ozconnection Posted January 30, 2010 Author Share Posted January 30, 2010 I'm definitely no expert here but I think the L series "hyper sensitivity to detonation" (as BRAAP puts it) theory goes something like the following. For whatever reason (poor/marginally designed/manufactured or just out dated) Nissan L series heads develop localized pockets of stagnant coolant during operation. If or when nucleic (spot) boiling occurs in those pockets, the vapor can collect and form an insulating layer between the liquid coolant and the cylinder head walls. Vapor has very little thermal conductivity (compared to water, NPG, etc.) resulting in hot localized head temperatures. These hot localized head temperatures result in a head that is prone to detonation. It appears that Evans NPG addresses the problem by providing a higher boiling point (the temperature at which liquid turns to vapor) and, according to their literature, "any locally generated vapor is immediately condensed back to liquid coolant avoiding the development of an insulating layer of vapor." This property of the coolant keeps the head walls wet allowing for much greater localized heat transfer as compared to a vapor layer. I don't trust marketing hype so I am looking for some real world testing. TimZ is one data point favoring Evan's NPG. If I remember correctly his setup is pushing out some serious power which would significantly tax the old L6 cooling system. So do you think it's correct to say that a higher overall temperature in the head due to NPG's lower heat transfer is negligible assuming the cooling system has the heat rejection capacity to keep up? Sorry ozconnection for kinda going off topic... Thing is - it doesn't run hotter. At all. In fact, my cooling system now works as well or better than it ever has. I am running the stock viscous clutch fan and the LD water pump, so that is probably helping a bit, but I now have far fewer problems with the coolant temps climbing above the 195 degree setpoint than I ever have. I'd love to get my hands on some of this stuff to try! eBay sellers of the stuff want over $100.00 to ship it to me and after some looking around it isn't easy to find locally. The web site for Evans doesn't show the container/bottle sizes available, so what may be a $30 dollar purchase may turn out to be a 60 or even 90 dollar exercise, then plus postage. You'd want this stuff to last forever at that price! (funnily enough, that's what the website blurb suggests). The website quotes a boiling point of 375 degrees F @ zero PSI coolant pressure for their NPG product. If still using a stock, mechanical water pump that runs up to 35 psi....will that increase the boiling point of this stuff even further? There is also a part A and B solution that's supposed to remove all of the scale and other contaminants from in and around all the coolant passages. Has anyone used this stuff and how well does it work? Could another product that claims to do the same be used instead of the Evans cleaner solutions to prep the cooling system? Cheers! Quote Link to comment Share on other sites More sharing options...
jeffp Posted February 4, 2010 Share Posted February 4, 2010 I have looked into the Evans glycol and the thing that bothers me about it is the heat transfer coff. Water has a cofficient of 1 Evans is about .78 or so, and standard 50/50 antifreeze about .82 so water is the best coolant. I don't really know of anyone that has data on a high hp engine with this stuff, and @ 25.00 or so a gallon, I am not confident it will help my engine all that much. Quote Link to comment Share on other sites More sharing options...
ktm Posted February 4, 2010 Share Posted February 4, 2010 Jeff, Tony and I both stated this and Tim acknowledged it, but Tim's first hand experience is saying otherwise. This may in fact be due to nucleate boiling creating a boundary layer. Quote Link to comment Share on other sites More sharing options...
Tony D Posted February 5, 2010 Share Posted February 5, 2010 Yes, the heat transfer may not be as good (this may necessitate a larger rejection side of hte equation), but this is offset by the nucleate boiling depression. If it stays adhered to pick up the heat and transfer it to the rejection device (radiator) then it will cool better than a 'more efficient' transfer medium which experiences thermal separation caused by runaway nucleate boiling. It is apparent that the L Head has some nucleate boiling tendencies, so trying the alternate fluids may pay off if you can build in excess rejection capability (multi-pass four core radiator perhaps) to reject the heat it does pick up. Does that make sense? While it transfers heat poorly, because it doesn't nucleate boil, it ends up taking more heat out of the head than a better coolant would due to it's boiling tendency. That all being said, Electramotive cooled 1000HP in Endurance Competition with straight water, so it IS possible to do without the exotic fluids! Quote Link to comment Share on other sites More sharing options...
