Today we will go into the basics of compression and cylinders, and how you can successfully get compression back in your cylinder.
There are a few things that we would like to point out before we start:
First, if you have any doubts about what is going on with your engine, it is always best to take it to an experienced mechanic for diagnosis.
You should never try to diagnose or repair your vehicle or airplane without professional training.
Second, the following information is not intended as a substitute for proper maintenance of your aircraft.
If you do not know how to perform certain tasks yourself, then you need to find someone who does.
For example, the FAA requires us to maintain our knowledge base and be able to perform basic repairs ourselves. We cannot recommend anyone else to do this work for you.
Finally, when discussing anything related to aviation, please keep safety in mind at all times.
This includes knowing how to properly use tools, reading manuals, and being aware of local laws and regulations.
Now let’s begin!
Compression Basics
The first thing you want to understand about your engine is that there are two types of engines: spark-ignition (SI) and diesel fuel injection (DFI).
In both cases, the main idea behind the design is to create enough pressure inside the combustion chamber so that the air-fuel mixture ignites and burns.
The difference between these two types lies in how they achieve this goal. SI engines rely on a spark plug to ignite the mixture.
DFI engines inject fuel directly into the cylinder via a fuel injector. Both methods work by creating a high amount of pressure within the combustion chamber.
To produce this high level of pressure, an engine needs to compress the air-fuel mixture.
Compression is the process of increasing the volume of the air-fuel mixture while decreasing its density. The result is more pressure than normal.
In order to increase the amount of pressure, you must decrease the size of the combustion chamber.
This means that you must reduce the distance from the piston top face to the end of the combustion chamber.
When you decrease the size of the chamber, you also decrease the volume of the chamber. This reduction in volume causes the mixture to become denser.
As the mixture becomes denser, it takes less space to occupy the same volume.
This relationship between volume and density is called the ideal gas law. It states that the total number of moles of a substance remains constant regardless of the change in temperature or pressure.
The ideal gas law tells us that the volume of a container containing a fixed mass of gas is proportional to the absolute temperature raised to the fourth power.
This means that if you double the temperature, you will quadruple the volume. To put this another way, if you heat up a can of soda, you will see it expand fourfold.
If you think about it, this makes sense because the volume of the can has doubled, but the amount of soda inside has remained unchanged.
The ideal gas law allows us to calculate the amount of pressure created within the combustion chamber.
Since we know the volume of the chamber, we can calculate the pressure using the formula P MRT where P is pressure, M is the number of moles of gas, R is the universal gas constant, and T is the absolute temperature.
How to Get Compression Back In A Cylinder
To get compression back in a cylinder, you need to do three things:
1. Reduce the size of the combustion chambers.
2. Increase the amount of air flowing through the intake manifold.
3. Increase the amount of fuel entering the combustion chamber.
Reducing the Size Of The Combustion Chambers
One of the easiest ways to increase the amount of air flowing into the cylinder is to remove the restriction at the exhaust port.
If you look at the image below, notice that there is a small hole at the bottom of the exhaust port. This hole reduces the flow of exhaust gasses out of the cylinder.
You can easily fix this problem by removing the cap and cutting away the part of the head that covers the exhaust port
Increasing Air Flow Through Intake Manifold
Another easy way to increase the amount of airflow into the cylinder is to install larger diameter throttle bodies.
Throttle bodies are used to control the amount of air passing through the intake manifold.
By installing larger throttle bodies, you will be able to increase the amount of fresh air entering the cylinder.
Increasing Fuel Volume Into The Combustion Chamber
Finally, one of the most effective methods for increasing the amount of fuel entering your cylinder is to add an injector pump. An injector pump adds additional fuel to the engine.
This extra fuel enters the combustion chamber before the spark plug fires.
An injector pump consists of two parts: an injector valve and a solenoid valve. The injector valve opens when the ignition coil sends a current pulse down its wire.
This pulse triggers the solenoid valve which opens allowing fuel to enter the combustion chamber.
An injector pump works best on engines with carburetors. However, if you have a direct injection system, you may want to consider adding an injector pump.
Final Thoughts
In order to get compression back in a piston engine, you must first reduce the size of the combustion chamber. You should also increase the amount of air passing into the cylinder.
Finally, you should increase the amount of fuel entering the combustion chamber.
If you follow these steps, you should see some improvement in performance and power!
Frequently Asked Questions
Is It Possible To Fix Bad Engine Compression?
Yes, it is possible to repair bad engine compression. There are many different techniques available to help you fix bad engine compression.
For example replacing a leaking part whether it’s a piston or piston ring, head gasket, or valves.
I decided to create this source of knowledge from my own experiences, in the hopes of helping budding pilots to get through their training.
So, if you’re thinking about becoming a pilot or are in the middle of your training, I hope that this website and my knowledge comes of some benefit to you. I’d love to think that my website made your experience a little less stressful and a lot more fun!
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