Cylinder Head flow rates

[jogi730]

Well I have had my cylinder head reworked now.
At 12mm valve lift I have the following figures;

Before After

Intake 121CFM 150CFM
Exhaust 88CFM 123CFM

Not entirely sure what this means, but I have been told I should be very pleased with these figures, especially the exhaust side as that had already previously had some work carried out.
Cheers
Chris

Got my head back and unfortunately figures are not quite as good as was told. Still had a reasonable improvement though.
Here are some pics;

[jogi730]

And here are the actual figures.



All these could have been increased further with oversized valves.

Cheers
Chris

[JP]

Intake figs look pretty spot on for the port workup. Exhaust looks a little tight in the bowls although the figs are not that far of from a 105-108cfm@10" max.


Oversizing the valves won't give you more flow at the top end only at lower lift as the restriction becomes the portmouth on the intake of these heads.


Looking forward to the end result once it's all bolted on.

[jogi730]

Intake figs look pretty spot on for the port workup. Exhaust looks a little tight in the bowls although the figs are not that far of from a 105-108cfm@10" max.


Oversizing the valves won't give you more flow at the top end only at lower lift as the restriction becomes the portmouth on the intake of these heads.


Looking forward to the end result once it's all bolted on.

Does the work look good though or are the pics not conclusive?
Many thanks

Chris

[G60Rallye]

As promised here are the figures from my cylinder head.

Firstly is a screen shot showing the inlet on the left, with the bottom figures showing the flow with the wagner inlet manifold on after it had been port matched. The right hand table is obviously the exhaust flow.



Secondly the graph.



Intake

Port 1 = Standard
Port 2 = Head with Clay port entry
Port 4 = Head with Wagner port matched intake attached

Exhaust

Port 1 = Standard
Port 2 = Head with with welded up exhaust ports
Port 4 = Normal exhaust ports ported as a comparison reference

[AustenW]

nice work

[Jamo]

What is meant by exhaust ports welded up?

[Error404]

i think they are welded to add material in order to dramatically reshape the ports

[JP]

^^^ nail on head. Guide is removed the roof of the port completely welded up. New guide holes machined and special longer guides fitted so the port can be completely reprofiled. I've done it twice on an I5 head. 3rd one in progress. once on a 1.8t head and once on a pair of RS4 heads. Each of them with astonishing flow gains and power delivery results. Unfortunately the time taken to do them makes me all to unenthusiastic to do them as it is not a money earner in respect to time but more the prestige of the end results.

[driftin jo]

What is meant by exhaust ports welded up?

I think what it is referring to is that the ports have been welded and reshaped for better flow.
It is often the case that you need to add metal to the port so that it can then be shaped for optimum flow. The reason you need to add metal/weld up a bit is often there is to much of a tight angle been cast into the port shape and there is no way to get the gas aimed were you want it by just removing metal.

[driftin jo]

^^Doh, trust me to have to go and pick the wife up before finishing my reply.

[Jamo]

So from the sound of it it's a long and expensive job?

[A80Avant]

can you give us a bit of a description of what excactly the reprofiling is ? i mean rather than getting the port bigger and polished, is the aim to get the flow of air going out from a different direction? And if so, what direction is that?

[JP]

^^^^^^ that unfortunately I will not post on a public forum. Not because of joe blogs but because of other professionals who then have an opportunity to bypass hrs and hrs of research and development. Sorry.

[DS2]

would there be any sence in modifying only the exhaust ports for them to "match" better with the intake flow numbers?