Irish passenger lists from shipping records can be found in Passenger Books of J & J Cooke, Shipping Agents. Sailings from Londonderry to Philadelphia Pennsylvania, Quebec, St. John New Brunswick & New Orleans Louisiana, 1847-1871
Source: Reference D.2892/1/1-14 (see also MIC.13 in the Public Record Office of Northern Ireland)
I have recently added twenty more ships to my free online JJ Cooke Ships Passenger Lists on Olive Tree Genealogy
Hope you find an ancestor or two!