TimZ Posted February 5, 2010 Share Posted February 5, 2010 Yes, the heat transfer may not be as good (this may necessitate a larger rejection side of hte equation), but this is offset by the nucleate boiling depression. If it stays adhered to pick up the heat and transfer it to the rejection device (radiator) then it will cool better than a 'more efficient' transfer medium which experiences thermal separation caused by runaway nucleate boiling. It is apparent that the L Head has some nucleate boiling tendencies, so trying the alternate fluids may pay off if you can build in excess rejection capability (multi-pass four core radiator perhaps) to reject the heat it does pick up. Does that make sense? While it transfers heat poorly, because it doesn't nucleate boil, it ends up taking more heat out of the head than a better coolant would due to it's boiling tendency. That all being said, Electramotive cooled 1000HP in Endurance Competition with straight water, so it IS possible to do without the exotic fluids! Agreed. The extra capacity in my case comes simply from the LD pump, some mild porting in the water passages in the front cover (the stock casting is not very flow-friendly once you look at it) a single core Ron Davis Radiator, and a shrouded stock mechanical fan (much simpler and flows a lot more air than any electric I could fit in there). With standard coolant I had chronic problems on hot summer days in slow traffic, not so much under power or at speed. Since I've changed to NPG-R, this has stopped for the most part - I still see some temperature creep in slow traffic on the hottest days (survived the Woodward Dream Cruise this year), but you should also take into consideration that I have protection against boilover to over 300 degrees F! Running 210 for short periods in traffic seldom happens, but shouldn't hurt anything if I'm not getting uneven cooling across the head due to nucleate spot boiling. The other thing that I took into consideration was that the NPG-R has those temperature capabilities at stock or less system pressures. I still run a full interior and heater, and need it sometimes here in Michigan! I really didn't like the idea of running really high system pressures with the 30 year old stock heater core and 10 year old stock molded heater hoses in the cabin. If you modify the cooling system for a reservior tank and pressure cap on the low pressure side you can actually run with a zero psi pressure relief and still get boilover protection to over 300 degF. I didn't go this far - currently running a stock pressure cap for simplicity. In the overall scheme of things ~$70 for coolant is peanuts compared to the money and time I have wrapped up in this thing, and I've been really pleased with the performance so far. Quote Link to comment Share on other sites More sharing options...
ozconnection Posted February 8, 2010 Author Share Posted February 8, 2010 Ok, I'm really happy with the cooling setup I have on the car now. I'm using a 180 degree thermostat (normal climate rating). I'm using Redline water wetter mixed with 10 litres of distilled water. My cooling system in the Cedric is 10.6 litres total capacity so that worked out fine. I'm running the Nissan LD28 water pump I got from Japan. Some minor mods were made to the front cover to make the pump fit, but those mods were minor and have been explained in the cooling around cylinder 5 sticky. I decided to keep the thermo fan setup. It's relay triggered by a simple Jaycar electronics 70 degree Celcius temperature switch placed at the top of the radiator fins outside the confines of the factory radiator shroud. It works perfectly and is cheap as chips at AU$5.75 each. The setup is to use the temp. switch (normally open) to trigger the relay at 70 degrees Celcius. At that temperature, the switch closes and the radiator fan cuts in. Watching the temperature guage move during engine warm up, the needle creeps to just beyond halfway when the water thermostat opens. The guage moves back closer to halfway (the rush of cool water through the engine) and at that time the fan cuts in as the hot water begins to rush through the top of the radiator. It runs continously for about 2 minutes and then begins to cycle off and on, one minute on, twenty seconds off etc. The laser heat gun confirms this, 73 degrees the fan switches on, 68 degrees it switches off. Works just like a modern car does.....perfect. The needle on the guage is rock solid man....it doesn't move. Sooooo, in a nutshell, I'm stoked! It's not a particularly complex setup and that's what makes it easy to service. That's important to me. I have to thank YOU guys out there for all of your advice and direction on the subject. Cheers everyone! And, I'm running a total timing of 38 degrees BTDC at 3500 rpms. Absolutely no pinging detected at all. Quote Link to comment Share on other sites More sharing options...
