Author Topic: Thermostats in a twin  (Read 5879 times)

Fairmountvewe

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Thermostats in a twin
« on: December 08, 2013, 12:36:45 AM »
Has anyone done this?  And how?  Do you put two thermostats in between the cylinders and the manifold, or just one at the outlet of the manifold?  I have assembled most of the required parts for my cooling system, and I want to use thermostats.  Thanks in advance for any help.

Peter
A human being should be able to change a diaper, plan an invasion, butcher a hog, conn a ship, design a building, write a sonnet, balance accounts, build a wall, set a bone, comfort the dying, cooperate, solve equations, analyze a new problem, and pitch manure. Specialization is for insects.

mobile_bob

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Re: Thermostats in a twin
« Reply #1 on: December 08, 2013, 01:55:54 AM »
i think you would be much better off with one thermostat on the outlet of the water manifold
two might work, but i suspect there might be issues with thermal balance between the cylinders?

are you planning on a water pump and an enclosed/pressurized system?

bob g
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buickanddeere

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Re: Thermostats in a twin
« Reply #2 on: December 08, 2013, 02:59:52 AM »
In an ideal world two stats would be theoretically better. Multiple stats are often seen on inline engines of six cylinders.

M61hops

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Re: Thermostats in a twin
« Reply #3 on: December 08, 2013, 06:28:31 AM »
I'd put 1 with about an 1/8 inch bleed hole at the outlet from the manifold.  Maybe fabricate a housing out a couple of pipe fittings?  Keep it as simple as possible!      Leland
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Fairmountvewe

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Re: Thermostats in a twin
« Reply #4 on: December 08, 2013, 11:59:54 PM »
I am planning on thermo-syphon with a rad and expansion tank.  I thought a single stat may lead to a situation where one cylinder is at temp, but the other is not, so the first cylinder just keeps getting hotter and hotter, or the second cylinder never gets up to temp.  With two stats, wouldn't each cylinder get up to temp, open its own stat, and merrily run along? Not sure.  That's why I am asking. 
A human being should be able to change a diaper, plan an invasion, butcher a hog, conn a ship, design a building, write a sonnet, balance accounts, build a wall, set a bone, comfort the dying, cooperate, solve equations, analyze a new problem, and pitch manure. Specialization is for insects.

mobile_bob

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Re: Thermostats in a twin
« Reply #5 on: December 09, 2013, 01:13:14 AM »
the hot water will rise up through the cooler water and open the tstat, so you have nothing to worry about.

with the little hole allowing some coolant to leak past the tstat, there will be enough circulation to get hot water up to the stat bulb so it can function.

if the two cylinders are balanced, they should both produce nearly the same heat to the coolant, probably well within the margin of error in measurements.

once running just check the exhaust coming off both cylinders with a infrared non contact pyrometer and see if the exhaust temps are very close to the same under load... if one is trailing you can alter that via linkage adjustments.

my vote is for the simplicity of a single tstat, nothing can be more frustrating than trying to sort out problems when you have more than necessary variables.

fwiw
bob g
otherpower.com, microcogen.info, practicalmachinist.com
(useful forums), utterpower.com for all sorts of diy info

cranelift1

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Re: Thermostats in a twin
« Reply #6 on: February 22, 2014, 11:45:18 PM »
Hi there Fairmountvewe
 On my 12/2 I machined a slight indent in the water outlet flange to match diameter of the thermostat, and just deep enough to hold it from moving. Drilled the small bypass hole in the thermostat as mention by the other guys, making sure it was at the top when installed, and the bulb of thermostat was facing engine, and it works just fine. KISS rule applied here. G'luck, Steve

Fairmountvewe

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Re: Thermostats in a twin
« Reply #7 on: March 04, 2014, 11:27:23 PM »
Well so far, I have machined a small groove in a 1 1/2 inch plumbing union for the Tstat to fit in, and that is pretty much where everything  will sit until spring.  I don't have the luxury of an enclosed, let alone heated shop, so in the true spirit of these motors, I do what I can, plan for what I can't, and wait for better days.  Thanks all for the input.

Peter
A human being should be able to change a diaper, plan an invasion, butcher a hog, conn a ship, design a building, write a sonnet, balance accounts, build a wall, set a bone, comfort the dying, cooperate, solve equations, analyze a new problem, and pitch manure. Specialization is for insects.

ronmar

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Re: Thermostats in a twin
« Reply #8 on: March 04, 2014, 11:44:59 PM »
I agree with a single thermostat.  I havn't ever come across an engine with multiple thermostats...  It is fairly easy to put a thermostat at a hose fitting provided you can find a thermostat that with a flange diameter the same as the outside diameter of the pipe/hosebarb that the hose slides over. A second hose clamp up the hose a little will compress the hose around the flange securing the thermostat in place.  Kinda like in this drawing.  I have done this on 3/4" pipe and hose using a outboard motor thermostat(very small diameter, but only around 120F reg temp)

PS 6/1 - ST-5.

cranelift1

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Re: Thermostats in a twin
« Reply #9 on: March 07, 2014, 04:39:58 PM »
I'll add a link to the photo's of how I installed my thermostat.
http://s1259.photobucket.com/user/WilyWilly1/media/P3020817.jpg.html?sort=4&o=1
http://s1259.photobucket.com/user/WilyWilly1/media/P3020819.jpg.html?sort=4&o=3
http://s1259.photobucket.com/user/WilyWilly1/media/P3020820.jpg.html?sort=4&o=2
Hope this clarifies how I solved this upgrade. There are of course many others ways that will also work.
G'luck,  Steve