|
|
Posted by maineSS [169.244.62.164] on Saturday, December 03, 2011 at 15:07:00 :
In Reply to: Question on boiling point posted by Leon in PA [72.25.32.59] on Sunday, November 27, 2011 at 16:44:49 :
Boiling coolant is a bad sign, it means you've lost control of cooling. When metal surfaces get hot enough to overcome the coolant's vapor pressure, film boiling starts and prevents coolant from contacting the hot spot. To prevent this, you need to either increase pressure, or use a higher vapor pressure coolant like straight Propylene Glycol. Water-based coolants need pressure in high-compression engines to achieve a practical radiator size.
The PW radiator works OK for low-power applications, but even a moderate V8 gets ahead of it. Pressurizing a 40-60 year-old rad is likely to blow it up, as corrosion and thermal cycling fatigue the tubes. Evans PG coolant doesn't have water, so pressurization isn't required, and doesn't corrode metals. It is pretty pricey, so best not have any leaks...