hi guys, i was striping down my 1.6 zetec and i noticed just how restrictive the exhaust outlet in the head is compaired to the manifold itself




just wondering have any of you ground out the extra metal useing the gasket as a template and did ye notice any difference? ill be grinding them out when rebuilding it, just said id ask your opinions

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try and look into the 2 litre head or 1.8 head as these i think have allready larged ports. but yeah you can large them out though, but im sure therell be complications.

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what sort of complications mate? it wont do any harm im sure?

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Wont do any harm opening up the ports on the manifold, just the same as fitting a performance manifold really.

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just get a 2.0

1.6 is poor for tuning and flow i beleive due to 22mm valves

yeah if your doing that amount of work to the cylinder head id do it to a 2 litre.

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personally dont think you will notice anything by just opening up the final outlet of the exhaust port, most restrictions are inlet and around the back of the valves where gasses change direction rather than a straight port, opening up to far and making the port to large can have a negative effect by the larger area resulting in slower exhaust gasses and stalling the flow

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Will

is it better to port and polish the exhaust and port the inlet to keep the flow and swirl rate with the air and fuel. by keeping the inlet rought the air and fuel wil mix easier and cause a more efficent burn?

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Will

i did it on my old 2.0l matched the ports and that but i wouldnt really bother with the 1.6 as it will take you ages to do it and and risk of more metal shavings going places where you dont want to go as you have to clean the head out very thorough

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fibre is my friend, more to come ;-) SI/T squirrel muncher

cool. can you notice the difference having it all ported and polished?

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dont know really till next friday when back on the Rolling Road but when i ported it i made a very basic flow bench to see if it improved flow, measured pressure drop difference between the ported and un-ported cylinder and seemed to show a improvement. Very basic principal.
With a bit of maths inlet up 5.5% improvement exhaust up 4.3% flow so hoping its reflected in power output

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Will

oh right cool let me no how she gets on please mate. real interested in getting the most amount of power out of the zetec nat. asp.

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thanks for all the comments lads, looks like ill just be cleaning all the sut out of it and leaving it standard size, id love a 2 liter but the insurance will just rape me so im gonna go 1.6 first thanks again guys

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have you takem the head off?

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