TimZ Posted February 8, 2010 Share Posted February 8, 2010 That's great that you've found a solution you are happy with - I always prefer a simple, elegant solution too. One thing that you didn't mention was the system pressure that you are running. If you are using straight water, I think you'll really want to run a higher system pressure than stock to regain some of the headroom for nucleate boiling protection that you lost by not using anti-freeze. I found this graph of pressure vs. boiling point for water that might be helpful... A data table for the graph can be found here: http://www.engineeringtoolbox.com/boiling-point-water-d_926.html Ok, I'm really happy with the cooling setup I have on the car now. I'm using a 180 degree thermostat (cold climate rating). I'm using Redline water wetter mixed with 10 litres of distilled water. My cooling system in the Cedric is 9.6 litres total capacity so that worked out fine. I'm running the Nissan LD28 water pump I got from Japan. Some minor mods were made to the front cover to make the pump fit, but those mods were minor and have been explained in the cooling around cylinder 5 sticky. I decided to keep the thermo fan setup. It's relay triggered by a simple Jaycar electronics 70 degree Celcius temperature switch placed at the top of the radiator fins outside the confines of the factory radiator shroud. It works perfectly and is cheap as chips at AU$5.75 each. The setup is to use the temp. switch (normally open) to trigger the relay at 70 degrees Celcius. At that temperature, the switch closes and the radiator fan cuts in. Watching the temperature guage move during engine warm up, the needle creeps to just beyond halfway when the water thermostat opens. The guage moves back closer to halfway (the rush of cool water through the engine) and at that time the fan cuts in as the hot water begins to rush through the top of the radiator. It runs continously for about 2 minutes and then begins to cycle off and on, one minute on, twenty seconds off etc. The laser heat gun confirms this, 73 degrees the fan switches on, 68 degrees it switches off. Works just like a modern car does.....perfect. The needle on the guage is rock solid man....it doesn't move. Sooooo, in a nutshell, I'm stoked! It's not a particularly complex setup and that's what makes it easy to service. That's important to me. I have to thank YOU guys out there for all of your advice and direction on the subject. Cheers everyone! And, I'm running a total timing of 38 degrees BTDC at 3500 rpms. Absolutely no pinging detected at all. Quote Link to comment Share on other sites More sharing options...
Tony D Posted February 8, 2010 Share Posted February 8, 2010 I'm using a 180 degree thermostat (cold climate rating). Actually, you're using the 'standard' thermostat. 82C. Cold (or Frigid, in Nissan Speak) is 90C, and Tropical is 72C. That's 160 (162), 180 (179.6), & 190 (194) F for you non-metric types! Quote Link to comment Share on other sites More sharing options...
ozconnection Posted February 9, 2010 Author Share Posted February 9, 2010 Actually, you're using the 'standard' thermostat. 82C. Cold (or Frigid, in Nissan Speak) is 90C, and Tropical is 72C. That's 160 (162), 180 (179.6), & 190 (194) F for you non-metric types! Thanks Tony, you're right. Quote Link to comment Share on other sites More sharing options...
