Xtnct00WS6

iTrader: (8)

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*

Bo White

iTrader: (59)

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

Xtnct00WS6

iTrader: (8)

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?

Bo White

iTrader: (59)

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.

orangeapeel

iTrader: (18)

Is that where it would be port matched to the intake? (where he is talking about smoothing it out)

CBX

Would the same apply for an LS1 head? Are there any differences?

Bo White

iTrader: (59)

Yes and yes. The top 2 pix are LS1.

CBX

On an LS1, should the exhaust ports be widened to the size of the header flange opening?

GuitsBoy

iTrader: (4)

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?

hals73rs

iTrader: (4)

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.

CBX

Should I try to make it a D shape?

white2001s10

iTrader: (4)

That sounds right to me.

Bo White

iTrader: (59)

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.

hals73rs

iTrader: (4)

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.

CBX

Thanks for the response. Thanks to Bo also.

hals73rs

iTrader: (4)

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.

CBX

So far, I have everything done with the exception of opening up the valve seats. Do you have any pictures of this? I have already blended the intake seats into the intake plenum without touching the chamfered face of the seat where it actually seals the valves. Do you guys do this? It would seem to be an area to pick up flow as the seat protrudes slightly. I didn't have to take off much at all.

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.

Worm

iTrader: (2)

Wow this is a great thread, I'm fixing to port some LS6 heads in the next month or so, can anyone point me to some more info, specifically on the chamber area?

CBX

Does anyone have a cutaway picture showing the intake? Especially the intake swirl ramp. I am trying to figure out how much I can remove to smooth it out. Thanks.

CBX

ttt