Re: Port & Polish

[mike tipton <mtipton@netten.net>]

Rob, to increase performance one must increase one or all three 
perameters that make a motor run. Fuel, fire, and air. Increase any one 
of these and you get a subsequent increase of power. The more you 
increase, the more power, to a certain point.

When you port, or enlargen, a heads intake and exaust tracts, this 
allows the motor more air volume into the combustion process, and makes 
more power.

When you polish or smooth out the intake or exaust tracts in the head, 
this "smoothing" also allows air to better reach (increase) and exit the 
combustion chamber. Also improving power, to a certain point.

This "art form" of porting and polishing(dental work) is skill, of much 
testing, tuning and involves years of experience. Also what may work for 
one engine, may not work for another. Each engine is unique, as is each
port & polish job.

Todays technoligy allows even this area of "craftsmanship" to be taken 
over by CNC machines, and Extrude Hones.  For us the comsumer its good, 
to a certain point, but even this high tech approach can't tell you how 
the head will run once installed on a motor.  This is where a "flow 
bench" comes in handy. Actually it is a nessesity to measure the 
"improvement in air flow".  But this is also no indication how the head 
will ultimately perform on the block it will be bolted too! 
The flow bench is used to make sure each individual chamber flow's the
same amount of air, and to check how much more "volume" of air the head 
will flow ported, compaired to stock. This gives one an "idea" of 
improvments in flow, which should equal improvments in power.

Once you know the combination of port shapes and sizes to use with the 
combination of valve sizes, and pistons, of a specific motor, and head, 
you have the knowledge to port and polish (dental work) a head and have 
it perform well. This is where the "skill & experience" comes into 
play, and why a "select few" can perform this type of work, and 
guarentee the results you seek!

                                          M