Introduction
Well, since I'm really new to these boards I thought I'd start off and contribute somthing to the Club Civic community, so I did a little write up for anyone who has quick questions about intercooling.
The Basics
To understand the importance of intercooler design, we first have to look at the concept of forced induction. When air is compressed in the turbocharger, it becomes hot. As it becomes hot, the air molecules spread apart which makes the intake air less dence, however being that it is forced induction, the air is still at much higher pressure levels then normal.
Intercoolers come into play when the hot air exits the turbo onto its way to the engine. If no intercooler is present, the intake air is at the mercy of the turbocharger efficency and piping design. Basicly, thats not good.
Detination is the key event to avoid. Detination occurs when the air the engine intakes is hot enough to spark the cylinder to fire without the cylinder being at the absolute top of the rotating axis, along with the exhaust valves to be open.
Intercoolers help cool this intake air, creating much cooler air, and making it safe to run much higher boosts.
How the Intercooler Works
The goal of the intercooler is to have your cake and eat it too. What do I mean? Well, the intercooler must meet two criterias:
1. It must cool the air. This is done by slowing the air down as it enters the core. The longer the air remains in the core, the more the energy from the hot air will be released into the cold air surrounding the core.
2. It must keep a pressure loss to a minimum. When air passes through the intercooler, the slowing process, inherently creates a pressure loss once the air exits the intercooler. Usually a pressure loss of 2 psi or less is designated as acceptable.
Air is cooled by passing it through the intercooler core, a series of fins that is designed to slow the air down. There are basicly two types of intercoolers, air-air, liquid-air. I will only be discussing air-air, being that it is the simplelist and most commonly used.
Intercooler Design
To judge the best size intercooler for your application, first look at the internal flow area.
To caculate the internal flow area, use (provided by Corky Bell):
Internal flow area = channel length x channel width x number of channels
Usually this will come to about 45%. Once you have this number, you must find the optimal area of the ambient face (its a big scary word for the size of the intercooler, speaking in terms of the face).
Area of charge air face = 25 in. ^2/.45
So for say, a 3 inch core, we would use this to find what we're looking for:
Width = 56 in. ^2/3 in. = 19 in.
To grab hold of a cfm number (cubic feet per mintue) of airflow for the intercooler, for lets say, 60 mph and 2 sq ft, use this formula:
Air Flow Rate = a x s s = 60 mph a = 2 sq ft
Air Flow Rate = 60 mi/hr x 2 ft^2 x 5280 ft/mi x 1/60 hr/min = 10, 560 cfm
End Cap Design
When choosing an intercooler, another important aspect to look at is end cap design, the sides, basicly, of the intercooler. You should have airflow and ease of air distribution as it enters the core. The end cap should be unrestrictive and should allow the air to spread out before it hits the cores.
Conclusion
This has been an extremely breif but hopefully helpful resource when you're looking to find some information about intercoolers and a little more about them. I strongly recommend buying and reading Corky Bell's Maximum Boost. It goes much more in-depth than what I have given and is a must-read before you even turn a bolt to start your turbo project.
T
Well, since I'm really new to these boards I thought I'd start off and contribute somthing to the Club Civic community, so I did a little write up for anyone who has quick questions about intercooling.
The Basics
To understand the importance of intercooler design, we first have to look at the concept of forced induction. When air is compressed in the turbocharger, it becomes hot. As it becomes hot, the air molecules spread apart which makes the intake air less dence, however being that it is forced induction, the air is still at much higher pressure levels then normal.
Intercoolers come into play when the hot air exits the turbo onto its way to the engine. If no intercooler is present, the intake air is at the mercy of the turbocharger efficency and piping design. Basicly, thats not good.
Detination is the key event to avoid. Detination occurs when the air the engine intakes is hot enough to spark the cylinder to fire without the cylinder being at the absolute top of the rotating axis, along with the exhaust valves to be open.
Intercoolers help cool this intake air, creating much cooler air, and making it safe to run much higher boosts.
How the Intercooler Works
The goal of the intercooler is to have your cake and eat it too. What do I mean? Well, the intercooler must meet two criterias:
1. It must cool the air. This is done by slowing the air down as it enters the core. The longer the air remains in the core, the more the energy from the hot air will be released into the cold air surrounding the core.
2. It must keep a pressure loss to a minimum. When air passes through the intercooler, the slowing process, inherently creates a pressure loss once the air exits the intercooler. Usually a pressure loss of 2 psi or less is designated as acceptable.
Air is cooled by passing it through the intercooler core, a series of fins that is designed to slow the air down. There are basicly two types of intercoolers, air-air, liquid-air. I will only be discussing air-air, being that it is the simplelist and most commonly used.
Intercooler Design
To judge the best size intercooler for your application, first look at the internal flow area.
To caculate the internal flow area, use (provided by Corky Bell):
Internal flow area = channel length x channel width x number of channels
Usually this will come to about 45%. Once you have this number, you must find the optimal area of the ambient face (its a big scary word for the size of the intercooler, speaking in terms of the face).
Area of charge air face = 25 in. ^2/.45
So for say, a 3 inch core, we would use this to find what we're looking for:
Width = 56 in. ^2/3 in. = 19 in.
To grab hold of a cfm number (cubic feet per mintue) of airflow for the intercooler, for lets say, 60 mph and 2 sq ft, use this formula:
Air Flow Rate = a x s s = 60 mph a = 2 sq ft
Air Flow Rate = 60 mi/hr x 2 ft^2 x 5280 ft/mi x 1/60 hr/min = 10, 560 cfm
End Cap Design
When choosing an intercooler, another important aspect to look at is end cap design, the sides, basicly, of the intercooler. You should have airflow and ease of air distribution as it enters the core. The end cap should be unrestrictive and should allow the air to spread out before it hits the cores.
Conclusion
This has been an extremely breif but hopefully helpful resource when you're looking to find some information about intercoolers and a little more about them. I strongly recommend buying and reading Corky Bell's Maximum Boost. It goes much more in-depth than what I have given and is a must-read before you even turn a bolt to start your turbo project.
T
