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Old 10-09-2009, 12:04 AM   #21 (permalink)
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It's good to think about and investigate stuff even if it doesn't pan out right away. Who knows when down the road the lessons find application?

Frinstance it could be someone comes up with a thermosiphon system that's good enough for hypermilers.

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Old 10-09-2009, 12:06 AM   #22 (permalink)
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Quote:
Originally Posted by Frank Lee View Post
It's good to think about and investigate stuff even if it doesn't pan out right away. Who knows when down the road the lessons find application?

Frinstance it could be someone comes up with a thermosiphon system that's good enough for hypermilers.
Which would certainly kick ass, but probably would not be using water under pressure. I think it would be using something akin to refrigerant, maybe ammonia or propane? (I've used propane to recharge a car's A/C system... it never gets hot enough in there to reach the auto-ignition temp, and even if it did, other components would fail, causing it to vent to atmosphere long before it was able to ignite.)
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Old 10-09-2009, 07:03 AM   #23 (permalink)
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When the fan belt broke on my Z car (defective) I drove it ten miles using pulse and eoc.
The air flow across the water pump driven fan was enough to keep the coolant moving with no belt to drive the alt or pump and fan.

It was actually cooler when I finished than it would have been with the belt working.


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Old 10-09-2009, 09:05 AM   #24 (permalink)
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Quote:
Originally Posted by Christ View Post
That's not true at all. The thermostat doesn't just stay open, this is the reason that grille blocks afford a shorter warm up time. The thermostat opens when the water touching it reaches a specific temperature. As the flow rushes past it, it cools down, lower than the temp at which the t-stat would be open, so it closes again. This heats the water up again inside the block. This happens several times before the engine has actually warmed up. A smaller radiator (or a grille block) prevents the water from cooling as much between cycles, so there are less cycles of heating and cooling until complete warm up.

I don't run with no thermostat. It was a goal I had, to be able to run without one and still have normal warm up times and no overheats. T-stats represent a fairly large restriction to flow, even when open fully, which loads the water pump. It's a negligible amount of power, but it's not like it'd be hard to do, and the smaller radiator has obvious aero benefits as well.
The thermostat has a specific range between it's opening and closing. (Probably about 20 degrees) After it opens to a cold radiator it will then close when the temp drops to its closing point keeping the motor temp within the thermostat's range. As long as the motor is in this range it is "warm". A smaller radiator will reduce the number of thermostat cycles but at no time during these cycles does the motor temp get less than the closing temp of the thermostat.

The only way a grille block would speed up warmup is through the reduction of cooling air flow through the engine compartment.

The restriction to water flow provided by the thermostat is necessary for efficient cooling. It slows the flow of the water to give the heat time to be extracted by the radiator. In a race car with no thermostat they put a restrictor in to accomplish this. Keeping up your cooling efficiency is even more important if you are reducing the efficiency of your radiator with a grille block.
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Old 10-09-2009, 11:40 AM   #25 (permalink)
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And here I was thinking about trying to get a larger radiator in the Insight. Yes, it's got more thermal mass, and that's bad, but if you had a larger radiator, would that allow a smaller grille opening?

I suppose what I want is a carefully designed radiator, don't care what size, where a small amount of air entering the engine room provides as much cooling as possible. Maybe a compact, three row radiator behind a small grille opening would work.

The Insight has the exhaust manifold integrated into the head for better exhaust heat retention and faster warmup. The downside of that, I'd imagine, is the need for more airflow across the radiator once the car is warm.
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Old 10-10-2009, 01:15 PM   #26 (permalink)
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I think the logic is good and it's smart thinking.Systems are designed for Furnace Creek,Death Valley,California and worst-case-scenario.----------- That's not to say that you couldn't get into trouble with a smaller system.You might rehearse for overheating by sliding or turning temp control to full heat,outside air,and full fan,to create auxiliary cooling in a bad situation.------------------ I my spare time,I would like to explore pressure drops across thermostats at various levels of "open." My HONDA thermostat is a work of art compared to Chevy,Ford,and Dodge units I've encountered.---------------- Also,during development of the Chrysler LH platform and powertrain,it was claimed that the water pump designed by computer for those series of cars,had the lowest hydrodyynamic drag of any ever tested.------------- Racers use "vintage" impeller tech,with cast hydrodynamic vanes rather than bent metal vanes.----------- Additionally,extra-duty towing packages include a "SMALLER" impeller pump to minimize cavitation caused by high tip velocities within the pump volute.-------------- It looks like the cooling system is very fertile ground for modding!
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Old 10-10-2009, 01:35 PM   #27 (permalink)
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I assume you'll make an external orifice for testing the pressure drop?

Like two thermostat housings bolted together, I mean, w/ the t stat between them, varying pressure/temp?

Could you also try varying mixtures of coolant/water or different types of coolant? I believe there is a viscosity difference, which could change hydrodynamic profile.

It would be great to find out that by varying your coolant mixture by 15-20%, you could get better efficiency from your engine... (Dreams, right?)
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Old 10-11-2009, 11:39 PM   #28 (permalink)
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Quote:
Originally Posted by Frank Lee View Post
I believe this whole premise to be incorrect.

When you reduce volume pumped by restriction, the load on the pump gets EASIER, not harder.

Example? Take a hairdryer and turn it on. Note the speed. Now block the flow completely. It speeds up! It wouldn't speed up unless the load was reduced.
Oops! Apples and oranges. The dryer example is only true because the medium is of variable density. Water can be considered (at least for this discussion) a medium of constant density. Here's the example- nudge your power boat bow-first up against the dock, then go full throttle. Note the max rpms. Then go out into the fishing channel where all the idiots in their row boats are, and go full throttle. Note max rpms. See?
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Old 10-12-2009, 12:09 AM   #29 (permalink)
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Are there variable vane water pumps?
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Old 10-12-2009, 12:17 AM   #30 (permalink)
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Quote:
Originally Posted by pstrbrc View Post
Oops! Apples and oranges. The dryer example is only true because the medium is of variable density. Water can be considered (at least for this discussion) a medium of constant density. Here's the example- nudge your power boat bow-first up against the dock, then go full throttle. Note the max rpms. Then go out into the fishing channel where all the idiots in their row boats are, and go full throttle. Note max rpms. See?
Interesting point...

but does a prop have comparable properties (pun!!!) to an enclosed impeller pump?

So I just went and got my spare sump pump- axial impeller like a car water pump- put it in the kitchen sink with water and turned it on with my hand over the outlet.

mmmmm... pump motor so powerful it didn't vary much, unlike the hair dryer. I thought it slowed under load ie. pumping water...

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