Siamese and/or port your TPI Base


If you are interested in porting, siamesing, or both to your TPI base, this if for you. You can opt to just port it, or siamese and port it.  Stock TPI bases are very restrictive, and every little bit counts.


You will need a few basics, like the porting bits.

1: cartridge rolls and a long shank
2: assorted grinding bits
3: cross buff kit.

You will also need someting to operate the bits.  An electric drill or air powered tool will work.  You will also need the TPI base.  I reccomend finding a spare, so that your car will not be down the entire time, and if you go to far, you won't be out a car till another can be found!


You can also go ahead and get a new set of intake gaskets, since you will need them to install the new intake.  You can use the gaskets to outline the ports so you know how much to take off.  You can see how much larger the gasket is compared to the manifold.  You want them to be the same size.  Also notice the casting bumps in the port.


The only real instruction needed once you mark the gasket, is to grind grind grind!  One point to mention is that the arrows on the left point out what seems to be the biggest restriction.  This is where I remove most of my material.  I used a socket that just barely fits in the port as a guage so that as I grind, I can make sure the diameter remains consistant.  Once the socket will pass all the way through, I use the sanding cartirdges to smooth it out.


If you are going to siamese the intake, you will also need a large cutoff wheel, and a dremel w/ a small cutoff wheel.  Use the large wheel to cut two horizontal grooves to remove the wall that seperates paired runners.  Then with the dremel and small wheel, cut out the back so the piece can be removed.


Here is the "wall" that will be removed.  This can be discarded.  Now you will need to use the same porting bits to remove all the sharp edges and make everything a smooth transition.


On the left is a just started pair of ports, and on the right is a completed pair.  Once you are done grinding, use the sanding rolls to smooth it out, and then you can use the Cross Buffs to make the whole port smooth as glass.  Since this is a dry manifold, it is OK to make the ports real smooth.

This manifold is ready to be cleaned and installed.  Since the ports on the head side were gasket matched to the lower intake gasket, it is best to do the same on the cylinder head if it is removed.  Obviously, if the heads are still on the motor, this isn't practicle, but is a suggestion if the heads are off.