B16a cylinderhead development pt.4

exhaust ports now for the b16 head
*this is exhaust port 1  (above)

the lighting shows the shape and contouring done to aid in flow exit
without increasing port volume too much that it lessens exhaust exit speed

overall , if the port exit speed is high enough, the engine has to work less to
rid itself of the exhaust fumes and spent gasses
which in turn could let us run a bigger cam or tweak on overlap
without as much drawback to it

-interesting tid bit , most honda cylinder heads has exhaust ports that are directional
 meaning none of them are of the same exit angle (left to right) from one another

- this pic is of exhaust port 1 (cylinder number 1)

*exhaust port 2 (above)

-notice the direction compare to exh port 1 , its angled to the same side
 but to a lesser degree

-very basic detail showing flow improvements done by way of
 proper shaping and contouring of the ports

*exhaust port 3 (above)

-now we see a directional change from left facing to right facing angle
 compare to exhaust port 2 for reference

- the guideboss in the exhaust port arent as obstructing as the intake ports
  so minimal shaping or material removal is needed , plus the flow now is in reverse
  compare to the intake guide boss , think of an aerofoil for reference

*exhaust port 4 (above)

-direction of the port is a lil more pronounced compare to exh port 3
 basically the number 4 port is now a mirror image of exh port 1 in reverse

-some people port the exhaust and try to reshape them in ways that
 they try to make all 4 ports angle to the same direction (straight)
 and it is possible , it also looks good
 unfortunately that is all that is good to it.. looking good
 as flow then vary from 1 exhaust port to another  ultimately making it inefficient

-port texture on the exhaust port is in some ways a lil different to texturing the intake
 for one , the critical importance of keeping fuel atomized is gone
 another , sooner or later the portwalls are coverd in carbon deposits

-making sure theres a uniform finish to the exhaust port is better
 smoothing it is ok... so long as it is uniform , so that carbon deposits  would stick
 evenly  ...we dont want sections with carbon and other sections clean 
 it only then means the shape has lost its benefit

so again... the term PORT AND POLISH
is quite a misnomer , since   we havnt and dont ever "polish" anything
as far as texturing goes