The 2 litre 16v head cutaway and maximum porting dimensions thread.

[Brian.G]

VW 2 litre 16V cylinder head. (Engine code, 6A)

RED=Cut Faces.
YELLOW=Exhaust Ports.
GREEN=Intake Ports.
NAVY=Waterways.
ALLOY=Original Casting Open To Air.

(Ill get measurements and specs up tomorrow and put up a few notes, broadband off all day here today since morn and only got logged on now, sorry for the delay, i nearly went mad too!
One thing to note this was a test head, the injector cut outs and valve guide bosses have been smoothed, 3 intake ports were polished, THERE WAS NO METAL GROUND FROM ORIGINAL PORT WALLS, just polished.
In the mean time ill let the pictures do the talking,
enjoy
B.G)

[Brian.G]

[Brian.G]

[Brian.G]

[Preen59]

Thanks for the pics man!


Note the angle of the exhaust valve and the short, sharp turn of the exhaust port. This is why (well, one of the main reasons) these heads are by today's standards, not that great as an atmo engine without decent port work.

[Brian.G]

Just getting the maximum porting dimensions together now, im going to try and make as simple as possible to understand so people can compare/go off these measurements if someone wants to take their head to the max and is afraid theyll hit a water/oil way.
Im going to present the measurement diagrams in 3d if you like, and show you how to make a simple datum point frame that can be fitted to a standard port(s) to take these measurements off so you can mimic them perfectly, or should i say use them to see how far you can go.
Ill leave a safety margin on them to allow minium port wall thickness of say 2.5mm(in spots) or so, i have to compare all the port wall thickness in a load of places first in order to get an average casting thickness, find the average and danger areas, and add a few mm for a safety zone.
I may even post 2 sets of dimensions, safe maximum dimensions for the experienced porter, and another set for the guys that like danger and want the MAXIMUM at all costs even if it means going near the borderlines.
Ill present the port diagrams in MS paint (no laughing now!!).

When i have time im going to run all these ''possible maximum'' port dimensions on my engine simulator(optimum port shape of course) package and see just what this head is theoretically able to flow.
Should be interesting even if it is simulated.
Thanks for the reply's guys, all for a good cause.

I forgot to point out that some of the cuts above arent at 90 degrees to each other, some had to be cut at 85degress in order to take in all i wanted intto account and at the same time avoid the valve seats and other stuff as i dident want to risk damaging my 400mm tct alloy blade doing it ££££££££££££££££.

Just dropping this in here to save me making a folder, ill re-edit this reply and get rid of all the small talk above so it contains all the details and specs/sizes so feel free to reply in the mean time as you wont effect me as its going to all be contained here, itll all make sense when im done, going to take a few hours.

THE INTAKE PORT.


Cross-section view below, coloured lines corresponding to the coloured cross-sectional circular measuring planes in the diagram above.



Please note that both tracts of intake ports are done in the Cross Section list below.
I just showed you the location of the cross sections of the right port in the drawing above to save the sketch getting cluttered.

Although it is all the one intake port at the point of entrance im going to treat it as if it were two so read carefully below, its pretty simple to follow really.
The whole point of this table below is for anyone that wants to take their head to the maximum.
Once i show you how to make the datum jig you will be able to look at specs below and with an Inside Calipers know in one second if you can go more or not in that particular area.

Obviously the port would look pretty odd if you were to take it out to each of these angle measurements shown below, thats not the full purpose of this table, its an indicator as to HOW FAR you can go in each particular place in order to perfect your desired port shape.

----------------------------------------------------------------------------------------------------------------------------------------------------
First measurement is actual distance between gauge wire and wall, second measurement is possible size with appropriate warning measure listed after.
THE INTAKE PORT MAXIMUM MATERIAL REMOVAL REFERENCE MEASUREMENTS.
WHITE CROSS SECTION 1.
(Please note some angle measurements to port wall on the first few cross-sectional planes will be marked N/A as the port has not yet merged into two at this stage)
Left Port.
0' = 14mm> 20mm
45' = n/a
90' = n/a
135' = n/a
180' = 14mm> 18mm
225' = 14mm> 18mm
270' = 14mm> 18mm
315' = 14mm 18mm

