Dimpling a LS port

[1972ho]

https://youtu.be/LqFpBzBLvWY By Eric

[hoffman900]

https://youtu.be/LqFpBzBLvWY By Eric

He should flow each port several times and take the average for comparison sake, especially since the largest difference between them all is only 1.5%.

This is SOP in laboratories when weighing things.

I still think golf ball dimples are misunderstood by most laymen and a conduit / duct is not where they belong.

[Circlotron]

Yep, golf ball dimples are for managing the turbulence and drag downstream of air passing around a spherical object, not for air travelling through what is essentially a conduit.

[WeingartnerRacing]

https://youtu.be/LqFpBzBLvWY By Eric

He should flow each port several times and take the average for comparison sake, especially since the largest difference between them all is only 1.5%.

This is SOP in laboratories when weighing things.

I still think golf ball dimples are misunderstood by most laymen and a conduit / duct is not where they belong.

I actually have it set up to take 15 readings at each lift point then it averages them. That is the numbers on the flow sheets.

[bob460]

Not a ls but fully dimpled by BES...............go to the 27:00 mark.........interesting

https://www.youtube.com/watch?v=5Y4uSFrIaB8

[hoffman900]

https://youtu.be/LqFpBzBLvWY By Eric

He should flow each port several times and take the average for comparison sake, especially since the largest difference between them all is only 1.5%.

This is SOP in laboratories when weighing things.

I still think golf ball dimples are misunderstood by most laymen and a conduit / duct is not where they belong.

I actually have it set up to take 15 readings at each lift point then it averages them. That is the numbers on the flow sheets.

I meant separate flow events. 1.5% could be sampling error, alone.

The way your illustration is shown in your video is essentially that of a corrugated pipe. Plenty of work done on those and understanding Reynolds numbers in them, and for velocities much slower in a running port. Take a look at those studies, models, and tests to see what is happening.

I think there is something to be said for rougher finished ports for carbureted applications, but that's a crux to fix wall wetting and carburetor's relatively large fuel droplet sizes. It's certainly not a dry flow thing.

Shark skin is also much misunderstood. A little bit of homework and one would find it to be directional to flow, it's a finer sandpaper grit equivalent than most realize, and in their case it's like the golfball... by creating turbulence to allow flow to stick to their body, they reduce the wake behind.

[levisnteeshirt]

I wonder if keeping the dimples in a straight line , and a gap between the lines would act like a vane that's getting popular

[hoffman900]

I wonder if keeping the dimples in a straight line , and a gap between the lines would act like a vane that's getting popular

What do you think that would accomplish?

I’m not asking in a mocking tone, just trying to make you think about what is happening and what that would accomplish.

Bryan Maloney outline what the “Glidden fin” does in another recent post.

If you can do some wet flow testing on your cylinder head, you will be mesmerized by what you see. It will tie in with your swirl and tumble observations.

Did you see a net gain in performance by improving swirl?

No, our goal was to prevent the swirl from ramping up so highly at high lift. When the goal is cylinder filling, we wanted the air column helix to chase the piston down the bore and not sling the fuel into the cylinder walls.
Street engines with low valve lift may benefit at low RPM from additional swirl; the valve L/D never gets high enough to where the swirl naturally spikes.
The often maligned reverse-swirl "Elkins fin" behind the intake guides can be beneficial in moderation. Some OEM's take this feature to the extreme.
A "Glidden fin" along the centerline of the floor of the intake port can add flow stability and help limit high lift swirl.

I suspect only a small few who use the “Glidden fin” understand it to that effect. It does look cool though, so I think there is a lot of that going around.

Since ports aren’t just straight tubes, people should be concerned with and understand Dean’s Vortices. It’s only been mentioned by one person on ST, and he is a friend of mine, so we have a lot of sidebars about this stuff.

[SpeierRacingHeads]

Boundary layer manipulation is 99% about wet flow.

You want a real test, spray alcohol/dykem in the port with and without.

[WeingartnerRacing]

Boundary layer manipulation is 99% about wet flow.

You want a real test, spray alcohol/dykem in the port with and without.

How do you want it done? 3ft away when I spray and how much time? It’s still on the bench so I could do that.

It is very hard to get a definite answer on wet flow because it’s not quantitative. I have thought about putting a small jet in the entrance and letting it pull some liquid then use the temperature from inside the bench to gauge how well a port vaporized fuel. (Latent heat of evaporation)

[hoffman900]

Boundary layer manipulation is 99% about wet flow.

You want a real test, spray alcohol/dykem in the port with and without.

How do you want it done? 3ft away when I spray and how much time? It’s still on the bench so I could do that.

It is very hard to get a definite answer on wet flow because it’s not quantitative. I have thought about putting a small jet in the entrance and letting it pull some liquid then use the temperature from inside the bench to gauge how well a port vaporized fuel. (Latent heat of evaporation)

I’m looking forward to Bryan Maloney’s post on wet flow and what he learned from the NASCAR Dodge program.

Honda when designing the V8 F1 engine injectors used pressure sensors in the intake port. The better / more complete the atomization, the denser the air, the faster the waves traveled in the port. Obviously that’s a bit involved. I believe they also had fuels that stained to look for wall wetting. Judging by Kaase’s video with the clear manifold, that looks to be a problem everywhere in a carbureted wet plenum design.

[SpeierRacingHeads]

Boundary layer manipulation is 99% about wet flow.

You want a real test, spray alcohol/dykem in the port with and without.

How do you want it done? 3ft away when I spray and how much time? It’s still on the bench so I could do that.

perfect!

I just usually put it in a spray bottle and pull the trigger 2 times. More than that it makes a bigger mess.

[maxracesoftware]

Boundary layer manipulation is 99% about wet flow.

You want a real test, spray alcohol/dykem in the port with and without.

How do you want it done? 3ft away when I spray and how much time? It’s still on the bench so I could do that.

perfect!

I just usually put it in a spray bottle and pull the trigger 2 times. More than that it makes a bigger mess.

a lot of years ago , i did this outside in back my Shop with Dykem Red Spray Dye with Shop Air pressure rig
on an old Jimmy Bell ported #292 Turbo Head
and red dye was showing Swirl pattern , but also the same as running Mixture residue ( and Red Dye )
was skipping area just above top of Valve Job about to as high as 0.200" height in Chamber wall across Intake Valve
i then added Clay there ... re-Flowtested that Head , and it gained a few CFM on my Bench

i also used some of the test rig parts with just garden water hose pressure
and looked at just solid water spray comes out around Intake Valve at various Valve Lifts on Bell's Turbo Head,
and it was mostly same pattern as Red Dykem Spray

Also tested same Bell #292 Turbo Head on Bill "Oz" Anderson's Swirl Meter
which verified Spray rotation directions i saw above

[BOOT]

Honda when designing the V8 F1 engine injectors used pressure sensors in the intake port. The better / more complete the atomization, the denser the air, the faster the waves traveled in the port. Obviously that’s a bit involved. I believe they also had fuels that stained to look for wall wetting. Judging by Kaase’s video with the clear manifold, that looks to be a problem everywhere in a carbureted wet plenum design.

Wet = Cool

Texture/surface area = More Fluid Cooling

High Volume Fuel = Even More

[BOOT]

Found this long ago and seen others on here post the same pic with the ball when this discussion comes up.

I have stuff that I'd add for wet flow but I'm saving it for my videos, when ever I get around to it LOL