Dave Walker of Emerald M3D on Modifying Cylinder Heads for Performance

Summary

In this video, Dave Walker from Emerald M3D discusses cylinder heads, specifically a supercharged Mini's first-generation BMW R50/R52/R53. He explains the engine's collaboration with Chrysler, its 1.6L capacity, and the challenges of forced induction. Dave demonstrates the importance of porting and polishing for gas flow, using a flow bench to measure air flow and valve lift. He emphasizes the value of quantifiable data over opinions, highlighting the process of head development and the quest for improved engine performance.

Takeaways

• 🚗 The conversation is about cylinder heads from a first-generation BMW R50, R52, R53 Mini Supercharged engine.
• 🔍 The engine is a collaboration between BMW and Chrysler, used in the Cooper S from 2001 to 2006.
• 🏎 The engine has a 1.6-liter capacity with a supercharger, originally designed as a naturally aspirated engine.
• 🛠️ Porting and polishing cylinder heads can improve their appearance but does not necessarily increase power.
• 🔍 The shape of the port is more important than the shine for performance improvements.
• 🔧 The script discusses the process of smoothing out casting imperfections in the cylinder head.
• 📊 A flow bench is used to measure the air flow through the cylinder head, providing quantifiable data rather than relying on opinions.
• 📉 The script explains how the flow of air stops increasing after a certain valve lift, which is important for camshaft design.
• 🔬 The use of a flow bench helps to determine the optimal valve lift for maximum flow, avoiding unnecessary mechanical stress.
• 🔩 The script mentions the importance of aligning the cylinder head correctly on the flow bench to ensure accurate measurements.
• ⚙️ The conversation also touches on the historical development of flow bench technology and its evolution from manometers to electronic sensors.

Q & A

What type of engine is being discussed in the script?

The engine being discussed is a first-generation BMW R50, R52, R53 Mini Supercharged engine.

What is the engine's capacity and what modifications were made to it?

The engine's capacity is 1.6 liters and it was originally designed as an aspirated engine. Later modifications included adding a supercharger.

What is the purpose of the supercharger in the engine?

The supercharger is used to force more air into the engine, which can increase the engine's power output.

What is the significance of the cylinder head in an engine?

The cylinder head houses the valves and plays a crucial role in the engine's performance by controlling the intake and exhaust of gases.

How does porting and polishing affect the engine's performance?

Porting and polishing can improve the shape of the cylinder head's intake and exhaust ports, potentially increasing airflow and engine performance. However, polishing alone does not increase power output.

What is a flow bench and how is it used?

A flow bench is a device used to measure the airflow through an engine's cylinder head. It helps to quantify the effect of modifications such as porting and polishing.

What is the importance of valve lift in terms of airflow?

Valve lift determines how much the valve opens, affecting the amount of air and exhaust gases that can flow in and out of the cylinder. However, there is a point where increasing lift does not increase airflow.

Why might an exhaust valve be lifted more than necessary?

An exhaust valve might be lifted more than necessary to reduce the stress on the valve train and to make the valve spring's job easier by reducing the abrupt stop at full lift.

What is the typical exhaust flow percentage in relation to inlet flow?

The exhaust flow is typically around 70% of the inlet flow, although some heads can reach up to 80%.

How does the position of the cylinder head on the flow bench affect the results?

The position of the cylinder head on the flow bench must be aligned correctly to ensure accurate measurements. Misalignment can lead to artificially higher flow readings.

What is the purpose of the manometers and probes used in the flow bench?

Manometers and probes are used to measure the pressure drop across the cylinder head and to probe the airflow within the ports, helping to identify areas of restriction or inefficiency.