Cylinder head dimples/golf balls Q
 

I watched a David Vizard video the other day around head porting and tests he has done. Very interesting stuff indeed.

He said dimpling/golf balling the head while extremely expensive has great benefits but did not elaborate.

I thought i saw some photos of heads that had this type of work done and certainly looked unique.
what's the benefit of it?
would you do it to the intake manifold as well?
anyone ever have it done or know someone that has?
is it something that only works with big cam lifts or large CFM heads?
how complicated is it to do?
and if it's that beneficial why wouldn't aftermarket cylinder heads have that as an option to buy if its something a CNC machine can do?

After seeing Davids video and mentioning of the golf balling, i did a quick youtube search about golf balls and there are many out that explain why they have dimples, however i haven't had a chance to watch them. I'm sure there is a science to that, and is that why its applied to heads?

PY has had some discussions on this.
(along with the grooves in the head chamber/deck)

I think more people/porters are using a rough grind now on ports and chambers?

:confused:

Would defeat the purpose of dimpling to begin with. Polishing the chamber is to prevent carbon buildup. Dimpling on the combustion side of the chamber enhances the swirling of the intake charge. Carbon buildup in the chamber would negate swirling. All the dimpled combustion chambers I seen( ARCA and NASCAR) have polished combustion chambers.

Dimpling enhances the swirling of the intake charge in the combustion chamber. A swirling intake charge combusts more readily and more completely, leading to better performance from the engine. I can’t imagine how much time it takes to properly dimple one combustion chamber.

https://www.facebook.com/groups/clio...3040043844660/

Does dimpling intake ports work?

Opinions here:
https://cliosport.net/threads/does-d...ork-no.817453/

A fwiw, Jim McFarland published quite a bit in Circle Track magazine including tech material on dimpling.

https://www.motortrend.com/how-to/en...ixture-motion/

"Of course, and we sometime get a little push-back on this notion, there's always the approach whereby the surface texture of the inlet track (manifold runners, cylinder head ports and combustion space (chambers and piston crowns) can be roughened (or dimpled) to create little eddys or Von Karman rings that energize flow surface boundary layers and improve fuel atomization. In this regard, and as a point of interest, I've heard from some engine builders that have given this approach a chance and were pleased by the results. Might give it some thought. It's not magic."

https://www.motortrend.com/how-to/en...y-faster-burn/





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Mythbusters a few years back covered a Ford Focus in clay, and dimpled the surface for aero, They said it helped more than just a percent point on drag.

26 MPG without dimples, 29.65 MPG with dimples, Here's a clip from that episode:

https://www.youtube.com/watch?v=VUiGhyHC-1A

Car makers say the reason for not making it, is they don't believe it would sell.

I believe Meaux did some back to back dyno tests and the dimpled ports made more power on the application he was testing.
There should be more golf ball experts in cylinder head r&d��

"It works on golf balls because those fly through the air."

Let's talk dimple porting. Effective practice or unnecessary wallet-lightening? Is the juice worth the squeeze?

https://www.facebook.com/EngineLabs/...254091/?type=3

"At the risk of oversimplification, these are similar to the effects of dimples on a spinning golf ball. In the case of the golf ball, they tend to provide flight stability (as opposed to no dimples). In an engine's inlet air/fuel charge path, they can help put fuel that has become separated from the air stream back into some measure of suspension for combustion enhancement, certainly when compared to un-combusted fuel that passes directly out the exhaust system."

From the Jim McFarland Mixture Motion link I posted above.


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thanks for the info guys, some good replies
and very odd about dimpling a car and actually trying it.... who would have thought that

Here is a link to Larry Meaux's thread (not sure if you have to join this one though):

Rough Texture

Some of the pics are missing now. (photobucket)
I think there are some golf ball dimples in there also.

:)

I talked to Don Johnston about this yrs ago. I saw pictures of this used on heads that supposedly came from Smoky.

In theory, dimples would increase the turbulence of the layer of air along the surface of the head. However, it seems that dimples are very sensitive to size and shape, so it would likely take a lot of testing to get the optimum config to make them work, as well as precise manufacturing. As far as aftermarket cylinder heads go, I don’t think that a CNC would be able to make dimples, at least not uniform ones on the inside of a curved surface?

The main benefit of dimples on a golf ball, reducing drag, wouldn’t apply to heads. When the air is flowing around the exterior of an object like a golf ball (or the exterior of the car on Mythbusters) dimples reduce the wake behind the car and reduce total drag. Since the air is flowing through the interior of the head, there is no rear of the object, and no wake for the dimples to reduce. Dimples in a head would actually slightly increase drag, in theory, but also add some possibly helpful turbulence.

https://www.scientificamerican.com/a...es-in-golf-ba/

Your comment that it would likely take a lot of testing to get the optimum config to make them work mirrors comments regarding Jim McFarland and his work.... he championed the use of strategically placed dimples in combustion chambers and on piston tops. Further, it may have worked for him using wet flow and computational fluid dynamics to develop. Those foolish enough to place random dimples on their pistons were no doubt disappointed.

Here: https://i.postimg.cc/9MQf7Zxq/Jim-Mcfarland-piston.jpg




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I wonder if all the big gas engine mfgs,International example ever fooled with 'dimples,and other ways ' to improve flow? I never witnessed any.

John, My computer software say that Larry's site has a massive amount of Malware
installed on it. BEWARE BEWARE.

Tom V.

My dad had a quip-joke: " Golf would become interesting again of they used goldballs without dimples."

So, the ball will knuckleball through the air without the dimples.
So, with dimples, there is a detached layer created that allows the goldball to fly/travel rather straighter. As for slicing/hooking the golf ball, the dimples perform like baseball stitching for the curveball.

Flow for HP: darn sure the inhale tract needs to be straight from fuel intro to intake valvehead. Valve needs a certain angle for best flow past the valvehead. Smooth inhale tract is still best for least CSA, and texture causes an increased boundary layer thickness causing need for more CSA to flow same as smooth& straight.

Combustion chamber: You must go figure that dimpling does ZERO for gaseous fuels like Propane, hydrogen, methane. However, i reserve an open mind to the effect on liquid fuels such as Gasoline and diesel. Dimple away, but oh my, that piston head sure drops liquid fuel no matter whut.

A carefully controller experiment would perfor fine-grain "jetting" adjustments to measure the chamber dimpling advantage. A leaner "jetting" for same HP under load & rpm would reveal the advantage. However small or large the jetting to leaner was, that would be advantage for reduced carbon,wear,and efficiency. Surely ping could remain independent and behaved for same octane...right?

LArry Meau's site was safe, but been awhile since last visit, so good to know not to use a home 'puter to visit.

Tom,
What software is giving you this? I was logged into Larry's site this morning using FireFox as my browser and Avast as my AV and got no notice of any problem.

Stan

I use Firefox and a very good Virus Scanner Tool that gets monthly updates.

Tom V.

There's a BMW shop in the Kansas City area called Metric Mechanic. They have a patented process called Surface Turbulence, where they add concentric grooves inside the ports and on the valves themselves. They claim it increases flow numbers and improves atomization. I think the idea is similar to putting dimples in the surface.

I looked around on their website a bit and didn't find any specific information on how it's done (after all they have a patent on it so I suppose they don't want to give out too much information) but there are pictures of their modified heads and valves out there on the Web.

The only place dimples make sense in an engine is on any short side radius. The reason a golf ball flies further is that the dimples allow the air to remain attached longer, reducing base drag. On a SSR, dimples will allow air flow to remain attached longer, facilitating an easier turn into the cylinder.

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