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Old January 20th, 2019, 06:23   #1
iluvmydiesels
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Default 'head work' (mk3)

im looking for some basic info on the subject.
i have a oem used head. in the planning stage to do work.
looking for basic info for head work. porting, valve job? if polishing is an option.
i know the ole 1.6 some personal porting is possible. im trying to find similar info for my AHU,
for a diesel is intake polishing an option?
same question for an angle valve job?
what else to do for 'porting' work, and also for exhaust ports? and such
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Old January 20th, 2019, 08:04   #2
Mongler98
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https://www.youtube.com/watch?v=iejDWSQEsqI

A DIY is not difficult, Frank06 is the guy here for serious work. A basic port gasket match is not that difficult with the right tools.
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Old January 21st, 2019, 16:42   #3
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Mongler, thank you for your recommendation.

That porting youtube is not what I would want to follow, but as the producer of the video says, there are differing opinions. The point with port wall finishing and most specifically, extrude hone finishing, it CAN cut in places that make the flow improved, and most definitely can cut and polish in places otherwise unreachable. But a mirror finish is NOT the right finish.

I made a post called 'Porting Porn', about 2 1/2 years ago, that was really given some sarcastic treatment by several self-proclaimed porting experts, and a member or two with an axe to grind... I was willing to show some of the angling and shape of the port. The reason for shiny; the proper finish in a video or picture would look flat and shapeless without the glint of a shined up port. The reflection displayed the shape. I might note, the self-proclaimed porting geniuses will take shots at me, but not give any pictures for their own designs. Instead, one in particular hijacked my post to advertise themselves.

The single most important bit of information about surface finish was given to me by a recently passed porting genius, Wade Newman, who worked for Dart for decades. I call him 'genius', as he performed the porting work on 4 different engines that set records in their respective classes. THAT is a man you can trust about porting. When I asked him most directly about porting finish and ceramic or other heat shielding coatings, his answer surprised me. "Whatever finish you use, the heat shielding company will change the surface. But it really doesn't matter. The more important issue with heat shielding is to carry the heat out of the head, where is does more good than any loss in port finish by spinning the turbo."

He also informed me of the method and reasoning behind what some call 'port match', which should really be called a 'reversion stop'. As one of the porters illustrated, under certain flow rates, a drop of water will be sucked up into the port, even though the flow is going out, which is the exact description of 'reversion', in a cylinder head. There is a simple trick to compensate for that. We use it. Thank you, Mr Newman.

We know other porting masters, and I do not claim that myself, as I am always learning, but when porting, and considering flow, it's a bit of a stretch to think maximum flow is the ONLY thing...it's not...unless your only interest is to run the engine for maximum performance all the time and therefore air speed... drag racing for example.

So also, that applies to valve seat preparation, as the engine under normal loading could never take advantage of a 7-angle seat cut. Even then, I really doubt there is much of any advantage. We regularly use a 3-angle cut. Even increasing valve dimension is a bit dubious under all but the highest performance situation. There is an issue of shielding on the intake we think does not help.

To get to the precision, matching port to port is something people claim you can't do, cutting by hand, and I disagree, within limits. We have used our Bridgeport to match depth of cut and radius, which helps a lot. Working within the exhaust and intake gaskets, you can get a better match for volume cylinder-to-cylinder.

If we ever get by encoder issues, maybe I can do some digitized porting. That would help more than anything, as the port size matching is a function of the machine.
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Old January 22nd, 2019, 04:26   #4
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Quote:
Originally Posted by Franko6 View Post
Mongler, thank you for your recommendation.
But a mirror finish is NOT the right finish.
monglers post & video are for gasoline head info, for one. its a hyundai head.
i was questioning the mirror finish the video shows for the combustion chamber, and i was also thinking if you left sanding and even wire wheeling unfinished you wouldnt fair any better.
i didnt watch all the video
i have a TDI head, there isnt a combustion chamber in TDI or diesel heads. (idi heads will have a pre-cup, <to note)
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Old January 22nd, 2019, 20:29   #5
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Quote:
Originally Posted by iluvmydiesels View Post
monglers post & video are for gasoline head info, for one. its a hyundai head.
i was questioning the mirror finish the video shows for the combustion chamber, and i was also thinking if you left sanding and even wire wheeling unfinished you wouldnt fair any better.
i didnt watch all the video
i have a TDI head, there isnt a combustion chamber in TDI or diesel heads. (idi heads will have a pre-cup, <to note)
ok, it was just a good link to a great channel that shows in depth how this can be done to any head.
He even states that there was really no point to the polishing but it was his engine and his OCD could not stop him from polishing his bling bling (as he so says)
Most if not all his videos he does a few things a bit unorthodox but clearly says that he is trying something new.
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Old January 24th, 2019, 23:35   #6
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It doesn't matter, gasoline or diesel. The whole point of the proper port texture is creating a vortice that is as close to the port wall as you can make it. There will always be drag, as there is a wall, but the attempt is to make the lanier flow as close to the wall as possible. That need eliminates 'polished'.
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Old January 25th, 2019, 00:03   #7
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Yeah, I think some turbulence in the airflow boundary layer of intake ports is generally a good thing. You'll see a lot of the high performance engines getting port jobs with dimpling in the intake ports. I think the dimpling increases flow as well as helping with fuel (gas) atomization. Sort of like how the dimpling on a golf ball helps it to fly further.
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Old January 25th, 2019, 05:40   #8
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Quote:
Originally Posted by turbobrick240 View Post
Yeah, I think some turbulence in the airflow boundary layer of intake ports is generally a good thing. You'll see a lot of the high performance engines getting port jobs with dimpling in the intake ports. I think the dimpling increases flow as well as helping with fuel (gas) atomization. Sort of like how the dimpling on a golf ball helps it to fly further.
Golf balls fly further because the ball has the dimpling, the dimpling causes tiny little vortexes that cause the ball to be slightly larger in surface area thus creating an area of low pressure, and this reduces drag and itís supposed to stabilize flight, some crazy voodoo aerodynamic thing I fail to understand. But it works, in fact I think its 11% or its 14% but the dimpled golf ball goes that much faster than further and straiter due to the dimpling. Mythbusters did this to a car and it technically worked but was moot due to the added weight of the clay on the car.
So in theory, the intake runner being dimpled would be able to increase air flow by decreasing the internal surface area (as itís the inverse shape) due to the tiny vortexes that decrease drag.
Iím not sure where the boost air comes in to play on this. If itís worth doing on a turbo application or not and where the boost level gets too high for the vortexes to work.
This is where aerodynamic engendering and computer models beat conventional wisdom in automotive application.
It really is porn though.
10/10 DO WANT>
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Old January 25th, 2019, 10:35   #9
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A friend of mine once set up a makeshift benchtop system for simulating flow while porting Harley heads. He had a squirrel cage fan, I don't remember if he pulled air and used a vacuum gauge or pushed and used pressure. Or what it told him, if anything, It was a long time ago.

