Work to restore the ss Great Britain's massive engine is almost complete, but a final £100,000 is needed to finish the renovation project.
The engine will be switched on in a special ceremony
The trust behind the repairs says it hopes local businesses can help with a last push to raise the remaining money.
An appeal brochure has already secured £10,000 in pledges, but more is needed.
The huge engine is due to be switched on by Top Gear presenter and Brunel enthusiast Jeremy Clarkson in a ceremony later this month.
He said: "In my programme about Brunel for the BBC's Great Britons series I said Brunel built modern Britain and Britain built the world, which means Brunel built the world.
"Well, not only did he build the world but he invented fast international travel around the world by designing the ss Great Britain, powered by this engine.
"The engine is the single most important part of the ship and will help visitors to Brunel's ss Great Britain understand the mechanics behind this innovative wonder."
Gary Musson, fundraising development officer said: "Donors will be recognised on an engine appeal plaque in the Dockyard Museum alongside the ship."
Those donating £1,000 or more will be given complimentary tickets to visit the ship, and the first 10 companies or individuals to donate £5,000 or more will receive two tickets to the 'Switching On' ceremony.