Engine coolant.
Discussion
As always, this is an issue on my car.
Been looking into various options.
Most likely, just running distilled water, and water wetter, with perhaps a small amount of anti-freeze.
But...
I also see products, that are a neat coolant. One says protects to -40, and has a boiling point of 180degC.
Is the ability to go to 180 without boiling a very good thing ?? I'm thinking it should be ?
I would imagine a lot of damage caused in an overheat situation, is due to the water boiling ??
When racing, sitting about, I have seen temps rise a little over 100degC, despite running a 78deg stat.
When driving temps do sit low around stat temp fine.
Airflow through the rad is a problem, mostly due to lack of shroud/cowling for teh fan.. ( now using a 16" puller mouted tight to the rad, which performs ok during normal usage, although will struggle in very hot days in traffic )
Will a higher pressure cap help things much ?
Been looking into various options.
Most likely, just running distilled water, and water wetter, with perhaps a small amount of anti-freeze.
But...
I also see products, that are a neat coolant. One says protects to -40, and has a boiling point of 180degC.
Is the ability to go to 180 without boiling a very good thing ?? I'm thinking it should be ?
I would imagine a lot of damage caused in an overheat situation, is due to the water boiling ??
When racing, sitting about, I have seen temps rise a little over 100degC, despite running a 78deg stat.
When driving temps do sit low around stat temp fine.
Airflow through the rad is a problem, mostly due to lack of shroud/cowling for teh fan.. ( now using a 16" puller mouted tight to the rad, which performs ok during normal usage, although will struggle in very hot days in traffic )
Will a higher pressure cap help things much ?
Hi Stevie,
I had all sorts of heating problems like this with my TR8. Plenty of air flow whilst on the move but not during heat soak when stationary. I used the biggest pacet fan but that just upset the ignition. I vented the bonnet which was great improvement at speed. I even got temps down to about 60 degrees during an experiment.
The cure which worked a treat was a crank mounted viscous fan ala US TR8.
The various fluids you mention still get hot and the heats got to be dumped via the rad. They may have a higher boiling point but heats, well, heat.
Boosted.
I had all sorts of heating problems like this with my TR8. Plenty of air flow whilst on the move but not during heat soak when stationary. I used the biggest pacet fan but that just upset the ignition. I vented the bonnet which was great improvement at speed. I even got temps down to about 60 degrees during an experiment.
The cure which worked a treat was a crank mounted viscous fan ala US TR8.
The various fluids you mention still get hot and the heats got to be dumped via the rad. They may have a higher boiling point but heats, well, heat.
Boosted.
The cooling systems efficiency is seriously compromised when the water boils, so running at a higher pressure will help this one aspect but there must be reasons why cars today don’t run with coolant systems at 1000psi so there is obviously an ideal pressure rather than, more is better add infinitum.
I think that part of the problem sometimes is that whilst the fan is sucking/blowing air through the rad, it is usually then just blasting it round the engine bay. Curiously, a similar problem to that which high end PCs have. Instead of having passive bonnet vents (which obviously only work when moving) how about fitting a couple of high-flow 5" fans under each? They can move a pretty huge amount of air, and some of them are sealed against dust (obviously not water, mud etc). Worth a go anyway, and if it does the job then you can look around for some more robust weatherproof units.
BogBeast said:
I run Evans NPG+ (Website)in my Ultima, works well if you use their pumps. Doesn't boil until 190c. They do a more extreme duty -r version that goes to 205c. Need to keep you oil temps under control tho'
Echo that - have you thought about oil coolers?
Most antifreezes are also corrosion inhibitors - essential on aluminium blocks (assuming you have an ally rather than cast iron (truck) LS1), and moany of them help to increase the thermal conductivity of the water - good for absorbing heat in the block and then dissipating it in the radiator.
