I call you Pookie, isn't it? Thanks Pooks!)
Right, so now we're all up to date on the future DOHC turbocharged six-cylinder future ahead of Martin's two-door Commodore, the great elephant in the room which needs to be addressed is the fact Monaros had a performance 6-cylinder variant from the very first time they burst onto the Australian market. Way back in 1968 Holden dropped the "HK" Monaro, named as it was based on the HK-series Kingswood sedans they were selling at that time.
A large, roomy five-seat grand touring coupe it today is remembered as the first proper muscle car from Holden thanks to the top-shelf GTS 327 model winning plenty of races across a variety of motorsport classes. Sold in three basic trim specs (Base, GTS, and GTS 327) many people forget the garden variety entry-level "Base" Monaro came with two choices of Holden's pushrod straight six, either a 2.6-litre (161cui) or 3.0-litre (186cui) engine.
The Base Monaro was a pretty plain looking thing, with very limited interior features and none of the flash styling we associate with muscle cars. Buyers of the mid-spec GTS, however, remedied this with go-fast stripes, sporty looking wheel covers (hub caps to us old punters), more gauges, and either a 210hp five-litre (307cui) Chevy V8 or a hotter 145hp high-performance variant of the three-litre 6-cylinder, called the "186S".
Packing nearly all the good looks of the far more expensive, limited-edition 250hp GTS 327 that was destined for racing glory, but coming in at a fraction of the price, the Monaro 186S sold like cold beers on a hot summer afternoon in Sydney. With a four-speed Opel-sourced manual the lighter weight over the big HK nose also helped handling and braking, though nothing was turning the family-sized Monaro (with its wooly steering and drum brakes) into a dynamic corner carver.
It has been suggested the 186S model was offered thanks in part to a push from a different General Motors department a few years earlier to get a hot 6-cylinder performance car up. Pontiac had been developing overhead-cam V8 engines as far back as 1961, with prototypes running around in cars for years.
Landing in 1966, it was a project which had been pushed internally by Pontiac's bossman, John Z. Delorean (yes, the fella later responsible for the car from Back To The Future). Pontiac was General Motors' performance division in the USA and he understood the engineering benefits to running a camshaft in the cylinder head, rather than buried in the block as most American engines did at that time.
Available in two guises from 1966-1968, Pontiac gave buyers the choice of either a basic "OHC-6" with 165hp, or a far-hotter Sprint-6 with 207hp. Though the OHC-6 was designed as a smooth-running upgrade to regular six-cylinder Tempest and LeMans mid-size models, the Sprint-6 boasted higher compression, a bigger carburettor, better intake manifold, upgraded valve springs, and other tuning work.
It was designed to be the first shot in what John Z had hoped would be a way Pontiac could postition itself as the engineering epicentre of General Motors, with overhead cam V8s to follow quickly. However, GM brass were famously focused on the numbers and that was where the overhead-cam projects fell down.
More expensive to produce than the basic iron-block pushrod engines of the time, the economies of scale killed the overhead-cam projects dead in the water. It came down to the fact that Pontiac were selling plenty of the cheap-to-produce iron pushrod V8s, so why bother with these costly engines?
Thankfully, the Aussies at Holden took note of the six-cylinder muscle car concept...
The 186S option was so successful Holden kept it around for the 1969 HT Monaro revision, and the following HG series in '70 and '71 as well. However by this time things had changed from under the Monaro.
Touring car racing was massive business globally in the 1960s and '70s, with the old "win on sunday, sell on monday" mantra ringing through car company boardrooms across the world. Ford, who were Holden's main competition Down Under, had started the muscle car wars with a "Mustang-bred" GT Falcon. From 1967 the GT Falcon engine steadily grew from a simple 4.7-litre (289cui) Mustang Windsor unit out to five-litres (302cui) in 1968, before FoMoCo got serious in 1969.
This was when the new XW Falcon scored a huge 5.8-litre (351cui) V8, which was bigger than Holden's vaunted 5.4-litre (327cui) Chevy-sourced small-block. Holden had countered with a Chevy 350 (5.7L) in the top-spec HT and HG GTS Monaros, but within the Holden Dealer Team, a push was on for a lighter, better handling car.
And, in 1970, Holden shocked locals by switching its racing programme from a burly V8 muscle car to a little six-cylinder coupe. The Torana GTR.
Known today by its code of "XU-1" the small LC Torana was based on an Opel-sourced mid-size platform that today would be considered almost a city car. Designed originally for a four-cylinder and as basic pedestrian transport, Holden engineers soon worked out how to lengthen the nose and jam a variety of their in-line 6-cylinder engines under the bonnet.
