How does the series of LEDs function as a temp display?
It uses the row of 7 LEDs to indicate coolant temperature, in 5c increments. Once it exceeds target temperature by some amount, it'll flash the lights in some pattern. It also uses the display to indicate status, like fan on/off, and temperature sensor or pump faults. It can also be configured to show pump speed instead.
One other question, what guided your choice of pump model? Since the 200 series is used for 3L engines, is the assumption that it can more than adequately supply coolant flow for any displacement below 3L?
So. This part wasn't particularly scientific on my part, for a number of reasons.
First, I was dead set on a Pierburg pump after learning about the tinyCWA. My inner BMW fanboy is likely a part of that, but there are also good reasons.
The integrated pump controller on the CWA lineup is fantastic, and since it uses closed loop speed control (senses impeller speed and adjusts motor power to maintain speed target), it can run extremely slow (18rpm), allowing it to have a huge operating range unlike normal pumps that can only run in a fairly tight range (like how the EWP115's controller goes into pulse mode if less than 60% speed is needed, likely because the pump motor may stall without warning at a lower duty cycle). So I wanted to stay with a CWA.
The CWA200 is the smallest CWA designed for engine cooling, designed originally for the engine in my 330i. The smaller options are all much, much smaller and are used for things like air to water intercooler pumps, so those are out of the question. The CWA200 is also much higher capacity than the EWP115 which I am pretty sure is plenty for a SOHC thanks to
@Ulix
The 200 keeps my 260HP 3.0L I6 in my 06' 330i cool under constant 5-7000RPM flat out track days on low speed courses, maintaining a safe temperature across the engine and the "Performance Mode" temperature target of 76c without a hiccup. Even though the X has more coolant flow restriction, it is surely not enough to make it such that it can't keep the temps across a 75hp eggbeater within reason. (yes I just called Lampredis finest an eggbeater, blame the 80s smog standards)
For reference, the CWA200 flows the same amount of water at 6.5psi differential pressure as the EWP115 does at 1.25psi diff. The 400 flows the same amount at 13psi.
So, the CWA200 is likely overkill in itself, and the CWA400 most definitely is, but there's a catch: the CWA400 weighs almost the same, and has nearly identical physical dimensions to the 200, all while being worlds more powerful. The only downside is that if it is extremely overkill and runs very slow all the time, it'll be operating less efficiently than a smaller pump running quicker. (efficiency generally trends upwards and then begins to fall as you near maximum speed)
In your case, where I imagine the K24 has a much beefier alternator than the X1/9s original one, there may not be much of a downside to the larger pump considering the wide speed control range. You can electronically cap its maximum speed via the controller, which is something you may need to do in that case for the after run function (runs max pump speed for 2min). The 400 pulls nearly 40 amps flat out vs the 16a of the 200. It is also more expensive.
EDIT - whilst researching the block off plate options for the K24, I found some posts discussing the use of electric pumps - one person had this to say regarding the overall efficiency . Doesn't seem to make so much sense (in terms of his opinion of the pump and potential damage), but what about the increase load on the electrical system, I can't recall now if you factored that - I assume you have.
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So the whole head cracking, gasket ruining, knock causing thing is basically what I blabbered about in the beginning: the difference in engine inlet and outlet temp, which is governed by heat load divided by flow rate. That would be an extreme example, but that metric is part of the reason I decided to upgrade the water pump instead of the radiator in the first place. I find it hard to believe that a CWA200 would struggle to maintain an acceptable temperature across a K24 with 240HP, which is 20 less than my 330i with its very overbuilt cooling system, but I also do not want to advise you to do something that could ruin what your time and money has gone into.
The point about efficiency I agree with less. People underestimate just how terrible mechanical water pumps efficiency gets at very high RPM. Even with poor alternator efficiency considered, I would still be comfortable saying the pump efficiency overall would be double digits % better, especially up top when you want it most.
Keep in mind that heat load is closely related to instantaneous horsepower output, not RPM, number of cylinders, or displacement.
another poster whose opinions I would trust had this to say (ignoring the issues with the K Tuned hardware) - he is using the 400 series with the 2L Honda drivetrain. Would it make more sense for me to be considering that over the 200 series?
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So, I inadvertently covered this above, but while it is most likely fine to use a 200, the downsides of going with the 400 aren't all that substantial apart from potential pump efficiency losses which would likely be tiny compared to the losses of a mechanical pump. Again, I seriously doubt you need the 400 at 240hp, but I am hesitant to speak confidently when I don't know the answer for sure. If you track the car regularly, it may be worth it to just take the plunge.
Also, your pump speed should be dictated by what is necessary to keep the temperature across the engine reasonable. When you start using a monstrous pump to make up for an undersized radiator, you end up wasting power and efficiency... diminishing returns, essentially.
Not sure where the 175LPM minimum on a 2.0L engine is coming from. That's a **** ton. A metric **** ton. As the requirement is dictated by power and not displacement, I wouldn't be too surprised to hear that "2.0 NA" in question is making a hell of a lot more than 240hp, but I could be wrong.
