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Rusty
"boiling removes heat" I have a hard time understanding that quote. When racers started using PG they were able to run 15:1 compression on "pump" fuel
due to the fact that boiling coolant created hot spots in the combustion chambers & in turn causes pre-ignition (they also reversed the coolant flow direction to bring the cooled coolant to the hottest part of the system, & all this with no pressure cap. The one disadvantage I see in the 13b is that it can't handle the potential higher boiling point of PG. I have a 3.0 L V6 that I reversed the cooling system on to use in the Christavia (that was before I got hooked on the 13B)
Georges B.
-------Original Message-------
Date: 06/27/05 12:13:55
Subject: [FlyRotary] Re: NPG + use in aircraft??
Has anyone used the NPG+ coolant in an aircraft? What are the pros and cons?
NPG+ is standard issue in the 912S, and perhaps the 912 also. If I'm not mistaken, Dave Leonard is running NPG+ now, and I'm running NPG-R.
The Evan's marketing folks can give you way more pros than I can think of, but I do think it's working very well. The primary benefit is the fact that it's native boiling point is in the 375F range, so you don't have to worry about a cascade effect of boil over if you unexpectedly run hot, lose pressure, etc. It's also not supposed to be subject to localized boiling around hot spots in the engine. Evan's claims this as a big benefit, but others, such as Tracy, think this boiling helps remove heat. It's a bit more environmentally friendly too, so it won't hurt the rats in John's hanger.
The high boiling temp means that you don't need to run a pressurized system, which is my favorite part. There's less stress on the system, and any leak that occurs, will be much slower (initially) than if there was pressure. I added an air separator tank, with a level sensor inside, so if I get a leak, I'll know about it before it gets to the level of the top of the engine. That was the best detection method I could think of.
The down side is the cost, and the fact that it doesn't transfer heat as effectively as traditional EG/water mix. Your temps will almost certainly go up some, but at least you won't boil over.
If the oil temp is below 180 F but the coolant is above 220F, is this detrimental to the 13B??
Define "above" :-) I don't think there's anything harmful about 220F, or a bit over that for coolant, since cars do it all the time. I believe the power will be reduced a bit at those temps though, and perhaps there will be more wear on the engine. I've heard that, but can't say if it's significant, or even true.
Cheers,
Rusty
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