Though not readily appreciated, understanding and optimizing an engine’s compression and compression ratio is a valuable tool toward maximizing performance.   This tech tip is from the full book, DAVID VIZARD’S HOW TO PORT & FLOW TEST CYLINDER HEADS. For a comprehensive guide on this entire subject you can visit this link: LEARN MORE ABOUT […]

I really wanted to title this chapter “In-Cylinder Turbulence and Combustion Dynamics,” but it wouldn’t quite fit. Nonetheless, it is where we are going here, because cramming a cylinder full of air is just one aspect of making power. Exactly how it is filled, and what we do with it once filled, still has a […]

So far I have covered a lot of technical details that could be described as peripheral. It’s important, but is not actually the hands-on stuff. I am now about to set that right.   This tech tip is from the full book, DAVID VIZARD’S HOW TO PORT & FLOW TEST CYLINDER HEADS. For a comprehensive […]

Valve shrouding may be something you have heard of (or maybe not), but it and its effects are closely tied with both the seat and port design that works best.   This tech tip is from the full book, DAVID VIZARD’S HOW TO PORT & FLOW TEST CYLINDER HEADS. For a comprehensive guide on this […]

In Chapter 1 of the full book, I brought attention to the fact that the number-one  impediment to flow on both the intake and exhaust side of things is the valve seat. You can know how influential it is, with reasonable accuracy, by determining the mean velocity at the gap between the seats of the […]

Granted, this chapter is titled “Porting Tools, Consumables and Safety,” but I address the safety issues first because it is vitally important you understand just how critical they are.   This tech tip is from the full book, DAVID VIZARD’S HOW TO PORT & FLOW TEST CYLINDER HEADS. For a comprehensive guide on this entire […]

In the late 1980s and early 1990s, production processes resulted in much more accurate castings. The result was head castings that had far more effective ports as received from the head manufacturer. This was the start of what can truly be described as the golden age of cylinder heads for the V-8 performance community and […]

When you throw a lit match onto a gasoline-soaked rag, it ignites very easily. This is not an experiment I recommend or that is even needed. However, when gas so easily combusts, it’s hard to imagine there ever being a problem igniting it in the cylinders of a hot, high-compression engine. The reality, though, is […]

May 2008 was something of a milestone for me as far as the modification of cylinder heads for more performance was concerned. It was 50 years since I performed my first cylinder-head flow test. The technique  I used was crude, to say the least, but it worked. Looking back on it many years later, I […]

Before getting into the subject of physically modifying cylinder heads, let’s look at the history and basic logic and techniques involved with establishing a cylinder head’s number-one criteria: airflow. A working knowledge here allows a better understanding of all the head characteristics we are attempting to improve and how they may each affect the others […]