LS6 head porting questions...with pics
LS6 head porting questions...with pics I'm about to start porting some LS6 heads and was hoping you guys could help me with the specifics of where to port.
Should the bottom of the intake port be ported? How about the perimeter? Does that get ported, and if so, how much? How about at the top, should those parts be smoothed out?
How much do you take out at the top of the exhaust port? Just D shape it like so:?
The top two pics are from Bo White. *If you mind me using these pics, lemme know and I'll take them down*
Should the bottom of the intake port be ported? How about the perimeter? Does that get ported, and if so, how much? How about at the top, should those parts be smoothed out?
How much do you take out at the top of the exhaust port? Just D shape it like so:?
The top two pics are from Bo White. *If you mind me using these pics, lemme know and I'll take them down*
No problem on the pix- youve been diggin 
lol. The red line on the cutaway is what I drew and thats how I port the roof so I would say .075" or a little less than 2mm. The floor I would leave alone and just smooth it out and the short turn radius were it loops around to the valve seat. The corners at the top of the intake ports are there were I squared up the port entrance on all the heads I do so thats just personal preference. The exhaust port exit should look like you have drawn 
lol. The red line on the cutaway is what I drew and thats how I port the roof so I would say .075" or a little less than 2mm. The floor I would leave alone and just smooth it out and the short turn radius were it loops around to the valve seat. The corners at the top of the intake ports are there were I squared up the port entrance on all the heads I do so thats just personal preference. The exhaust port exit should look like you have drawn The middle arrow at the very top is the short turn radius were it loops around to the valve seat? Sorry, I'm new to all this head lingo
The corners at the top of the intake ports would be ok to smooth out too then?
The corners at the top of the intake ports would be ok to smooth out too then?
When the intake is bolted up to the heads I dont think those corners, there or not, will matter. The rounded top part is there for injector placement. Look at the first pic, were the floor drops off just before the valve is is the short turn. Just make sure the turn is even and smooth.
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Originally Posted by CBX
On an LS1, should the exhaust ports be widened to the size of the header flange opening?
Originally Posted by CBX
On an LS1, should the exhaust ports be widened to the size of the header flange opening?
No........ Just slim down the guide and smooth the walls. Open up the valve bowl/seat area to about 90% of the valve size. It don't take much work on the exhaust to make it flow.
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Originally Posted by hals73rs
No........ Just slim down the guide and smooth the walls. Open up the valve bowl/seat area to about 90% of the valve size. It don't take much work on the exhaust to make it flow.
Originally Posted by GuitsBoy
I had planned on smoothening it out without opening it up too much. Im going to try and take off .030 from the sides and top and give it a D shape, but im going to leave the floor and short side radius alone and only lightly smooth it. Can anyone else comment on this?
I dont try to make it an actual D shape, more like a circle with a flat bottom- if that makes any sence 
. The main thing I do is modify the roof of the port and the sides I just blend.
. The main thing I do is modify the roof of the port and the sides I just blend.
Originally Posted by CBX
Should I try to make it a D shape?
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Originally Posted by hals73rs
No, don't make it a D port. As Bo said, most of the exhaust flow will be in the roof of the port. However, being this is your first time porting, I don't recommend making big changes in the port shape. By opening up the exhaust valve bowl/ seat area to 1.40, narrowing the guide, smoothing the walls and basically blending it all in will net over 215 cfm (no pipe) with stock valves. On the intake, cut out the rocker boss, narrow the guide, open up the valve bowl/seat area to 1.80, smooth the walls and blend it all in. I wouldn't recommend opening up the runners more than .150 for a first time porter. Doing all this to the intake would net about 285-290 cfm with stock valves. Good luck........ and as always error on the small side. It isn't necessary to make huge changes to get good flow #'s.
Originally Posted by CBX
Thanks for the response. Thanks to Bo also.
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Joined: Oct 2005
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Originally Posted by hals73rs
You're welcome. If you are wondering how to open up the valve seats to the appropiate 1.80/1.40 diameter......... take a spare exhaust and intake valve to your local machine shop so they can turn them down the that diameter. Use these valves as a guide to open up the seats to the proper diameter. Work slowly and creep up on it. Work in this area is most critical for flow. And again, be conservative if in doubt.
I am not sure how to proceed with the combustion area. If I just leave this part alone how much flow am I giving up? I don't want to make any mistakes.
