Splayed Valve Heads Porting

[zok15]

I have been binging the David Vizard vids recently, and I was very intrigued by his 5 video series on head porting.

1: https://youtu.be/eLJU1h-raUg

2: https://youtu.be/eLJU1h-raUg

3: https://youtu.be/gIPKoH57mTA

4: https://youtu.be/mQwon4Gfzfo

5: https://youtu.be/V21BdS_Rvgw

He says he gets really good results by opening up the port on the same side as the cylinder wall because it directs air to the center of the cylinder, but he is working with small block and big block motors. With the splayed valves that already point the air to the center of the cylinder, I imagine that opening up both of the port sides evenly would be more ideal.

Other items mentioned include slowing down air on the port floor so it can better make the tight radius turn it needs to go around, and he suggests creating a teardrop shaped bump on the floor of the port. It is interesting as it is very similar to the shark fin vane on the 2.8 intake ports. He has a few other suggestions for the port floor as well.

He also says that the greatest restriction in the airflow is going around the valve, and makes a point to open up the bowl to 88-92% of the diameter of the valve. He grinds and shapes the valves as well, but our splayed valve 60*V6 heads already have valves that are shaped like he re-shapes his. In addition he shows just how much a good 3 angle valve job and a 30* valve seat can improve flow by the valve.

After watching his videos I am extra impressed with the intake port designs of my LZ9 heads, the coffin shape port really supports the way that the air wants to flow, and this is accomplished with the splayed valves that also have the benefit of pointing both valves at the center of the cylinder which is supposed to seriously help flow since there is very little shrouding of the valves and due to direction of airflow.

I ported my heads very similarly to how he suggests, and when I was porting mine, I was trying to use the same reasoning he does, "how does the air want to flow?"

Wanted to open this topic up to discussion as it is very interesting.

[Shaun41178(2)]

With the splayed valves I clean the flashing out throughout the port, and blend the bowl. I also open the throat to around 90-91%

Without back to back flow testing, there is now way to know what works best and fiero owners aren't gonna invest just for these heads which I don't blame them. I wouldn't either

Which is why I just try to do basic cleanup on them, and make them about all the same shape wise port to port. Simple cleanups rarely if ever hurt flow.

[zok15]

I looked into making a DIY flow bench and it is not a cheap or simple job. I am not sure how much I opened the throats, I basically opened them up and blended them into the first angle cut for the valves. It was quite significant. I think this is probably the most bang for your buck without a flow bench. I did shape the valve guide hump to make air flow around it better, and opened up the sides a little bit as well as smoothed the floor transition which is pretty abrupt. I did not open up the port where it meets the intake, just smoothed it and removed casting imperfections. I used some calipers to try and make all the ports the same.

Mod Everything on Youtube seems to have access to a flowbench and likes 60*V6 motors, wonder if we could ship some heads to him. Keep one port stock and shape the others in varying degrees and compare them all.

[Shaun41178(2)]

Eric weingartner on YouTube will flow the heads either stock or ported, and give you the results. And it's cheap. Maybe 30 plus the shipping. He has a professional bench too.

[ericjon262]

Eric weingartner on YouTube will flow the heads either stock or ported, and give you the results. And it's cheap. Maybe 30 plus the shipping. He has a professional bench too.

Eric would also suggest that it's very easy to make the throats way too big on the intake, but opening them up on the exhaust isn't necessarily a bad idea.

https://youtu.be/AHzWi0E2TdM

[zok15]

Interesting, his numbers do line up with what I had seen as well with 92% being the upper limit. I think I am probably 90% or slightly below, I basically blended the throat into the bottom most cut on all the valves, probably ate up a little less than half of that bottom cut. I had the machine shop do a performance multi angle valve job and cut the backside of the valves to match prior to porting. Looks like I could have gone larger on the exhaust bowls according to Eric though. I also did not take too much material around the boss that the valve guide is pressed into, I just smoothed it and tried to shape things for air to flow around it. Seeing some of these examples it looks like I could have removed a lot more material, but I was worried about the valve guide shifting over time.

Overall I think that my heads will definitely outflow stock and have more material that could be removed to improve performance further if I ever choose to. I had found a bunch of info that I used to port my heads at the time, but I did not find any info as good as what I have recently found.

The stock exhaust bowl was much worse than the stock intake bowl, kind of hard to tell from the pics, but it was much more of an abrupt transition compared to the stock intake bowl.

Unported exhaust bowl



Ported exhaust bowl



Unported Intake Bowl



Ported intake bowl



Exhaust runner



Intake runner

[SappySE107]

LZexhaustflow.jpg (109.82 KiB) Viewed 1389 times

https://www.60degreev6.com/vb5/forum/pu ... post427070

[ericjon262]

for a long time I've been considering building a custom intake, sometime this past week, I took a head I had sitting in the garage and put it in a bandsaw and cut it up for research, while this is a LX9 head and not an LZx head, I figured it was worth posting the pictures here, a thread about canted valve heads.

I made 6 cuts on it to better evaluate the ports, and how they meet the manifold flange. I made 4 vertical cuts, and 2 horizontal.







Vertical cross section of an intake port. in this view it's fairly clear that the port exits very close to perpendicular to the flange, which makes designing the intake a little easier.





Horizontal cross section of the intake port. in these pictures, we can see that the "short side radius" approaches the flange perpendicular, however, the "long side radius" curves towards the short side as it approaches the flange. it doesn't look like the curve of the port really matches the curve of the intake manifold though. this could be helpful for my intake plans.















as far as porting the heads is concerned, here are my thoughts on the LX9 head.

While not paper thin, the casting doesn't offer much room to grow, I would guess that the valve guide area protrudes into the port and could probably be profiled some, but the hard part becomes the manifold gasket, it really doesn't offer much room to grow and blend any changes into the rest of the port, and making a custom gasket for this intake/head is quite a bit more difficult than something like a small block chevy. if I were to go the route of a custom gasket, I would build a custom intake, and use sheet gasket material glued to the intake so that the pushrod holes can be cut out of the gaskets, and the individual ports still seal. this would definitely be more of a "full race" setup, but the LIM also shouldn't need to come off that often (hopefully).

[zok15]

Very cool, thanks for sharing