Propylene glycol as antifreeze 3

[Slim3]

Has any one run tests on head temperature vs coolant temp on plain water vs straight Propylene Glycol coolant?

Someone said they noted higher coolant temp when using PG vs water.

Due to the steam pockets that form in areas of the combustion chamber cooling system using water and PG will continuously wet the metal and not cause these pockets.

If a coolant were receiving more of the combustion chamber heat, would it not show higher temp at the coolant temp sensor?

I would think that it would be necessary to test head temp vs coolant temp using both water and PG to know what was happening.

 

[patprimmer]

Propylene glycol has a substantially lower specific heat than water so a similar quantity of energy transfer via heat transfer would result in a higher temperature rise, however the transfer would be less as the delta T is reduced. How much this offsets the extra area if stem pockets are forming is a point to consider. It may be quite variable depending on conditions and individual castings.

Regards
Pat
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[IRstuff]

The bottom line is that PG has SUBSTANTIALLY poorer cooling capacity than water, to the extent that whatever benefits that a higher boiling temperature might have is negated.

And, it's not clear that boiling is that bad, per se. Phase change sucks up huge amounts of energy, to the extent that it might completely make up for the loss of coolant coverage on the HT surfaces.

The most volume efficient heat transfers are often phase change materials (PCMs). Now, typical installations of PCMs are limited usage, since the material volume is limited. In a recirculating system, PC might be OK in some range above boiling point. Just consider boiling in a pot. The vapor bubbles are removed by their own buoyancy and convection currents in the water, and the pot bottom is never liquid free for very long.

TTFN
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[Slim3]

I was looking for a coolant that I could trust, mainly for the high boiling point so I can run an atmospheric pressure system as my automotive background taught me that most of the cooling system problems and failures on all automobiles were a direct result of high pressure in the system, not the equipment itself.

I know the steam pockets exist in the combustion chamber area of the cooling systems and the use of a pressure system tries to suppress these, so when I read that some stock car builders found that the PG kept the metal wet in those areas and thus required little to no pressure in the system. Thus eliminating hot spots.

I have built an experimental cooling system on my show car and from what all of you say, I really need to test both plain water and PG to see what works rather then accept that PG is the answer. I have ruled out the poisonous Ethylene Glycol antifreeze.

I have thermo couplers to measure actual head temp so I will be able to see what the difference is between the coolant and the cylinder head itself using each as a coolant.

This is going to be used only as a show car so it will not be exposed to freezing weather.

Thanks group.

 

[IRstuff]

Even at 50/50, PG/water BP is only 10° higher than pure water. Only if you run pureor nearly pure PG do you really get a drastic increase in BP, but you'll increase the viscosity, and therefore make the coolant pump run harder.

Pure PG's thermal conductivity and specific heat are substantially poorer (30%, 70%) than water's. You only gain 70% increase in temperature, but you'd need something like a factor of 3x deltaT or 3x fluid velocity and radiator area to get the same amount of heat out. A higher fluid velocity would make the pump work harder.


TTFN
faq731-376

 

[evelrod]

Bottom line, Slim3 ? (Don't take me wrong because you sound like a kindred spirit)

You ask if you can use 100% PG in an automotive cooling system and my answer is a qualified 'yes'.
Be prepared for astronomical temps in any marginal system. 300f is not at all uncommon and if the rest of your engine can endure and the oil temp is maintained at a much lower temp, it works. How do I know? I tried it on a Model A Ford. Was it worth the effort? NO, it was not, aside the 'learning experience'. I did not damage anything obvious but the expense and monitoring effort was a waste of time. A new, modern radiator core was much cheaper and more deficient in the long term.

Of course if you are 'pushing an agenda' then, have at 'er, sir.

Rod

 

[Slim3]

The engine is a Olds 215 CI V-8 and I converted it's cooling system because this design engine had a history of heating problems. I blocked off the large transfer ports at the rear of the block to head and drilled out all of the so called "Steam Holes" larger in the head and block and added a few more. Then I blocked off the inlet ports on the block and added three inlets at the core plugs on each side of the engine and added four new inlet ports near the exhaust ports directly into the head cooling jackets. This gave me 14 inlet ports for coolant and I used all four outlet ports on the head to a coolant manifold that I installed a thermostat housing.

I mounted a remote water pump and manifold circling the engine to supply coolant to all 14 ports. Yes, part of the reason I want a atmospheric system is due to my complicated external cooling supply system. (limited access to all the external connections) This V-8 is stuffed into an MG.

No coolant travels more than 8 to 10 inches through the engine and all cylinders and all combustion chambers receive the same temp coolant from the radiator. The radiator is a aluminum hot rod radiator designed for a 350 GM and a Jaguar blow through fan is used. With this design I believe I can slow down the speed of the coolant but will run tests to see if that is advantageous or not.

I planed to monitor inlet and outlet coolant temp and actual head temp to get a better picture of what is happening.

This engine has been my hobby and it is started on direct injected compressed air but runs on gasoline.

I ran the engine on a test stand before installation and was able to correct all known leaks and was able to confirm that the carburetors were tuned and ignition timing was correct for all the changes.

