Porting How-to

Fri, 26 Dec 2003
From: kim steele
Subject: Porting (a tutorial) LONG !!

Well, I sat down here to say a few things about porting & here's the
resultant novella ..... Hi Ho :>)

For porting cast iron, it's best to either use an air powered or
electric die grinder (<- my fave). A drill can't turn the R's a carbide
burr will need to really be very effective, since carbide burrs work
best at or above 20,000 rpm. On aluminum, like an intake manny or a
head, there are special (ex$pensive) wide fluted cutters made that are
really the only bit suitable for this type work. Though standard carbide
burrs can be used on aluminum, they will quickly load up the flutes on
the cutter & cease to do any further cutting until the flutes are
cleaned out. I don't recommend the bonded stone type cutters as these
will wear quickly when porting, make tons of dust while doing so and are
also quite prone to shattering & becoming some very fast moving
shrapnel at the speeds most die cutters turn, which is NOT a cool thing

Dremels are waaaay too light duty a tool for port work. While they're
fine for shaping plastic or other soft materials, a cast iron manny or
0-2 housing will just sneer at you if you pull one of these puppies on

The best die grinders I've used yet are Makitas & I LOVE mine, but
.. they ain't cheap, my 2 blue babies cost $250 each. Makita has
discontinued production of a really nice small & light model they used
to offer called a G600 (or something like that). These can still be
found online here & there for sale (new) however & are a very sweet
die grinder & run about $100. One of these models was my 1st electric
die grinder & it lasted for about 10 yrs before it died.

The newer Makitas are bad ass tools (bad enough that they both come with
a removeable side handles, like typically seen on 1/2 drills !) & are
generally lighter than many other brands, a major consideration for a
tool that will spend many hours in your hands :>) One of mine is the
high speed model which turns up to 27,000 rpm & the other is their
buffing model which turns a max of 7,000 rpm & both are adjustable
speed. I believe Makita has already stopped making the 7,000 rpm model,
which is a shame, since they are truly ideal for polishing out the
finished port work & are really the "cat shit" to use with a cut off
wheel, since the lower tool speed makes them much easier to use than a
high speed die grinder for this application.

While Milwaukee & Dewalt offer some very rugged & well made die
grinders, I find them heavy & ungainly for porting. The Makitas
(relative) light weight & the thinner snouts they incorporate into
their die grinders make them my personal choices for porting. These
will allow access to some places these other tools can only dream of
reaching with your carbide burrs ! Metabo, Hitachi & Bosch also have
some good die grinders too, but if $250 sounds steep for a die grinder,
don't even THINK of lookin at one of theirs !!!!!

For die grinder bits I usually use either Travers Tool, J&L Supply, MSC,
or WW Grainger, though the 1st 2 are a lot cheaper :>) I've also found
some killer deals on Ebay. I always prefer a "double cut" over a
"single cut" style carbide burr as they will offer better control of the
bit while it's being used. Single cut burrs are more prone to cause the
die grinder to jump in your hand when cutting, while the double cut
burrs are less prone to do so. A typical decent price for a quality
carbide burr will be $6 - 15 each. DO NOT try the cheepie route & buy
the rotary burrs / files, which are made of much softer metals & won't
last long at all ..... unless you're workin with plastic :>) The
special wide fluted aluminum cutters typically will start at around $15
ea. & I've spent as much as $32 ea. for some really good ones.

I like the "christmas tree", "flame", or "egg" style / shape bits the
best overall, though "spherical head" cutters have some interesting
applications too ! You'll want to stay away from any bits that come to a
point or a flat / straight edge on the end of the bits as these are
really good at making accidental gouges ahead of where you're trying to
cut & require additional work later to smooth out the unintended
"ouchies" made by the nose of these type cutters.

Carbide burrs are also be available in different OD sizes & the right
choice for the OD of your cutters will be tied to the capabilities of
your die grinder itself. If you have a cheapie die grinder you'll be
better off with an OD of no larger than about 1/4", while a more
powerful die grinder will be capable of ODs of 1/2" or so, which allows
for faster roughing in cuts.