When coolant boils you get air pockets in the waterways, and air is crap at conducting heat, therefore you get vastly increased likelihood of overheating (as well as the potential for local heat spikes caused by airlocks....
chassis 33 said:
Boosted LS1 said:
The cure which worked a treat was a crank mounted viscous fan ala US TR8.
Isn't torsional vibration a killer for crank mounted fans?
Regards
Iain
I don't know but this was the factory arangement on the TR8 and it works really well. I'd do it again, every time. In fact it's the one piece of rover kit that I've kept so that I can fit it to the lsx.
Boosted.
I think that having the coolant tolerate very high temperatures is no good unless you have an engine that can too, and by the time the coolant has reached 100C you're probably going to be in trouble because of differential thermal expansion. A better solution is to stop the coolant temperature going that high in the first place.
If you've got an overheating problem it'll inevitably be caused by insufficient air flow, insufficient water flow, or insufficient thermal connection between the two. You can get a good idea what the problem is by looking at the air and temperature differences across the rad, but there are some common gotchas you might look for.
Check the air temperature in front of the rad. If it's significantly higher than ambiant then you've got an air recirculation problem. Diluting the cold air with hot air directly reduces the cooling capacity so if you're getting 25% hot air mixed in with the cold that's a lot of cooling lost. This problem is likely to go away as soon as you get above walking pace so that's another clue to watch out for. It's best not to mount the fan too close to the rad, you want half an inch to let the air flow stabilise between the two.
You also want to make sure that the fan draws air over as much of the matrix as possible, in other words duct it over as much of the area as possible, in which case you'll probably have the fan a couple of inches back from the matrix anyway. When you're stationary, your cooling capacity is roughly proportional to the area of the rad that has cold air moving through it. A 16" fan in a 16"x20" radiator is only covering 60% of the area. Put it another way, you would increase the effective area of the radiator by a factor of 1.6 if you duct the fan over the whole area. You can see how much greater the effect will be if you have an even smaller fan on an even bigger rad. Ducting the fan over the whole rad also reduces the air speed through the rad, but the effect of this is tiny compared to the huge change in the area being cooled. There's a temptation to worry about restricting the ram air through the radiator by ducting it all past the fan. If that's really a problem then you can put blow-off panels on the back of the duct, but it's unlikely to be a problem unless you have really tiny fans.
As far as the coolant goes, you will need to keep the anti-freeze strong enough to prevent internal corrosion (especially if you have an alloy rad or engine) but adding antifreeze is likely to lower the specific heat capacity of the coolant so no more anti-freeze than necessary. Water wetter is good, but I don't think you should need any exotic coolants unless you are deliberately running the engine a lot hotter than normal. Having an engine designed to run at 80C and letting it run over 100C is a recipe for trouble anyway.
If you've got an overheating problem it'll inevitably be caused by insufficient air flow, insufficient water flow, or insufficient thermal connection between the two. You can get a good idea what the problem is by looking at the air and temperature differences across the rad, but there are some common gotchas you might look for.
Check the air temperature in front of the rad. If it's significantly higher than ambiant then you've got an air recirculation problem. Diluting the cold air with hot air directly reduces the cooling capacity so if you're getting 25% hot air mixed in with the cold that's a lot of cooling lost. This problem is likely to go away as soon as you get above walking pace so that's another clue to watch out for. It's best not to mount the fan too close to the rad, you want half an inch to let the air flow stabilise between the two.
You also want to make sure that the fan draws air over as much of the matrix as possible, in other words duct it over as much of the area as possible, in which case you'll probably have the fan a couple of inches back from the matrix anyway. When you're stationary, your cooling capacity is roughly proportional to the area of the rad that has cold air moving through it. A 16" fan in a 16"x20" radiator is only covering 60% of the area. Put it another way, you would increase the effective area of the radiator by a factor of 1.6 if you duct the fan over the whole area. You can see how much greater the effect will be if you have an even smaller fan on an even bigger rad. Ducting the fan over the whole rad also reduces the air speed through the rad, but the effect of this is tiny compared to the huge change in the area being cooled. There's a temptation to worry about restricting the ram air through the radiator by ducting it all past the fan. If that's really a problem then you can put blow-off panels on the back of the duct, but it's unlikely to be a problem unless you have really tiny fans.
