Forged or Cast pistons ?

[227bhp]

HJG said:

I would be cautious anodizing the entire crown. The anodized layer will act as a thermal barrier, greatly reducing the splash cooling effect from the oil beneath (or through the gallery wall if gallery cooled). The chamber will retain more heat, which will contribute to detonation and perhaps even pre-ignition in extreme circumstances.

Anodizing of the ring groove is commonly used to prevent microwelding and wear resistance from ring pounding.

Edited by HJG on Thursday 13th August 15:52

This is true, do you have any hands on experience with this process?
We can utilise other methods to reduce chamber temps and det' if we need to so it won't be a problem, we want the heat in there though, it has no practical use being transferred through the piston into the oil.

[Mr2Mike]

227bhp said:

What I do know is the growth on such a small area such as a ring groove is negligible and can be eased by application of a piece of 250 grit paper and 2 minutes of time.

The bottom of the ring land needs to be perfectly flat to provide a good seal to the ring. Making the ring groove narrower through anodising and then opening it up again with a bit of 250 grit is hardly going to improve things. Piston manufacturers that use anodising will size the grooves appropriately prior to an anodising process, which is something you should be considering if you really must have some anodised bits on your piston.

However, this is a completely pointless exercise. Tune the engine properly and there should be no need to do anything to the piston other than the normal machining for compression, height and valve cut outs.

[227bhp]

Mr2Mike said:

Piston manufacturers that use anodising will size the grooves appropriately prior to an anodising process,

Mr2Mike said:

However, this is a completely pointless exercise.

So piston manufacturers and car engine manufacturers are performing completely pointless exercises on an hourly basis? Ok.

Can you define 'bottom of ringland' for me please? Exactly which part are we talking about here?

I can tell you now the minuscule amount needed to restore ring groove width is neither here nor there and can be accurately done quite easily, it's to three metric decimal places and so small it's practically immeasurable in a groove without investing in some quite expensive equipment.

[Mr2Mike]

227bhp said:

So piston manufacturers and car engine manufacturers are performing completely pointless exercises on an hourly basis? Ok.

No, piston manufacturers may anodise parts of a piston for specific purposes. Those purposes are unlikely to include increasing longevity during a session of ham fisted engine tuning.

227bhp said:

Can you define 'bottom of ringland' for me please? Exactly which part are we talking about here?

The part that gas pressure pushes the ring against.

227bhp said:

I can tell you now the minuscule amount needed to restore ring groove width is neither here nor there and can be accurately done quite easily, it's to three metric decimal places and so small it's practically immeasurable in a groove without investing in some quite expensive equipment.

With a bit of 250 grit paper in your hand? Do you think the piston manufacturers would agree that this was an appropriate method of sizing ring grooves

I find it odd that many, many thousands of powerful and reliable competition engines have been built without the engine builders feeling the need to fk around with anodising bits of piston. Clearly they know nothing.

[227bhp]

Mr2Mike said:

227bhp said:

So piston manufacturers and car engine manufacturers are performing completely pointless exercises on an hourly basis? Ok.

No, piston manufacturers may anodise parts of a piston for specific purposes. Those purposes are unlikely to include increasing longevity during a session of ham fisted engine tuning.

227bhp said:

Can you define 'bottom of ringland' for me please? Exactly which part are we talking about here?

The part that gas pressure pushes the ring against.

227bhp said:

I can tell you now the minuscule amount needed to restore ring groove width is neither here nor there and can be accurately done quite easily, it's to three metric decimal places and so small it's practically immeasurable in a groove without investing in some quite expensive equipment.

With a bit of 250 grit paper in your hand? Do you think the piston manufacturers would agree that this was an appropriate method of sizing ring grooves

I find it odd that many, many thousands of powerful and reliable competition engines have been built without the engine builders feeling the need to fk around with anodising bits of piston. Clearly they know nothing.

That's one of the most idiotic, badly put together, cock-eyed and misquoted set of arguments i've seen in a while. It's not even worth me bothering to put an argument to as I don't have the time, nor need to lower myself to your low level of intelligence.

[Pumaracing]

227bhp said:

The total depth of the process goes 50% into the aluminium and 50% (the growth) is outside of the aluminium, this is fact. What I believe is that the process (if it's anything like zinc plating) doesn't like to get into internal cavities as much so the growth there isn't as great anyhow, but i'm not sure on that.
What I do know is the growth on such a small area such as a ring groove is negligible and can be eased by application of a piece of 250 grit paper and 2 minutes of time. The gudgeon pin hole can be masked off or maybe (not as good) be taken out after with a fine hone. Is the pin hole normally a part of a piston which wears? I don't believe so, but am open to correction.

I just dusted off one of my engineering books from the early 1800s and it appears '1 thou' is 0.0254 mm From what I have observed aluminium doesn't grow that much when hard anodised by someone who knows what they are doing whilst using the correct equipment properly.

227bhp said:

To MR2Mike

That's one of the most idiotic, badly put together, cock-eyed and misquoted set of arguments i've seen in a while. It's not even worth me bothering to put an argument to as I don't have the time, nor need to lower myself to your low level of intelligence.

