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FF's Quadriplegic!
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Discussion Starter #1
So I heard porting a valve chamber can increase responsiveness. If so, what would be the best for street? What are the advantages over each other?

1. Full Circle
2. Half Circle: only one side is left stock
3. Stock

If I use full circle; I would probably have less worries about the piston hitting the head as apposed to the others, but I'm sure daily driving would suck.

What do you think? [wrenchin]
 

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Moved To SVT Performance Chat.

Technical Chat is for technical discussions relating to general maintenance, electrical issues, engine trouble, and recalls.


rudel said:
If I use full circle; I would probably have less worries about the piston hitting the head as apposed to the others, but I'm sure daily driving would suck.
Porting won't have anything to do with the combustion chamber, so it won't affect piston clearances. Porting on the intake side and exhaust side consists of taking excess metal out of the port area, including the bottom edges of the valve guide in order to take out obstructions to the air flow. You're basically removing whatever metal is in your way from having a straight shot, as big as possible, to the back side of the valve.
 

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FF's Quadriplegic!
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Discussion Starter #3
We are talking about the same thing right? Im not talking about porting the intake and exhaust ports or valve diameter. I'm talking about the dome undernieth.

I had it in technical, because this could be for the regular zetec and duratec guys too. We don't really have a performance catagory for both cars together or "In General Performance"

Full Circle


Half Circle


Stock
 

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I knew what you were talking about Rudel........ I did my head last year. I'll Pm ya.
 

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( o Y o )
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I know John PM'd you, and I know he did his own porting of both the intakes and CC of the head.

Wouldn't removing those areas decrease compression (maybe only by a little)?

Secondly, if I were to do any work in the CC, it would be towards improving combustion (which means improving flow and having a more evenly distributed fuel in the CC so as not to develop hotter areas and cooler ones).

Thoughts on this? Let me know if my thinking is wrong here.
 

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The Librarian
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I knew what you were talking about Rudel........ I did my head last year. I'll Pm ya.
Isn't that considered "unshrouding the valves"?
Unshrouding is generally done when larger valves are installed.
I'm not sure how much it will help with stock valves.

It will lower compression depending upon how much material is removed.
A thinner head gasket or mild head milling will make up the difference though.
 

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We are talking about the same thing right? Im not talking about porting the intake and exhaust ports or valve diameter. I'm talking about the dome undernieth.

I had it in technical, because this could be for the regular zetec and duratec guys too. We don't really have a performance catagory for both cars together or "In General Performance"

Full Circle
Unshrouding the valves is allways worth doing , in the picture of yours I left up the places at 12:00 is all that needs to be cut , On the flow bench this was the only help that increases low/mid lift flow and I have been doing this with my heads http://focus-power.com/view.php?showme=Ported_ZX3_Head that picture shows what helped the best , cutting any more then that didnt help any so I made a cutter for that cut

This has been something all alone with the higher priced heads were not doing and should of been I feel

Dont get carried away with a lot of porting in the combustion chamber there is some small things (pictured in the added link) you can do that does help

Tom
 

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Isn't that considered "unshrouding the valves"?
Unshrouding is generally done when larger valves are installed.
I'm not sure how much it will help with stock valves.

It will lower compression depending upon how much material is removed.
A thinner head gasket or mild head milling will make up the difference though.
You are correct , it will does help even with stock valve size , larger valves respond to this even better

Tom
 

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How many times have I said this ?

From artical above.

If you don’t
test on a dyno
you will never really know what
gains you have made, or indeed
where you have lost out. A fl ow
bench is ideal to study and test what
you have done to the airfl ow
characteristics, but any professional
with fl ow bench and dyno
experience will tell you that once
you bolt it onto an engine it all
means very little anyway as fl ow
bench data often doesn’t relate to
engine performance in any way
shape or form.

This is what I have been saying about the "high flowing" heads that are out there , Just because the flow numbers that people post are great it does not mean that head will make good power , that was a good read and I agree with most of it , some of it is worthless for the Focus engine

Tom
 
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