BTTF DeLorean, Time Machine

DeLorean Time Machine

The DeLorean time machine is a fictional automobile-based time travel device featured in the Back to the Future franchise. In the feature film series, Dr. Emmett Brown builds a time machine based on a DeLorean DMC-12 car, to gain insights into history and the future. Instead, he ends up using it to travel over 130 years of Hill Valley history (from 1885 to 2015) with Marty McFly to change the past for the better and to undo the negative effects of time travel. One of the cars used in filming is on display at Universal Studios Hollywood.

DeLorean, Time Machine
DeLorean Time Machine. Photo: Oto Godfrey and Justin Morton

The control of the time machine is the same in all three films. The operator is seated inside the DeLorean (except the first time, when a remote control is used), and turns on the time circuits, activating a unit containing multiple fourteen- and seven-segment displays that show the destination (red), present (green), and last-departed (yellow) dates and times. After entering a target date, the operator accelerates the car to 88 miles per hour (141.6 km/h), which activates the flux capacitor. As it accelerates, several coils around the body glow blue/white while a burst of light appears in front of it. Surrounded by electrical current similar to a Tesla coil, the whole car vanishes in a flash of white/blue light seconds later, leaving a pair of fiery tire tracks. A digital speedometer is attached to the dashboard so that the operator can accurately gauge the car’s speed. Various proposals have been brought forth in the past by fans of the movie franchise for why the car has to be moving at 88 mph to achieve temporal displacement, but actually the production crew chose the velocity simply because they liked how it looked on the speedometer.

BTTF DeLorean, Time Machine
A back view of the DeLorean time machine. Photo: Oto Godfrey and Justin Morton

Observers outside the vehicle see an implosion of plasma as the vehicle disappears, while occupants within the vehicle see a quick flash of light and instantaneously arrive at the target time in the same spatial location (relative to the Earth) as when it departed. In the destination time, immediately before the car’s arrival, three large and loud flashes occur at the point from which the car emerges from its time travel. After the trip, the exterior of the DeLorean is extremely cold, and frost forms from atmospheric moisture all over the car’s body.

DeLorean Time Machine, interior
Inside the cabin facing front. Photo: Oto Godfrey and Justin Morton

A few technical glitches with the DeLorean hinder time travel for its users. In the first film, the car has starter problems and has a hard time restarting once stopped, much to Marty’s repeated frustration. In the second movie, the destination time display malfunctions and shows random dates (mostly January 1, 1885), which partially cause Doc to be sent to 1885. In the third movie, the flying circuits (added by Doc in 2015), fuel line, and fuel injection manifold are damaged, preventing the car from moving under its own power.

Future DeLorean Time Machine, interior
Inside the cabin facing rear. Photo: Oto Godfrey and Justin Morton

The time machine is electrical and requires a power input of 1.21 jigowatts (gigawatts) to operate, originally provided by a plutonium-fueled nuclear reactor. In the first movie, Doc has no access to plutonium in 1955, so he outfits the car with a large pole and hook in order to channel the power of a lightning bolt into the flux capacitor and send Marty back to 1985. During Doc’s first visit to 2015, he has the machine refitted to hover above ground in addition to standard road driving, and he replaces the nuclear reactor with a Mr. Fusion generator that uses garbage as fuel.

DeLorean Time Machine, Mr Fusion Home Energy Reactor
A replica of the DeLorean Time Machine’s Mr. Fusion Home Energy Reactor. Photo: Oto Godfrey and Justin Morton

Although the Mr. Fusion unit provides the required power for the time machine, the DeLorean is still powered by an internal combustion engine for propulsion. The fuel line is damaged during Marty’s trip to 1885 in Back to the Future Part III; after he and Doc patch it, they attempt to use whiskey as a replacement fuel. The test fails, destroying the car’s fuel injection manifold and leaving it unable to travel under its own power.

Time circuits, time machine
The time circuits in a replica time machine. Photo: Oto Godfrey and Justin Morton

Doc and Marty consider options to reach the required 88 mph (such as pulling it with horses) but ultimately settle on pushing the car with a steam locomotive. For the extra power needed to push the DeLorean up to speed, Doc adds his own version of “Presto Logs” (a chemically treated mixture of pressed wood and anthracite) to the locomotive’s boiler and chooses a location with a straight section of track long enough to achieve 88 mph.

Time circuits, time machine
The time circuits in a replica time machine. Photo: Oto Godfrey and Justin Morton

The power required is pronounced in the film as one point twenty-one “jigowatts”. While the closed-captioning in home video versions spells the word as it appears in the script, jigowatt, the actual spelling matches the standard prefix and the term for power of “one billion watts”: gigawatt. Although rarely used, the “j” sound at the beginning of the SI prefix “giga-” is an acceptable pronunciation for “gigawatt.” In the DVD commentary for Back to the Future, Bob Gale states that he had thought it was pronounced this way because it was how a scientific adviser for the film pronounced it.

DeLorean Time Machine, replica
DeLorean Time Machine replicas. Photo: Terabass

Fictional timeline

  • For most of the first film, the 1.21 gigawatts are supplied by a plutonium-powered nuclear fission reactor and, with the absence of plutonium, a bolt of lightning channeled directly into the flux capacitor by a long pole and hook in the film’s climactic sequence. At the end of the first film, and for the remainder of the trilogy, the plutonium nuclear reactor is replaced by a “Mr. Fusion Home Energy Reactor” generator possibly acquired in 2015. The “Mr. Fusion” device apparently converts household waste into electrical power; the name suggests nuclear fusion. Due to a “hover conversion” made in 2015, the car also becomes capable of hovering and flight, though it lost this ability at the end of the second film.
  • The DeLorean returns to 1985 and proceeds to travel to October 21, 2015, to stop Marty’s future son from committing a crime. While there, the DeLorean is stolen by Biff who then travels back to November 12, 1955, the same day as the climax of the first film, to give his past self a sports almanac to be used for gambling. Once Biff returns to 2015 without Doc’s knowledge, the duo return to 1985, but find themselves in an alternate timeline where Hill Valley is ruled by Biff that Doc described as 1985A (alternate 1985). The DeLorean then travels back to 1955 to restore the timeline, but in the aftermath, it is struck by lightning again in the very same electrical storm, this time by accident. According to writers Bob Gale and Robert Zemeckis, the lightning causes the DeLorean to spin at 88 miles per hour, and Doc later states in a letter to Marty that the bolt caused a “gigawatt overload” which “shorted out the time circuits and destroyed the flying circuits”. The DeLorean then disappears from 1955, travelling back in time to January 1, 1885 (earlier in the film, Doc mentions that the time circuits are not functioning correctly; several instances in the film that show the time circuit display showed 1885 as the destination when the time circuits malfunctioned).
  • Once in 1885, the DeLorean is hidden in a mine because suitable replacement parts to replace its destroyed microchip will not be invented until 1947 (presumably referring to the transistor, invented in that year). Doc and Marty recover the DeLorean from the mine in 1955, and Doc builds a vacuum tube circuit assembly to replace the destroyed microchip circuitry and restore the vehicle’s time travel capabilities. The tires have disintegrated in storage, so Doc replaces them with whitewalls. The gasoline engine is still functional, but the flying circuits are not.
  • In a letter Doc wrote to Marty in 1885, Doc states he is happy in his new life there and requests that Marty not attempt to retrieve him, but instead to return to 1985 and destroy the DeLorean, believing that it has brought them and the world nothing but disaster. However, Marty and the Doc of 1955 learn of tragedy to come Doc’s way when he is murdered by Biff’s grandfather, Buford “Mad Dog” Tannen, on September 7, 1885; therefore, 1955 Doc agrees to send Marty back to the Old West to rescue himself.
  • When Marty arrives in 1885, the DeLorean’s fuel line is pierced by an arrow during an Indian attack. He and Doc patch it and attempt to use whiskey as a replacement fuel, since commercial gasoline is not yet available; the test fails, destroying the fuel injection and ignition systems and leaving the car unable to travel under its own power. Its final trip, from 1885 to 1985, is propelled by a steam locomotive that has Doc’s version of “Presto Logs” (pressed wood treated with anthracite) added to the boiler to provide the extra power needed to push the car up to 88 mph; once this speed is reached, the Mr. Fusion unit provides the power required to activate the flux capacitor and make the jump through time. Doc replaces the 1955-style wheels with cast iron train wheels that fit on the track rails. He uses the old tires and a wooden support to cushion the locomotive’s “cow catcher” and the car’s rear end. Since each of the three “Presto Logs” fire at different intervals with increasing power, Doc installs a boiler temperature gauge on the DeLorean’s dashboard to indicate when the car will experience a sudden burst of acceleration.
  • Once the DeLorean makes its final trip from 1885, it arrives back in 1985 and is immediately destroyed by an oncoming freight train running in the opposite direction. Marty is able to bail out of the car seconds before the train strikes. Later the Time Train, which is Doc’s second time machine, appeared in the same spot where the DeLorean was destroyed.


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