Hidden Secrets of a Formula 1 Piston

[matthewgrant71]

Sure, I wrote a blog post about it here: https://modatek.co.uk/piston-accumulator-groove-tech/
. . .

Once combustion pressure drops again, does the accumulator groove discharge back to the top ring groove, down to the lower rings or both.

To be honest, I don't know. My guess would be a bit of both.

[saviour stivala]

Once combustion as well as compression pressure drops, (they, both leak, at least some, bypass the ring cylinder sealing interface), the pressure accumulated in the accumulator groove, which while under pressure tends to creat a seal to the cylinder wall more effective Tthan the piston ring itself, and so acts like a perfect seal, once that accumulated prssure drops, the sealing is no more, so the reduced pressure which has now lost its seal to cylinder wall, can leak either past the bottom ring as well as up past the top ring. The piston ring sealing to cylinder wall in F1 engines by increasing ring tention (material wise), will creat much more friction that saps power than sealing by accumulator groove pressure, this because accumulator groove pressure is only present when needed, one half of the four strokes.

[saviour stivala]

At least up to the NA 2.4L V8 only 2 rings where used on F1 pistons, a compression and an oil control rings. It is believed that a 0.8mm/0.7mm tich compression rings were used with a 2.0mm oil control ring. There was a time during the 3.0l v10 qualifying only engines that no oil control ring was used and still blow-by was (combustion and compression gasses) no problem. It is not believed that gas ports/holes to aid in pressuring the compression ring were used. instead the gas pressuring behind the compression ring was obtained by design clearance between the lands of the compression ring grove and the ring itself. The smaller the tichness of the compression ring the faster the pressure behind said ring buils-up and let go. Compression piston rings are obviously designed to minimize blow-by 'gasses escaping past piton', which means that there is no such thing as a 100% sealing compression ring. But most if not all of the blow-by gasses that escape by the compression ring, (all while combustion is in progress, and all while compression is in progress) are totally arrested/stopped by the sealing effect of the pressure grove below the compression ring. It is only the pressure build-up inside the pressure grove that is leaked iether up past the top ring or down past the oil control ring is leaked once the pressure and so the sealing effect of the pressure grove is minimized by end of combustion and end of comprssion.

[Hoffman900]

Once combustion as well as compression pressure drops, (they, both leak, at least some, bypass the ring cylinder sealing interface), the pressure accumulated in the accumulator groove, which while under pressure tends to creat a seal to the cylinder wall more effective Tthan the piston ring itself, and so acts like a perfect seal, once that accumulated prssure drops, the sealing is no more, so the reduced pressure which has now lost its seal to cylinder wall, can leak either past the bottom ring as well as up past the top ring. The piston ring sealing to cylinder wall in F1 engines by increasing ring tention (material wise), will creat much more friction that saps power than sealing by accumulator groove pressure, this because accumulator groove pressure is only present when needed, one half of the four strokes.

Um, that was quite a bit of gibberish. What can cause sealing is back pressure on the ring. Either through lateral or vertical gas ports. Vertical ports are common in drag race engines that see frequent rebuild intervals. Lateral in more “endurance” type engines.

In a F1 engine, just like in every racing engines from drag racing to NASCAR, etc, is they use the dry sump (or a vacuum pump where dry sump isn’t legal) to draw down the crankcase pressure. This allows you to run increasingly lower tension rings. The downside is you need piston oil jets (plus coating strategies) to also lubricate the piston pin to keep it from galling.

OP, what crankcase pressure did these engines see?

[saviour stivala]

The compression piston ring is designed to minimize blow-by, gasses ascaping the piston. The combustion and compression gasses that finds their way behind the compression ring, through the clearance (in F1 use) disgned between the top land and piston ring, to aid in tensioning the ring against the cylinder wall, does not totally seal/totally prevent blow-by. It is the accumulator grove bellow the compression piston ring that totally seals against the cylinder wall when pressurised by the blow-by the comprssion ring gasses. This sealing is maintained for as long as the accumulator grove is pressurised.

[saviour stivala]

The accumulator grove bellow the compression ring when pressurised by blow-by the compression ring gasses, is much more effective as a seal aganst the cylinder wall than the compession ring itself.

[Hoffman900]

The compression piston ring is designed to minimize blow-by, gasses ascaping the piston. The combustion and compression gasses that finds their way behind the compression ring, through the clearance (in F1 use) disgned between the top land and piston ring, to aid in tensioning the ring against the cylinder wall, does not totally seal/totally prevent blow-by. It is the accumulator grove bellow the compression piston ring that totally seals against the cylinder wall when pressurised by the blow-by the comprssion ring gasses. This sealing is maintained for as long as the accumulator grove is pressurised.

The accumulator groove provides a volume to drop blow by pressure. I have no idea what you’re rambling about, per usual.