Right Port.
0' = 14mm> 20mm
45' = 14mm> 18mm
90' = 14mm> 18mm
135' = 14mm> 18mm
180' = 14mm> 18mm
225' = n/a
270' = n/a
315' = n/a
----------------------------------------------------------------------------------------------------------------------------------------------------
GREEN CROSS SECTION 2.
(Please note some angle measurements to port wall on the first few cross-sectional planes will be marked N/A as the port has not yet merged into two at this stage)
Left Port.
0' = 14mm 17mm
45' = n/a
90' = n/a
135' = 14mm 17.5mm>1.5mm to water way
180' = 14mm 16.5mm>1.5mm to w/w
225' = 13mm 16.5mm>1.5mm to w/w
270' = 13mm 16.5mm>1.5mm to w/w
315' = 13mm 16.5mm>1.5mm to w/w

Right Port.
0' = 14mm 17mm
45' = 13mm 16.5mm>1.5mm to w/w
90' = 13mm 16.5mm>1.5mm to w/w
135' = 13mm 16.5mm>1.5mm to w/w
180' = 13mm 16.5mm>1.5mm to w/w
225' = 14mm 17.5mm>1.5mm to w/w
270' = n/a
315' = n/a
----------------------------------------------------------------------------------------------------------------------------------------------------
PINK CROSS SECTION 3.
Left Port.
0' = 13mm 16.5mm>2.0 to rocker interior area
45' = n/a
90' = n/a
135' = 12mm 15.5mm>1.5mm to w/w
180' = 13mm 16.5mm>1.5mm to w/w
225' = 13mm 16.5mm>1.5mm to w/w
270' = 13mm 16.5mm>1.5mm to w/w
315' = 13mm 16.5mm>1.5mm to w/w

Right Port.
0' = 13mm 16.5mm>1.5mm to rocker interior area
45' = 13mm 16.5mm>1.5mm to w/w
90' = 13mm 16.5mm>1.5mm to w/w
135' = 13mm 16.5mm>1.5mm to w/w
180' = 13mm 16.5mm>1.5mm to w/w
225' = 12mm 15.5mm>1.5mm to w/w
270' = n/a
315' = n/a
----------------------------------------------------------------------------------------------------------------------------------------------------
BLUE CROSS SECTION 4.
Left Port.
0' = 13mm 16.5mm>1.5mm to spring seat area directly above
45' = n/a Although the port divide starts here I wont count it as it is dead alloy carring no water way at this point and can be ground.
90' = n/a Although the port divide starts here I wont count it as it is dead alloy carring no water way at this point and can be ground.
135' = 9mm 14mm>1.5mm to w/w
180' = 10mm 14mm>1.5mm to w/w
225' = 11mm 14mm>1.5mm to w/w
270' = 13mm 18mm>1.5mm to w/w
315' = 13mm 17mm>2.0mm to w/w

Right Port.
0' = 13mm 16.5mm>1.5mm to spring seat area directly above
45' = 13mm 17mm>2.0mm to w/w
90' = 13mm 18mm>1.5mm to w/w
135' = 11mm 14mm>1.5mm to w/w
180' = 10mm 14mm>1.5mm to w/w
225' = 9mm 14mm>1.5mm to w/w
270' = n/a Although the port divide starts here I wont count it as it is dead alloy carring no water way at this point and can be ground.
315' = n/a Although the port divide starts here I wont count it as it is dead alloy carring no water way at this point and can be ground.
----------------------------------------------------------------------------------------------------------------------------------------------------
LIGHT BROWN CROSS SECTION 5.
Left Port.
0' = 12mm 22mm, guide boss area, plently of material.
45' = 12mm 14mm>1.5mm to w/w
90' = 10mm 13.5mm>1.5mm to narrow w/w in port divider
135' = 9mm 13.5mm>1.5mm to w/w
180' = 10mm 14mm>1.5mm to w/w
225' = 12mm 15mm>1.5mm to w/w
270' = 12mm 15mm>1.5mm to w/w
315' = 14mm 17mm>1.5mm to w/w

Right Port.
0' = 12mm 22mm, guide boss area, plenty of material.
45' = 14mm 17mm>1.5mm to w/w
90' = 12mm 15mm>1.5 to w/w
135' = 12mm 15mm>1.5mm to w/w
180' = 10mm 14mm>1.5mm to w/w
225' = 9mm 13.5mm>1.5mm to w/w
270' = 10mm 13.5mm>1.5mm to narrow w/w in port divider
315' = 12mm 14mm>1.5mm to w/w
----------------------------------------------------------------------------------------------------------------------------------------------------
LILAC CROSS SECTION 6.
Measured off the valve stem cut piece as the cross-sectional plane line depicts in the above drawing.
Left Port.
0' = 5mm 8mm>1.5mm to w/w
45' = 6mm 9mm>1.5mm to w/w
90' = 11mm 16mm>1.5mm to w/w
135' = 10mm 12mm>1.5mm to w/w
180' = 11mm 16mm>1.5mm to w/w
225' = 9mm 14mm>1.5mm to w/w
270' = 7mm 9.5mm>1.5mm to w/w
315' = 7mm 9.5mm>1.5mm to w/w

