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Heads Porting


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If you want a high horsepower car you should do some porting job. Here is few pictures showing before and after.

 

This picture shows how the heads looks like before porting. The intake (top) and the exhaust (bottom) are full of carbon. Also the chambers are covered with lots of carbon and this is one reaso that can cause detonation.

 

head3.JPG

 

And the following two pictures shows porting job for the intake (top) only. I did some polishing of the chambers too but its not finished yet. And i still need to port the exhaust walls. In these pictures you can see the valve guides matched with the intake wallls (something that Nissan did not bother doing). The surface its also bit rough because as i was reading it helps the fuel to be delivered easier to the chambers for burning. And finally the top valve openings are bit enlarged

 

head1.JPG

 

head2.JPG

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i may be wrong there bud but it looks like you,ve gone done a bit far on the valve seats,porting can increase breathing but to much polishing can have an adverse effect on "swirl" and the burn efficiency

 

The intake walls are not polished. In the 3rd pictures it looks like they are but they are not. Only the chambers are polished a bit.

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i didnt build this engine, thought i would pay someone to do it for me this time :)

 

In fact removing those exhaust restrictors are PITA job to do and most tuners dont bother doing. I still didnt do mine because i didnt find a grinding stone that can eat those aluminium shit walls.

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Yours are thinned in the middle. I wanted to do it also but i am very tired. :)

5 more cylinders to go.

 

LOL i ported & polished the inlet manifold so i know how much hard work it is ;) anyway stop talking on here and get the other 5 done :p

 

I went for the biggest port job you can get on the zed, so hopefully will help with all that flow :hyper:

 

Mike

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LOL i ported & polished the inlet manifold so i know how much hard work it is ;) anyway stop talking on here and get the other 5 done :p

 

I went for the biggest port job you can get on the zed, so hopefully will help with all that flow :hyper:

 

Mike

 

I have to match the exhaust manifolds with the heads and still need to take the heads back for 3-angle job. It looks like this will never finish :confused:

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You don't want to match the exhaust manifolds with the heads exactly.

Try to leave a difference with the manifold being a few mm bigger and offset to the top, helps stop reversion by reflecting the +ve pressure waves back.

If you match exactly you will be down on power.

Not such an issue with log type manifolds or turbo type cams but still good practice.

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You don't want to match the exhaust manifolds with the heads exactly.

Try to leave a difference with the manifold being a few mm bigger and offset to the top, helps stop reversion by reflecting the +ve pressure waves back.

If you match exactly you will be down on power.

Not such an issue with log type manifolds or turbo type cams but still good practice.

 

Right now the exhaust manifolds are at least 1mm smaller than the heads. And yes you are right. If its bit bigger its even better.

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Thats a lot of work and a long old job your a more patient man than me.

 

What I would like to know is, if you do all that work will you know weather the heads flow correctly and will the combustion chambers and ports be balanced to each other.

 

Actually its better to do a flow test before porting and after porting. But since no one does a flow test here where i leave i can only assume that what i am doing is right. :D I did my research before starting doing this job and i believe i am on the right track.

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"Props" for tackling it yourself :) It's not something I have the skill to do so had mine for the VH done by CTM Engineering in Dagenham. Nothing extreme but enough to matter: ported the Inlet and Exhaust ports, cleaned up the combustion chambers, skimmed the surface and done a bit of de-masking around the edges of the valves (also had the cams reground).

 

VH45DEHeadsandCams004reduced.jpg

VH45DEHeadsandCams008reduced.jpg

VH45DEHeadsandCams020reduced.jpg

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