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Old 07-13-2008, 06:16 PM   #2
vex
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Default Different Radiator Types

**Note: This portion is still under going modification**
Here's a brief explination of the different radiator types:
Single Pass:

This picture isn't 100% accurate. It does give a general idea of how the temperature is going to look across the radiator though. Since hotter fluid is less dense than colder fluid the heat is spread more evenly across the top (since stock is down flow instead of cross). This results in the hotter portion of the coolant being retained above the cooler portion before it is all returned to the engine via the lower outlet. This however is not all that effecient from a cooling standpoint as the radiator begins to heatsoak. The hotter coolant will eventually raise the average temperature throughout the radiator causing the radiator to return hotter and hotter coolant. However--this is completely dependent on your heat generating modifications (turbo, etc).
Double Pass:
The double pass is slightly more effecient at cooling. This is a cross flow type where the hot incoming coolant is cooled as it travels accross the radiator. It is then further cooled when it travels accross the radiator again to the outlet. This kind of setup is helpful in that the coolant is given far more time to cool as it travels accross the radiator. Unfortunatly this also reduces turbulence with the coolant and therefore reduces heat transfer capacity. If turbulence can be added the coolant will transfer more heat more effectively... but that's a discussion for another section.
Triple Pass:
*Picture Forth Coming*
A triple pass or an N-Pass is similar to the 2 pass radiator in that it allows the coolant more time to cool. Again, the coolant is passed from one section of the radiator to another, and at each time it is exposed to more (cooler, and cooler) surface temperatures before being returned to the engine block.
4-Pass:
The biggest pass I've ever heard about. Usually reserved for large displacement and heavy horsepower applications a 4-pass radiator starts to see a diminishing return in cooling ability. These radiators are rare to come by in off the shelf type, and usually are reserved for custom manufacture (Read that as expensive). The idea is taking a 2-pass and basically adding another 2-pass below it. You get twice the cooling time as a regular 2-pass, but you have to make a compromise. That is either in weight, or in the amount of coolant that is being pulled into the engine. If the volume of coolant available to the engine remains the same (effectively doubling surface area), you make up for the cooling performance in weight. If teh volume of coolant is allowed to decrease to maintain specific surface area of the radiator,then the effective time for the coolant to cool is reduced as it pushes more coolant to the engine sooner. The best adivce with regard to these radiators would be: know your goals and understand that a 4-pass may be overkill for a majority of the cars out there.

Number Of Rows (Cores)


Single Row
The number of rows is a balancing act between the cooling ability of the radiator and the weight to which you wish to hold your car. Usually single row radiators are used strictly in racing in which air flow is always occuring over the radiator providing enough CFM to allow the heat to dissappate quickly with little repercussions on the engine. On the road, might not be the best option as we deal with stop and go traffic and the heat may not dissappate quickly enough to maintain a healthy engine.

Double Row
Double rows are fairly common, especially on stock radiators. These handle a fair amount of heat and are able to hold more coolant in a double row compared to a single row. This however has drawback that as the radiator reaches temperature, the radiation from the front row will pass on to the rear. But this radiation is usually neglible at speed.

Triple Row
Triple rows improve upon the cooling ability of the radiator another step. Similar to the Double Row it maintains the same pros and cons. The added benefit of the multi-row radiators is that they allow for additional coolant to be available to the engine. This decreases the chances of over heating yet raises the average temperature gradient over the radiators surface area.
Attached Images
File Type: gif TwoPass.gif (11.4 KB, 190 views)
File Type: jpg SinglePass.jpg (9.7 KB, 186 views)

Last edited by vex; 07-16-2008 at 09:06 AM..
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