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2g head port and polish job *UPDATE*

This was my first port job on a 2g head I plan to use on #1707 open to all criticism. Will post more pics of the head once i get to the combustion chamber and exhaust side.
Before

After

 
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alansupra94

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Yeah flow ratings and velocities will be needed to determine if anything was done.
 

3rdstrikedsm

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There is very little gain in a 4g63 esp a 2g head in porting and the best thing you can do is clean up the casting flash esp where the seats are pressed in but gains will be very very minimal at best.
 

yes thats why i switched to the 2g head. Would love to get some numbers on it but sadly no access to a flow bench where i live
 

curtis

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Ok one newb mistake I see, if you look to the lower left and lower right it dips. Hard to take a 1/2 inch roll of sand paper to make a straight line. But you can take a bottle of Dykem paint it on then scribe and then take a hand file and make flat. Besides that just stay away from the short turn radius and make all the casting flash go away. Also on the intake side don't try and make it 100% smooth you needs some roughness to help atomize fuel in the port. By the bench you'll loose some flow but pick up HP on the road.
 

donniekak

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Porting without a flow bench can cause some major issues. To figure out the airflow per cylinder, the ecu divides the total airflow by 4, to calculate the injector duty cycle for each injector. The problem is when the ports don't all flow the same. If one cylinder flows 10% more air than the other 3, it just run's 10% leaner. Now with an aem, and 4 wideband sensors, this can be tuned around.
 

prove_it

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Yes, it is better to have the head flow benched after porting and polishing.

I however feel that if you really only polish and keep the porting to a minimum and you can't flow bench it then you'll still be ok. The reason I feel this way is because look at a stock head from the factory. I had a bone stock head that showed about a 8% higher flow in one cylinder. It's pretty common for stock heads to not be matched. The factory gets it close but casting flaws and the bowl to valve seat have very different flaws and flow rates. Going in and cleaning this up will improve flow, but as long as you don't get crazy it's my opinion that your flow will be close enough that you'll be fine, as long as your tune isn't crazy aggressive that is. I have ported several heads this way and never had an issue. I have never truly ported or altered the shape of the ports though, only cleaned up casting flaws and smoothed it all out.

OP from your pics it looks ok, but it looks like you've cut into the port and altered the orginal port shape. This can cause issues and you may want to have it checked.
 

KT

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Quoting donniekak:
The problem is when the ports don't all flow the same. If one cylinder flows 10% more air than the other 3, it just run's 10% leaner. Now with an aem, and 4 wideband sensors, this can be tuned around.



Agreed, and your injectors should be tested as well to compensate for differences there too. I think you meant four EGT probes, not WB02s since you can't put the WB02 sensor in the manifold.
 

donniekak

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People do it all the time.
click


Quoting KT:
Quoting donniekak:
The problem is when the ports don't all flow the same. If one cylinder flows 10% more air than the other 3, it just run's 10% leaner. Now with an aem, and 4 wideband sensors, this can be tuned around.



Agreed, and your injectors should be tested as well to compensate for differences there too. I think you meant four EGT probes, not WB02s since you can't put the WB02 sensor in the manifold.

 
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beaner

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I think prove_it is right. Aside of the way the head flows out of the box, consider that the intake manifold doesn't distribute equally, the fuel rail doesn't distribute equally (afaik), and 99/100 times the 4 injectors never flow the same. Blindly hogging the sh*t out a head is a stupid move, but cleaning it up is just fine IMO. It seems in every thread about doing anything to the head someone has to chime in and say a flow bench is required. It's like some info that just gets regurgitated over and over to the point people think it really is required and it absolutely is not.
 

The flow bench #s is really an old board joke which is why only some people get it. /ubbthreads/images/graemlins/wink.gif
 

I port most heads I use.... I mostly just do the exhaust side for any material and lightly clean the intake side.. I've never not seen gains this way just almost always a give and take... take a little low gain a little high... I did a 7mgte head once and the difference was night and day!
 

cheekychimp

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I don't want to jack the OP's thread but with all this talk about port shape, I have to ask this ...

I have said a few times that I believe the 2G head design made the Cyclone manifold redundant. Obviously there wasn't enough room to blend two runners at the smaller 2G port and the higher velocity that the smaller port created likely equaled or bettered the gains that the long runners of the Cyclone created. At least that was what I thought. I spoke with Ken one night regarding this and he said he had mated quite a few Cyclone manifolds to EVO III heads (essentially the same as a 2G heads) with good results. The only way to do this is by hogging out the 2G intake port to match the Cyclone by doing a bit of gasket matching.

Whether or not this is necessary and whether or not it has any effect on the top end (I imagine using an SMIM would net significant gains up top) I am not sure, but I decided based on Ken's experience to try this out and for low end and mid range response, I am very satisfied with the results.

So what is wrong with this mod in theory and where have I supposedly LOST performance by hacking up a perfectly good 2G head? I'm just confused because contrary to popular belief it really does seem to work extremely well.
 
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