# Looking for piston details explained

1. Jun 7, 2007

### 5.0stang

I'm trying to find an article or something similar online that has a diagram of a piston and explains the different parts of the piston.

For example, trying to find out what the piston's compression height, ringland, deck thickness, ring grooves, etc.

I would like to know what all of these mean.

A particular piston I'm looking at says:

Compression Height: 1.090
Ringland: .220, .140, 075.
Deck Thick: .325
Ring Grooves: 1/16,1/16,3/16

What do those numbers mean?

Thanks from a newbie:)

2. Jun 11, 2007

### brewnog

Compression height is the distance from the centre of the gudgeon pin to the crown of the piston (the flat bit on the top).

Ring land is the distance between the rings; hence top ring land is the distance between the top ring and the crown.

Ring grooves are the grooves into which the piston rings sit.

I'm not sure about 'deck thick', I imagine it to be the thickness of the top deck taken at its thinnest point.

3. Jun 11, 2007

### 5.0stang

Anyone got a piston diagram that is labeled?

4. Jun 12, 2007

### FredGarvin

5. Jun 12, 2007

### brewnog

That's what I was going to suggest too, but it's not actually a piston parameter because it's dependent on other components, whereas all the others are piston-specific. I think there's a subtle difference between piston/deck height volume and deck thickness.

I'll try and remember to ask next time my piston man is around.

I've got a labelled piston diagram but it's in a book and doesn't have all the parameters you were after. I'll see what I can find at work, failing that I'm certain you'll find something on the Federal Mogul or Mahle websites.

6. Jun 12, 2007

### FredGarvin

I was thinking the same thing when I saw that. However, couldn't that parameter be changed simply by changing the height of the piston? I honestly have no idea why one would do that other than increased pressure. Is that usually an option with pistons?

7. Jun 12, 2007

### brewnog

Yes it could be changed by altering the height of the piston, that's why I don't think it's a piston parameter; it's as much to do with the crankshaft, case, and conrod as the piston itself.

You'd be changing it to alter the engine's compression ratio for power and efficiency.