I'm currently porting a head for my engine, just wandered if anyone has any pictures of 'professionally' done ones or some of your own work? It'd be good to compare.

Cheers

all i could find of my head...

1.6 (aee) engine.. seen with valve guides removed, before polishing

below, looking into the intake ports through dcoe intake manifold

Edited 7 January, 201016 yr by SkodaBoy

the BVH on my g40 (done by the guy who does jabbasport's heads).

inlets:

exhausts:

exhausts again

I never got around to actually modifying the cylinder head as I'm incredibly lazy.

This may help however.

10" of water.

I would concentrate on the short side radius and the valve guide.

There was a very good thread on SWDubs with lots of descriptions, pictures and flow figures of a ported 1300 head. Unfortunately it died, but the guy that did the work is on ClubGti, mr hillclimber. Here's another thread he wrote, but about the 8v big block head.

It would be tricky to get a really good shape without using something to measure air flow.

But it wouldn't be hard to make a pitot style flow bench.

Or even an orifice style bench.

Using a pitot probe to measure air velocity is a really useful tool and isn't too difficult to make at home.

I got a picture of runner castings from a GT Vs G40 inlet manifold if your interested.

God is the 1.0 head that restricitve?, cant wait to bolt my GT head and cam , 1.3 manifold and HIF38 carb onto the AAU block. Should be 1L rally killer!

Cheers guys,

I didn't bother taking out the guides, since it was initially a practice/'just have a go' head, but if i don't mess it up too bad i'll put it on and see if theres any difference good or bad.

I don't know if this was a particually bad cast, or they're all like this, but there was some seriously bad casting marks and ridges before i started. I've basically smoothed them out, i didn't enlarge much since i dont want to go too far/loose lower down torque. The exhuast side in particular had a big step in just below the sea, which i've just smoothed into the rest of the port. There isn't much room to work in them though which is annoying.

What do you suggest i do with the short side? I've smoothed it out a bit, since it was basically a right angle ridge.

The thread on swdubs was very good, it was for the earlier style head and i'm working on a hydraulic one. Mr Hillclimber has some of the pictures/text saved i think, hopefully he will repost on the new forum.

I havn't got any flap wheels small enough to make the finish better yet, but I'm not sure that is where the gains would be anyway... it's more shape than polishing...

God is the 1.0 head that restricitve?, cant wait to bolt my GT head and cam , 1.3 manifold and HIF38 carb onto the AAU block. Should be 1L rally killer!

I think the 1.3 head is restricted. The ports and valves are much larger, but it only flows about 10% more.

I would use a 1.0 head as a project. There is more scope to remove material in the correct places to develop a good flowing port with higher velocity.

If you notice the ports flow the same. Flow over 6mm is poor for both the 1.0 and 1.3.

I think piper sell a cam that lifts to 11mm or something. It would be totally wasted on an un-ported head as the flow just isn't there.

i hate to throw a spanner in the proverbial works, but big ports does not necessarily mean big power gains. what you gain at peak rpm you WILL loose somewhere else in the rev range

it's a 1.6 AEE head

exaust

inlet

dit this before my bike carb conversion

The ins, looking through a DHLA inlet manifold, the ridge is the gasket..

can only get a link going..

http://alkaspace.com/is.php?i=88514&img=DSC00634.JPG

Edited 7 January, 201016 yr by randombadger69

What do you suggest i do with the short side? I've smoothed it out a bit, since it was basically a right angle ridge.

That's a good start. Really you'd want a pitot tube to map the port velocity.

If you look at the cut away section I posted earlier you can see the velocity on the SSR is quite high. This is caused by the air becoming turbulent when it's trying to turn too sharply.

You could remove some material opposite the SSR as too.

I havn't got any flap wheels small enough to make the finish better yet, but I'm not sure that is where the gains would be anyway... it's more shape than polishing...

What I like to use is a split rod with some 80 grit sand paper.

I took an old drill bit, cut a slit in the end, then wrapped some 80 git on it and taped it in place.

You'll find it cuts and finishes better is you use a lubricant. WD40 is fine.

I've been meaning to modify a head for ages. I was going to have a go at fitting a 38mm inlet valve in a 1.0 head and port that.

Edited 7 January, 201016 yr by varnish

Knobloch 38/33 3f/PY head

Knobloch 38/33 3f/PY head

Any chance of a look at the valve guides, and head face?

it's a 1.6 AEE head

exaust

inlet

dit this before my bike carb conversion

what kind of gains did you achieve with the aee after the work?

mirror polished

Not really what you want for an inlet...

nope, mirror polish makes it worse from what i hear.

Would be best with a flap wheel run down it!

nope, mirror polish makes it worse from what I hear.

Could be the exhaust side.

That's true, but it depends what "worse" is, as it's subjective.

A mirror finished port may flow just as well if not better on a flow bench. In which case that would make it better.

If flow numbers were all we were interested in.

Of course for an engine we want more power.

It is commonly stated hat fuel pools in the intake ports if you have a mirror finish. This is how I understand it:

Air is funny stuff. It behaves like a liquid and although it doesn't weigh a lot it does have mass and is subjected to all the same laws of motion and inertia that other liquids are.

Just for reference 100 cubic feet of air weighs 3.4 kilos.

The thing to remember about liquids (and air) with regard to good flow (in a pipe) is laminar and turbulent flow.

Turbulent flow is chaotic. The air loses energy fighting with itself in the port flowing in all directions, which results in poor flow.

Laminar flow is where the air all flows in the same direction. However it's not that simple as even in laminar flow the air is moving at different speeds and at different pressures (the two are related).

During laminar flow the air forms tight layers.

Each layer has to sheer past the one next to it. The result is an ark or domed flow front as you can see in the picture above, caused by each layer sheering past the last one a little bit more.

The air in the layer next to the port wall also has to sheer past this. The resulting friction from the wall can actually make the air unable to sheer past the port wall and it stops moving altogether.

This is why the fuel would fall out of suspension on a mirror polished intake port. The air carrying the fuel has stopped moving, so the fuel has to stop moving too.

With a slightly rough texture the layers of air are less uniform at the wall, and is flow is probably slightly turbulent keeping the fuel in suspension.

Stage 3 BVH head from Impulse

INLETS

EXHAUSTS

INLET