Mini exhaust port bias?

[panic]

I'm reading, for the Nth time, my dog-eared copy of "Tuning the A Series", but have come to an abrupt halt on Page 248.
The text states that "the outer ports tend to be better if exhaust pipes are towards the top and biased outwards. Fig. 10.3"

However, Fig. 10.3 (Page 249) shows the pipe centers (and arrows) biased inward and towards the bottom.
???
Even if the drawing is inverted (but not the comment in the drawing), the arrows are still backwards?

Was the text a typo, which should have read "the outer ports tend to be better if exhaust ports are towards the top and biased outwards"?

[FlowSpecialist]

The drawing and arrows are correct. The text is wrong. It should perhaps read "it's a good idea to position the exhaust manifold so that the exhaust port is towards the top of the bore of the exhaust pipe. A central location is fine for the middle port but the outer ports tend to be better if the ports are towards the top and outside edges of the bores of the exhaust pipes."

The reason is we ideally position the offset lip between port and exhaust pipe at the inside of any bend in the port where the flow is slowest and will most easily tend to reverse flow. The lip so created will help stop that reverse flow.

The central port is siamesed and symmetrical so the offset can also be central laterally. We're only concerned about the shortside bend here which is at the bottom of the port so that's where the pipe bore goes.

The outer ports bend both vertically and laterally so we position the offset to take account of both of these. Flow will be slowest at the bottom and inside edges of the ports so the exhaust pipe is positioned down and inwards.

It's a fairly small point to be getting overly concerned about but then it shows the level of attention to detail that DV goes into and that ultimately makes the difference between good engines and winning ones. After a certain level of development on engines this small we generally don't easily find 5 more hp in any one place. What we might still do though is find half a hp in ten different places, each of which on their own won't be measureable but which when combined add up to an engine that seems to be identical to someone else's but actually runs rings round it.

In fact it would make a good addition to the technical articles to write one on the areas that this sort of small difference can be found. From my own work, which has in many ways concentrated on similar lines of thought and attention to detail to DV's over the years I could offer the following starting points.

1) The perfection of valve seats in terms of width, angles of top and bottom cut and concentricity to the guide.
2) Valve guide to stem clearance kept as tight as humanly possible without causing seizure.
3) Trying to achieve the perfect cylinder bore honing finish and angle of crosshatch.
4) Streamlining and radiusing every oil hole and drilling in the block, head, crank and pump to maximise oil pressure for a minimum pumping loss.
5) Doing the same for oil return drains to get oil back to the sump as fast as possible instead of it collecting in the head and upper block.
6) Similar treatment to the cooling side of things.
7) Attention to piston ring prep rather than just bolting them in as they come out of the packet.
8) Block and other component cleaning to clinical standards so you aren't wrecking the engine with swarf induced friction before it's even reached the track.

Dave