ozconnection Posted February 9, 2010 Author Share Posted February 9, 2010 That's great that you've found a solution you are happy with - I always prefer a simple, elegant solution too. One thing that you didn't mention was the system pressure that you are running. If you are using straight water, I think you'll really want to run a higher system pressure than stock to regain some of the headroom for nucleate boiling protection that you lost by not using anti-freeze. I found this graph of pressure vs. boiling point for water that might be helpful... A data table for the graph can be found here: http://www.engineeringtoolbox.com/boiling-point-water-d_926.html Thanks TimZ!! That information is great. To be honest with you, I haven't checked system pressure since putting in the LD pump, replacing the CSR unit. I should've but I haven't....yet. I'm expecting, however, that my pressures are at least as good as what they were with the standard aftermarket spec water pump that I was originally using. An interesting sidepoint is that even after flushing the coolant, there must have been some small pockets left over. The colour of the water with water wetter is tinted green...the water wetter itself is flouro pink!! So there is a little anti freeze/anti boil left in the mix!! Quote Link to comment Share on other sites More sharing options...
Tony D Posted February 9, 2010 Share Posted February 9, 2010 I bought a Harbor Freight Radiator Tester. OH MAN I forgot how handy those things were! With the usual caveat of 'change to a good Liquid Filled Ashcroft Precision Gauge' they function great, and will show you interesting things about your cooling system. (And with their included adapters, just about ANY cooling system!) Whoodathunkit that a 20+ year old Chevy heater core and hoses would stand up to 45psig static pressure? They did, and gave me much needed confidence during recent water pump leakage diagnosis. Next time I come to Oz, should I pack a 'sacrificial tool kit' to accidentally leave under a rock some place near Eastern Creek Raceway for some deserving Aussie to find? Save shipping, use my baggage allowance and entry exemptions to cheat your local import duty people. I'm up for international intrigue on a chicken-foot scale! LOL Quote Link to comment Share on other sites More sharing options...
ozconnection Posted February 9, 2010 Author Share Posted February 9, 2010 I bought a Harbor Freight Radiator Tester. OH MAN I forgot how handy those things were! With the usual caveat of 'change to a good Liquid Filled Ashcroft Precision Gauge' they function great, and will show you interesting things about your cooling system. (And with their included adapters, just about ANY cooling system!) Whoodathunkit that a 20+ year old Chevy heater core and hoses would stand up to 45psig static pressure? They did, and gave me much needed confidence during recent water pump leakage diagnosis. Next time I come to Oz, should I pack a 'sacrificial tool kit' to accidentally leave under a rock some place near Eastern Creek Raceway for some deserving Aussie to find? Save shipping, use my baggage allowance and entry exemptions to cheat your local import duty people. I'm up for international intrigue on a chicken-foot scale! LOL Any man bearing gifts from afar is welcome to visit me and my folk down under anytime. Nice one Tony! Just let me know in advance next time mate. Quote Link to comment Share on other sites More sharing options...
Tony D Posted February 10, 2010 Share Posted February 10, 2010 With the way the electrical contractor is crying about the fuses they chose for the machines I started last year, I may just end up back there to pound heads. "Stupid choices in engineering (without consulting us) on your part, does not necessitate a back charge approval on my part." "Sometimes you eat the bear, sometimes the bear eats you!" What is it with contractors wanting everybody to pay for their mistakes in specification of components? Quote Link to comment Share on other sites More sharing options...
woldson Posted February 10, 2010 Share Posted February 10, 2010 Simple, they are just protecting their giant "self-esteem"! Quote Link to comment Share on other sites More sharing options...
Tony D Posted February 10, 2010 Share Posted February 10, 2010 If this was an API machine, I could just goodwill the fuses, they're only about $5000. But this is an industrial machine, selling for about 1/10th the cost, and they cust costs by sourcing the switchgear on their own instead of through us... "You do the work on your own, you accept those risks!" How hard is this as a concept to grasp? Apparently with Dxxxxx'x Exxxxxxxxx in Australia, it's not graspable! Quote Link to comment Share on other sites More sharing options...
ozconnection Posted February 21, 2010 Author Share Posted February 21, 2010 AND, as a final statement, I added a 20 psi coolant recovery radiator cap, up from the original 13 psi one. Ten bucks worth. There, I'm done. Quote Link to comment Share on other sites More sharing options...
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