Tailored Fit – Performance Aluminum Radiator R&D, Part 3 – Production Sample and Test Results

And we’re back. We couldn’t just mention reality makeover shows without building the tension somehow. It’s the unforgettable two-part season finale for the MK7’s radiator overhaul, and since I’m sure you’re already brimming with anticipation, let’s dive right in.

Previously on the Mishimoto Engineering Blog, we left you with the first look at our design in its prototype form, along with some questions about the flow pattern. How many passes will the coolant make through our new design? Hang around to find out. But first, our production sample is in the house, and we’re eager to show it off.

Here it is in all its shiny, all-aluminum glory. When we say all-aluminum, we mean it. This radiator was redesigned from the ground up for maximum durability. We swapped all the plastic from the stock design for aluminum from the core to the end tanks, mounting points, and the inlet and outlet. In fact, our inlet and outlet are CNC-machined for a perfect fit to the factory Volkswagen quick-disconnect radiator hoses. To improve the radiator’s lifespan, we also incorporated strutted tubes into the core. These supports formed within the coolant tubes help maintain the core’s rigidity. In other words, as the chassis flexes when you’re nailing that apex, the struts in the coolant tubes prevent the radiator core from twisting with the car. Less flex means less chance of blockages from crimped tubes or leaks from a cracked weld.

Durability isn’t the only objective with our new radiator design; helping the MK7 keep its cool is also on the list. To achieve better heat management, we expanding the core by 15mm for a total thickness of 42mm and a 56% increase in core volume. The greater volume and increased fluid capacity improve thermal management and keep coolant temperatures more consistent. Our core features a 4.5mm fin pitch, coupled with our louvered fins that promote heat dissipation. Overall we were able to increase the external fin surface area by 76%, which we hope to prove useful in our testing.

On paper, these improvements make for a much better performing radiator, but will they prove to be useful when equipped on the MK7? To find out, we called on the heaviest hitting MK7 variant there is, the Golf R. We chose one of the hottest hatchbacks in the US to put the new design under the heaviest stresses that the cooling system can see from the factory. We strapped the R to our Dynapacks and performed our continuous load test. This test consists of calibrating the Dynapacks so that we can hold vehicle at 3200RPM while at wide-open-throttle, or WOT. This simulates (and often exceeds) the harshest driving conditions that the MK7 Golf will ever see. We performed the same test for all three of the radiators.

Wait, three radiators, you say? Correct. Before starting our testing, we were still questioning the coolant flow pattern through the core and felt it best to test each version before making a final decision.

To make sure that we didn’t slow down production, we opted for fabricating our triple pass radiator. Our lead fabricator, Mike, evenly spaces the end tank dividers and tacks them in place to create the triple-pass flow.

We found no discernable difference in performance between the single pass and triple pass designs in a head-to-head comparison. In some applications, forcing the coolant through the core multiple times allows for greater heat dissipation. However, a few factors can affect a multiple-pass core’s performance, including pump speed, pressure drop, and airspeed. For some applications, keeping the coolant in the radiator longer can prove detrimental, which is what we found in the MK7’s case. We found that a triple-pass core layout yields the same performance as a single-pass design.

When compared to the stock unit, our radiator produced a significant increase in performance. With our single-pass radiator installed, we noted a 5°F drop in global coolant temperatures during testing. Five degrees might not sound like much, but in the automotive realm, every degree counts, especially when you’re hitting the track. A reduction in global coolant temps means we’re reducing the coolant temperature throughout the entire cooling system, which also aids in engine oil temperature management.

Volkswagen launched the MQB with a one-size-fits-most mentality. However, if you’ve made it here, it’s safe to assume that your MK7 MQB based Golf variant requires more of a tailored fit. Something to help it stand out against the crowd. Something to keep one of the hottest hatchbacks of all time from losing its cool. An extra 5°F drop in global coolant temperatures thanks to a sturdy new radiator should do the trick. Make sure you get yours today:

Performance Aluminum Radiator, fits Volkswagen MK7 Golf TSI/GTI/R, 2015+

Thanks for Reading!

-Nick

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