Well now. Don't hold back eh?

Not only were all of Mike's points very valid but you seem to have some major misconceptions about both the process, its benefits and in particular the dimensions that are relevant here. Perhaps the need to refer to an engineering book to convert imperial to metric offers us a clue but I'm equally happy to work in both. A micron is a millionth of a metre or a thousandth of a millimetre. Hard anodising case depth is usually a minimum of 25 microns to normally about 50 microns although thicker case can be specified on request.

25 microns is 0.025mm = 0.001". (1 thou)
50 microns is 2 thou.

Now indeed this case is produced as 50% within the existing material and 50% as surface growth so even the lightest anodising would add half a thou to every surface although this would never be a perfectly reproducable dimension and it would usually be somewhere between half and one thou per surface.

So in a piston ring groove, and yes of course the fluid would get fully into that and completely anodise it, you'd be looking at between at least 1 thou and 2 thou reduction in width. That's the normal total side clearance of a new ring FFS! The ring ain't going to fit into the groove after it's been anodised. But you think you'll sort that out in 2 minutes with abrasive paper.

Now how in the name of all that's holy do you think you're going to get W&D paper into a 1mm or so wide ring groove and evenly and precisely restore its original dimension at both top and bottom when the hard coating in the groove is now the same hardness aluminium oxide as the abrasive paper is made of which therefore won't even touch it? And all in 2 minutes? In fact there's no simple engineering process at all that can restore a hardened ring groove back to its pre-anodising dimension never mind something you think you can do by hand in 2 minutes.

You're in some sort of cloud cuckoo land here.

The gudgeon pin bore situation is as bad or even worse. Pin to bore clearance will be as little as 2 or 3 tenths of a thou as new. Even the bare minimum 1 thou reduction in bore diameter after anodising will obliterate that and pin bores are not usually finished by honing anyway even if you could find someone to try and do that on such a hard surface. They're finished by roller burnishing with hardened steel rollers which relies on the aluminium being soft enough to yield to that and the hard oxide surface will not only fail to respond to that process but also bugger the tooling.

OE manufacturer hard anodising is done by careful R&D to establish the exact surface growth for a given alloy composition after a set process time in solution, making every necessary piston dimension small enough to allow for that and then not having to bugger about with things later. In the case of ring grooves that additional clearance is usually 2 thou (0.05mm) and then the anodising process is set up to not exceed that. Pin bores will certainly be masked off completely.

But you're going to chuck a one off set of pistons at someone who won't have any precise idea of how much surface growth will occur in that particular alloy at any given process time and then hope to sort out all the problems later when most of the machining that will be required to make the pistons even work again is actually close to impossible.

Good luck. After you've scrapped the anodised pistons please let us know how the engine eventually runs with the second set.

[Mr2Mike]

227bhp said:

That's one of the most idiotic, badly put together, cock-eyed and misquoted set of arguments i've seen in a while. It's not even worth me bothering to put an argument to as I don't have the time, nor need to lower myself to your low level of intelligence.

As a great engineer once said, "Wise men don't need advice. Fools won't take it."

[Pumaracing]

Mr2Mike said:

As a great engineer once said, "Wise men don't need advice. Fools won't take it."

I don't actually remember saying that but my memory is not what it used to be

[neiljohnson]

Silly arguments aside I'm finding this an interesting read
Out of interest its been suggested to me that ceramic coating Pistons can be used too good affect, does anyone have any experience of this?
I've avoided it thus far as having seen ceramic coating start to flake off an exhaust manifold after a while I wouldn't want that to happen to my Pistons!!!

[Boosted LS1]

I've built a reasonable number of ls and cosworth 24v engines using pistons with coated crowns. I've never had an issue with it. The manufacturer I use doesn't coat the grooves, just the crowns and top ring land.

[neiljohnson]

Boosted LS1 said:

I've built a reasonable number of ls and cosworth 24v engines using pistons with coated crowns. I've never had an issue with it. The manufacturer I use doesn't coat the grooves, just the crowns and top ring land.

So the manufacturer of the Pistons does it?
Tbh this I would be happy with it was the suggestion of getting them done after that I am sceptical about

[neiljohnson]

Boosted LS1 said:

I've built a reasonable number of ls and cosworth 24v engines using pistons with coated crowns. I've never had an issue with it. The manufacturer I use doesn't coat the grooves, just the crowns and top ring land.

So the manufacturer of the Pistons does it?
Tbh this I would be happy with it was the suggestion of getting them done after that I am sceptical about

[Boosted LS1]

^ Yes. They can coat the crowns and give you a nice slippery skirt coating if you want it. The manufacturers assume all the responsibility and sell you a finished set of pistons. It's the way I prefer to buy them.

[Mr2Mike]

Pumaracing said:

I don't actually remember saying that but my memory is not what it used to be

It was definitely from some old geezer born in the 1700's

[227bhp]

Mr2Mike said:

Pumaracing said:

I don't actually remember saying that but my memory is not what it used to be

It was definitely from some old geezer born in the 1700's

"Without data you're just another person with an opinion" is a good one too.