As far as the coolant goes, you will need to keep the anti-freeze strong enough to prevent internal corrosion (especially if you have an alloy rad or engine) but adding antifreeze is likely to lower the specific heat capacity of the coolant so no more anti-freeze than necessary. Water wetter is good, but I don't think you should need any exotic coolants unless you are deliberately running the engine a lot hotter than normal. Having an engine designed to run at 80C and letting it run over 100C is a recipe for trouble anyway.
Warm air re-circulation, is something I do need to look into, and seal up, as no doubt that is a contributing factor.
I have some passages blocked, but not all.
Fitment of my fan is totally dependant on the space I have. I simply cannot improve on it, nor can I duct or shroud the entire core.
I think my problem is largely airflow, rather than coolant flow. I'll seal up the front of the car as best I can, so the rad can only draw from the front, and have little-no recirculation from the engine compartment.
Then just go for water wetter and distilled water, with a little antifreeze...
Next query... what is the best antifreeze to use ??
I have some passages blocked, but not all.
Fitment of my fan is totally dependant on the space I have. I simply cannot improve on it, nor can I duct or shroud the entire core.
I think my problem is largely airflow, rather than coolant flow. I'll seal up the front of the car as best I can, so the rad can only draw from the front, and have little-no recirculation from the engine compartment.
Then just go for water wetter and distilled water, with a little antifreeze...
Next query... what is the best antifreeze to use ??
Pete - did you fit an electric 'assist' pump - does this help it traffic jam situations..
After all - a mechanical water pump is just an agitator and not a very good pump. I've often been advised to keep a few rev's on in stationary traffic as the pump is not really pulling the cool water from the rad fast enough.. so the assist pump sounds like a good idea for those of us who sit in traffic.
What do you think.
After all - a mechanical water pump is just an agitator and not a very good pump. I've often been advised to keep a few rev's on in stationary traffic as the pump is not really pulling the cool water from the rad fast enough.. so the assist pump sounds like a good idea for those of us who sit in traffic.
What do you think.
rev-erend said:
Pete - did you fit an electric 'assist' pump - does this help it traffic jam situations..
After all - a mechanical water pump is just an agitator and not a very good pump. I've often been advised to keep a few rev's on in stationary traffic as the pump is not really pulling the cool water from the rad fast enough.. so the assist pump sounds like a good idea for those of us who sit in traffic.
What do you think.
After all - a mechanical water pump is just an agitator and not a very good pump. I've often been advised to keep a few rev's on in stationary traffic as the pump is not really pulling the cool water from the rad fast enough.. so the assist pump sounds like a good idea for those of us who sit in traffic.
What do you think.
It's a farily common mod on the rx7 to replace the pulley driven water pump with an electric unit. This helps under the scenario above and, more importantly, prevents high rpm cavitation which can effectively stop water flow around the block!!!
Waiting for this to be fitted when I get my new turbo installed as temps can be a problem.
Keeping the revs up in traffic can help, because the water flow is roughly proportional to revs but the heat output from the engine only rises very slightly with revs. But that only works if you have enough air flow too.
I ran with a little EWP in series with the mechanical pump to act as a 'booster', the engine ran cooler in traffic and it was also handy to wash out heat soak after a hot run. I didn't dare leave it on for long though. The problem is that these little pumps are extremely restrictive and limit the water flow once the engine is revving. I thought about running a bypass round the EWP to get the best of both worlds, but I haven't found the bits for a good cheap one-way valve yet. In any case the little Davis-Craig pump I was using doesn't seem *particularly* substantial and I'm a bit concerned about long term durability if it was left on the car long term. The pump I used was the biggest pump D-C do, but it still only flows round about 5% of what the mechanical pump puts out. The thought of using these pumps to completely replace the mechanical pump is rather alarming. Even with the mechanical pump blowing through them, the restriction is very significant. Still, the experiments showed that bosting the water flow rate at tickover helps the cooling significantly in my car, which suggests that just raising the tickover speed would probably help too.
