Photos and more of a description of leaf size shape, bloom size, shape and color might help narrow it down but SilverSurfer may be on the right track with
Red Horse-Chestnut (Aesculus x carnea) whose flower shape and size look similar. For comparison, here are images from our database of all 3:
Although Delonix regia (Royal Poinciana) grows very tall, I doubt it would survive in zone 8a.
Pride of Barbados (Caesalpinia) doesn't grow that tall and is listed as zones 9 to 11. I had one that was killed by frost when we lived in Florida zone 9a.
Red Horse Chestnut (Aesculus x carnea) grows from zone 5a to 8b so Silversurfer may be on the right track with that possibility.
