Is a thermostat needed?

[Brock.Ward]

SO i have a 19' boat and took the thermostat out completely. What do i even need a thermostat for? There is no heat in the boat? Leaving it out opens the way for more water and a cooler engine? Is there really a need for it?

 

[haulnazz15]

Re: Is a thermostat needed?

Obviously you don't understand how the thermostat functions. Part of the reason you have a thermostat is becuase it keep the operating temps in a specific range. The engine runs better at higher temps (like the 140-160 deg range) which uses less fuel and creates more power. Using no thermostat makes temps stay too low and can lead to poor operation. The thermostat also makes sure that you don't have ice cold water going though hot manifolds, it allows the engine to warm the water and then exit through the hot manifolds/risers.

Use a thermostat, it's a $5 part.

 

[Brock.Ward]

Re: Is a thermostat needed?

I do understand, i think you might not. ICE cold water wouldnt run thru the manifold because it was always stay cool without a thermostat, engines also run much better the cooler they run...Its not about the money its about the cool engine...On cars you use a thermostat to get heat. Any engine is an engine...I dont quiet think your response is too accurate.

 

[Aviator5]

Re: Is a thermostat needed?

Engines do not run better the cooler they are. Engines run better at normal operating temperatures they designed for.

 

[cheetah90]

Re: Is a thermostat needed?

I do understand, i think you might not. ICE cold water wouldnt run thru the manifold because it was always stay cool without a thermostat, engines also run much better the cooler they run...Its not about the money its about the cool engine...On cars you use a thermostat to get heat. Any engine is an engine...I dont quiet think your response is too accurate.

This is true with high hp race motors.

 

[Kainon]

Re: Is a thermostat needed?

thermostats aren't used on cars to just get heat, they are there to maintain an opertating tempature of the engine for help maintaing air/fuel ratio which effects MPG and Drivability. In cars and trucks and other Marine Closed Cooling systems the thermostats are 180-195 ( closer to the boiling temp of water ) they can do this as the 13-15psi in the closed system along with the Coolant helps raise the boiling point.

Without a pressurized system or coolant a lower temp of 140-160 is used.

If you run without a thermostat you'll use more fuel and create noxious fumes.

Dragsters dont need thermostats as they run for such short bursts, they never warm up.. in fact some dont have water in the engines at all, NASCAR cars run at constant speeds and are thereby generating constant heat unlike a car or boat that is going fast and slow.

 

[haulnazz15]

Re: Is a thermostat needed?

Okay then, believe what you want. You want to know why high HP race motors want to run cooler? They produce TONS of heat, so it isn't hard to get them up to operating temperature, it's hard to keep them COOLED to operating temperature. The normal auto engine isn't the same due to much lower compression and rpm range. But you know better than the engineers from all different engine producers AND those at Mercruiser/Volvo, etc.

 

[Kainon]

Re: Is a thermostat needed?

ps.. there are boats that have heaters to keep the occupants warm.

 

[Howard Sterndrive]

Re: Is a thermostat needed?

aluminum pistons aren't round until they come up to operating temperature. The piton pin bore has a lot of mass, and expands more with temp rise. The piston is designed to be round once it is hot.

Once the engine heats up, the pistons fit the cylinders properly, the valves stay clean of carbon and soot, and the oil flows to all the tight spots it needs to lubricate

the thermostat is responsible for all of that....

in 19' boats

 

[carolynrose]

Re: Is a thermostat needed?

The most overlooked reason for a thermostat is it's metering of coolant. The open diameter of the thermostat is specifically designed to allow the correct amount of coolant to flow by, that is why each vehicle has a specific thermostat.
Some vehicles will even run hotter without a thermostat because the coolant flows by its radiator or heat exchanger too fast and does not get adequate time to cool.
The manufacturer spends big bucks on designing an engine to perform in a certain way, removing and changing parts changes the parameters for which it was designed. We don't run a thermostat in our race car, but we run a restrictor plate in it's place to make sure the coolant flows slow enough through the radiator to get cooled, this is a specific use vehicle. If you make changes to your car or boat make sure you know what your doing.

 

[45Auto]

Re: Is a thermostat needed?

I do understand, i think you might not. ICE cold water wouldnt run thru the manifold because it was always stay cool without a thermostat, engines also run much better the cooler they run...Its not about the money its about the cool engine...On cars you use a thermostat to get heat. Any engine is an engine...I dont quiet think your response is too accurate.

Actually, you're totally wrong and Haulnazz15 is 100% accurate.

Over-cooling your engine is slowing you down and costing you power. What do you think pushes your pistons down?

