Port question

[jlmtx2002]

I was bored today, so I threw together an enclosure for 2 dad kmh 8s. The numbers are 56.5l, 10.5d, and 5.75h. These are inner measurements. The subs are behind each seat facing up, and the port is in the middle facing up. The port is 10.5x3x30ish. The port goes down around 4in or so then Ts out something like 12in. Each way. The port Ts 3in from bottom. This was supposedly tuned at 32/33 htz. After listening to it I would guess the tuning is more are mid 40s maybe even low 50s. Not sure where I went wrong. Any input would be helpful. I realize there is nothing I can do to fix it other than rebuild which is what will end up doing. I just don't want to make the same mistake again.

[Robert8252]

With your dimensions I'm coming up with around 37hz-38hz tuning depending on much much the port takes up.