The Estes “E” series rocket engines are the “Big Boys”. These are used in some of the larger and high altitude model rockets. These burn for 9 seconds and then pop the parachute after 6 seconds. They come 3 engines in a pack with igniters and plugs.
Here is a link where you can buy them online and super cheap….Buy Estes Model Rocket Engines E9-6 at Amazon.com