^^^ Bigger turbo's need more flow. So, to keep the same velocity, you would need to increase the port size proportionally to the turbo size.

Really with F/I, you don't have to worry about swirl charge, or pulse charge. The air is not being sucked in at all, it's being force feed. That is part of the reason cat backs increase HP so much on F/I cars.

The thing that is more important is cam timing, you don't want to loose to much of the intake charge. With a N/A car, you leave the exhasut port open a little longer to help pull in more charge, & evacuate the burnt charge. But on a F/I car it will just throw the charge back to the turbo.

You really don't need to increase the port size all that much on the 2.8l. just clean them all up & smooth them out. If you are going to make them bigger, you have to increase the intake mani & throttle body to match.

 

And the 2.8 cams are more aggressive. Gains are said to be around 35-50 HP for the complete 2.8 head swap w/ cams. This is one of the reasons I have 2.8s sitting around. One formy car and one for my friends project. I was almost positive on the blocks being the same but I'd hate to weld up manifolds and find out that the 2.7's have something different machined in the back etc.

 

Very true.

Hay dnt mean to jack the thread, but wile we talking bout heads, I/M etc, would it be worth wile doing the Extrude Honing on the I/M to get all the rough castings out that u cant get to by hand?

 

Yup, it all has to work as a unit, from the intake, to the exhaust, so if you enlarge one part, you should also enlarge the others to match.