Right Port.
0' = 5mm 8mm>1.5mm to w/w
45' = 7mm 9.5mm>1.5mm to w/w
90' = 7mm 9.5mm>1.5mm to w/w
135' = 9mm 14mm>1.5mm to w/w
180' = 11mm 16mm>1.5mm to w/w
225' = 10mm 12mm>1.5mm to w/w
270' = 11mm 16mm>1.5mm to w/w
315' = 6mm 9mm>1.5mm to w/w
----------------------------------------------------------------------------------------------------------------------------------------------------
GREY CROSS SECTION 7.
Measured off valve stem.
Left Port.
0' = 10mm 14mm>1.5mm to w/w
45' = 10mm 14mm>1.5mm to w/w
90' = 10mm 14mm>1.5mm to w/w
135' = 10mm 14mm>1.5mm to w/w
180' = 10mm 14mm>1.5mm to w/w
225' = 10mm 14mm>1.5mm to w/w
270' = 10mm 14mm>1.5mm to w/w
315' = 10mm 14mm>1.5mm to w/w

Right Port.
0' = 10mm 14mm>1.5mm to w/w
45' = 10mm 14mm>1.5mm to w/w
90' = 10mm 14mm>1.5mm to w/w
135' = 10mm 14mm>1.5mm to w/w
180' = 10mm 14mm>1.5mm to w/w
225' = 10mm 14mm>1.5mm to w/w
270' = 10mm 14mm>1.5mm to w/w
315' = 10mm 14mm>1.5mm to w/w
----------------------------------------------------------------------------------------------------------------------------------------------------

[Brian.G]

THE EXHAUST PORT.


Cross-section view below, coloured lines corresponding to the coloured cross-sectional circular measuring planes in the diagram above.



Please note that both tracts of Exhaust port are done in the Cross Section list below.
I just showed you the location of the cross sections of the right port in the drawing above to save the sketch getting cluttered.

Although it is all the one Exhaust port at the point of entrance im going to treat it as if it were two so read carefully below, its pretty simple to follow really.
The whole point of this table below is for anyone that wants to take their head to the maximum.
Once i show you how to make the datum jig you will be able to look at specs below and with an Inside Callipers know in one second if you can go more or not in that particular area.

Obviously the port would look pretty odd if you were to take it out to each of these angle measurements shown below, thats not the full purpose of this table, its an indicator as to HOW FAR you can go in each particular place in order to perfect your desired port shape.

----------------------------------------------------------------------------------------------------------------------------------------------------
THE EXHAUST PORT MAXIMUM MATERIAL REMOVAL REFERENCE MEASUREMENTS.
WHITE CROSS SECTION 1.
(Please note some angle measurements to port wall on the first few cross-sectional planes will be the same both left and right as the port has not yet merged into two tracts at this stage)
Left Port.
0' =
45' =
90' =
135' =
180' =
225' =
270' =
315' =

Right Port.
0' =
45' =
90' =
135' =
180' =
225' =
270' =
315' =
----------------------------------------------------------------------------------------------------------------------------------------------------
GREEN CROSS SECTION 2.
(Please note some angle measurements to port wall on the first few cross-sectional planes will be the same both left and right as the port has not yet merged into two tracts at this stage)
Left Port.
0' =
45' =
90' =
135' =
180' =
225' =
270' =
315' =

Right Port.
0' =
45' =
90' =
135' =
180' =
225' =
270' =
315' =
----------------------------------------------------------------------------------------------------------------------------------------------------
PINK CROSS SECTION 3.
Left Port.
0' =
45' =
90' =
135' =
180' =
225' =
270' =
315' =

Right Port.
0' =
45' =
90' =
135' =
180' =
225' =
270' =
315' =
----------------------------------------------------------------------------------------------------------------------------------------------------
BLUE CROSS SECTION 4.
Left Port.
0' =
45' =
90' =
135' =
180' =
225' =
270' =
315' =

Right Port.
0' =
45' =
90' =
135' =
180' =
225' =
270' =
315' =
----------------------------------------------------------------------------------------------------------------------------------------------------
LIGHT BROWN CROSS SECTION 5.
Left Port.
0' =
45' =
90' =
135' =
180' =
225' =
270' =
315' =

Right Port.
0' =
45' =
90' =
135' =
180' =
225' =
270' =
315' =
----------------------------------------------------------------------------------------------------------------------------------------------------
LILAC CROSS SECTION 6.
Left Port.
0' =
45' =
90' =
135' =
180' =
225' =
270' =
315' =

Right Port.
0' =
45' =
90' =
135' =
180' =
225' =
270' =
315' =
----------------------------------------------------------------------------------------------------------------------------------------------------
GREY CROSS SECTION 7.
Left Port.
0' =
45' =
90' =
135' =
180' =
225' =
270' =
315' =

Right Port.
0' =
45' =
90' =
135' =
180' =
225' =
270' =
315' =
----------------------------------------------------------------------------------------------------------------------------------------------------

[Brian.G]

MAKING THE DATUM JIG AND USING IT TO TAKE REFERENCE MEASUREMENTS.

