increasing operating temp

[captnpgn]

On a volvo 5.7 carb.set-up would there be any gains in performace/ fuel economy by increasing my 140 deg. thermostat to a higher, say 165 deg. or so thermo?

 

[Reel Poor]

Re: increasing operating temp

Is the boat raw water cooled or does it have a closed cooling system?<br /><br />Engine temp is relative to corrosion factors that exist in some marine enviroments, especially salt water. It all depends on the mineral content in the water where you boat (not sure which minerals would really be harmfull in fresh water). <br /><br />As far as increasing performance, probably not enough to even show on a GPS. Fuel economy may increase enough to notice over a long period of run time, but for a days outing I doubt you would see any increase.

 

[paulie0735]

Re: increasing operating temp

First confirm which one is recommended by the manufacturer. I agree with reel poor, increasing operating temp my help a little with economy but it’s normally done in late model vehicles to help with smog control systems. I suspect if you increase the normal operating temp by fitting a hotter thermostat than is recommended you may have trouble keeping it cool when it’s under load at WOT as your cooling system may not be efficient enough to keep the engine temp under control at the higher level.

 

[captnpgn]

Re: increasing operating temp

Thanks guys, I was just curious. I had a previous 3.8 omc that ran 170 deg. with no problems. Run in fresh water only and rarely does it see wot, maybe 3/4. Trying to stay away from the gas pumps as much as posible.

 

[ron7000]

Re: increasing operating temp

I would have to say engine temp and thermostat temp would depend on operating environment as to whether it's beneficial or not. In the case of only running in summer where its 80+ outside and water temp is 70+, I would agree that going from a 140F thermostat to a 160F thermo or higher would be of little benefit. But if you're running in fall or early spring where temps are 50-70F and water temp is 60F or less, then a hotter thermo such as a 160 or 170 definitely can be beneficial over a 140F for reasons like quicker warmup time, hotter oil temps in the range of 180-220F, and better combustion especially when the engine is carbureted. If the engine is raw water cooled then there should always be an adequate supply of cooling water to maintain engine temp regardless of the thermostat being used. That's assuming the raw water pump or outdrive impeller are working as they should. A hotter engine is always a more efficient one, if you want to talk about power then that's totally different. The other big factor would be maintaining oil temperatures < ~240F if you go a hotter thermostat.