Lamborghini Diablo - Powertrain

By Alisdairsuttie / Thursday, 24 February 2011 / Loading comments

The Lamborghini V12 engine probably warrants a whole series of books thanks to a history that goes right back to the Miura. In simple terms, the Diablo's version was a carryover from the Countach, so it's a 60-degree V12 mounted longitudinally in a square-tube spaceframe chassis. It uses an aluminium block and heads with chain drive to double overhead cams on each bank of cylinders.

On its debut, the Diablo came with a 5707cc capacity, with 87.0 x 80.0mm bore and stroke, and a power output of 485bhp at 7000rpm. It also produced 428lb ft of torque at 5200rpm, helping the first Diablo from 0-60mph in 3.9 seconds and on to 202mph. The engine was fitted with Lamborghini's LIE fuel injection, which did little (apparently) to alleviate the average fuel economy of around 14.0mpg.

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This model used the accepted rear-wheel drive set-up of supercars of the period and came with a five-speed transaxle. With a single dry plate clutch that was heavy even by supercar standards, this early Diablo is not reckoned to be the best to drive by most owners. Anyone buying a Diablo will become familiar with regular clutch changes as the engine's power and torque put considerable strain on the gearbox components. The starter motor also takes a lot of abuse and is an engine-out job at most garages, though some specialists can do a starter motor swap with the engine in place, considerably reducing the cost of a change.

In 1993, the VT (viscous traction) four-wheel drive transmission arrived and with it came a significantly lighter clutch pedal. This makes VT Diablo models a much better bet for anyone who wants to use their car regularly. Four-wheel drive also helps tame some of the off-the-line traction and cornering foibles of early Diablos, though it also brought more front tyre wear. Hard driving will see the front driveshafts deteriorate quickly, especially with track use, as four-wheel drive Diablos tend towards initial understeer due to the broad rear tyres. The viscous coupling in the four-wheel drive transmission works by sensing the loss of traction at the rear wheels and sending power to the fronts. In extreme conditions, 40% of power can be sent to the front wheels.

The Diablo was never offered with a sequential manual gearbox or F1-style paddle shifts, though the gearbox was improved in 1994 for a smoother, quicker change. Traction control, called TCS, first appeared on the SE 30 anniversary model and was soon rolled out to standard models.

With early 5.7-litre VT models, the gearbox's primary driveshaft is not really up to the power of the engine, so look for evidence it has been uprated to a later type. Clutch slave cylinders also fail at around 12,000 miles, while the gear lever itself can snap due to the heavy shift of early cars and weak metal used for the lever in earlier models.

Early Diablos up to 1994 used a hydraulic cam chain tensioner, which continually tightens the chain till it snaps with resultantly expensive bills. A manual adjuster was introduced in 1994 and should have been fitted to most cars as a service item by now, but it's still worth checking. While in the engine bay, Diablos are very sensitive to oil level, so make sure it's at the correct mark and been changed regularly. Oil pumps can fail as a result of low oil level, so keep an eye on this.

Catalytic convertors are another drivetrain item that can cause problems on early Diablos, often destroying their filtering innards. Many owners will have ditched the original exhaust in favour of an aftermarket sports system, which does away with this problem but can make a Diablo anti-socially loud and unwelcome at track days.

In 2000, the 6.0-litre V12 engine arrived with 87.0mm x 84.0mm bore and stroke, upping power to 550bhp. Helping the power gains were a new 32-bit engine management processor, magnesium cylinder heads and variable intake valve timing.

The GTR went further to produce 590bhp thanks to a mutli-throttle intake manifold, titanium con rods in the engine and lightened crankshaft. There was also a bespoke exhaust and reworked engine management to cope with the demands of racing.

Throughout its life, the Diablo was offered with varying power outputs. Notable among these is the SE 30 Jota, which was a factory upgrade for the 525bhp SE 30. The Jota boasted 595bhp for 0-60mph in 3.7 seconds and a 211mph top speed to make it the fastest road-going Diablo ever built.