I ran with a little EWP in series with the mechanical pump to act as a 'booster', the engine ran cooler in traffic and it was also handy to wash out heat soak after a hot run. I didn't dare leave it on for long though. The problem is that these little pumps are extremely restrictive and limit the water flow once the engine is revving. I thought about running a bypass round the EWP to get the best of both worlds, but I haven't found the bits for a good cheap one-way valve yet. In any case the little Davis-Craig pump I was using doesn't seem *particularly* substantial and I'm a bit concerned about long term durability if it was left on the car long term. The pump I used was the biggest pump D-C do, but it still only flows round about 5% of what the mechanical pump puts out. The thought of using these pumps to completely replace the mechanical pump is rather alarming. Even with the mechanical pump blowing through them, the restriction is very significant. Still, the experiments showed that bosting the water flow rate at tickover helps the cooling significantly in my car, which suggests that just raising the tickover speed would probably help too.
Cooling problems are most likely to be airflow related but you can help things a little by making the best out of your coolant liquid.
Pure simple water is about the best coolant available and antifreeze/anti-corrosion additives dilute it's cooling effectiveness.
Most antifreeze mixtures contain corrosion inhibitors but not necessarily all!
For your summer months running you could fill with distilled water and a corrosion inhibitor instead of antifreeze.
With only a 1% dosing required you still have 99% water for cooling compared to the much higher dosing levels required for antifreeze (anything up to 50%!)
Holts used to do a three-part "heavy duty" coolant flushing kit. The three steps are 1. Chemical flush 2. Neutralising flush 3. Corrosion inhibitor. Don’t know if it's still available.
Another source for a corrosion inhibitor is Fernox copal as used in central heating systems. Can be bought in DIY stores or plumbers shops.
You obviously need to swap back to antifreeze for the winter months when the cooling system has an easier job of it anyway.
Pure simple water is about the best coolant available and antifreeze/anti-corrosion additives dilute it's cooling effectiveness.
Most antifreeze mixtures contain corrosion inhibitors but not necessarily all!
For your summer months running you could fill with distilled water and a corrosion inhibitor instead of antifreeze.
With only a 1% dosing required you still have 99% water for cooling compared to the much higher dosing levels required for antifreeze (anything up to 50%!)
Holts used to do a three-part "heavy duty" coolant flushing kit. The three steps are 1. Chemical flush 2. Neutralising flush 3. Corrosion inhibitor. Don’t know if it's still available.
Another source for a corrosion inhibitor is Fernox copal as used in central heating systems. Can be bought in DIY stores or plumbers shops.
You obviously need to swap back to antifreeze for the winter months when the cooling system has an easier job of it anyway.
stevieturbo said:
I did try the DC pump on my old Rover V8 engine. Personally I thought it was a POS.
However, many people do seem to have good results with it, which does surprise me a little considering the feeble amount of water it actually flows..
For industrial laser optics cooling applications I've always been amazed at how much cooling a small flow of water is capable of achieving! IIRC 1 litre per minute dumped 1KW easily! I don't know how these numbers compare but maybe someone else does? However, many people do seem to have good results with it, which does surprise me a little considering the feeble amount of water it actually flows..
Running the feeble leccy pump in parallel with the mechanical one might work well particularly if the pipework to the DC pump is much smaller than the mechanical pump flow. Alternatively a cheap solenoid valve could be used to shut off the auxiliary pump flow when it is not energised eg when the revs increase above idle where the original pump starts to work.
All that said a simple alternative is to rest your big toe on the loud pedal to keep the rev range where the mechanical pump is operating on its "curve"
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