The dimpling affect is interesting, obviously something to it.

But when I met Frank, he instantly reminded me of Bernie, knowing how something worked was never good enough for him. He had to know why down to every little detail. Both excellent brains to pick.
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Old January 25th, 2019, 10:46   #10
turbobrick240
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Quote:
Originally Posted by Mongler98 View Post
So in theory, the intake runner being dimpled would be able to increase air flow by decreasing the internal surface area (as itís the inverse shape) due to the tiny vortexes that decrease drag.
Iím not sure where the boost air comes in to play on this. If itís worth doing on a turbo application or not and where the boost level gets too high for the vortexes to work.
This is where aerodynamic engendering and computer models beat conventional wisdom in automotive application.
It really is porn though.
10/10 DO WANT>
https://www.youtube.com/watch?v=Dg5wVkddLSE
The dimples actually increase the internal surface area. It's all about the flow properties of the boundary layer. A turbulent boundary layer flows more when the shape is irregular (like an intake port). A laminar boundary layer flows more through a straighter pipe. So dimpling is useful in some areas of the intake and counterproductive in other areas (like a fairly straight intake manifold runner).
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Old January 25th, 2019, 18:04   #11
Mongler98
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Quote:
Originally Posted by turbobrick240 View Post
The dimples actually increase the internal surface area. It's all about the flow properties of the boundary layer. A turbulent boundary layer flows more when the shape is irregular (like an intake port). A laminar boundary layer flows more through a straighter pipe. So dimpling is useful in some areas of the intake and counterproductive in other areas (like a fairly straight intake manifold runner).
my mistake, defiantly meant to say increasing. Interesting, im sure some computer will chuck out some 3d model of how many dimples, how big and small each are and in what areas.

On a slights different subject but to my point, i saw a really cool video on a 3d printed car featured on jay leno's garage.
LOTS of parts are generated by a computer and they look VERY VERY organic as if it was a bone that grew inside an animal and its because animals and plants have had millions of years to evolve and be the MOST efficient with the materials it gets.
Here is the video, https://www.youtube.com/watch?v=vPv7PwS50OE
i always think that the future of car and motor tech is to the organic side of computer 3d modeling and 3d printing. imagine if a engine was made like this. I did see that there are some parts on new prototype engines like this, like connecting rods for example. Saw it at SEMA last year. BLEW MY MIND.
Dimpling reminds me of our attempt to get that extra 1-3% to add to our power curve.
What would you guys say to the option of dimpling the exhaust ports, I know that its a bad idea for a few reasons, mainly heat spots and crack propagation, but what if you used a ceramic coating over it. Lets say that this coating was able to negate any hot spots. Is it still a bad idea? And to that point, why not in the first bit of the turbo snail or the entire housing? Faster flowing right?
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Old January 25th, 2019, 18:41   #12
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Nature definitely has many valuable lessons for us. Honeycomb is a prime example. Bees created one the ultimate material efficient, lightweight yet strong design architectures millennia before we ever gave it any thought.
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Old January 25th, 2019, 20:59   #13
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Nature definitely has many valuable lessons for us. Honeycomb is a prime example. Bees created one the ultimate material efficient, lightweight yet strong design architectures millennia before we ever gave it any thought.
YEP,
BTW bees dont make honey comb hexagonal, they make it round to start with, it ends up that way due to the stacking of circles.
(learned that one from *Cody's Lab)
but yea, still awesome
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Old January 25th, 2019, 23:17   #14
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YEP,
BTW bees dont make honey comb hexagonal, they make it round to start with, it ends up that way due to the stacking of circles.
(learned that one from *Cody's Lab)
but yea, still awesome
I don't think it's been definitively determined whether the hexagonal construction is an evolutionary adaptation or just a natural phenomenon based on the physical nature of the beeswax. I'm leaning towards it being an evolutionary adaptation.
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Old January 26th, 2019, 03:49   #15
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golf ball dimpling... on my post, "porting porn", comparisons were drawn on engines with varying port finishes, including dimpling. On a Honda cylinder head, the volumes were improved only in the most extreme high port speeds; ones I don't know that the above-average TDI will ever achieve, since it appears we can't seem to get the engine to go 9000rpm. Boundary layers are improved by methods that do not require golf ball dimpling are more realistic;
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