Ok now we have all our maximum safe removal measurements so I'm going to show you how you can check your Cylinder Head off these measurements with a very simple datum jig and an inside callipers.

Your going to need two intake valves, one valve guide, a 3mm bit, some 2.5mm strong wire, a hacksaw, a vernier callipers, and a few other small bits.

The valves below.



Measure 75mm from top of valve and mark it, either with a fine pen or some tape as I have done below.



Cut, probably best to use grinder as there quite hard, finish up to the tape with the grinding stone to bring to 75mm.



Next, cut the valve guide into two approx 12mm lengths.



Drill these with a 3mm bit, dot punch first.



Fit onto valve stems and make sure the centre of the 3mm hole is EXACTLY 48mm from the top of stem.



Superglue or as i did soldier them in place, again making sure nothing moved, top of stem to centre of 3mm hole 48mm.



Mark with paint so youll know which way holes are facing when viewed from below.



Right you can leave them aside for a minute or two, now onto the 2.5mm wire.

Youll need a few bits, lets start with the intake side, cut two pieces approx 95mm long.
Once you have them cut point one end of each on the grinding stone.



Measuring from the tip come 15mm at a time up along wire.
Mark positions with a pen, once your happy lightly track each mark all around the wire with a junior hacksaw or dremel.
Its very important not to bend the wire, it must be 100% straight. I used high chrome wire but im sure the core of a stainless high chrome welding rod would do fine.
The purpose of these tracks is to hold a tiny band of paint to match the colours in my port cross-section sketch above.
Maybe not that necessary but its easier to go off the colours instead of counting the grooves.



Heres what you should have when complete.



Wire should fit snugly into hole and not shake about.


(more to follow)

[16v_kid]

very good info...

[Brian.G]

Leave the above bits in my previous post aside for the minute.

Next up youll need a bit of material approx 100mm long(not important) approx 12mm wide, 3mm thick, it can be anything, steel, brass, possibly even a lolly pop stick.
Mark out as shown below.



With that same 3mm drill bit drill the two holes.



Mark the location positions and track each edge with a junior hacksaw, also mark mid point on ends and track them too as shown below.





Turn piece over and counter-sink the 3mm holes with an 8mm bit, be VERY careful you dont go all the way through.
You just want to leave say 1mm of the 3mm hole at the tip of countersink.



Intake jig all done, the stems can be used in the exhaust jig too so you'll only have to make one set to keep it simple.



Now onto the exhaust jig, follow the drawings, same as intake port really but with different dimensions.

[Brian.G]

Back to the wire again, you'll need two pieces 60mm long and 65mm long, point tips as before and from the tip mark the 5 points with 11mm between them.
Track around as before.



You should be left with this when finished, apply paint to grooves finishing in white at the straight end.



Thats the datum jigs made!!
----------------------------------------------------------------------------------------------------------------------------------------------------

SETTING UP THE JIG AND USING IT TO REFERENCE THE MEASUREMENTS LISTED ABOVE.

Right, first, give the intake face of head a good clean with water paper or a fly cutter in a milling machine.
Insert two studs into lower holes that are used to affix intake manifold, one stud either end of head.
(in my case head was cut so i used to holes near each other, you wont have that problem!)



From the side of this stud mark a line 28mm up, this is your datum line for setting the jig and also the mid-way position of port mouth.



Scribe a light line along head.



Like so.



Now the stems.



Insert into guide from the bottom up, MAKE SURE the red marks indicating when the hole is pointing straight out, parallel to each other.



Using a piece of 3mm stock(if you used 3mm for the position pieces this will work perfect)set the stems 3mm shallower than head face.
You could do this a number of ways I guess but this is the handiest I think using parts on hand.
Perhaps tape on a rebated block to head face to ensure they stay exactly 3mm back, I set them once and they dident move afterwards. You just need to make sure they are 100%, easy.



Insert wires into holes, remember its the long set of wires.



