Prior to the Cerbera, TVR had purchased V8 engines from Rover and then tuned them for their own use. When Rover was purchased by BMW, Peter Wheeler didn't want to risk problems should the Germans decide to stop manufacturing the engine. In response, he engaged the services of race engineer Al Melling to design a V8 engine that TVR could manufacture in-house and even potentially offer for sale to other car-makers. In an interview for the television program Top Gear, Wheeler explained "Basically, we designed the engine as a race engine. It was my idea at the time that if we wanted to expand, we ought to make something that we could sell to other people. We've ended up with a 75-degree V8 with a flat-plane crank. The bottom-half of the engine to the heads is exactly as you would see in a current Formula One engine."
Wheeler was quoted at the time of the car's launch as saying that the combination of light weight and high power was too much for a road car, a quote which ensured much free publicity in the press. Enthusiasts still argue about whether this was a typical example of Wheeler's legendary frankness, or an equally typical example of his PR chief Ben Samuelson's knack for saving on advertising costs by creating a story.
The result was dubbed the "Speed Eight" (official designation 'AJP8' after Al Melling, John Ravenscroft and Peter Wheeler, a 4.2 L V8 producing 360 horsepower (268 kW). A larger version of the engine was later offered that displaced 4.5 litres and output rose to 420 horsepower (310 kW). This larger engine was also fitted with a crankshaft that was made of steel for added strength and reliability. The smaller motor allowed the Cerbera to still achieve up to 185 mph (297 km/h).
The AJP8 has one of the highest specific outputs of any naturally aspirated V8 in the automotive world at 83.3 hp/litre for the 4.2 and 93.3 hp/litre for the 4.5. Later models of the 4.5 litre engine were given the option of being to the 'Red Rose' specification, which increased its output to 440 bhp (97.7 hp/litre) when fuelled with super-unleaded (high octane) and the driver pushed the unmarked button on the dashboard which altered the engine mapping to suit.
In some cases, real-world outputs for production V8s (4.5 in particular) were down from TVRs quoted output. Some of these have seen some form of modification (ECU, induction, exhaust etc.) to bring the power back up to the factory quoted output.
One of the unique attractions of the V8 Cerberas for many owners was the loud backfire produced on the over-run, usually when the throttle was disengaged, and particularly at low speeds. In fact this was the result of an argument at the factory between one of TVR's executives and the engineers mapping the engine. The engineers wanted to map out this "irregularity" to improve fuel efficiency and CO2 emissions, whilst the executive insisted it was exactly the kind of thing owners would like. In the end a compromise was reached in which the popping and banging remained on the 4.5 L cars.
The engine is also unusually compact for a V8. According to TVR, the total weight of the finished engine is 121 kilograms.
With the success of the Speed Eight program, Wheeler also undertook the design of a "Speed Six" engine to complement it. This engine also made its debut in the Cerbera. Unlike the Speed Eight, the new engine is 4.0 litre inline slant six (I6) design. It also differs from the V8 in having four valves per cylinder to the Speed Eight's two.
