d16z6/d15b vtec IM development pt.4

here is a picture  from the throttle flange side viewing the plenum and runner entry

-runner entry has taken shape after initial rough work and smoothing

-the dividers inbetween the runner entries are now more profiled

-total work would lead to a slight plenum volume increase, which is welcomed
  for a slight improvement on top end breathing 

*remember  the purpose of the plenum (even its meaning) is much like a reservoir
or an air tank/chamber  where  the intake tract's rush of inlet  gets to slow down
 expand  with an attempt at having "supply" per runner action

d16z6/d15b vtec IM development pt.3

here's an inverted shot, which shows the entry a lil' better than the previous picture

including the stock untouched yed "number2" runner :)

and the initial stage of runner entry enlargement

d16z6/d15b vtec IM development pt.2

Here's a shot of the porting (initial shaping) in its rough stage

we intended to leave the number3 runner to be ported last
so our keen viewers could see some sort of before and after in this pic

- runner entry ported to give a bit of flair

-runners slightly enlarged to give it a mild taper  to the flange outlet

d16z6/d15b vtec IM development pt.1

the d16z6 / JDM d15b / ESI (local to the phils) manifold  has some long runners swooping upward to the plenum , since the platform is mostly a commuter effort
and OEM , low rpm driveability prolly was the main concern

downside is, it is quite convoluted as far as flow goes  especially when the engine set up is hotter than stock,

here we do the ff :

cut open the plenum , to be able to port the runners, and slightly flair up the entry
for improved flow , porting the runners from the flange side
and tig welding the plenum shut

picture above :  is of the bare plenum surface and runner entry surface

B16a cylinderhead development pt.5

Bigger now to show details of the exhaust port

and the lighting and shadows help visually
in showing the overal shape achieved

-notice the port's curve from valveseat to throat all the way to the exit
 the attempt is to shape it to achieve a gradual of a bend as possible
 without needing too much material removal , we avoid hogging out the ports

- the lighting shows this (roof section of the port) and the shadows  help
  visualize the blending on the splitter and short turn radius

next pic showing much of the same, but with more visible details

shadow and lighting doing its part in showing the overall port curve/bend and smoothness

- notice the casting marks on the throat (splitter side) still a little bit visible
  hogging it out isnt needed  unless you dislike torque :)
  even on the port exit at the outer perimeter the casting flash is a bit visible 

- notice at the base of the splitter (top of the splitter in the pic) some of the
  tiny dots are casting bubbles , no need to totally remove them
  as the only benefit we can get from that is cosmetic in nature
  and port volume increase isnt really needed here
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this cylinderhead was done for a client
who has a simple build that is a b16a (1600cc)
on a 4door EK variant sedan

with these heads + decent cams and a good exhaust
it has run well into the 13second range in the 1/4mile
and thats with just a 1600cc displacement

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

B16a cylinderhead development pt.3

a shot of the ports, viewing from the chamber side

the lighting indeed helps to show the texture of the port surface
for better fuel atomization

and how it changes in texture as it reaches the throat and to the seat

-in theory this is to speed up flow as it reaches the valve
 with attempts at generating more possible flow and intake charge
 into the combustion chamber

- the section between guide boss and splitter is noticeable here
  with regards to work done to minimize obstruction in flow

- guide boss itself is seen here having more "aerodynamic" profile/shape

another shot from the chamber viewing the intake ports

- here, a more visible guide boss  shaped with a more aerodynamic profile
  some chop it all off, some shorten it ,  but by shaping it this way
  you minimize volume increase and actually maintain a higher flowspeed

- notice the texture change of the port leading to the throat
  and the throat being concentric to the valve seat

another shot from the chamber side, this time showing both valve entry

- this was taken bfor being totally finished  as evidenced by the texture change
   but also best illustrates the work done to it,

- the keen eye may notice , the port itself is still pretty "mild" as far as port enlarging
  and or sizing goes ,
  but funny enough this head will promote good intake flow velocity
  thats good for making decent torque 

- this head could work on smaller displacements and do wonders with regards to
  torque and power production
  and still be able to work with larger displacements , with just changes in
  camshaft profile to match