Air to Water Intercooler Pump Sizing

Hi,

I am working with a 3SGTE MR2 with an Air to Water intercooler setup. In short, we have reached the flow limit of the exisiting air to water core as it is rated for 500 hp and the car is producing 400-500 hp. Intake temps are starting at 90*F to almost 135*F by the end of the run. Needless to say to it is time for a revamp of the intercooling setup.

The new core selection I have no issues with, rather it is the water pump selection that I would like some input towards. Is there a way to determine the required flow rate for any given setup? The current pump fitted to the car is a Rule 500 gph pump with -12AN lines all around. Being that is an MR2 the radiator for the air to water system is mounted in the front of the car and the intercooler is mounted in the trunk. In my mind a pump that is too small will not be as effective and a pump that is too large will create create turbulence and flow restrictions within the system. Any input is appreciated.

Thank you!

Sadly I don't have a nice simple formula for pump sizing. I've had little to do with A2W intercooler setups other than my own drag car which we ran a 1000 gph bilge pump which worked well but I can't say was 'ideal'. One consideration with bilge pumps is that while they are high volume flow, they don't like working against pressure so it's important to run oversize lines, or step up to a higher flow than you really need. The danger of a flow rate that's too high is that you risk circulating the water too fast where it doesn't have time to pull heat from the core. Realistically the most viable option would be to test and measure results at a couple of different flow rates. This will also take into account your entire installation and any flow restrictions that exist too.

Seems to be a few threads with similar questions on pumps, like this. I thing one is a double post of this in a different sub-forum?

Andre is dead on with the comment about bilge pumps, while it wasn't that easy to find useful spec's on it, there was this "Max. recommended discharge head 2m." To put that in perspective, it corresponds to a pressure head of ~ 20kPa, or 2.8 psi. Remember, that flow rate they cite will normally be at 0m pressure head and full battery voltage.

There are some ways of estimating the flow rate, but without actually testing every part it's difficult.

Easiest may be to disconnect the radiator outlet and run a hose from it to a known volume container, and run a hose from a reservoir (you can top it up with a garden hose if needed) placed above the radiator to the hose that was removed. Also use a volt-meter to monitor the voltage drop across the pump. If you can, place pressure monitoring gauges before and after the pump.

When the pump is turned on, the pump'll draw from the reservoir run it through the charge cooler and return it through the radiator to the container. From the container volume and time taken you can approximate the installed flow rate. By monitoring the voltage across the pump you can estimate how well it's working and whether you need to address the wiring circuitry for it.

Most manufacturers will have charts showing nominal flow at different pressure heads (the difference between inlet and outlet) and voltages - some will include current draw, too, as with many motors V and A are not proportional. With the data from above, you can figure out if you actually need a new pump, what you need to look for in the pump, and possibly most important, whether your wiring is allowing the pump to operate close to optimum - it doesn't take much of a voltage drop to drastically affect the flow of the pump.

Or, as I said in the other thread, get a bigger pump than you expect to need, and use a controller to optimise flow.

Oh, forgot, it's IMPORTANT that the pump be placed before the higher resistance parts of the plumbing, best place may be close to the radiator outlet, and low down so it is immersed while filling, as very few are self priming and will burn out without the water cooling them.

It isn't perfect, but gives you something to work from. Your current radior supplier, and the replacement, should have flow Vs pressure

Thank you both for the input, this is very informative and helpful. Controlling the pump really seems like a very good option, and performing the system tests will absolutely help with designing the new setup. I will update this thread with the results after configuring the new setup.

Thank You!