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Top Five Overheating Cars - Tech Knowledge

And how to keep them alive

Text By , Photography by Manufacturers,

Nissan 240SX
Just like other major components in a car, the radiator cannot work on its own. It has supporting parts that help it perform its function more efficiently and among them is the factory fan shroud. Believe it or not, Nissan didn't put in the fan shroud just to take up room or “ugly” your engine bays appearance. The 240SX shroud facilitates the function of the radiator fan as it helps your cooling system to perform at its peak. Many 240SX owners make the mistake of removing their cars fan shroud thinking it doesn’t have an important role in the cooling system or the engine bay would look “cleaner” without it. Removing both the shroud and replacing the stock-pulley driven fan with a pair of electric fan "upgrades" has been known to actually flow much less than the stock fan as it increases the probability of overheating. A properly functioning shroud like the factory piece should be designed to extend all the way past the fan or else it won't pull sufficient air through the radiator. Improper shrouding will cause the fan to pull air from the area of least resistance, which means most of the work the fan does will simply be swirling air around inside the engine compartment rather than drawing cool air through the radiator. Unless your vehicles cooling system is modified, we recommend keeping the factory plastic shroud to prevent overheating, no matter how unsightly in appearance it may be.

Radiator Shootout: OEM VS. Aftermarket
Factory radiators were designed to perform well in daily driven conditions, but have a tendency to fail under strenuous heat cycling and endurance situations. To show the advantages of upgrading to an aftermarket radiator, we conducted a series of temperature tests with an EVO IX using its factory radiator versus a Koyo aluminum radiator to see if upgrading the radiator is a worthwhile investment for most owners. We headed down to HB Speed in Fountain Valley, CA, to make use of their Dynomite data acquisitions dynamometer to datalog coolant temperatures during test runs with each variant installed. Before testing, we set up four high-powered fans and retrofitted two HKS temperature adapters with K-type thermocouple sensors on upper and lower radiator hoses to monitor the temperature of coolant flowing into and out of the radiator. A thermocouple delivers a quicker, more accurate response to rapid temperature changes in comparison to common in-dash water temperature meters.

The EVO was given four hours between each dyno run to completely cool off and was tested using only water, to maintain consistency. HB Speed's Jon Drenas assisted in data logging temperatures on the dyno, and ambient air temperature, cylinder head temperature, and idle temperatures were logged before and after each session.

Pitting the OEM radiator against the Koyo R-Core aluminum unit, our first test commenced with a full-throttle dyno pull to redline. With an ambient air temp of 95-degrees Fahrenheit, the data graph showed the 53mm-thick Koyo aluminum unit displaying a clear advantage over the stocker. Both radiators began testing at 175 degree Fahrenheit, and comparative data between the two radiators showed the aluminum Koyo radiator maintaining coolant temperatures three to four degrees cooler than the OEM unit throughout testing.

The final comparison was an endurance test in which the EVO was spun on the dyno at a constant 4,000 rpm at five pounds of boost for an elapsed time of 60 seconds to simulate a gradient uphill climb. With our Koyo radiator in place, coolant data collected from the upper radiator hose to the cylinder head ran about seven degrees cooler, and coolant entering the engine was four to five degrees cooler than stock.

HOTBOX
HB Speed, Inc.
10595 Lawson River Ave.
Fountain Valley
CA  92708
714-378-3966
www.hbspeed.com
HKS USA
13401 S. Main Street
Los Angeles
CA  90061
310-491-3300
www.hksusa.com
GReddy Performance Products
9 Vanderbilt
Irvine
CA  92618
949-588-8300
www.greddy.com
Koyo Cooling Systems
15 Doppler
Irvine
CA  92618
949-727-7054
http://www.koyorad.com
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