There are also bits available with 6" long shanks for getting into
deeply recessed areas, but these must be used with the utmost care as
any extra side loading of the bit, past a certain pressure point, will
cause the shank to bend, quickly and sharply, something you DON'T want
happening to a mean ass carbide cutter turning 20,000 or so rpm :>0

Carbide burrs are typically available with 1/8" or 1/4" shanks & both
will have their specific purposes. For fine detail type work, a 1/8"
will do great, but for all the roughing in & major cutting operations
you'll do better with the 1/4" shank cutters. Most die grinders don't
come with the 1/8" collet needed to use the 1/8" cutters, but can
usually be purchased separately for an extra $10 -20. You'll also need
some metal cutting oil to periodically dip your burrs into to help
extend their life. Stop your die grinder briefly, dip the cutter in the
oil & then put the cutter back inside the part you're working on &
lightly against its surface before restarting the die grinder. This
will throw all of the excess cutting oil on the bit onto the inside
walls of the part you're working on, instead of on you, the table,
walls, etc. as will occur if you restart your die grinder outside the
part :>)

I finish up all port work with a cartridge roll to smooth up all the
slight imperfections typically left by the carbide burr cuts. These are
made from emory cloth which is wound and glued together which will be
fitted to a special cartidge roll mandrel. These are also available from
the same sources as are the carbide burrs & run from .25 up each,
while the mandrels will be from $2 - 5 ea. . There are a few different
shapes & sizes to choose from & they are available in varying grits
for different finished textures . BTW, grit sizes for these start at
about 36 - 40 grit (very coarse) & run to about a 220 grit (fine).
The best, longest lasting and most exspensive cartridge rolls I've used
are made by 3M. These aren't cheap, but they will typically outlast
most other brands nearly 2 - to - 1 !

For a truly "polished" finish, I recommend either a very fine grit
cartridge roll, like a 220 grit, or my real fave is a product available
from only a very few manufacturers which is a cartridge roll made of a
"scotchbrite" like material. These will leave the smoothest finish
possible (short of extrude honing" and are very easy and forgiving to
use. These are usually pretty expensive bits (for a cartridge roll) &
kinda hard to find though.

To anyone claiming to be able to port an exhaust manny in 30 minutes,
I'd sure like to get a look at their work. I spend waaay too much time
on them, making sure every detail is as perfect as I can get them &
typically take 4 - 8 hrs to do a manny & another 1 - 4 hrs on 0-2
housings, depending on what the customer is after from the port work.

On exhaust mannies, be sure to mark out (a good metal scribe will be
your best tool here) the plenum exit areas with a new gasket before
starting & open the plenum out to the gasket line. Then blend a
smooth (flow enhancing:>) radius to break the edge that will be left
where each runner enters the plenum (good flow HATES sharp edges). Make
sure to leave as much of the center divider wall in the plenum opening
as possible, since it IS needed to help direct the exhaust gasses flow
through the plenum & assists with anti-reversion of the gasses into
the adjoining ports. If you wind up cutting the divider wall any more
than a little, it may eventually break off pieces which will wind up
being force fed directly to your exhaust turbine wheel & destroy your
boost generating toy !!!

Next buff the "roof" areas of the runners (cartridge rolls needed here)
into the plenum. The exhaust runners coming from the head side will
only need to be buffed smooth to help the exhaust gasses flow more
smoothly from the head ports. I also raise the top of the exhaust
runners (where they mate to the head) to match the top of the exhaust
manifold gasket opening. This will help the exhaust gasses flow exiting
the head, in the area where it will be seeing the most flow (along the
roof of the port), as it enters the exhaust manny :>)

To get all the extra exhaust flow possible, you should match the porting
on the exhaust mannys port roof with a bit of porting to also raise the
port roofs on the exhaust ports in the head itself. A slightly larger
opening in the exhaust manny itself compared to the heads exhaust ports
will be beneficial in the anti-reversion category :>)

0-2 housings just need to have the bumps and such smoothed out & then
polished to help the exhaust gasses have the smoothest (least restricted
path :>) into the exhaust system. Be careful if you do any serious
porting to these parts as I've found some nasty casting flaw "pockets"
in these parts which have led to a lot of extra work to smooth
everything out when you hit one ! One such flaw I found in Nathan Clays
housing that went all the way through to the outside of the housing
after cutting away only about a 1/16" of an inch of the inside of the
part led to having to weld up the resultant hole !!

