engine efficiency

[torcano]

I was told by my marina mechanic that my 4.3 L MPI Mercruisers will run more efficiently at 180 degrees compared to 160 degrees. Does that make sense?

 

[JustJason]

Re: engine efficiency

I love it when 1 guy thinks he's smarter than 30 engineers...

 

[abj87]

Re: engine efficiency

I love it when 1 guy thinks he's smarter than 30 engineers...

Its true but above 160 the salt will precipitate out of the water and build up in the cooling passages. And the engineers know this

 

[haulnazz15]

Re: engine efficiency

Many engines run better in the 175-180 degree range, but many times, it's the cooling system that limits it. Raw water-cooled engines usually run cooler due to the constant flow of cold water and never get the temps up that high. The closed-cooling offers a more consistent temperature that can be easier to increase to allow better effiency. The downside is that at 180, you are that much closer to overheating the engine.

 

[Lodgepole]

Re: engine efficiency

The boiling point of H2O at sea level is 212F. The boiling point drops 2 degrees for eack 1000 ft altitude. On an automobile, you have a pressure cap which captures air in the cooling system and when heated. this air as well as the coolant expands and causes pressure in the system which is the equivelant of adding atmospheric pressure and raising the boiling point. With a sea water boat system, you have no pressurization of the cooling system. Depending on your altitude, your boiling point may be a lot lower than 212. Where I live, the boiling point is 194 F. Sure makes it hard to cook beans.

 

[torcano]

Re: engine efficiency

I supposedly had new 160 degree thermostats put in but my temperature guage is reading 170. Could he have put in the wrong thermostats? Should I pick up an infrared temperature gun and get a temperture reading off of the manifolds? I'm starting to understand why it is better for me to do these things myself.

 

[Zackman]

Re: engine efficiency

I supposedly had new 160 degree thermostats put in but my temperature guage is reading 170. Could he have put in the wrong thermostats?

No, that's normal.​

Should I pick up an infrared temperature gun and get a temperture reading off of the manifolds?

Yes, and check it at least yearly. Along with the risers, etc.​