Heating up a gas makes it expand. The hotter you can keep the cylinders of your engine without causing detonation, the more power it will make. Keeping your engine too cold is just pulling heat out of your heads and giving you less expansion (pressure) to push the pistons down. The thermostat holds the temperature as high as possible without causing engine damage for maximum power and efficiency.

You don't have to believe me, this stuff has been around for literally centuries. It's in every first year engineering thermodynamics course.

From Physics in an Auto Engine:

If an ideal engine could be built, it would NOT have any cooling done to the cylinders DURING the power stroke, to allow the pressure inside the cylinder to remain as high as possible. The cooling system has the negative effect of chilling down the gases inside the cylinder that we want to be pushing the piston downward! So the very existence of the cooling system necessarily reduces the power and torque that an engine can create!

http://mb-soft.com/public2/engine.html

If you can read a PV diagram, this Otto cycle diagram (your boat motor operates on what is called the "Otto cycle") from MIT shows the same thing:

Figure 3.8: The ideal Otto cycle

Figure 3.9: Sketch of an actual Otto cycle

Figure 3.11: Ideal Otto cycle thermal efficiency

The ideal Otto cycle efficiency is shown as a function of the compression ratio in Figure 3.11. As the compression ratio,

, increases,

increases, but so does T2 . If T2 is too high, the mixture will ignite without a spark (at the wrong location in the cycle).

http://web.mit.edu/16.unified/www/FALL/thermodynamics/notes/node26.html


T2 is the temperature at the top of the compression stroke. Efficiency of an internal combustion engine increases as T2 increases up to the point where detonation occurs.

Running without a thermostat is reducing the pressure of the expanding gases in your cylinder by keeping the temperture lower than it has to be. You're costing yourself both power and fuel economy. But if it makes you happy, don't let facts slow you down, keep on trucking!

 

[Utahboatnut]

Re: Is a thermostat needed?

Why did you ask the question if all you are going to do is argue with the responses you get. You seem to be knowledgable on the subject so why ask just take it out and go with it that way. Save room and time for people who are truly seeking GOOD advise which is what you have recieved thus far.

 

[haulnazz15]

Re: Is a thermostat needed?

Some vehicles will even run hotter without a thermostat because the coolant flows by its radiator or heat exchanger too fast and does not get adequate time to cool.

Absolutely the truth.

 

[Brock.Ward]

Re: Is a thermostat needed?

Not arguing, gees you guys are tough here, thanks for all your advice, it helps!

 

[Philster]

Re: Is a thermostat needed?

As a lesson, you were operating from a flawed premise: That cooler is better.

Next time, make sure your premise jives with the point you are making.

Now I am gonna go remove my waterpump, because hotter is better, right?

 

[Silvertip]

Re: Is a thermostat needed?

Ever notice that NASCAR engines run several laps before being turned loose. That's to get the engines and gear lubs up to operating temps. In that business, a NASCAR engine is fastest and most powerful just before it blows up -- which is usually around 260 degrees. Merc, Volvo, and OMC don't make the current crop of engines -- GM does and they have a place for a thermostat for a reason and it is not just to make the engine more expensive.

 

[45Auto]

Re: Is a thermostat needed?

Now I am gonna go remove my waterpump, because hotter is better, right?

Depends on how you define "better". It'll make a little more power until it starts detonating, then it'll weld itself into a lump (would make a good anchor) a few seconds later!

You could probably count on it running reliably for about as long as a typical Top Fuel dragster motor - about 4 seconds at a time between total rebuilds:

Facts about Top Fuel

The block is machined from a piece of forged aluminium. It has press-fitted, ductile iron liners. There are no water passages in the block, which adds considerable strength and stiffness.

The cylinder heads are machined from aluminum billets. As such, they, too, lack water jackets and rely entirely on the incoming air/fuel mixture for their cooling.

 

[sethjon]

Re: Is a thermostat needed?

You better listen to haulnazz because hes dead on.

 

[Brewman61]

Re: Is a thermostat needed?

Even if you someone doesn't really see the reason, or understand why some things are the way they are, I like to look at it this way-

A factory will kill to shave a dollar off the cost of making something, it's a buck straight into their pocket. Multiply that buck by hundreds of thousands of units a year, and the money adds up very quickly.

Therefore, it stands to reason that they would gladly forgo the expense of plumbing in a thermostat if there was not legitimate use for it. And I"m betting it costs a bit more than that buck for them to do so.

Incidentally I had a car once with a stuck open thermostat. Car couldn't pass emissions testing because it was running rich- the engine management system thought it was very cold outside, and kept the car running rich and wasting all kings of gas.

 

[Eric 3.7LX Alpha 1]

Re: Is a thermostat needed?

This really is a good thread because this is not the 1st time someone wanted to remove the tstat. Good one to save.