Step # 1
Balance the engine rotating assembly. Most performance articles just assume the engine is balanced when they quote specs. It is really a no-brainer. When the engine is balanced, it will not fight itself. Most engines are balanced just enough to keep them from shaking apart. There is a good amount of tweaking that can be done. The essence of a balanced engine is that when one rod and piston are going up on one side, the rod and piston on the other side weighs the same, and the center of force is in the center of the rotating assembly. Were you to be twirling around you would not want to have a 50-pound object in your right hand and a 10-pound object in your left because you would constantly be using a large amount of energy just to stand up straight. That is the jist of balancing an engine's rotating assembly.
Step # 2
Centerline-deck the block. This is another balancing technique. By center line decking a block you have the same amount of cylinder volume on the right bank as you have on the left bank. You can also shave off a little extra on the block and the cylinder head, in most cases (check carefully if you are not sure on reassembly) This will raise the compression ratio. You can't go too high or you will not be able to burn "pump gas," or gas you can easily buy at your local service station. If you are not sure how much room you have you can test it. Put the short block assembly together before you shave the block or head. Put some modeling clay on top of the piston. Then bolt the heads down and make the complete long block assembly. Rotate the engine over. Then take the heads off to see the indentation the valves made in the clay. This will let you know how much room you have to play with. That is to insure that your valves and pistons do not collide. Most modern engines, especially the overhead cam versions, do not have very much room to play with, maybe about twenty thousandths from the original factory thickness. They make some specialized dome pistons that will raise compression also.
Step # 3
You can port the cylinder heads to increase the flow. The more volume of fuel you can manage to get into the engine and efficiently burn the more horsepower and torque you will gain, especially at higher RPMs. A simple technique to do this is bowl cutting the area where the valves go. You can machine out the bowl for a larger valve head size on the intake and the exhaust. A rule-of-thumb is that if you do not have enough room for both, always do the intake rather than the exhaust. The intake has to suck the air and fuel in. The exhaust port has the spent mixture pushed out. You can also gasket-match the intake and exhaust manifold ports. Place the appropriate gaskets on the ports and mark the excess metal that is not under the gasket. Then take a die grinder and remove the excess. You can go a little ways into the intake but you want to keep the majority of the port rough so the air and fuel will mix up and atomize as they flow into the engine. If the port is smooth it will just dump globs of fuel into the cylinder and waste it by not burning efficiently.
After doubling the horsepower of your engine the price goes up exponentially. The examples I gave above could run up to $5,000.00 depending on the engine for around 400 horsepower in a small block Chevy. By comparison the NASCAR engines are above $40,000 for the 900 plus horsepower they produce. With just a little selective work and parts doubling is easy.
Balance the engine rotating assembly. Most performance articles just assume the engine is balanced when they quote specs. It is really a no-brainer. When the engine is balanced, it will not fight itself. Most engines are balanced just enough to keep them from shaking apart. There is a good amount of tweaking that can be done. The essence of a balanced engine is that when one rod and piston are going up on one side, the rod and piston on the other side weighs the same, and the center of force is in the center of the rotating assembly. Were you to be twirling around you would not want to have a 50-pound object in your right hand and a 10-pound object in your left because you would constantly be using a large amount of energy just to stand up straight. That is the jist of balancing an engine's rotating assembly.
Step # 2
Centerline-deck the block. This is another balancing technique. By center line decking a block you have the same amount of cylinder volume on the right bank as you have on the left bank. You can also shave off a little extra on the block and the cylinder head, in most cases (check carefully if you are not sure on reassembly) This will raise the compression ratio. You can't go too high or you will not be able to burn "pump gas," or gas you can easily buy at your local service station. If you are not sure how much room you have you can test it. Put the short block assembly together before you shave the block or head. Put some modeling clay on top of the piston. Then bolt the heads down and make the complete long block assembly. Rotate the engine over. Then take the heads off to see the indentation the valves made in the clay. This will let you know how much room you have to play with. That is to insure that your valves and pistons do not collide. Most modern engines, especially the overhead cam versions, do not have very much room to play with, maybe about twenty thousandths from the original factory thickness. They make some specialized dome pistons that will raise compression also.
Step # 3
You can port the cylinder heads to increase the flow. The more volume of fuel you can manage to get into the engine and efficiently burn the more horsepower and torque you will gain, especially at higher RPMs. A simple technique to do this is bowl cutting the area where the valves go. You can machine out the bowl for a larger valve head size on the intake and the exhaust. A rule-of-thumb is that if you do not have enough room for both, always do the intake rather than the exhaust. The intake has to suck the air and fuel in. The exhaust port has the spent mixture pushed out. You can also gasket-match the intake and exhaust manifold ports. Place the appropriate gaskets on the ports and mark the excess metal that is not under the gasket. Then take a die grinder and remove the excess. You can go a little ways into the intake but you want to keep the majority of the port rough so the air and fuel will mix up and atomize as they flow into the engine. If the port is smooth it will just dump globs of fuel into the cylinder and waste it by not burning efficiently.
After doubling the horsepower of your engine the price goes up exponentially. The examples I gave above could run up to $5,000.00 depending on the engine for around 400 horsepower in a small block Chevy. By comparison the NASCAR engines are above $40,000 for the 900 plus horsepower they produce. With just a little selective work and parts doubling is easy.
No comments:
Post a Comment