LS6 heads - Where to port?
LS6 heads - Where to port? I just got my LS6 heads and I'm looking to do a little porting on them before I put them on. Where should I concentrate my work to get the most benefit without removing much material? It looks like the bowl will need blending with the seat on the intake valves and maybe a little on the exhaust. I also plan to polish the chambers. What about the spark plug bump that's in chamber? Should I remove that and smooth everything down, or should I leave it to promote swirl? Also, I thought I read somewhere that you can't take the valve guides down to much because there is a water jacket beneath them, is that true?
Joined: Apr 2006
Posts: 3,891
Likes: 1,137
From: Grand Rapids, Michigan
You also should polish your entire exhaust port. Keeps carbon buildup to a minimum. I port heads occasionally as a side job and it's not that difficult, just time consuming. You have to be EXTREMELY careful not to remove too much material anywhere you port, not just because of water jackets but due to slowing down port velocity. I'm looking for a pair of perimeter bolt heads right now to do a port job on. Most of my experience is with LT1 heads. Took a set of stock Camaro castings and went from max 208 CFM Int./ 135 CFM Exh. to 243 CFM Int./ 182 Exh.
Originally Posted by Whistler
Why would you bother when you can buy them brand new, CNC'd with springs for under a grand?
https://ls1tech.com/forums/generation-iii-internal-engine/450636-patriot-performance-243-s-pics.html
https://ls1tech.com/forums/generation-iii-internal-engine/414121-ls6-head-porting-questions-pics.html
(These are Dart heads...just use as a reference)
https://ls1tech.com/forums/generation-iii-internal-engine/514551-dart-225-after-info.html
Yeah, I picked up this set with the stock sodium-filled valves and low miles for a good price, so that's why I'm doing them myself. If I had a grand to spend on the work, then I'd do it. But I have more time than money right now. I'm just looking to do a little bit of work, but I don't want to get myself into trouble. Thus, why I started this thread. Thanks for the replies.
It's not a grand for the work. The heads you have are worth something if you sell them, and then you have valvesprings you will have to buy for an aftermarket cam that the new ones include. So really, the difference is only a few hundred $$ which is a bargain considering that the CNC'd ones will actually increase your power, and the ones you're going to try and learn to port on will likely result in you losing power, or producing marginal gains. Take the 30 hours or so you'ld spend monkeying with them and go work doing whatever it is you do, and theres your new heads.
I'm not trying to **** in your cornflakes...I've ported a half dozen sets of LS1 heads myself, with increasing gains as I got better at it, but it was time consuming as hell, but this was 4 or 5 years ago, when the MTIs and GTPs were getting a couple grand for a set of ported stockers, so it was worth my time. The new stuff is so cheap it's just not worth it.
I'm not trying to **** in your cornflakes...I've ported a half dozen sets of LS1 heads myself, with increasing gains as I got better at it, but it was time consuming as hell, but this was 4 or 5 years ago, when the MTIs and GTPs were getting a couple grand for a set of ported stockers, so it was worth my time. The new stuff is so cheap it's just not worth it.
I hear what you're saying Whistler, but I don't need new complete heads. I would just like to clean up the existing set and retain the stock sodium-filled valves. If there was a sponsor that would provide the CNC port and chamber work with a head milling that retained the stock valves and didn't increase the size of the ports all that much then I'd go for it. This isn't my first set of heads that I'd be working on, but I'm no expert either and would easily turn my heads over to have them CNC'd for $200-$300.
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Verdad Gallardo So, going back to my original question. What areas should I watch out for when I do this clean up work? Where are the water jackets that I've seen referred to before? How far do you go down on the rocker bosses before you hit the threads?
It is interesting how folks tell you what to do instead of answering your question. 1. Take out the rocker boss so that it aligns with the walls of the port. 2. I like to take some of the bulge out of the guide area...streamline them a little. This is also a good area to make sure the port walls are free of casting flaws. The air wants to take the easiest path. 3. Blend the bowls like you suggest...make sure seats are not lipped out beyond the port wall. 4. On the intakes get the short side radius to be a nice smooth radius. 5. I also like to open up the sides of the chambers to help with valve shrouding...you may need to mill the heads or use thinner gasket to keep from losing compression...you might as well get your quench tighter as their is free hp there.
6. Remember to port match your intake so the airflow is smooth into the head. It is crazy to have great head ports and mess the flow up before it gets their. 7. A good free flowing exhaust will help pull in more air. Good luck
6. Remember to port match your intake so the airflow is smooth into the head. It is crazy to have great head ports and mess the flow up before it gets their. 7. A good free flowing exhaust will help pull in more air. Good luck
Thanks Chuck. That's what I was looking for. Right now I've just started cutting back the spark plug boss on all the chambers to get better flow around it. I probably won't cut the rocker bosses back to far. I don't want to have to deal with thread sealant and all that.
