Further details as per internet search. Please confirm. Thanks.
Appears that the shared hosting Apache server has a 1 Meg LimitRequestBody setting. Since Apache is before PHP, Apache is the bottleneck, and in this case, PHP never gets my long posts. The shared hosting environment does not allow for form posts over 1 Meg, regardless of the downstream PHP settings. Ie: the PHP post_max_size and upload_max_filesize don't make a difference for form posts. When the form post is smaller, my PHP script DOES execute properly. Also, when I set LimitRequestBody to 3000 (3K), I can get my small form posts to fail with the same 413 error. So, I can make the limit smaller, but I cannot make the limit larger than 1 Meg.
So you cannot do any form post more than 1Meg in godaddy shared hosting environment.