Adding performance upgrades to your engine brings multiple benefits: they look good, sound great, and give you that extra horsepower you crave. You may have seen our recent article highlighting some straightforward DIY engine mods that you can do in your own garage and won't break the bank.
Remember, though, that every change that's made for the better has the potential to introduce some unwanted side effects. All engines produce heat, and that heat must be carried away from the engine and dissipated to the atmosphere. That is the job of the cooling system. As we add power to the engine, we also increase the amount of heat created, and the side effect in this case is the possibility that the factory cooling system is not up to the task of shedding all of that additional heat.
All is not lost, however, as there are cooling system upgrades which can save the day. To add even better news, many of these performance mods are reasonably priced AND well within the means of the average DIYer to install in a home garage.
Not every vehicle with increased engine performance is going to need every one of these coolant enhancements. You will need to do some sleuthing to help decide which one, or which combination of these, will do the trick for you. Factors to take into consideration include the condition of the OE part; the potential fitment of the new cooling components; the degree to which the new part will reduce temperatures, and your available budget. If you are planning to DIY it, also consider your own degree of comfort with installing the parts.
But as we said, we think that all of our suggestions below are within the capabilities of the weekend garage warrior. If you've changed your own oil, replaced brake pads and rotors, and have done some engine tuning, you should be quite comfortable swapping out some coolant hoses or installing auxiliary electric fans. Many of the items in our list of suggestions below are part of routine maintenance anyway. So if the part in question is due to be replaced, it's the perfect time to go with an upgraded component. One last comment before we dive in: keep in mind that for many of these, the cooling system must be partially or fully drained (with a COLD engine only!) and you should therefore also ask yourself if it's time for some fresh antifreeze.
Radiator caps
A properly-functioning radiator cap keeps the antifreeze in the cooling system under pressure. As the liquid's pressure is raised, its boiling point increases. This is a good thing, and allows a factory system to operate at temperatures up to around 250 degrees F without overheating (ordinary water at atmospheric pressure boils at 212 degrees F).
Modified engines, especially those that are driven hard, will see coolant temperatures AND pressures increase. Most standard radiator caps will release pressure at a certain point as a safety measure, sending it either to an overflow tank or onto the ground. However, if a radiator cap is installed with a higher pressure rating, the boiling point is raised, spillover is avoided, and the engine won't overheat. Installation is as simple as removing your old radiator cap (with a COLD engine only!) and installing the new one, usually with a quarter-turn of the cap.
These radiator caps from Skunk2, designed to fit many Honda and Acura models, raise the coolant pressure from 1.1 bar (16 PSI) to 1.3 bar (19 PSI). The Blox Racing aluminum radiator cap will fit a number of different Asian imports, and has a pressure rating of 1.3 bar (19 PSI), well above the factory rating for these cars. The CSF OE-style Engine Coolant Radiator Pressure Mini Cap fits a variety of Asian cars and trucks going back to the early '80s, and is available in ratings of 13 lbs., 16 lbs., and 20 lbs.
For something a little different, be sure to check out these "Thermocap" radiator caps from Mr. Gasket. The caps include a temperature gauge built right into the top, and it includes scales in both Fahrenheit (F) and Centigrade (C).
Thermostats
Automotive thermostats, as simple in concept as they are, have been misunderstood for years. A number of well-intentioned mechanics and car owners, thinking that the cooling system doesn't need a thermostat, have removed the devices and chucked them, only to wonder why the engine still overheats (or why they no longer can get heat in the passenger compartment).
A thermostat plays a critical and necessary role: it blocks coolant flow to the radiator when the engine is cold, thereby helping the engine reach operating temperature more quickly. And once it does open, it regulates flow to the radiator to help prevent overheating. (Removing a thermostat can prevent an engine from ever reaching correct temperature, which is actually bad for the motor.)
If the engine has been modified for more power, the driver will likely put greater demand on it, running it at higher RPMs. Those faster engine speeds may try to push more coolant past the thermostat. If, in an attempt to increase coolant flow, the engine has been fitted with a high-flow water pump, a standard thermostat may have difficulty keeping up. In either case, a performance thermostat can allow greater coolant flow yet still control temperatures.
These Mishimoto thermostats are "low temperature", designed to open at lower temperatures and help high-performance engines keep their cool. The high-flow series of thermostats from the folks at MotoRad are just what their name describes: high-flow units which increase the amount of coolant that can circulate through the radiator. A standard thermostat flows about 37 gallons of coolant per minute, but the MotoRad high-flow units allow up to 56 gallons per minute, a significant increase. The LN Engineering low temperature thermostat, specially designed for Porsches, is designed to open at 20-25 degrees F lower than factory, ensuring that the thermostat is fully open when the coolant temperature reaches 180-185 degrees F. This more efficient coolant temperature control can help improve horsepower as well as fuel economy.
Coolant hoses
You may be surprised to read that there are 'performance' versions of coolant hoses. After all, a coolant hose's job is easy: move the coolant from one component to another, such as from the engine to the radiator and back again.