Safety!! -->

I recommend using some good thick leather gloves when porting and
prefer long cuffed welding gloves myself. The full length welding
gloves are a plus since they are insulated / padded, which helps a lot
with the vibration that gets transmitted to your hands doing port work.
Failing to wear gloves will quickly make you wish you had ! Oftentimes
I've picked up a die grinder to make some quick little cut & neglected
to don my gloves, only to spend time later diggin out some of the tiny
sharp shards from the cutting operation that wind up in my fingers :>(

It is recommended that you use a good pair of either safety glasses
(with side shields) or goggles & additionally a full face shield when
porting. Metal finding it's way into your eyes is NO FUN, hurts like
hell & will cost from $100 -500 to have removed by an eye specialist !
This IS the voice of experience talkin here, so ........ KEEP YOUR EYES
SAFE !!!!

It's also recommended that you wear a tee shirt & cover up with a long
sleeve shirt over it, buttoned up as tightly as possible. The long
sleeve shirt keeps the metal off your arms & such, while the tee shirt
will keep it from getting to your skin. I also recommend tucking the tee
shirt into your pants & leaving the longsleeve shirt out & loose.
It's best to cover your hair with a hat or something to prevent the
metal from winding up in your scalp too. As strange as it may sound,
womens hose pulled over you hair works great ! It keeps the metal
particles from getting into your scalp while still allowing good airflow
to the scalp, not a bad deal when you're all bundled up like friggin
Nanook Of The North (as you should be) when doin portwork !

You'll be best served to use a good quality dust mask like a 3M or a
Gershon "dual strap type" dust mask when porting. The cheesy single
strap style POSs are best left hangin on the shelf where you find them,
as they are actually pretty worthless at keeping anything smaller than
about a bee from gettin up your snoot :>) While it wouldn't seem that
porting would generate metal particles small enough to wind up being
inhaled, I assure you it does. When using cartridge rolls for the
finish buffing, there will be a lot of both metal dust and dust from the
sacrificial loss of the cartridge rolls as they cut / wear away & this
shit will load up the ole proboscus in a hurry, so be good to yourself
& get a good dust mask !!! These will run about $2 - 3 each for a good
one & you'll be amazed (thankful) after some time spent porting to
see what you'll find has been collected on the outside of the mask
instead of inside your nose & lungs ! Secondarily, I always port with
a good fan blowing from behind me to keep as must metal away from me as

One more thing !!

Porting will generate a ton of sharp metal slivers that will wind up
both on & stuck into your clothes, socks and shoes. If you're not
careful, these will also wind up being transferred into your homes
floors and / or carpet & typically found some time later as you pad
about the house barefoot. If you're lucky, at least you'll be the
(unlucky) one to re-discover the unexpected fruits of your porting
labors instead of the lady of the house or even one of the kids.
Getting metal stuck in your feet is another NO FUN deal & even worse
when the ole lady or the kids find one of your "little friends", which
can lead to being chased around the house with a big frying pan /
rolling pin, (here in the good ole South, she may just get out your
pistola & chase you around with that for a while !) or whatever else
is heavy and handy at the moment, all the while she'll likely be
screaming out all kindsa deragatory things about your family lineage &
threats relevent to your future well being!

Your best defense against such stuff (unless you're down right into pain
& suffering and just LIKE being chased madly around by an enraged
feemale) is to strip down to the skin & blow yourself (and your
clothes) off with air before coming back in the house after you and the
die grinder are finished getting jiggy with your ported parts & then
take your clothes straight to the washing machine !

Kim Steele

[email protected]