Gaspi101

Just remember to use PI gaskets, and a dab of RTV around the coolant passages.

Gaspi101

And what were your numbers BEFORE the manifold swap? If you give those, then maybe your post would make a bit more sense.

Mr. Jones

I did not think this was tough but
a stock 98 makes 225hp, I did not dyno with just a x-pipe and cats.
lets say its worth 10hp. thats about 235.75 at the crank (I use 15% for drive train lose).
I made 255fwhp as stated, you know the rest.
I recommend and made the plates because its better to match the port shape
than not. Have you ever port match a manifold that was original equip. or a direct replacement.
There is always room for improvement just compare gaskets to the ports on any head or manifold.
you will see the manufacture did not do a good job.
I offered my site as help and stated use the instructions and pic
I never said you must use plates. if you go threw the trouble of doing the manifold why not
make the most of your effort.
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|MusTang

yep pretty nice wrap over the non pi hole there.
i wonder if their is enough materiel on the heads to open them a little to match a little bit more the intake.

Mr. Jones

Yes there is room and this can work out to be the best combination.
you have to be very careful not to get chips in the ports. If you do get them in and near the valve
you probably will not get them out. you can't use a magnet (alum.) and when they go into the cylinder they will
damage the cylinder walls.
now for the good news
I read a method that is suppose to work-I was not brave enough to try.
clean the ports and gasket surface (carb/TB cleaner) whip them out, don't spray the ports and
let it soak into the cylinder. duct tape the cyl. below 1" from the top of the port.
now seal the port/tape with grease (heavy wheel bearing grease)
cover as much around the engine as possible chips are going to fly.
line up the gasket and scribe a line to follow use dye or paint to accent the scribe line.
With a die grinder and a carbide bite go to it.
vacuum as much as possible when done. wipe out the grease and chips.
remove the tape. one set of PI gaskets and some RTV around the water jacket port (head side only)

96 TBird 4.6

is it a must to have those PI gaskets/ plates whatever they are? and if so, how much do they cost? and will they improve my gains from the manifold?

Gaspi101

Again, you do NOT need an adaptor plate to mate the PI manifold to the NON-PI heads!!! All you need are the PI gaskets! There is a difference between a gasket and an adaptor plate. If you do not know this humble slight difference, you should not even think about THINKING about doing the manifold swap yourself.

CHEERS!

96 TBird 4.6

thanks again for the input guys, i appreciate this help. and no, i will not be doing the swap myself, im having a mechanic who comes to peoples houses to work on cars who does it as a side job. but i will be watching and learning.

one more question- does the PI gasket come with the manifold or will it have to be ordered in addition to the PI manifold?

Mr. Jones

you have to order a set.
you need manifold gaskets PI 99-2004), coolant tube (99-2004), 2 o-rings for tube,
antifreeze
I recommend a thermostat and o-ring and if the belt is old do that too.
you might need some heater hose and clamps

2000GT4.6

Maybe this is why you didn't realise any gains?? They make the plates for a reason. You need a nice smooth route for the airflow. Anything else will cost you power.