But as we've discussed above, engine mods, whether they are hotter cams, oversize pistons, or supercharging, raise the heat. That means that every single element of the cooling system must tolerate that extra heat, and that goes for the hoses too. Adding to the concern is the 'wear and tear' element: all rubber parts eventually deteriorate and require replacement, which is the case for all coolant hoses. If you've modded your motor and the hoses are due for replacement anyway, it's a perfect time to investigate installation of performance coolant hoses.
Hoses made of silicone better stand up to high temperature and pressure. They also are better at resisting deterioration from oil or fuel exposure. And let's not forget the bling factor, as many of our silicone hoses can be purchased in your choice of color. Hose kits from Mishimoto are available to fit a wide variety of cars, with hoses in black, red, blue, or even camouflage.
Radiator and heater hose kits from HPS include all the underhood hoses you need. Stainless steel clamps are also included. The silicone is reinforced with polyester for additional strength, and the kits can be had in your choice of color. Radiator hose kits from the Cold Case brand fit late-model domestic products, and offer some color choices not found at other manufacturers.
Auxiliary cooling fans
With radiator caps, thermostats, and hoses, we've covered standard maintenance components for which there are performance upgrades. Moving to our next product, auxiliary cooling fans, brings our focus to devices which are supplemental to your existing cooling system.
All vehicles have cooling fans. In the old days, the fan typically mounted on the water pump shaft, and was driven by a 'fan belt' off the crankshaft pulley. In recent decades, fans have been electric, thermostatically controlled, and mounted directly to the radiator which minimizes parasitic losses by eliminating the drive belt.
If you find that your cooling system requires a way for the radiator to shed its heat more quickly, the installation of additional (auxiliary) fans can be the answer. These fans are usually mounted directly against the radiator itself, either in front (so-called "pusher" fans) or behind (so-called "puller" fans). The choice between the two is usually made based on available space for the fan. In some cases, puller fans are more efficient, as pusher fans sometimes block the flow of additional air.
Product attributes to take into consideration when making an auxiliary fan selection include but are not limited to overall diameter, fan thickness, fan blade direction of travel, CFM (cubic feet per minute) air rating, inclusion of a shroud, and electrical installation (thermostatically controlled or manually switched).
This universal electric cooling fan from Hayden has a number of advantages. Its 14" diameter makes it small enough to fit in a variety of automobiles; it is reversible, so it can be installed either as a pusher fan or a puller fan; and mounting hardware is included for a simple and straightforward installation.
The Flex-a-Lite Black Magic Electric fan can be used to replace an existing electric fan when greater cooling capacity is needed. A built-in radiator shroud combined with a full contact rubber seal help ensure that the maximum amount of air is brought through the radiator.
The Jetstreme dual fan from Maradyne is a compact design which still manages to feature double fans for extra cooling power. The Jetstreme is reversible so it can be installed either in front of or behind your radiator, depending on where is best fits.
Water pumps
Our final performance cooling upgrade product, water pumps, brings us back to something we consider a wear-and-tear item. While modern water pumps may last 100,000 miles or more, they do not last forever. What's more, a water pump failure while driving will likely leave you stranded, and could cause engine damage. For those reasons, a number of auto enthusiasts replace water pumps on a time-or-mileage basis, rather than waiting for a catastrophic failure. Whichever route you're inclined to take, it's an excellent opportunity to consider upgrading to a better pump.
But what makes a water pump a "performance" pump? Water pumps which are improvements over factory pumps will have larger and stronger impellers to move coolant more quickly; stronger bearings to deal with high pump loads; and aluminum construction to maintain strength while saving weight. All belt-driven pumps create parasitic losses which rob horsepower; the ultimate performance water pump swaps out the mechanical pump for an electric model, the RPMs of which can now be computer-controlled.
These Supercool water pumps from Tuff Stuff Performance use aluminum to save weight and improve heat dissipation. The manufacturer claims a drop in coolant temperature of 20 degrees F, and last but not least, the pumps are available in several finishes, including polished, black, red, or blue.
The Weiand Action-Plus series of water pumps are designed to be bolt-in replacements of your factory pump. Their steel anti-cavitation impellers provide maximum coolant flow for any street application, and the pumps' bearings and seals (which are major wear areas) have twice the load capacity of a standard pump. For the ultimate water pump upgrade, check out the Stewart Components electric water pump. This unit completely replaces your engine's mechanical pump and is remotely mounted, giving you lots of mounting options. The pump has a 10,000 hour lifespan, and can move up to 55 gallons per minute (GPM) at 12 volts. The pump draws only 8 amps, and weighs only 5 pounds.
We hope this overview gives you the needed insight to making simple and affordable upgrades to your ride's cooling system. Note that our Performance Engine Cooling Category also includes radiators, coolant tanks, and thermostat housings, as well as links to oil coolers for engines, transmissions, and power steering units. Be sure to check those out!