Compared is the China DVD from Zoke Movies (Hong Kong Uncut Version) with the Japanese Laser Disc from Shochiku-Fuji Home Video.

In most of the countries the Hong Kong Version was released.
But in Japan a unique cut was released (Laser Disc + video). This cut includes two longer fight scenes in the first half of the film and another short violent sequence in the final. These scenes were cut for Hong Kong and that's the reason they're missing in the releases in other countries, too. Moreover only the Japanese Version shows the Jackie Chan typical credits with the bloopers.
The reasons for the cuts are unknown. Golden Harvest seems to be responsable for that because their production logo doesn't pop up in the Japanese Version, but it does in other Jackie Chan releases in Japan.
Probably "Heart Of Dragon" shouldn't be considered as an action film but as a drama. Another aspect is that Julie Sue's two melanchonic music tracks were replaced by two less melancholic instrumental tracks. As a result the two longer fight sequences and the credits had to be cut as well because the credits also show parts of those sequences.

The missing violence in the final is the biggest mystery. On the one hand it's well known that Jackie Chan is not a big fan of too explicite violence, on the other hand the HK Version includes similar stuff (stabbing with an iron bar and slaying with a sword for instance).

The running times of the cut scenes refer to the HK Version.
The further difference in running time is a result of rounding up and rounding down to a whole or to half a second.
Running time HK Version: 1:30:39 Min. (1:28:54 Min. Credits excluded)
Running time Japan LD: 1:38:06 Min. (1:35:02 Min. Credits excluded)

Extended scenes: 4 = 7 Min. 18 Sec.
Replaced score 3 = No time difference

Opening credits:

0:00
In the Japanese Version the Golden Harvest logo is missing. That's why the HK Version is longer here.
19 Sec.

Fight training in the woods:

1:38
Replaced score:
In the Japanese Version the entire song "China Blue", sung by Jackie Chan, was used. In the HK Version it's an instrumental track.
Chan's very dynamic song suits better in this scenario than the alternate song in the regular version which seems to be used to build up the tension.
No time difference


Fight in the methadone medical center:

7:59
Extended scene:
A couple of thugs attack the medical center, where Chan is supposed to transfer the guy from the police station, to take hostages. They contain the employees, one of them gets punched in the face and falls down on the ground to the others. They put on the coat for employees and have a little conversation.
Meanwhile a police car with Chan and his companion arrives at the medical center. They get out of the car and walk to the entrance. On the way over there a patient talks to them, but they ignore him.

Chan and his companion run up the stairs where they face two men chatting. Chan turns around to them and looks irritated, but then he continues running up. A further, on a bank sitting "nurse" watches them coming up the floor and warns his accomplice at the desk where Chan shows his C.I.D. card and the guy behind the desk prepares someting to drink. Chan looks around distrustfully. While the guy behind the desk is passing the beverage to Chan's companion, Chan recognizes that the so-called "employee" has a tattoo on his arm. Chan inspects him more precisely and identifies him while his companion is drinking the beverage he got passed. Chan yells at him but he's alrady destracted with pain.

Chan's surprised and gets hit on the head, he falls into a bed. After that he fights with some thugs in several rooms where he shows his common Kung Fu stuff with a lot of kicks and punches, wooden chairs and other furniture.

The leader passed the threshold of a door and apparently tries to escape, but Chan involves him into a fight immidiately. After knocking him out with a flying kick, Chan fights with some goons until they're finished off as well.

Chan keeps on fighting with the leader, they chase and fight each other in the floors and the stairway. The leader finally gets pushed over the handrail, falls down and lands very uncomfortable in the first floor where some police men are already waiting for him.

Chan shouts at his colleague, then he runs upstairs again, draws his weapon and runs around the floor. The arrival of an ambulance is shown.
Change of scenery: Chan and some of his colleagues are at the police station. One of them finishes his phone call, goes to Chan's boss and a police man. They chat; the boss has to sign a document. Then Chan is supposed to sign the document, too. He talks about it with his boss because it's about the justification of the strategy he used. His boss tells him to be smooth but he kind of reproaches him as well. Chan sings small and agrees, his boss leaves the room. Chan signs the document, looks doubtful and leaves, too.

180 Sec.


Fight in the parking lot of the restaurant:

27:02
Extended scene:
Meng Hoi reenters the restaurant and talks to the guys at the other table. Chan's girlfriend's watches the entrance and the other guys.
Cut to the parking lot: the guys leave the restaurant smirkingly and notice Chan, Hoi and the rest of the "gang" standing next to each other. That's why the guys start posing, too. Some of them open their shirts. Hoi wants to leave without attracting attention, but he's stopped by Chan, a short conversation with him included. One of Chan's friends tosses Hoi to the others; they run close to their opponents and celebrate some Kung Fu moves. Hoi says something to Chan in an intimidated way.

And the fight begins. Chan does very well (as usual), but Hoi has huge problems with his first opponent and has to accept a lot of hits. Chan helps him, Hoi grabs Chan's C.I.D. card and shows it to the guy in the red shirt he got hit by in advance. But he's absolutely unimpressed (he thinks the card would be a fake) and hits Hoi again.

The fight goes on: Meng Hoi tumbles spectacularly, Chan fights the guy with the red shirt and finishes him off (nice slow motion sequences). After that some other fights are shown, the typical comedy stuff included.

Due to Chan's friends having problems every once in a while, he helps them and "clarifes" the situation. In opposite to that he has to stop one of his friends from almost killing his opponent.

Two opponents still fight, Chan, Hoi and the rest gather around them in a circle. When Chan's friends' opponent recognizes his solitary fight (his friends took their cars and escaped) he takes off his shirt and jumps the fence. Hoi shouts at him while he's on the run, but Chan and his friends carpet him for that (Chan is more friendly, but the others are very rough). After that we see Chan leaving, then Hoi.

174 Sec.


Jackie & Sammo at home:

38:09
Replaced score:
In the HK Cut a more melanchonic song by Julie Sue is used while Chan's brother's looking for a job is shown. The Japanes Version uses a more brightly song which shows Sammo Hung's looking for a job as well. Even though the second songs fits to that scene, it's a disadvantage of the Japanese Version that the lovely song by Sue is completely lost.
No difference


Final:

1:18:45
Extended scene:
The employee staggers und holds his face; Chan bashes him with a pickax in his stomach. The employee crumples in the corner; Chan leaves.

3,5 Sec.


After the final:

1:24:13
Replaced score:
In the HK cut Julie Sue's song pops up again, the Japanese Version comes up with an instrumental track until the credits are shown. Even though the instrumental track emphasises the melanchonical atmosphere in that scene, the lovely song by Sue is lost again.
Kein Zeitunterschied


Credits:

1:28:54
Extended scene:
The credits of the HK Cut are much shorter because the outtakes are missing. Here are some more details:
HK Cut: The freeze frame of the two brothers is longer, two more flashs are shown. Then the credits start, the screen becomes black.

Japan LD: The freeze frame of the two brothers is directly followed by a longer sequence showing the bloopers.

Furthermore the instrumental track by Julie Sue keeps on playing in the HK Version. In opposite to that in the Japanese Version the song "Tokyo Saturday Night", sung by Jackie Chan, was used for the credits (the two other songs by Jackie Chan within the film are mentioned as well).
To sum up, I can say that the credits of the Japanese Version run quite longer. To be exactly
80,5 Sec.