Place strip on top making sure you centralise it on all the saw cuts on its edges in relation to port width, and line the cuts in the ends on the scribe mark you just made.



If you have a scrap head now is the time to fill the countersinks around wire with soldier OR if its a good head and you fear a torch may warp it, use a two pack epoxy in there they dont take much holding really.
Im going to soldier mine as ill be using this tool many times.

You can now see with the jig in place measurements can be taken in seconds with the inside callipers, and the great thing about it is for most porting work you can leave the stems in place and just pull strip and wires as a unit once soldiered giving you instant access to get the burr in there again for any fine tuning.
It is important though to make sure stems dont move out of reference when checking specs, they wont though as there's no work on them, but double check every time.

[Brian.G]

SETTING UP THE EXHAUST JIG AND USING IT TO REFERENCE THE MEASUREMENTS LISTED ABOVE.

Insert two studs into lower holes that are used to affix exhaust manifold, one stud either end of head.
(in my case head was cut so i used to holes near each other, you wont have that problem!)

From the side of this stud mark a line 30mm up, this is your datum line for setting the jig and also the mid-way position of port mouth.

Please note the jig must be setup on port two, port one being at the belt end.


Scribe line at port centres as done on the intake side.



Insert the two stems into guides from the bottom up, MAKE SURE the red marks indicating when the hole is pointing straight out, parallel to each other.
This time you must set studs 12mm back from face of head.
You could do this a number of ways I guess but this is the handiest I think using parts on hand.
Perhaps tape on a rebated block to head face to ensure they stay exactly 12mm back, I set them once and they dident move afterwards. You just need to make sure they are 100%, easy.



Insert wires into holes, and place strip on top, remember its the longer wire thats goes on the right.



Soldier or glue, put a red mark on the left hand end of jig.



Place in vice and cut at approx angle as show taking into account where the red mark is in the picture, cut must be exactly on the centre of strip, cut down to to port width mark.



Cut out the little triangular piece, do this both ends, be careful and make sure you dont bend wires.

Should look like this when done.



The purpose of cutting ends out at an angle is because jig has to be inverted for measuring ports 3 + 4.
Ports 1 + 2 are mirror images of 3+4 so to save making two jigs these cuts at ends make it possible for the jig to be used on all four.
If they weren't cut the strip wouldn't allow datum wires to enter port straight as the strip would be kicked on manifold face.
See below, the angle cut allows jig wires to enter at correct angle, same as before, just make sure you keep it on your port centre line.



An easy way of knowing if you have jig the correct way round is just check to see if red dot is pointing to centre of head and not towards the flywheel or belt ends.

Thats it Guys, your now ready to take your measurements and start checking where the material can be taken out of, Im going to spend the next while filling in the co-ordinates so you can use them for reference.
I still need to pick a safety margin, ill post safety margin too when I come up with one Im happy with.

The jig is real easy make, describing how to make it actually took longer.
Remember, make it as accurate as you can, after all its pretty basic but the measurements must be adhered to.

[Brian.G]

Exhaust side specs up tomorrow.
Came across this on my travels:

''VW 16v head:
The VW 16v head is a performance nightmare. I think VW introduced the
head merely to say they had one, as they obviously didn't care about
performance when they designed it. VW began design of the 16v head
about 1980. It went through various metamorphasizing phases before
it was released. On one version, the exhaust cam was gear driven,
but VW ultimately chose chain drive because it was the quietest way
to drive the exhaust cam. (The quietest way they would consider;
they obviously chose not to allow the exhaust cam to be belt driven
with the same timing belt as the intake cam...which would have been
the quietest by far.) According to my sources, VW was planning to
introduce the head as early as 1984-85, and some 80000 units were
produced. Then it was discovered that some engineer forgot to design
water in the casting around a pair of exhaust valves. Overheat =
cracked head ==> junk 80000 castings <==> put the program back a
couple of years.

Before the head came out, rumors were circulating as to its design
characteristics. All of us in the high performance business cringed
at what we heard. We heard that VW had designed the head with the
exhaust valves top dead center over the combustion chamber; the
intake valves cocked over about 20 degrees. We said if that was true,
the head was junk. We couldn't believe VW (read that ANYBODY) would
introduce a high performance head with such awful flow characteristics.

When I saw my first 16v head (off the motor), all my nightmares turned
into reality. Actually, it was worse than I thought. The exhaust valves
were top dead centre, but the exhaust ports exceeded a 90 degree bend
to allow the gas to exit. This head was obviously not designed for
performance. The valves spacing is too close together, thus putting
in bigger valves would be near impossible. The only possibility of
obtaining higher performance was porting and polishing.''