Height Compression

What Is Piston Compression Distance?

The piston height compression is the dimension or the distance from the flat top of the piston to the center of the piston pin. 

The piston compression distance is also referred to as the piston pin height to avoid confusion. The piston compression distance is adjusted relative to the required efficiency of the engine. The precise person compression height increases the efficiency of the engine at a high speed.

The compression height is the distance between the center of the wrist pin to the crown of the piston.

For calculating the piston compression height, use the following formula:

$$ \text{Piston Compression Height (CH)} = \text{BH} - \frac{1}{2}\text{CS} - \text{RL} - \text{DC} $$

Or

$$ CH = BH - 0.5 \times CS - RL - DC $$

Where:

• CH is the compression height
• BH is the block height
• CS is the crank stroke
• RL is the rod length
• DC is the deck clearance

Practical Example:

Let the block height be 6 inches, the crank stroke be 3 inches, the rod length of the engine be 1.5 inches, and the deck clearance be 2 inches. Calculate the piston compression height.

Solution:

We know the piston compression height formula:

$$ CH = BH - 0.5 \times CS - RL - DC $$

Insert the given values:

$$ CH = 6 - 0.5 \times 3 - 1.5 - 2 $$

Calculate step by step:

$$ CH = 6 - 1.5 - 1.5 - 2 = 1 \ \text{inch} $$

$$ CH = 0.0254 \ \text{m} $$

The piston compression height is 1 inch or 0.0254 m.

Size of the Compression Piston:

There are three things you need to decide when deciding the size of the piston.

• The Block Height
• The Connecting Rod Length
• The Stroke Length

The Block Heights:

The block height is measured from the crankshaft to the centerline of the deck.

The Connecting Rod Lengths:

The Connecting rod length is measured between the centers of the big end and the little end.

The Stroke Length:

The stroke length is twice the distance from the centerline and the crankshaft.

Working of this Calculator:

Let's have a look at the simple working of the piston compression distance:

Input:

• Enter the Block height, Crank stoke, Rod length, and Deck clearance in their respective fields
• Tap Calculate 

Output:

• Height Compression

FAQs:

What Are the Benefits of High Compression of Pistons?

Higher compression allows for a larger amount of fuel/air mixture to be successfully combusted and you can generate more power by the larger piston compression distance.

References:

From the source of Wikipedia: Height compression human.