size of 270 exhaust port

Hi All,
I am trying to see how many exhaust cfms I Can get through my 270 exhaust port? anyone know the open square inches of the 270 exhaust port ? or max hp can 270 handle without back pressure issue?
Thanks,
Tmcboat

I have no idea as to the CFM capability.

V-8 or other?

The V-8 Y-pipe for the 270 will have 3" inlets and down tubes. (275 is 95mm)
From the transom shield to the Intermediate housing will be similar to other AQ series drives.

Where it becomes the most restrictive will be at the transition from the Intermediate housing to the 270 lower unit porting, and the rather restrictive 270 style exhaust outlet housing.

A 280, 290 or SP lower unit will be somewhat less restrictive.


For ultimate non-restricted exhaust..... thru-the-transom would work best.


.

Spent a lot of time and money on this issue some years ago... see ( as clarification, I'd installed a 280 drive on a 270 transom shield)


https://home.comcast.net/~rfierro/site/?/page/Thru_Transom_Exhaust_Project/&PHPSESSID=e9200284a128af346a04f1e16e9829db

sandkicker said:

Spent a lot of time and money on this issue some years ago... see ( as clarification, I'd installed a 280 drive on a 270 transom shield)


https://home.comcast.net/~rfierro/site/?/page/Thru_Transom_Exhaust_Project/&PHPSESSID=e9200284a128af346a04f1e16e9829db

Click to expand...

The above link is broken ( Comcast discontinued web hosting for customers).
Attached is the text of the web page. Any one interested in the pictures, let me know and I see if I can find the sources.