RSX Radiator: To Upgrade, or Not?
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| Mishimoto's Dual Core Aluminum Radiator for the Acura RSX |
The Question
Radiators with plastic endtanks can be found in many stock cars, such as the Acura RSX. The plastic degrades over time and turns from black to brown as it becomes more brittle with heat cycles. This can be the cause of leaks if they crack, and just the color itself sometimes encourages drivers to spring for larger racing-oriented radiators, because "why not?"
As you put miles upon miles on your RSX, you're likely to sustain some damage to the stock radiator fins. They're thin, and made of aluminum and bend easily. This can be another reason people choose to move to a "racing style" dual core radiator. If you're getting a new radiator anyway, it may as well be an upgrade, right?
Price
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| Separately Purchased Mishimoto Fans and Shroud |
Coolant Reservoir Location
It's also worth mentioning that there's no proper mounting location for the OEM coolant overflow reservoir. On my unit, I had to put a bolt in a spare hole on the radiator and zip tie the reservoir to it. It's not exactly a deal-breaker, but it's inconvernient.
Longer Heatup Time
The aluminum radiator allows the car run cooler, which can be a big advantage on the track, or driving a high strung naturally aspirated or forced induction car. It cools off much more quickly than the stock radiator due to the difference in thickness. However it may take longer to get up to temperature on a stock RSX since the larger radiator holds more coolant, especially if there's air moving through the radiator while you're moving
Cooler Heat In Cabin
Engines require being run at a certain temperature range to make sure the metal parts inside expand at a certain rate to a certain clearance and runs properly. Also, it'sresponsible for making your heater work properly. If you cool off the system too much, your heat will be cold and you'll put more wear on the engine. This can mean that if you get a larger radiator, during winter with more cold air passing through the radiator, it can lead to your heat in the cabin not getting warm enough.
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| Mishimoto 1.3 Bar Cap |
Higher System Pressure
Additionally, the radiator cap for the Mishimoto radiator is rated for 1.3 bar / 19PSI. The stock cap is rated for 1.1 bar / 16PSI. This uprated cap will put more stress on your cooling system by holding 3 pounds more of nominal pressure. I found a lot of leaks testing the system for 19PSI that weren't present under that pressure. In practice, they chose the higher pressure cap to increase the boiling point of the coolant to further prevent overheating. I would recommend installing the stock cap, but it doesn't fit the Mishimoto unit.
Inferior Drain
As a final point, the drain on the bottom of the radiator is designed less intelligently than the stock radiator drain. The stock drain bolt only has to be partially unscrewed to drain the coolant, and it controls the coolant flow so it drops out in a neat column. The Mishimoto radiator drain bolt is just that - a bolt. It has to be fully removed, so sometimes I drop it in the coolant bucket by accident. Then the flow of water is so urgent that it runs off the front subframe and goes everywhere. It makes a mess every time.
Making The Choice and Sourcing
Whatever you do, for naturally aspirated builds on the K-Series, stick with the stock single core radiator. While the Mishimoto radiator may be appropriate for track cars running higher than stock compression and turbocharged or supercharged cars, 190 - 270 crank horsepower cars like most of the ones out there do not need it. The stock radiators are cheaper, get up to temperature faster, and take less coolant. For those reasons, I suggest sticking with it for your street-given car.
If your radiator is leaking or you're in need of a new one, RockAuto has some manual transmission-specific radiators that are single-core and will keep your car running properly. Amazon and eBay mainly have Automatic Transmission models. Those are fine for autos as well as manuals, but you'll just have to cap off the additional inlet and outlet at the bottom of the radiator.
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| Manual Transmission Radiator for the Acura RSX |
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| These fittings are for auto-transmission cooling, and should be capped off on the manual RSX |
If you decide that with the power level you're running that your cooling system may need a boost, the Mishimoto radiators do offer cooling beyond the OEM radiator's abilities. There are some sacrifices you make, but that's normal for any high horsepower build. In that case, here's links to purchase what you need:
