Need Torque? Need Horsepower? Port and Polish!

Let's talk about four stroke gasoline engines. This will be basic talk and basic facts. The entire airflow system of an engine, (carburetor, manifold, heads, and headers) is critical to engine performance. An internal combustion engine is basically a breathing machine. A gas four stroke engine is an air pump. It inhales oxygen and fuel, ignites it, and exhales carbon monoxide. It uses gas to keep itself going. Air in and air out. Mix a little gas with the air and it will keep going. The efficiency of an engine to perform those three tasks determines its horsepower and torque output.

As a result the engine makes heat and it makes the crankshaft go around and around. More air and gas makes more heat and more around and around (RPM). It uses air and gas and it creates heat and RPM. The heat, or at least most of it, we get rid of with the cooling system. The RPM is what we are after. No RPM results in no torque and no horsepower. Torque and horsepower is really our goal. We would like to have more torque and horsepower with less heat and less gas consumption and maybe even less RPM.

Cylinder heads, where all three of these functions take place, are the critical element in this system. It is there where all of the air and fuel flow is directed. The more efficient heads are at directing that flow, the better the overall performance output. That’s where porting and polishing come into play. So where is the key to engine performance? It’s in the cylinder heads!
With that in mind let's fast forward to a test question. How much HP does your car engine make? Let me clarify a little. Let's say you have a stock 350 Chevy with a Q-Jet. The book tells us that the engine makes, let's say, 220 HP. So what is your answer? If your answer is 220 HP you didn't understand the question. There's a difference between what your engine makes and what its net usable HP is at the rear wheels. Confused yet? Engines have parasitic losses. If you are in business this would be called the "cost of doing business". It takes power (remember air and gas) to rotate all that spinning stuff inside your engine. And don't forget it takes power to get the air in and then out again and more power to run a water pump and fan to keep your engine from melting into a glob of metal.

With so many ways to use power and air and gas it is actually possible to have such an inefficient engine that the net output is near nothing (think Federal Government). So, your little engine really makes more power than you know but some of it is used up in the process of making power. So your 350 Chevy has a net result of 220 HP. It makes and is capable of making so much more (think NASCAR, 850 HP). The more restrictions you remove inside your engine the more that 220 HP will increase.

Now let's talk about where power is made. We will call this our "power made-power lost distinction". You have probably heard that "power is made in the head". Isn't it then true that power is lost in the head? How is it lost? What can be done about it? Now we're getting somewhere. Here's something to twist your brain sideways. Camshafts, that is bigger ones, and blowers, turbos, and superchargers, are trying to minimize the poor airflow characteristics living in your cylinder head. Call it damage control, waste management, loss mitigation, etc. Face it; you are sick in the head. Like any good shrink worth his fifty minutes will tell you, it's good to acknowledge it and then deal with it (think Dr. Denny).

There are impediments to better air flow in your cylinder head. Imagine the inside of an old water pipe that is narrowed down with hard water deposits and rust and dirt. Now imagine Roto-rooter to the rescue. Or imagine drinking a milkshake through a bent or clogged straw. You get the point. If you can streamline the head, air will flow much more easily, robbing less power from your engine, and allowing the 220 HP number to be closer to 300+HP.

Porting and polishing removes detonation-causing hot spots and casting flashes, and increases the air and fuel flow characteristics in all areas of the head, including the intake and exhaust ports, valve pockets, and combustion chambers and all radii. More air flow equals more fuel which equals more horsepower and torque. This clearly increases performance, including fuel economy. Porting and polishing the cylinder heads can unlock more horsepower from your engine than you probably thought possible.

Porting and polishing the heads provides the finely detailed attention required to bring your engine to a higher level of efficiency. More than any other single factor, the porting process is responsible for the high power output of an engine. Nothing can take the place of properly ported heads. Moving air and fuel through the heads is a major problem for engines running at speed and head porting helps to alleviate this. The net result is more torque, more horsepower, and more fuel economy, all at less RPM. And there is more good news. While cams, blowers, and turbos wear out, porting and polishing your cylinder head never wears out (think, all of the good and none of the bad!). Now that we have brought this up again, remember that big cams and turbos and blowers all have a lag time. Properly ported heads do not suffer that same malfunction! So let’s get porting and polishing so you can enjoy more torque and more horsepower! Dr. Denny out.

Dr. Denny does custom head porting & polishing. For more information go to DR.DENNY.COM