The go-fast GTR model was a striped up two-door muscle car variant, aimed squarely at younger buyers who didn't need the big roomy five-seat interior of the Monaro. The base GTR scored a 2.6L (161cui) 6-cylinder and in a 900kg LC the 123hp made it plenty fast for the time.
What many of the kids focused on, however, was the top-spec model called the XU-1. Packing a hot, 160hp triple carburettor-fed 186S engine the XU-1 was designed to race.
With the heaviest LC Toranas rated at a little over 1000kg, some 500kg lighter than Ford's thundering new 351cui GT-HO Falcons, Aussies got to watch a proper David versus Goliath battle on the race track. Week in, week out, the little Toranas showed what Minis and Lotus Cortinas had years before: big grunt is great in a straight line, but light weight is what often wins races.
By the time of the LJ model in 1972 the XU-1's engine had grown to 3.3-litres (202cui) and power had jumped to 187hp. The police famously used LC and LJ XU-1 Toranas as pursuit specials back in these days, such was their storming performance.
By 1973 the racing regulations had changed. Safety concerns prompted authorities to replace Series Production (ie: standard, road-going cars raced using homologation rules) with purpose-built touring cars under the Aussie Group C rules. In 1974 Holden launched an all-new, locally-designed LH-series Torana, and it ushered in a new era.
The new range was topped by the SL/R models, boasting either a 3.3-litre 6-cylinder or (for the first time in factory guise) the choice of two V8s in the Torana range. Though the LH Torana was bigger and heavier in every dimension than the previous LC and LJ models, it also proved to be faster with the factory-fitted five-litre V8 (SL/R 5000).
While the SL/R 5000 (and later L34 and A9X homologation specials) went on to become racing legends, the older XU-1 Toranas became staples in grassroots motorsport, especially rallying, hill climbs, and circuit racing. Their mix of light weight, compact dimensions, and big-six power kept them at the pointy end right through the 1980s.
Through the 80s, as Holden downsized to the Commodore model (see HERE for that history lesson) there were slim pickings for fans of fast 6-pot GM-H tin. The old Holden in-line six was well-past its used-by date, though we did get a rare treat in 1986 with a car many Aussies consider the Down Under local to Buick's epic GNX model: the VL Commodore Turbo.
Packing a 200hp turbocharged RB30 three-litre straight-six, it made the VL-series Commodore a stunningly fast car from a roll. The engine had been sourced from Nissan to get around the fact Holden's own, old 6-cylinder was too expensive to run on the new unleaded petrol mandated in Australia from January 1, 1986. The overhead-cam Nissan fixed that for Holden, who smartly negotiated exclusive use of the single-cam turbo engine variant for their own uses.
As the Holden 5-litre V8 (304cui) was still laboured with an emissions-strangled carburettor set-up, the turbo-6 Commodores were the road-going performance models of choice, even today. And it was the last time Holden ever put a fast six ahead of a V8 model, sadly.
Holden's own go-fast performance car arm, Holden Special Vehicles (HSV) was born in a 1988 agreement between Tom Walkinshaw Racing and GM-H. It replaced the previous Holden Dealer Team which had, under ownership by racing legend Peter Brock, had turned out plenty of fast road-trim Commodores through the '80s, but had to be abandoned by Holden after Brock's wild descent into quackery with "healing crystals", "Energy Polarizers" and all manner of absolute bulldust.
While they released the odd six-cylinder special edition through the years, these were largely overshadowed by the more powerful, faster V8 variants. Holden had moved in 1988 to a pushrod EFI 3.8-litre V6, originally derived from Buick but redesigned In the mid-'90s to the Holden Ecotec engine.
Fans of fast 6-cylinders got a boost, literally, in 1996 with the introduction of the L67 engine. Boasting an Eaton supercharger it was offered in VS, VT, VX, and VY Commodore series, as well as the CV6 Monaro, and had up to 220hp. But, while it found fans it was hampered by only coming with an automatic transmission, and GM-H's own focus on V8 powerplants - especially the 300hp 5.7-litre LS1 which hit Australia in 2000.
The ultimate incarnation of the L67 came in the 2001 HSV XU6, which took its name from the legendary Torana of the early '70s. Packing 241hp it marked the final proper hot-six Holden to be developed locally, but by then the V6 was being absolutely clowned by Ford's four-litre Barra, which had been developed under the codename "Seagull" as Ford engineers knew "it would crap on everything".
