Chris White

Evans coolant - boiling point at zero PSI = 375f !!
Lots of good things about the Evans coolant, it can be a pain to switch over a used engine since all the old coolant has to be flushed out.

I have not had an oil leak on a Cometic gasket - but virtually all th egaskets I have used are on newly machined blaocks / heads. The coolant 'ear' can be a little bit of a pain - a thin film of sealant helps there.

toddk911

26 psi....love it!!!!

You running E85?

Willard Bridgham 3

Just some real data. Water has higher specific heat, lower film coefficient, lower viscosity than any glycol-based coolant including Evans. Given this data, water is a better coolant.

Chris White

True points (As always Willard knows his engineering!)...but significantly less system pressure is a benefit for ‘older’ plumbing components and the ability to avoid localized vaporization (common in 951 heads due to hot spots) as well as a reduction in cavitation issues may be more of a plus than reduction in specific heat.

I am not sure that the viscosity in an issue in the coolant system, we are not trying to get high flow rates and the mechanical pump is well up to the task. If you were converting to an electric pump I might have some concerns.

Adonay

Thats a interesting point what about the turbo waterpump thats electric..

Chris White

The turbo pump does not see any significant pressure drop.
The mechanical water pump can see quite a bit of pressure differential. For example on a small block Chevy race engine it is not uncommon to see block pressures of 50psi. I would not be surprised to see similar numbers in our engines – the water passages from the block to the head are fairly small – significant restrictions. No such restrictions for the turbo coolant pump.

theedge

In general yes, but when you include the boiling points into it.... Which reduces system pressures and avoids localized hot spots which can lead to detonation.... And Evans is a "life time coolant".

Each has its strong suits.

toddk911

So what is actually dropping the pressures in the system by using Evans? Just the fact that there is no water to steam/pressurize?

I was going to ask the water/latent heat question also but figured worst case you only drain the Evans during the summer and re use, or treat it as a once a year $40 expense for the cooling system. Again, pretty cheap insurance as the "hot spot" issue is very prominent in our cars as Chris confirms; and he is the internals GENIUS of the 951 motor.

Cory9584

Race gas, there is no e85 around here yet.

Chris White

Yep, the system pressure (as measured at the ‘radiator’ cap on the expansion tank) is caused by the expansion of the coolant – as liquids approach the point of vaporization they expand, at vaporization they expand a crap load. Water based coolants are run right near the point of vaporization, in fact they rely on the sealed nature of the system to prevent vaporization – this is why you NEVER remove a cap on a hot sealed system. The Evans coolant does not vaporize until 375f unpressurized so there is very little pressure in a system running at typical temp ranges.

Not sure why you would want to drain it on a regular basis…you can add the Evans coolant in the engine and just leave it ‘forever’!

Now you are going to make me blush…

One interesting note about the Evans coolant – if you spill some on the engine and it runs down into the wonderful areas that like to hold liquids (like the drives side balance shaft cover) it will stay there forever smelling like hot coolant! Because the vaporization temp is so high it will never evaporate off like normal water / coolant. The stuff will sit there and smell like coolant forever! The first time I used the Evans coolant I did this and kept wondering why the engine always smelled of coolant – I looked for leaks everywhere. Finally I wash down the engine with a lot of water and it diluted the Evans enough that it filly evaporated the next time the engine got hot…

The other word of warning is that this stuff is slicker than snot on wet concrete….!

theedge

You wouldnt use it as a once a year thing... It will work in all weather. Ive used it in -15-20F. Its also a lifetime coolant, it should last for over 500,000 miles. It just changed color with age and heat.

adrial

Mine leaks from the high pressure oil passage that brings oil up to the head (exhaust side, rear of engine). This is with the 2nd gasket and increasing the torque to i think 70 ft lbs (this was a year ago) with ARP Studs. Block and head were both milled ...

Thumbs down for Cometic at this point for me.