| You can always reduce operating temperatures by increasing the percentage of water in any water/glycol mixture. Plain distilled water has twice the heat transfer (cooling) capability compared to glycol-based coolant mixes, but shouldn't be used alone as a coolant since it lacks corrosion inhibitors and water pump seal lubricating properties.
WaterWetter is often used because it reduces the surface tension of water (the property that makes it bead-up) thereby improving further water's superior heat transfer ability while also adding the necessary lubricants and corrosion inhibitors. It can also be added to a water/glycol mix.
Most important, WaterWetter will reduce coolant temperatures across-the-board under all operating conditions. It's big advantage is use in modified engines having increased heat loads, and under high-load, high-rpm track conditions.
It's important to note, however, that for normal street riding in cooler and moderate weather it also can prevent the coolant from reaching optimum temperatures. Across-the-board temperature reductions of 15°F under all riding conditions are commonly experienced using WaterWetter.
I had to removed the water plus Water Wetter mixture from my 916's cooling system. On a 75°F day my coolant temperatures would only reach 140 - 170°F. I tried covering a section of radiator, but temperatures still stayed below 175°F. At these temperatures, the ECU is still adding extra fuel for warm-up conditions (below 175°F) by adding more fuel. The tailpipes were black and gas mileage was down.
An engine should be at its design operating temperature (usually mid-gauge) to make good power. Operate at too low a temperature and the engine is less efficient and makes less power. Higher temperatures are more thermodynamically efficient, but run at too high a temperature and you exceed the thermal expansion design basis of critical components and raise fuel octane requirements. Modern fuel injected motorcycles use engine management computers incorporating a coolant temperature sensor to retard the engine ignition timing to compensate for any increase in octane requirement when operating temperatures increase.
Most stock-engined sportbikes are designed to produce their best power when coolant temperatures are close to 200°F.
[Edited on 12-31-2004 by Shazaam!]  |