The Holden V8 engine, also known in some circles colloquially as the Iron Lion (versions from 1969–1985 were also often called the Holden 253 or Holden 308 up until 1974 then Holden 4.2 and Holden 5.0, depending on their capacity), is an overhead valve (OHV) V8 engine that was produced by the Australian General Motors subsidiary, Holden (GMH), between 1969 and 2000.
The engine was initially fitted to the Holden HT series in 1969 and was later utilised in a series of updated versions in the Torana and Commodore ranges. The final iteration, the heavily revised HEC 5000i, was phased out of Holden passenger vehicles with the release of the VT Series II Commodore and the WH Statesman and Caprice in June 1999, both of which featured the 5.7L Gen III V8 imported from the United States. However, the engine remained in production for a little while longer and continued to be available in the Commodore VS Series III utility (which sold alongside the VT sedan and wagon as no similar vehicle was available in that range) until the new generation VU Ute debuted in late 2000.
In addition to being Holden's mainstream performance engine throughout its production run, higher performance versions were fitted to limited-edition vehicles available through Holden Dealer Team Special Vehicles (HDT) and later Holden Special Vehicles (HSV). It was also utilised within limited production vehicles from other manufacturers as well as in kit cars.
The engine has a successful history in various forms of motorsport, most notably in Touring Car racing through the Australian Touring Car Championship and the Bathurst 1000 until 1995, as well as in Formula 5000 and other racing applications such as Sports Sedans.
It can also be found in Australian powerboats fitted with inboard engines, especially those used for water skiing.
History In 1964 Ford and Chrysler in the US released V8 versions of their respective Falcon and Valiant models which Holden expected to soon be released in locally assembled or produced versions. In response, in January 1965 the company's engineering division initiated a forward engine program review and concluded that by 1969 a V8 option was a necessity for Holden, with forecasts of 35 per cent of all Holdens sold in 1970 to be V8s, rising to 50 per cent by 1975. Initially six capacities from were planned over a 12-year life cycle, but early in the design phase this was reduced to just two, an 'economy' 253ci (4143cc) and an enlarged 'performance' 308ci (5044cc) version, which became known as the 4.2L and 5.0L respectively.
Design targets of a weight of , which was lighter than equivalent US engines, and a net output of and at 4000rpm and at 2400rpm were set for the 308, which was mechanically identical to the 253 except for a larger bore and bigger pistons, along with heavier counterweights on the crankshaft to compensate for the increased reciprocating mass. Originally an alloy inlet manifold was specified to reduce weight, but this was changed to iron when problems were encountered in the casting process. The exhaust manifolds were also cast iron but the timing case cover remained as an alloy item.
The initial pre-production engine was the 253, which not only met but greatly exceeded the design targets. The complete engine assembly from fan to flywheel and all auxiliaries weighed in at 460 lb, around 12% less than the design target, while net output for the higher compression (9.0:1) version fitted with a 2-barrel carburettor was with 262 lb.ft of torque, which matched or exceeded the targets set for the larger 308. The design was also very compact with a width of 22 inches, and was only 80 lb heavier than the straight six, but producing over 40% () more power than that engine in standard form. The first running engine was delivered in October 1966. Unfortunately, the engine failed after just four days testing from a seized oil pump; however, the problem was found to be caused by swarf residue rather than a fault in the design or the quality of the components. Further testing proved that the engine was smoother and more durable than Holden's six cylinder, no mean feat as the 186 was considered a smooth and reliable engine in its day.
The new engines were initially intended to be offered as part of the 1968 Holden HK range, but production issues caused the project to run behind schedule and consequently 307ci Chevrolet engines imported from Canada were used instead. Initially the 283ci engine was to be used but it was replaced in North America for the 1968 GM model year with the 307ci engine - this engine was used instead for HK. GMH had already planned to use the 327ci Chevrolet engine in the HK GTS327 and it would have originally been fitted in the HK range alongside 253 and 308 if things had gone as planned. The 253 made its public debut in the Holden Hurricane concept car at the 1969 Melbourne International Motor Show, albeit it in a highly modified form featuring increased 10.1:1 compression, big cam and solid lifters, and producing over . The new engines entered mass production soon after in the HT model range, with the 253 being used for manual vehicles whilst the 307 SBC was retained for automatic vehicles. The 308 however debuted in the HT Brougham at the same time but as automatic only (two different imported 350ci Chevrolet engines (auto and manual versions) replaced the 327 and thus the HK GTS327 became the HT GTS350). The 253 was initially only available with a 2-barrel carburettor while the 308 was only ever available with a 4-barrel carburettor (except for when it was used in Bedford trucks in the late 70's). Once the Canadian 307ci engines were used up the 308 became available across all models in the HT range, including the 2-door Monaro coupe. At the same time an automatic option was made available behind the 253 and a manual was available behind the 308 (previously automatic only when 308 was only available in Brougham).
