increase engine heat for better efficiency?

>The engine will be more efficient if you can keep the engine running at a cooler temperature.<

Not according to most engineering books.

What is needed is a warm engine fed cold dense clean air.

 

I have been using the 15w-40 Delo 400 oil for at least 10 years in the boat. Both engines are original and both have been rebuilt, one before I got boat, and other by me 2 years ago. The entire exposed engine parts are all 50-50 antifreeze, the only raw water exposure is a bronze tailpiece attached to the risers.

One of the changes I made when they introduced E10 gasoline was to go from Rochester 4GC to Quadrajet carbs and block off the exhaust heat that runs into the intake manifold. So the intake runs cooler than it did. Those changes made big improvements in how the motors ran on the E10 fuel.

Since the intake and carb get less heat means a 180* thermostat is less likely to be causing trouble, I think if I switch. Cooler intake air, hotter engine.

I dont run this boat at wide open throttle. I cruise around 1500 rpm most of the time. Idea of going to 180* is maybe get a little better efficiency. On a boat even small improvement means lots of money saved on fuel.
I dont want it pinging, wont know unless you try. Can always go back to cooler ones.

 

wow havn't see a 4gc for a while
I can just remember when one model Mercrusier had them, 225 early II drive or something

 

4GC design terrible with E10. Huge float bowls, secondary float bowl only used if throttle opens a lot. So fuel goes stale.
With the float bowls on outside, boat rocks, fuel sloshes, engine were always cutting in and out. Dont know if it was the jets getting uncovered or it was sloshing out the vent tubes.
Engines always heat soaked so took lots of cranking after a run to restart.

The 4GC carbs always stunk up the bilge after a run with gas fumes.

The quads which I rebuilt and modified various jets and opened up idle tubes have no smell, no heat soak, no cutting in and out and starts up better. And have electric chokes.
With only 1 float instead of 4 floats, much better. 4 times fewer floats to get pinholes and leak.

 

I also got rid of the mechanical fuel pumps went to Carter electrics and PSI regulators . So I can prime without cranking forever. E10 always dried up in the bowls real fast.

 

I love the quadie from back in the day, cut my teeth on them as an apprentice
Had them on GM cars in OZ and of course all the marine engines
You can get enough fuel through them to make almost 500ftlbs on a big block

 

> A 8 to 10 degree increase in temp can result in a reduction of 40 % of the oils life

It can, but not in the "too cold being raised to the low side of normal" range that we are talking about. I'd expect increased oil life due to more moisture being driven off. And less wear and better fuel economy.

 

The evans coolant is waterless, and it carries less heat away. So whatever engine it's in, just take note that the cooling ability will be slightly lower than before.
That being said, it doesn't corrode and react like water does, so maybe it's possible that after years of use, it would be even.

In theory, thicker engine oil like diesel engine oil, in a gas engine would make it last longer, but I know of a few stories of failure, because the oil didn't lubricate the top end properly, because of flow problems. On cars at least. Depends on the engine.

 

sdowney717,
Getting the engine hotter will reduce friction and increase efficiency.

But I suspect that running really hotter like 230 degrees F would allow you to lean out the mixture for some REAL economy. Unless you can lean out the mixture the increase in efficiency will be fly stuff.

A gas engine needs a rich mixture to run fairly well when cold and can lean out when warmed up. Could one lean considerably more if the coolant temperature was raised considerably higher than normal? Perhaps 250 to 300 degrees is possible with a very high pressure cooling system. But could one continue to lean the mixture? And by how much? And would it deliver much greater efficiency?

Obviously the cooling system wouldn't have hoses. It would have steel pipes and heavily constructed heat exchangers. To experiment one could use a manually controlled valve for temp control. I wonder how hot the oil would get w the coolant at 250 degrees or so? If you ever lost pressure it may be a bit of a bomb as well.

Has there ever been experiments to discover the upper limits of cooling system temperature? One would think so.

 

For a long time Caterpillar offered "Ebulent Cooling" on their large Diesel engines in stationary service. The ordinary cooling system passages were used to generate steam at 15 PSIG. That corresponds to 250F steam saturation temperature. The water/steam mixture was generated at the cylinders and heads, rose upward by natural circulation to a steam separator tank, where the steam was bled off to industrial processes, and the 250F water then flowed by natural circulation back into the engine cooling passages. These engines always had separate oil coolers with their own cooling water supply system.

I had two 1100 cc (67 ci) motorcycle engines, each producing maximum 110 Rear wheel horsepower, although normal driving did not use full throttle for much time. I monitored oil temperatures in both, one ran at about 230F, the other 250F in the hot summer driving. These engines were exclusively oil cooled, with big oil nozzles directing a jet of lube oil right onto the exhaust valve areas, then flowing down the cylinder cooling channels to the oil pump.

And finally there is the "Still Engine" where the cooling system of a Diesel is used to generate steam at about 100 PSIG, and the steam is used to provide considerable extra power output with steam engine cylinders. These engines ran their cylinder cooling water jackets at 338F. Several large installations of these types were used for railroad locomotives and shipboard propulsion, mostly in the 1930s - 1940's. They were not successful because of the complexity of operations, but they did function well enough to give reliable power even with the high cylinder coolant temperatures. I suspect lots of air cooled racing motorcycle engines ran with cylinder temperatures above the temperatures mentioned here.

 

such a was having a cooling system, arent we trying to heat gas and make it expand!!
everyone needs adiabatic engines, would add like 30-40% thermal efficiency to SI or CI engines

 

jonr: "I was referring to less actual wear (say 1/2), as seen here:

http://www.cooltechllc.com/Boss/imag...mp_640x480.jpg

I don't know what effect oil viscosity would have on this data but clearly thicker isn't always better, even for wear."
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The cylinder wear experienced in the presented graph is largely due to water condensation on the cylinder walls, which can wash off oil and contaminate the oil. We burn "hydrocarbon" fuels, composed of hydrogen, which reacts with oxygen, forming H2O, water, plus carbon, which produces CO2, carbon dioxide. If the cylinder walls are cold, then lots of combustion water condenses on the cylinder walls, and screws up the lubrication.

As far as oil viscosity and machinery wear, I do not know of any conditions where higher viscosity oil would result in greater wear, except in cases when the oil cannot get to the bearing surfaces, but that is not an issue for what is being examined here. Greater parasitic friction, yes with higher viscosity oils, but lower machinery wear.

 

something has to pump that thick oil....
not to mention there is almost no market for thick oil so you would have to assume all the technology is in thin oil and running at high temperature

 

What I am talking about is 5-30 spark ignition (SI) oil vs. 15-40 Diesel oil (CI). Both work very well in modern internal combustion piston engines. Oil pumping is easily accomplished with either oil, and lubricated surfaces get plenty of either oil when in service. The lower viscosity 5-30 SI oil has slightly lower friction, but more engine wear. IF an engine is pushed to its limits with respect to bearing loads, the 5-30 engine will always fail before the 15-40 engine will.

Beyond the viscosity issue, there are the anti-wear and anti-scuffing additives in the CI rated oil. The US EPA tried outlawing these additives alltogether, as they can interfere with catalytic converters, and some are considered environmentally unfriendly. However the heavy duty trucking industry Diesel engines began to show increased wear and premature failures, so the EPA was lobbied to get rid of the additives prohibition for Diesel engine oils. Many Diesels need these additives to survive a satisfactory life. In today's US market, SI rated oils do not have these additives, CI rated oils do.

 

so do SI engines with non roller cams
put a cam and lifters in an old engine and you have to run it in with Shell Rotella