[saviour stivala]

The compression piston ring is designed to minimize blow-by, gasses ascaping the piston. The combustion and compression gasses that finds their way behind the compression ring, through the clearance (in F1 use) disgned between the top land and piston ring, to aid in tensioning the ring against the cylinder wall, does not totally seal/totally prevent blow-by. It is the accumulator grove bellow the compression piston ring that totally seals against the cylinder wall when pressurised by the blow-by the comprssion ring gasses. This sealing is maintained for as long as the accumulator grove is pressurised.

The accumulator groove provides a volume to drop blow by pressure. I have no idea what you’re rambling about, per usual.

I am sorry not being able to help you understand what I was saying, more so after my last post.

[matthewgrant71]

Just to clarify a few comments here.

The high pressure gas in accumulator groove doesn't provide a seal, it stabilises the top and second rings, which helps them to seal better.

[Hoffman900]

Just to clarify a few comments here.

The high pressure gas in accumulator groove doesn't provide a seal, it stabilises the top and second rings, which helps them to seal better.

Yeah, that was clear from the get-go. Thanks for jumping in.

[saviour stivala]

The high pressure gas in the accumulator groove is part of the same gas that has leaked/bypassed the the top pressureised compression ring. Proving that even a pressurised against the cylinder wall metal compresion ring leaks some gasses. I never said that the accumulator groove when pressurised does not help stabilize the top and bottom rings. What I was saying was that the accumulator groove when prassurised also creats a perfect seal to the cylinder wall like no metal made comprsion ring can. The accumulator groove when pressurised works in the same way the SKF HYDRAULIC COUPLING system works against the cylinder wall, with the difference that the pressure is not big enough to expand the cylinder was outwards. The benefit of the pressurised accumulator groove in pistons is that the higher friction created by the sealing pressure is only there for the two strokes needed, while friction by the compression ring is present on all strokes of the piston.

[Hoffman900]

The high pressure gas in the accumulator groove is part of the same gas that has leaked/bypassed the the top pressureised compression ring. Proving that even a pressurised against the cylinder wall metal compresion ring leaks some gasses. I never said that the accumulator groove when pressurised does not help stabilize the top and bottom rings. What I was saying was that the accumulator groove when prassurised also creats a perfect seal to the cylinder wall like no metal made comprsion ring can. The accumulator groove when pressurised works in the same way the SKF HYDRAULIC COUPLING system works against the cylinder wall, with the difference that the pressure is not big enough to expand the cylinder was outwards. The benefit of the pressurised accumulator groove in pistons is that the higher friction created by the sealing pressure is only there for the two strokes needed, while friction by the compression ring is present on all strokes of the piston.

You can acknowledge you just don’t know what you’re talking about. It’s healthy.

[saviour stivala]

The high pressure gas in the accumulator groove is part of the same gas that has leaked/bypassed the the top pressureised compression ring. Proving that even a pressurised against the cylinder wall metal compresion ring leaks some gasses. I never said that the accumulator groove when pressurised does not help stabilize the top and bottom rings. What I was saying was that the accumulator groove when prassurised also creats a perfect seal to the cylinder wall like no metal made comprsion ring can. The accumulator groove when pressurised works in the same way the SKF HYDRAULIC COUPLING system works against the cylinder wall, with the difference that the pressure is not big enough to expand the cylinder was outwards. The benefit of the pressurised accumulator groove in pistons is that the higher friction created by the sealing pressure is only there for the two strokes needed, while friction by the compression ring is present on all strokes of the piston.

You can acknowledge you just don’t know what you’re talking about. It’s healthy.

Sounds like you are so sure what you're talking about.

[Hoffman900]

The high pressure gas in the accumulator groove is part of the same gas that has leaked/bypassed the the top pressureised compression ring. Proving that even a pressurised against the cylinder wall metal compresion ring leaks some gasses. I never said that the accumulator groove when pressurised does not help stabilize the top and bottom rings. What I was saying was that the accumulator groove when prassurised also creats a perfect seal to the cylinder wall like no metal made comprsion ring can. The accumulator groove when pressurised works in the same way the SKF HYDRAULIC COUPLING system works against the cylinder wall, with the difference that the pressure is not big enough to expand the cylinder was outwards. The benefit of the pressurised accumulator groove in pistons is that the higher friction created by the sealing pressure is only there for the two strokes needed, while friction by the compression ring is present on all strokes of the piston.

You can acknowledge you just don’t know what you’re talking about. It’s healthy.

Sounds like you are so sure what you're talking about.

Speak for yourself. It reads like AI gibberish and using techno jargon to try to sound smart.

OP literally said that’s not what is happening.

[saviour stivala]

You can acknowledge you just don’t know what you’re talking about. It’s healthy.

Sounds like you are so sure what you're talking about.

Speak for yourself. It reads like AI gibberish and using techno jargon to try to sound smart.

OP literally said that’s not what is happening.

Yes. I speak for myself unlike you echolalia OP (original poster). Having said that, it is a right of yours not to agree with others opinion, but no need to be rude expressing your disagrement.