Porting a 1G Head

[Colossus]

I was thinking about porting my 1g head. I dropped it off at the machine shop, and get it back tomorrow. It's getting the bowls and holes enlarged to support 1mm oversized valves, HKS 272/272 cams, crower springs, titanium retainers, hot tanked, etc.

I also spoke with a reliable shop around here for port work, as the machine shop didn't do porting. They said it wasnt really necessary as the head flows so much as it is now (way more than say..an integra head). With all these larger mods and such, I was wondering if I'd need to port to get the full benefit? The shop asked me to drop it off for porting before machining, but they neglected to tell me that when I spoke with them the first time around. They said the porting would mostly just be a lot of work to get rid of small nicks and such, but wouldnt really do so much as for enlarging the runners and such.

What are you suggestions/opinions on porting? Is it something to get a good amount of flow out of, or is it already at a good enough size as it is?

 

[peregrine]

like they said, the heads flow alot stock. i would do just a minor touch up on the ports and smooth it out to glassy smoothness.

 

[minywheats]

when looking to port your cylinder ehads, make sure that you DO NOT port them to be super smooth. The losses experienced by you port surface finish accounts for only 4% of the total losses. Look more at porting any large casting bumps, sharp edges around the valve seat, and reducing the angle of airflow into your yalve port by contouring the inner radius of your valve port. To smooth out your port to a glossy finish would cause your ports to become "wet" with gas and not flow properly and give you jack shit for fuel atomization. Too many people focus on making the port soo smooth, where in fact the main restrictions are in the valve pocket area. If you've got a good shop with a flow bench, have them put the head on it and use a stick with string tied tightly on it to see where the air turbulence is, then work with that part of the port.

 

[Maglin]

The exhaust ports can be polished... it's the intake ports you want to have a rough surface... as said before the short side radious is where you will see your biggest gains, but it is also where you can do the most damage from what I understand. I'm no porter but those are just basics.. I believe I've read that some porters even add to the top of the runners on the bend to smooth out the airflow.. Makes the runners smaller which helps bottom end and sometimes actually increases airflow through the runner...