[227bhp]

Pumaracing said:

227bhp said:

The total depth of the process goes 50% into the aluminium and 50% (the growth) is outside of the aluminium, this is fact. What I believe is that the process (if it's anything like zinc plating) doesn't like to get into internal cavities as much so the growth there isn't as great anyhow, but i'm not sure on that.
What I do know is the growth on such a small area such as a ring groove is negligible and can be eased by application of a piece of 250 grit paper and 2 minutes of time. The gudgeon pin hole can be masked off or maybe (not as good) be taken out after with a fine hone. Is the pin hole normally a part of a piston which wears? I don't believe so, but am open to correction.

I just dusted off one of my engineering books from the early 1800s and it appears '1 thou' is 0.0254 mm From what I have observed aluminium doesn't grow that much when hard anodised by someone who knows what they are doing whilst using the correct equipment properly.

227bhp said:

To MR2Mike

That's one of the most idiotic, badly put together, cock-eyed and misquoted set of arguments i've seen in a while. It's not even worth me bothering to put an argument to as I don't have the time, nor need to lower myself to your low level of intelligence.

Well now. Don't hold back eh?

Not only were all of Mike's points very valid but you seem to have some major misconceptions about both the process, its benefits and in particular the dimensions that are relevant here. Perhaps the need to refer to an engineering book to convert imperial to metric offers us a clue but I'm equally happy to work in both. A micron is a millionth of a metre or a thousandth of a millimetre. Hard anodising case depth is usually a minimum of 25 microns to normally about 50 microns although thicker case can be specified on request.

25 microns is 0.025mm = 0.001". (1 thou)
50 microns is 2 thou.

Now indeed this case is produced as 50% within the existing material and 50% as surface growth so even the lightest anodising would add half a thou to every surface although this would never be a perfectly reproducable dimension and it would usually be somewhere between half and one thou per surface.

So in a piston ring groove, and yes of course the fluid would get fully into that and completely anodise it, you'd be looking at between at least 1 thou and 2 thou reduction in width. That's the normal total side clearance of a new ring FFS! The ring ain't going to fit into the groove after it's been anodised. But you think you'll sort that out in 2 minutes with abrasive paper.

Now how in the name of all that's holy do you think you're going to get W&D paper into a 1mm or so wide ring groove and evenly and precisely restore its original dimension at both top and bottom when the hard coating in the groove is now the same hardness aluminium oxide as the abrasive paper is made of which therefore won't even touch it? And all in 2 minutes? In fact there's no simple engineering process at all that can restore a hardened ring groove back to its pre-anodising dimension never mind something you think you can do by hand in 2 minutes.

You're in some sort of cloud cuckoo land here.

The gudgeon pin bore situation is as bad or even worse. Pin to bore clearance will be as little as 2 or 3 tenths of a thou as new. Even the bare minimum 1 thou reduction in bore diameter after anodising will obliterate that and pin bores are not usually finished by honing anyway even if you could find someone to try and do that on such a hard surface. They're finished by roller burnishing with hardened steel rollers which relies on the aluminium being soft enough to yield to that and the hard oxide surface will not only fail to respond to that process but also bugger the tooling.

OE manufacturer hard anodising is done by careful R&D to establish the exact surface growth for a given alloy composition after a set process time in solution, making every necessary piston dimension small enough to allow for that and then not having to bugger about with things later. In the case of ring grooves that additional clearance is usually 2 thou (0.05mm) and then the anodising process is set up to not exceed that. Pin bores will certainly be masked off completely.

But you're going to chuck a one off set of pistons at someone who won't have any precise idea of how much surface growth will occur in that particular alloy at any given process time and then hope to sort out all the problems later when most of the machining that will be required to make the pistons even work again is actually close to impossible.

Good luck. After you've scrapped the anodised pistons please let us know how the engine eventually runs with the second set.

I'm sorry, but not a lot of what he stated was of any use to the debate at all.
Do you have any experience with this or is it just what you would presume will happen?

[Mr2Mike]

227bhp said:

"Without data you're just another person with an opinion" is a good one too.

Absolutely. Do you have some?

[227bhp]

Mr2Mike said:

227bhp said:

"Without data you're just another person with an opinion" is a good one too.

Absolutely. Do you have some?

I'm the man with the piston in his hand so yes i'd say so. It's been chronically busy here the last couple of days and continues to be so, i'll post up some more over the weekend if I get chance.

[Pumaracing]

227bhp said:

Do you have any experience with this or is it just what you would presume will happen?

It's just what I gleaned from Google after a quick trawl. I'm actually a brickie in real life but I'm really bang tidy on'th intergoogles. I can find owt I can if I search hard enough.

[Mr2Mike]

227bhp said:

I'm the man with the piston in his hand so yes i'd say so.

But they are standard pistons, so can't yet be included into your data set. How many pistons have you anodised the ring grooves on and then opened up the grooves by hand with a bit of wet and dry which have then gone on to make more power or last longer than pistons which haven't had this treatment?

Pumaracing said:

It's just what I gleaned from Google after a quick trawl. I'm actually a brickie in real life but I'm really bang tidy on'th intergoogles. I can find owt I can if I search hard enough.

There's mortar this than meets the eye. Do you have concrete evidence?