Principles of a Pro Touring Car (Part Two: Breathing)


Principles of a Pro Touring Car (Breathing)

What makes a car go is fuel and fire. But without air and specifically oxygen in that air there won’t be any fire. Nor tiny explosion that drives your piston down, and those good looking tires on your good looking car will just stand there looking pretty. Think of it like this. Say you are sitting down watching tv. You are breathing without thinking about it. All of a sudden you hear the ice cream truck playing that little song outside. Your ears prick up. You look out the window. “Oh, no!” you might say, “He’s getting away!” So you put on your running shoes and run hard down the street to catch him. Now you are breathing hard if you are like me. Yippy! You caught him. Your lungs were designed to both watch tv quietly and to breathe hard while running down the street to get that delicious fudge bar. That’s what we will be aiming for with our pro touring car, too, using the PRINCIPLE OF BREATHING. The better that car can breathe the better it can run hard.

Air follows a pathway into, through, and out your engine. The idea is to allow your engine to ingest the maximum amount of air possible when it needs it so that your engine will have the maximum amount of power on demand. After a certain point on a pro touring or other high performance car you might even have to upgrade the size of fuel line and the capacity of the fuel pump to keep up with the fuel demand to match the breathing capacity built in. That sentence was a moutful.

I’ll start with the basic parts that make up your INTAKE AND EXHAUST SYSTEMS. Later on I’ll describe some special parts that can make your car more athletic. Air starts at your air cleaner housing and goes past the air filter and down your carburetor or throttle body. The carburetor is a mechanism that is in both the intake and fuel systems because it meters and mixes the air and fuel together.

Next, there is the intake manifold, which has a plenum directly under the carburetor with pipes running to each cylinder. You might think if you want this car to really breathe get a huge carburetor and an intake manifold with huge sewer pipes running to your engine. This doesn’t work on a street car because you have to maintain air velocity and vacuum. With high air velocity and vacuum the engine responds better to the throttle and you have good pickup. That’s called throttle response. Now, we get to the cylinder head. It has an intake port and valve that opens into the combustion chamber directly over your cylinder.
The copyright of the article Principles of a Pro Touring Car (Part Two: Breathing) in Pro Touring Street Cars is owned by Matthew Manning. Permission to republish Principles of a Pro Touring Car (Part Two: Breathing) in print or online must be granted by the author in writing.

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