D16y8 Cylinder Head development : Hybrid d15b project

                    A shot depicting the contours and attempt at flow improvement of the exhaust port
one of the hard things to do with the exhaust is porting and maintaing a nice "round" port  and such

- You can see the texture and work on both sides/banks of the splitter and port itself
   the splitter could be knife edged , but by doing so , has its consequences
   like increasing the CSA at that zone/section of the port and possibly killing velocity
  

this is it for today.... some updated pics soon as some machinework is done :)
stay tuned!

D16y8 Cylinder Head development : Hybrid d15b project

                                                  The exhaust end of the business :)
this is as it sits, pending machine work i.e.
-deck surfacing/milling to achieve the needed compression
-mirror surfacing the deck *milling finer , to ensure superior seal and longer lasting head gasket life
-3 angle valvejob , that incorporates concentric bottom cut , and a top cut that improves discharge coefficiency of the port itself

D16y8 Cylinder Head development : Hybrid d15b project

Good pic again to show some details : the opposing view of the intake ports from the chamber into port
the camera angle is to the direction of the port bias
it shows the work done to it  , limiting the portwork/material removal so to not enlarge the port too much

- the short turn radii is visible and the abrupt turn is now gone and inplace  a nice gradual turn
- the port shape leads into the "throat" and then right before the valve seat nicely now vs when stock

D16y8 Cylinder Head development : Hybrid d15b project

an awesome shot depicting the work done ,  and a good pic to describe it all
-the faint line on the side of the port.. is still visible as proof  of the amount of material removed (not much)
-the overall port shape  and turn./bend can be seen due to the lighting
-alot make the mistake of making things "bigger"  thinking its better or "more" flow which kills velocity
-this kind of port work (the pic above) will do wonders, and keep up with a bigger camshaft to aid top end
-yet maintain an ideal grunt in the lower rpm range + and achieving better fuel efficiency is common

D16y8 Cylinder Head development : Hybrid d15b project

pics of the intake ports, showing  the biased ports to the right ( to the left when inverted )
the goal is ofcourse, higher port velocity ...obviously for superior torque improvement  , this pic shows some details around that goal and work.. as some casting marks at the tip of the divider is still visible (hogging this out will tend to inhibit port velocity) 

D16y8 cylinder head development : hybrid d15b project

d16y8 cylinder head from the 96-00 civic variant : key differences to its d16z6/d15b counterpart is the biased ports to induce "swirl "  and a closed style chamber much like the b18c1 GSR  compared to a b16a

the finished product : 043 (mexico) casting SRDmotorsports ProStreet heads 40x35.5

its now running (at the time of posting)
and the specifications are :

90.5x78.4 = 2017cc type1 vw

40x35.5 SRDmotorsports Pro Street heads
90.5 Mahle piston and cylnder set
78.4 CBperf 4340 chromoly crank
k8 camshaft + 1.4 ratio rockers
dual 48 IDA's (weber carburettors)
1 5/8 merged header w/ fatboy muffler
9.1:1 static comp

it holds its own at the two race circuit its been to...
competing with a couple of 2110cc beetles ,
a 2332cc is its current nemesis  :)

so i guess the lack of displacement didnt matter,  POWER is in the HEADS

here's a better shot of the intake ports , some like shaping the entry to bias one direction or another
while some like to turn them to D ports,
i myself prefer looking at the intake ports as 1 part of the whole intake tract which includes the intake manifolds , and carburettors
and as such , it is shaped to correlate with the rest of the system
taking note that
1- flow will always be faster at the short turn radii (radius/bend) just like flowing rivers
2- having a larger "delta" between the speed at the short turn and long turn will cause fuel to drop
  out of suspension (lesser mist, more of a puddle) which isnt really good for economy and performance
3- different intake manifolds give different flow entry to the head's intake ports

the same shot with no lighting, just raw picture as it is to the naked eye

overall goal for the head development is :
improve torque (first priority)
flow well enough to have a healthy mid range and carry over to the top end (6-6,500rpm)
aid in keeping fuel in suspension (air/fuel mist) so that it doesnt rely on "fat" main jets  when tuned

next post will cover a lil more info on the engine itself

here on a slightly angled shot of the same exhaust port we can see the short side radii better
and how it is contoured and slightly widened
and light trail in the pic shows the whole exhaust port being a gradual smooth bend to promote higher exhaust exit speed
if always been a proponent for high exhaust exit speed on the heads i work on and the reasons are
1- it has the capability to improve Volumetric Efficiency across the board (if the rest of the engine is good)
2- it becomes less sensitive to good or bad exhaust/header (ofcourse a better header will have good gains)
3- it lets you take advantage of not needing the biggest exh valve or exh. duration/lift
4- with the engine being able to expedite spent gasses, it generally runs less hot or wastes less energy

the exhaust ports on the mexican 043 casting is small, which makes it a very good candidate for portwork
because we are now free to reshape it as we see fit, without sacrificing excessive volume gain on the port itself ,   this pair has had minimal work and material removal done to it .
Reshaping the short side radii and a bit of roof work near the exit was all thats needed
and smoothing out the whole exhaust tract

here's another shot (the next chamber) of the intake ports from the chamber side
to show a lil more of the contouring thats been done etc

                                   here's a shot from the chamber side into the intake port itself
                 notice the concentric shape / contour  from seat to port and into the short side radii
       this is the most we can get as far as "straightening" the port , without having to excessively remove
material and increase port volume (too much port volume kills airspeed) which in turn  reduces the available torque that can be made

better lighting , to show the intake ports and how the shape has taken place from its "stock" casting

top priority in this 043 work is high airspeed , which can almost directly relate to better and wider torque range in the rpm scale of the engine ; ofcourse cam selection and compression does play a role too

                                         a better view of the intake port entry , port roof and all
              showing minimal material removal (streamlined ports = high airspeed ) on the ports itself

                       043 heads (mexican casting)  fully ported and improved flow
              i call this "super street" , which could be considered "stage2" for some
        *for a costumer/client that wishes to run these on the street with ample torque
         and be able to run/compete in the local road race competitions for vintage cars