 

[evelrod]

For that little engine I only know of one person that has extensive experience. John McCoy of Omnitech Engineering. We are using one of his cylinder heads on our Lotus Cortina race car.

http://www.omnitech-engineering.com/auto/Auto-oil-pump.asp

Rod

 

[Slim3]

Thanks Rod, cool web site. Looks like first class work. I have 5 of the 215's, four Olds and one Buick (the one Rover used)

I have rebuilt the Rover version 215 for people. I think Rover claimed that the casting process GM used was a problem and they corrected that but visually I couldn't see any other changes.

What ever GM did in the lubrication system and crankshaft design must have been right, as every 215 I pulled down, they all had great cranks in them no matter how worn out the cylinder walls, pistons etc were. Same with the Rover versions.

One of my Olds 215s shows possible signs of what Rover said in that it had the aluminum separated from the cast in cylinder liner. I just use it for fit checks as I have stuffed one in an MG.

This is the MG I am thinking of using the Propylene glycol in.
From what every one says, I better do some testing first.

 

[evelrod]

Haven't corresponded with John about the 215 lately, but as memory serves, it was making a reliable 540hp and was scheduled for a road race car.
Yes, they certainly do good work and, not outrageously expensive, either...Depending, of course, what level of preparation you are after. We are on our second season with his DOHC Lotus head and the engines leak down is still 3% to 5%, all.

Rod

 

[rmw]

Have you done a search on this site? There have been some really in-depth discussions of PG/water. Here's a good one"

thread108-312238

Lot of good automotive expert knowledge presented in that thread.

In the industrial application I described in that thread, boiling point elevation would have been a really beautiful feature for us, but in reality PG provided next to squat. The little bit it gave was a drop in the bucket so to speak.

rmw

 

[IRstuff]

"PG provided next to squat"

That's because you need to be close to 85/15 before BP elevation turns the corner on the curve:

TTFN
faq731-376

 

[Slim3]

It seems that one just can't win on coolant. I am disheartened again. If you want good heat transfer use water, but it will freeze and boil, You can add one poisonous antifreeze and you loose some of the heat transfer and gain leaks and still need to pressurize the system to stop it from boiling or you can use Propylene glycol straight and gain the high boiling point but loose the heat transfer. Or mix it 50/50 and have to pressurize it and pay 5 times what the poisonous stuff cost.

It sounds like I best just use water with some kind of water pump lube in it since my car is going to be just a show car. If my design of the cooling system cools too well then I may run tests on the propylene glycol.

 

[evelrod]

Slim, we are not allowed, by the rule book, to use any type of antifreeze/coolant in our race cars. To get around that in the old days, I used water soluble oil as a pump lube and some dishwasher anti spot stuff. Now that I have moved into the 21st Century, I simply buy a bottle of Red Line Water Wetter or any one of several mfrs that make similar 'surface tension' modifiers in all my cooling systems. Good anti corrosion protection and the overall max temp on any given day is substantially lower...race car engine...street engine, not so much to actually SEE...but it's still there.

Running 100% PG was informational. I learned that it is totally impractical in any normal automotive application. You can also get some info from articles by Smokey Yunick but you'll need to dig for it.

Rod

 

[rmw]

Slim3,

Poisonous? Go into your kitchen (or store) and take a bottle of vanilla and read the ingredients. PG is one of them. Bon appetite.

IRstuff,

Good info. I had not seen that chart. Problem is, we need the stuff to transfer a significant amount of heat from the process while giving adequate freeze protection when the process is offline worse than we needed the boiling point elevation.

All 3 would have been golden, but we still needed to be able to pump the fluid through some sophisticated heat transfer equipment in a variety of conditions as well. To get the right combination, we can handle the boiling point elevation by raising the system pressure - exactly what the radiator cap does on most autos. We obviously do it with something more sophisticated than a radiator cap.

rmw

 

[patprimmer]

Re boiling and freezing points. I guess brine is out of the question because of corrosion.

Regards
Pat
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[Lou Scannon]

I have yet to see a cast stainless steel engine block! And that would be a heat transfer issue in itself... doh!

 

[patprimmer]

Many boat engines run with raw sea water cooling systems. High nickle cast iron is probably not out of the question for an engine block. In fact some high performance Small Block Chevs had a high nickle block. Not enough to be stainless, but probably enough to reduce corrosion somewhat. I certainly ran one in a boat for over 10 years. It needed a back flush every few years to prevent small rust scales that became dislodged from blocking smaller water passages.

Regards
Pat
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[evelrod]

I'm not having huge corrosion problems in my vintage/antique engines, at least the 'all iron' versions. One of them, built in 1929 and in more or less continuous service with only water as a coolant has proven totally sound on it's last UT inspection/rebuild about a year ago. I did have a cylinder head needing replacement but that's understandable on a 83 year old side valve engine.
I have had really horrendous corrosion problems in the Al/Fe engines, though...no surprises.

Of course I must volunteer that the 83 year old Ford spent it's entire life here in SoCal, never needing antifreeze. However, I am told by some of the Model A club group that pre war cars used mostly alcohol/menthol or, simply drained the system during winter. I met one fella that said he used 'coal oil' (kerosene) for coolant during winters of the New England area. I suppose it would work...I think I'd want to be careful around open flame, though...;o)

Rod

 

[L4189]

Propylene glycol is the stuff they use to protect fresh water systems in yachts and RV's during winter layup and we use to run it through the raw water system of the engine with it puking on the ground for the same reason. Didn't hurt the cats any.

As for running straight water, locomotives run straight water with something like NALCO 2000 rust inhibitor which also works well for the ceramic pump seals.