Is it max execution time, or is it the socket time out?
If it is the latter, try the ZipStream instead, as it'll send the data as the files are compressed (won't help if it is a single large file being compressed though).
I assume the mas execution time is set by your host/provider.
The closest I can come to this is:
php.net/manual/en/function.set-time ...
But again, that'll only work if your sever isn't running in "safe mode".