A poor choice in pump can greatly reduce the performance of any intercooler system. What people don’t know, is that there are many features of a pump that control its performance. Furthermore a pump that works well in one system, may not be good for another. ZZPerformance has tested pumps from Rule, Flojet, Centri-puppy, Jabsco, Shurflo, Central machinery, GM, JC whitney, Johnson, Attwood and others. We know what works, what doesn’t and why.
12 volt intercooler pumps can be divided into two categories: Positive displacement pumps and centrifugal pumps.
Flojet and Central machinery are the most popular, positive displacement pumps in our market. A positive displacement pump has the advantages of self-priming, good durability, and high flow in a restrictive system. The disadvantage of these pumps is their heavy weight, typically high current draw, high noise levels, and low GPM ratings. They should be used only in systems where the fittings, IC core or lines are small. Many people make the mistake of believing that the lines an intercooler ships with determine the flow capability of the system. This is rarely the case. In systems like the Thrasher, the fittings into the core approach 3/8 of an inch at some points. With the transmission coolers the intense kit uses for the front cooling, you find the same problem. In systems like these a positive displacement pump is usually your best choice. While they may be rated a little lower in flow than centrifugal pumps, the actual performance will be higher in a restricted system.
Centrifugal pumps like the Rule and GM pumps have very high flow ratings. This is an inherent advantage of this style of pump. They also draw very low current and boast extremely low weight. These pumps are ideal for any intercooler system where you have no restrictions. The downside of a centrifugal pump is that it doesn’t self prime and won’t flow well into a head. The priming problem is cured with our IC fill kit and the restriction issues can be solved by using a properly designed intercooler system. Another advantage of the Rule pump (asside from cost) is that it works with the IC pump controller. Since this controller improves the performance of any intercooler system, it’s a good idea to buy a pump that will work with it.
Current draw of a pump is important. The more current a pump draws, the more power it’s robbing off of the alternator and ultimately your engine. This current is turned into heat which is transmitted into the coolant and adds an extra load on your front mount radiator. Since the entire point of an intercooler is to get rid of heat, you can see why low current draw is ideal.
The flow of a pump is very important. Assuming you can cool the liquid down with a good front radiator; the higher the flow, the better your system will perform. We tested this using city water on our supercharger dyno. Flow ratings all the way to our max of 12 GPM produced higher temp drops after the core. The conclusion is this: In an ideal intercooler system, you want the most cooling you can fit up front paired with the highest flowing pump you can find.
We have tested the Bosch intercooler pumps used in the GM supercharged 2.0 liter and it performs well. Better than any pump we have ever tested all things considered. Free flow it topped 8GPM with 13.1 volts and pegged our 12GPM gauge at 16 volts. Even restricted by a smaller IC core, it managed almost 5 GPM at 13.5 volts!
It weighs 2.2 pounds, has 3/4″ fittings and draws ~2.7amps at 13.5 volts. Depending on voltage and load it drew 1.8 amps at low and 3.5 amps max. It works with our intercooler pump controller as well.