Cooling systems

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immortality
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Cooling systems

Post by immortality »

Hi Guys,

All this talk of thermostats and thermofan on/off settings has me thinking about engine cooling systems (again).

Now I'm led to believe that a lot of modern engines have the thermostat in the lower hose/inlet and this leads to much more consistent engine temps right through the engine rather having cold coolant entering the block and extremely hot coolant exiting the heads when the thermostat is in it's conventional position.

To me there does seem some logic in this concept, has anybody have any experience with this type of system?

I first read about this type of cooling system years ago in a Street Machine mag but hadn't though about it till recently when it came up in a discussion on another forum.
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vlad01
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Re: Cooling systems

Post by vlad01 »

yes this type of system is a lot more even temps throughout the engine and also allows a lot quicker heat up time.

I have seen this type of system home brewed on valiant straight 6 on a local valiant nut's car.

All jap older (mid 90s) and newer cars and pretty much all modern other makes of car run this setup these days.
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Re: Cooling systems

Post by VL400 »

My Toyota 1UZ is this style of system along with many others, thermostat is in the lower hose. Uses a dual stage thermostat to circulate coolant in the block with the thermostat closed and a cold engine. Gets it close to operating temp way faster and no hot spots.

This was 1980s Japanese technology!
immortality
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Re: Cooling systems

Post by immortality »

Right, so there is definitely merits to this type of setup.

I guess the question is how do we do this on our V6 engines then?

Heating up quicker is a definite bonus, especially in winter time :)

edit:I guess something like this in the lower hose with the bypass hose plumbed back into the top radiator hose would do the trick.
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Would make thermostat changes on the L67 so much easier too.
Last edited by immortality on Tue Jan 03, 2017 8:30 pm, edited 2 times in total.
MAGP
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Re: Cooling systems

Post by MAGP »

The theory works quiet well.

Nissan Xtrails had 2 thermostats in them 1 in the top housing and another in the bottom housing (on the block). I don't know if other Nissans did but Xtrails certainly did.

Davis Craig EWPs with a controller work on the idea that the EWP acts like a thermostat and only operates when coolant temp in the top hose reaches a certain temp. Using a PWM the pump cycles on and off allowing the coolant to gradually increase in temp but also allowing a more uniform, and quicker, across the entire cooling system increase in coolant temp. I have one of these on my 350 and it is set to normal VT thermostat temps. I also have a 160 degree thermostat (35 degrees lower than normal) in the thermostat housing to aid in faster warm ups. When the vehicle was being used with this setup the engine temp was the most stable it had ever been. No overheating in summer, no running cold (160 degree thermostats just don't heat up enough) in winter, the two systems combined worked brilliantly. When I get the 350 running again I'm thinking of moving the temp sender to the bottom hose before the pump and setting it at 160 like the thermostat.

There was also an article in either Street Machine or Performance Street Car about a thermostat housing that was made to be spliced into the bottom radiator hose. The thermostat used was selected to ensure the coolant temp in the bottom of the radiator was what opened and shut the thermostat. This meant the radiator was not only used to cool the water but more correctly it was used to control engine temp and stop thermal shock. Thermostats on the top hose, or top housing, would allow cold or cool water to enter the engine because the radiator keeps the water cool, with the temp control in the bottom hose or bottom of the radiator the radiator coolant is at operating temp or close to it so the engine doesn't get a gut full of cold water as soon as the thermostat opens.
immortality
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Re: Cooling systems

Post by immortality »

Yeah, I read an article many years ago in Street Machine, was something about a big block with chronic overheating issues and moving the thermostat to the lower hose as well as some other mods solved the issue. I believe it was some system designed by a guy named Bennett.
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Re: Cooling systems

Post by pman92 »

Definitely a better setup and all new cars use it. Alloytec's and all newer Holden V6 also use it.

Only thing you really need to do to make sure it works is have coolant flow over the back of the thermostat (ie heater or bypass circuit), because if you don't then as you can imagine it would never open sitting in the cold bottom hose.

Other advantage is the thermostat sees colder temperatures so I guess it may last longer, and there's definitely less chance of it failing if the engine is overheated for whatever reason. If it's sitting in the top it's almost guaranteed the wax pallet will crack open if you cook it
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immortality
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Re: Cooling systems

Post by immortality »

Our V6 engines already have a bypass allowing hot coolant back to the waterpump without going through the radiator so our engines don't get the total cold shock that older engines get.

Found a few little bits about the Bennett cooling system, found this interesting bit about water pumps, http://www.gt40s.com/forum/attachment.p ... 1325851092.

I think I need to find a new waterpump with cast impeller rather than the cheap pressed steel version with the straight vanes that are much more likely to cavitate....
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Re: Cooling systems

Post by vlad01 »

Since when could you get pressed steel impeller pumps for V6? I've only ever seen cast or billet impellers on them.
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immortality
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Re: Cooling systems

Post by immortality »

Previous pumps I've bought have been pressed steel impellers.

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Last time I went to repco to get a water pump all the ones they had on the shelf were pressed steel too, even the GMB ones :(
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