On that lip from the port to the seat. I've noticed that there is about 1/16" to 3/32" of extra seat material sticking out into the port past the port wall. If I cut the seat all the way back to the port wall, is that going to negatively affect the seat in anyway? This is going to be a daily driver that will have a good amount of mileage on it, and I don't want to compromise the heads' longivity by cutting it too much. Thanks for the help.
On that lip from the port to the seat. I've noticed that there is about 1/16" to 3/32" of extra seat material sticking out into the port past the port wall. If I cut the seat all the way back to the port wall, is that going to negatively affect the seat in anyway? This is going to be a daily driver that will have a good amount of mileage on it, and I don't want to compromise the heads' longivity by cutting it too much. Thanks for the help.
Joined: Apr 2006
Posts: 3,891
Likes: 1,137
From: Grand Rapids, Michigan
Keep in mind that in all likelihood you'll need to factor in the cost of a valvejob. When you port for your first time it only takes a split second to slip the grinder and nick a valve seat. On the intake side, it's good to cut the valve seat in a bit to mate up with the port wall or vice versa, unless it's so mismatched that cutting into the seat will effect the integrity of the seat itself. Since this is your first time, I wouldn't worry so much about cutting all the material out, just put a nice radius on it and eliminate sharp edges. This is especially important on the short side radius. It's pretty difficult to get the short turn on the intake from both sides - invest in a good set of 6" wide flute carbide cutters to help with that. You do NOT want to remove a lot of material from the short side. Just smooth out the area where the factory did the plunge cut with the valve machine and make sure it's a nice smooth radius. Get a porting kit from Standard Abrasives, this will have everything you need in it (aside from carbides). Here's a before and after of the chamber on a pair of LT1 heads I did. You can see where I cut into the seat a bit on the intake side:
Originally Posted by ChucksZ06
It is interesting how folks tell you what to do instead of answering your question. 1. Take out the rocker boss so that it aligns with the walls of the port. 2. I like to take some of the bulge out of the guide area...streamline them a little. This is also a good area to make sure the port walls are free of casting flaws. The air wants to take the easiest path. 3. Blend the bowls like you suggest...make sure seats are not lipped out beyond the port wall. 4. On the intakes get the short side radius to be a nice smooth radius. 5. I also like to open up the sides of the chambers to help with valve shrouding...you may need to mill the heads or use thinner gasket to keep from losing compression...you might as well get your quench tighter as their is free hp there.
6. Remember to port match your intake so the airflow is smooth into the head. It is crazy to have great head ports and mess the flow up before it gets their. 7. A good free flowing exhaust will help pull in more air. Good luck
6. Remember to port match your intake so the airflow is smooth into the head. It is crazy to have great head ports and mess the flow up before it gets their. 7. A good free flowing exhaust will help pull in more air. Good luck
I appreciate all the advice everyone has given me on here so far, whether it be to do it myself or to just get them CNC ported. I'm glad people did finally answer my question and thanks to LS1Formulation and Xtnct00WS6 for providing pics. I will more than likely need to do a valve job. Like I said before, this isn't my first rodeo when comes to porting heads, but I'm no expert either so I will probably end up nicking the seats. I'm also going to have them decked probably .005 to clean them up as well after the porting.
What about that small lip/machine cut mark right outside of the seats as they transition into the chamber? I've always taken that off when I've done my heads, but every picture that I see on this board always shows that nobody did anything with it. I'm sure its not worth much, if anything, on flow, but I take it out anyway. Anybody got a comment on that?
What about that small lip/machine cut mark right outside of the seats as they transition into the chamber? I've always taken that off when I've done my heads, but every picture that I see on this board always shows that nobody did anything with it. I'm sure its not worth much, if anything, on flow, but I take it out anyway. Anybody got a comment on that?
Originally Posted by Quick Double Nickel
I appreciate all the advice everyone has given me on here so far, whether it be to do it myself or to just get them CNC ported. I'm glad people did finally answer my question and thanks to LS1Formulation and Xtnct00WS6 for providing pics. I will more than likely need to do a valve job. Like I said before, this isn't my first rodeo when comes to porting heads, but I'm no expert either so I will probably end up nicking the seats. I'm also going to have them decked probably .005 to clean them up as well after the porting.
What about that small lip/machine cut mark right outside of the seats as they transition into the chamber? I've always taken that off when I've done my heads, but every picture that I see on this board always shows that nobody did anything with it. I'm sure its not worth much, if anything, on flow, but I take it out anyway. Anybody got a comment on that?
What about that small lip/machine cut mark right outside of the seats as they transition into the chamber? I've always taken that off when I've done my heads, but every picture that I see on this board always shows that nobody did anything with it. I'm sure its not worth much, if anything, on flow, but I take it out anyway. Anybody got a comment on that?
