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PostPosted: Mon Jul 02, 2007 9:32 pm 
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(Reference: this thread)

I've been meaning to write this up for awhile. About a day and a half after I sent my "That's not good enough, you'll either have to do better or refer me to someone who can" e-mail back to the marketeering drone, I got a voicemail from an engineer at Evans Cooling. He and I played phone tag for about nine days, but finally connected and spent about 80 minutes talking over my questions. It was a fast-paced conversation that kinda went in a bunch of directions at once -- this guy was definitely an engineer and an enthusiastic car geek -- so a transcription would be screen garbage. But I took notes.

Water pumps: Pointless to change impeller styles on pump installations that involve an unshrouded impeller, such as the G/RG and 2.2/2.5 applications. He discussed multiple trials with multiple impeller configurations on multiple unshrouded-impeller applications, and did so in enough detail that I was convinced he wasn't BSing. No benefit to modified impeller design w/unshrouded impeller.

Coolant: 440_Magnum is correct, the reports of lower temp gauge readings with Evans NPG+ waterless coolant are nonsensical (or possibly the result
of other cooling system changes done at the same time, e.g. big new radiator replacing small old one). For any given set of conditions, the temp gauge will read higher, because there's more heat in the coolant (less in the engine metal). This is consistent with the theory of vapour barrier & localised hot spots (w/water-based coolant) vs. nucleate boiling (w/waterless coolant), and is also consistent with the ping abatement that has been observed in engines running Evans Waterless.

Specific heat/heat capacity/heat transfer: my guess was correct; NPG+ has a lower heat capacity but this is more than counterbalanced by the improved heat transfer at the engine-to-coolant junction due to the elimination of localised boiling/vapour barrier. So: waterless has less heat carrying capacity but a greater percentage of that capacity is available for actual use cooling the engine; water-based coolant has greater heat carrying capacity but a lower percentage of that capacity is available for actual use cooling the engine.

The flip side of this coin is that some stock radiators may not be adequate with NPG+. The lower heat carrying capacity is not counterbalanced by any other phenomenon in the radiator as it is in the engine, because vapour barriers do not occur in the radiator.

Viscosity: At -40°, the stuff is about the consistency of a not-very-fresh frozen margarita. Still pumpable with ease, and will thin to normal liquid consistency as soon as the engine begins warming it up. At 0°F, its viscosity is almost identical to straight ordinary ethylene glycol coolant.

I am satisfied with these answers. None of them was scripted, and it was clear to me I was speaking with someone who has his hands in (and on) the actual development and testing of this stuff. I think I will probably try it.

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Last edited by SlantSixDan on Sun Dec 23, 2007 1:12 pm, edited 1 time in total.

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PostPosted: Tue Jul 03, 2007 6:15 am 
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Interesting! I may have to order some for my Dart project. It does sound like I may have to tune the engine specifically for this coolant when running EFI.

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PostPosted: Tue Jul 03, 2007 7:06 am 
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Nice info, Dan. They must have some chemically knowledgable folks there.

That would be somewhat of a feat if they can make the heat capacity higher while retaining the other favorable properties. Seems like that might require a completely different chemical system than the one they are using.

Thanks,

Lou

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PostPosted: Tue Jul 03, 2007 4:13 pm 
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Seems like the reduction of ping (due to fewer hotspots) would be worth the price of admission.

Can this product be purchased now, and if so, where?

-Mac


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PostPosted: Tue Jul 03, 2007 4:21 pm 
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http://www.evanscooling.com/main25.htm

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