Porting a type 4 head, Not much of a short side Options

[Shivers]

I moved this from the Paddock, thought I put it here. Because the port is almost straight, with little long side short side turns, with what there is , do you find it necessary to slow the flow down on the “short side” to get good flow out of the valve. I was reading about something mepstein posted a picture of. Small divots, like a golf ball. So I’m going to do that on the long side, just wondering if there is any reason not to also do it on the short side. Thanks guy’s smile.gif

[Superhawk996]

FWIW the intake port isn’t the bottleneck to flow, it’s the exhaust that has to practically make a 90 degree turn in a very short distance.

[burton73]

@Shivers
Just so you can see the HAM RAT head on the 2270 before Jorge rebuilt them, this gives you an idea of what this looks like from one of there heads back over 15 years ago

Best Bob B

[rfinegan]

Here is a pic 2.0 Porsche heads for my intake. Not my work but good for compare?
enjoy

[rfinegan]

@burton73 can you post a pick or 2 of the chambers please. I am touching up the seats and need to CC match the chambers, and trying get a good idea where to take material out...

[914werke]

Bob do you have pics of the exhaust?

[Shivers]

FWIW the intake port isn’t the bottleneck to flow, it’s the exhaust that has to practically make a 90 degree turn in a very short distance.

Thanks, yes it is, open it up and polish it is pretty much my answer there hoping to get some tips if there are any. It is really short and coming out of the valve so none of this pesky stuff about one side of the ports airflow can blow its turn and cut off the other side of the of the ports airflow messing up getting in the valve effectively.

Thanks for the pictures, so far not seeing any speed bumps to slow air down. Seeing a little port shaping, seen that before on a type 4, I’ll keep that in mind, I run carbs so I can match the aluminum intakes.

[Superhawk996]

Take a look at this thread and exhaust port cutaway (post #27) and some suggestions

http://www.914world.com/bbs2/lofiversion/i...hp?t241436.html

I have a set of HAM heads in storage - will try to get you a picture next time I’m in town and can find the heads

[Superhawk996]

Thanks for the pictures, so far not seeing any speed bumps to slow air down.

I think you might be misunderstanding the dimples. Or maybe it’s just what you mean by slow down the airflow.

They don’t slow down the airflow. They reduce drag by creating a turbulent boundary layer. They help keep airflow attached to the surface as it ducks behind a curving surface.

https://www.livescience.com/32446-why-do-go...ve-dimples.html

[Shivers]

Thanks for the pictures, so far not seeing any speed bumps to slow air down.

I think you might be misunderstanding the dimples. Or maybe it’s just what you mean by slow down the airflow.

They don’t slow down the airflow. They reduce drag by creating a turbulent boundary layer. They help keep airflow attached to the surface as it ducks behind a curving surface.

https://www.livescience.com/32446-why-do-go...ve-dimples.html

Thank you, yes I do understand the theory. I’m looking to see if anyone had to put bumps in to cause turbulence which will slow the air down. It does not look like, on the ports I’ve seen so far in these pictures that this is happening. I’ve read a couple articles on it, and what they are saying is basically what you said. In the little divots it creates a little storm. That pressure created holds the airflow off the metal like a lubricant. It is going to take forever to do all four ports but from what I have read, it will be worth it to get that extra velocity.

[Shivers]

Take a look at this thread and exhaust port cutaway (post #27) and some suggestions

http://www.914world.com/bbs2/lofiversion/i...hp?t241436.html

I have a set of HAM heads in storage - will try to get you a picture next time I’m in town and can find the heads

Wow, they sure did some work on the 2.0 head in the exhaust port. Not much left to remove. Looks like I’ll be sanding and polishing it.

[Shivers]

Why golf balls are dimpled.

https://m.youtube.com/watch?v=bUsATpg_Xr4

[Shivers]

Calabria says the optimal surface coverage with dimples is 80%, delivering the highest performance

[burton73]

@burton73 can you post a pick or 2 of the chambers please. I am touching up the seats and need to CC match the chambers, and trying get a good idea where to take material out...

Hope this helps.
The exhaust system is a Tangerine Racing unit, not sure that I have a good picture of the exhaust ports on the heads. I have to look through my pictures N good pictures just this


Best Bob B

[Shivers]

@burton73

Thanks Bob (IMG:style_emoticons/default/smile.gif)

[Shivers]

It tells me that someone that knows a heck of a lot more than I do about working ports and chambers didn’t find it necessary to taper the chamber for quench. And I do not see any substantial unshrouding going on around the valves. That is info I didn’t have, and being I also have no flow bench there was no way for me to find out. So for me Bob, it helps. Thanks dude. @burton73

[infraredcalvin]

If I’m understanding correctly, there is a short side and a long side of the chamber, you are trying slow down the velocity at the short side to even out airflow on both sides… so, why not speed up the long side, dimple that side only…

[Shivers]

If I’m understanding correctly, there is a short side and a long side of the chamber, you are trying slow down the velocity at the short side to even out airflow on both sides… so, why not speed up the long side, dimple that side only…

There is a short side, but it is such a small difference between it and the long side on the 2.0 heads I’m working on. Compared to our exhaust port that has an obvious short side. I was thinking about leaving the last 1” blank on the short side just before the valve. I need to do this work outside, it was 120 the other day so I’m still reading. (IMG:style_emoticons/default/smile.gif)

[live free & drive]

This video explains more clearly about how dimples effect airflow in a cylinder (tube) - about halfway through the video:

https://www.youtube.com/watch?v=KzXcglAhxps

[Shivers]

This video explains more clearly about how dimples effect airflow in a cylinder (tube) - about halfway through the video:

https://www.youtube.com/watch?v=KzXcglAhxps

Thank you, I'll watch it tomorrow. I'm better in the morning (IMG:style_emoticons/default/smile.gif) (IMG:style_emoticons/default/sad.gif)