The 253 and 308 soldiered on essentially unchanged into the HG Holden and HQ Holden Series. The V8 engine also appeared from 1971 in the Statesman range of large size luxury cars which Holden established as a separate marque replacing the Holden-badged Brougham. Initially both the 253 and 308 (and imported 350ci engine) were offered in the HQ V8 Statesman model and 308 standard in HQ Deville but after HQ both the 6cyl and V8 Statesman (Custom) models were dropped leaving the 308 powered HJ Statesman Deville as the base Statesman variety. This continued for the HX, HZ and WB.
At the end of HQ (and earlier for LH Torana release) the 253 and 308 engines were referred to by their metric names: 4.2L and 5.0L. Apart from minor external changes like cable throttle and minor changes to ensure the engine fitted the Torana engine bay the 4.2L engine in HJ and LH was the same as the HQ engine. At the HQ to HJ transition GMH changed the power output figures on all engines from "advertised horsepower" to proper GM20 test "SAE Gross hp". The power ratings on all engines dropped. The HT-HQ advertised power figures for the 253 and 308 were respectively: 185 hp and 240 hp. The SAE Gross figures for these engines was 175 hp and 227 hp. GMH Technical and Engineering literature shows these revised power figures for HJ but it took a while for it to appear in Sales literature - LX Torana release information shows the 4.2L as 175 hp and the 5.0L as 250 hp. The HJ 5.0L was a very different engine to the HT-HQ 308 though. The engine received a lift compression ratio from 9:1 to 9.7:1 and had a new camshaft which was basically the same valve timing as used in the HK-HQ SBC engines (prior to HJ the 308 used the 253's smaller camshaft but retarded 5 degrees). The revised 5.0L was SAE Gross rated as 250 hp which was a 23 hp gain on the HQ 308. In LH SLR5000 Toranas built after HJ release and LX SLR5000 and SS with RPO L31 built prior to HX Holden this revised 5.0L engine created a very fast car. The revised 5.0L engine performed so well that GMH dropped the planned 400ci engine from HJ Caprice and other optioned HJ Holden as the emissions strangled 400ci SBC out of North America was no improvement over the local 5.0L. The flip side of the extra power and torque meant that the Trimatic transmission that was used prior to HJ was not strong enough for the revised 5.0L in a full size Holden or Statesman and it was replaced with the imported TH400 transmission.
In 1974, both the 253 and 308 engines (now called 4.2L and 5.0L) were added to the Torana range for the first time in the LH series (after an aborted attempt by Holden Dealer Team boss Harry Firth to introduce the V8 to the smaller LJ in 1972 which was stopped by the "supercar scare"). In fact the SLR5000 only weighed 40kg more than the XU-1. Some of the lower performance Toranas were light, but the six-cylinder LJ XU-1 weighs 1140 kg while the SLR5000 L34 only weighed 1180 kg with the high performance V8. The engines were also offered on the revised LX released in 1976, which from July of that year saw emission-controlled versions of the 'Red' engines introduced to comply with the new ADR27A regulations on fuel and exhaust emissions. The V8 was dropped as an option in the final model in the Torana series, the UC released in 1978. There was a high performance version of the 308 engine built in 1973 by Repco for the Formula 5000 series. It was built as a 302ci (4940cc) engine using a slightly smaller bore than the production 308 (3.960" versus the 308's 4"). It was a much stronger block than the production block and featured 4 bolt mains and 11.7:1 compression with either Lucas fuel injection or Weber carburettors. GMH asked REPCO to use some of the ideas and parts for this engine and produced the higher performance 308 engine (engine code L34). The LH SLR5000 was released that used a standard 5.0L engine. A little while into LH, GMH built a limited number of SLR5000 vehicles (263) with an engine code L34 along with a whole host of other parts fitted for the manufacturer's championship endurance rounds. To comply with racing rules the car had to raced as manufactured with no further engine modifications. The whole car was homologated. The A9x used the L34 motor. Due to the Supercar scare the car which was the fastest production car in the world (in the future all hot 308s would be aftermarket delivered not standard Holden production engines) was still lower in HP. It had more power than most of its combinations in the future mainly due to its high compression motor. It had larger valves, and a four-barrel inlet, 750cfm carb. Due to the rules of the day race teams could put any carby with same number of venturis and modify the exhaust from the first join. As delivered the standard exhaust headers were not particularly efficient and lowered the cars power output as delivered down to near stock. However, when set up for racing this engine produced excellent amounts of power. Cam and carby were unrestricted so the cars internals where heavy duty and designed to maximise airflow, but cam, carby and exhaust restrictions due to CAMS racing rules lowered the engines optimum output. The L34 was never advertised except when journalists from' Wheels Magazine' found out about it. GMH ensured that only CAMS licensed teams could buy one. The car eventually was nicknamed the L34. The letters L34 were the engine code, and the car would soon be referred by the code from now on. The L34 had the code on the model plate there is nothing on an A9X that states it's an A9X and the A9X had to use the L34 motor from an L34 to race.