Hotter thermostat for FE

[bhazard]

30 mpg with a ram 2500 and a 5.9?

wow

edit: confused, is this thread regarding the truck in your garage profile? I see you mentioning having TBI in the thread but the truck has a cummins?

[stovie]

Originally Posted by comptiger5000

You're better off keeping the higher temp t-stat and cooler fuel to avoid vapor lock. Try warming the fuel, but not enough to vapor lock it.

You're missing the point here. Dropping the engine temp only increases the ping threshold a little. Hotter/cooler air and fuel have a much greater effect. Ideal for high compression is reverse cooling flow (heads first, then cylinder walls), a 180* or 195* t-stat, and cold air coming in. For FE, the same equation with warm air would be good (although not as high compression). Running the engine too cold is counter-productive, and also increases wear.

i looked at the pressure of fuel online at 140 it says it will hit 29 psi but if u have a pressurized system the fuel will stay liquid tell injection and thats all i was saying, and from what i read lower temps only increase wear if u try it in a used engine thats broke in at higher temps with lower tolerences if you build a engine for the lower temp and higher CR then it's "SUPPOSED" to work i guess

[comptiger5000]

True, if it's built with lower temps in mind, then it's ok (although ring wear is still a little faster, as cylinder wall lube isn't quite as good). However, the 4.0 wasn't built for that, and isn't meant to run that cold. They're toasty engines by nature.

It's tough to vapor lock an injection system, but given enough heat, certainly possible. There have actually been some issues with vapor locking the 4.0 in hot weather. Newer ones had a heat shield over the exhaust manifold runners where they connected to the head, as well as some shielding for the injectors to avoid this.

[stovie]

i'm also planing on ceramic coating the exhaust and nansulating the intake cause the intake gets to almost 300 degrees at idle and full temp right at the last 3 -4 inches of the ports so if i do though's two things then i'm hoping for cooler intake temps and better power and FE with the fuel heater also, from what i understand colder intake is better then the warm air intake as long as the fuel is also heated for better atomization and more power so you can hit lower rpms on cruising if your geared right anyway

NanoBoost liquid applied automotive parts coating for thermal insulation

[UFO]

Quoting myself here, but I filled up last night, and confirmed a huge increase in fuel mileage with my thermostat change. That's two tanks in a row, one B33, one B65 where I got 46mpg, 6mpg better than previous tanks. My worn out thermostat was regulating 165F before, now 192F.

That's a 15% gain!!

Originally Posted by UFO

I just got a big jump in economy by replacing my thermostat. It was running coolant temperature at 165F with the worn out part. Now it runs 192F. Completely fooled the ScanGauge, I was running normal tank mileage around 40mpg, filled up today and I actually had 46mpg. And I calibrated my pump nozzle just to be sure, I was so surprised. I filled the tank the same way too, but if it didn't really fill, I will catch the drop next fillup.

[ShadeTreeMech]

Originally Posted by pasaunde

In theory, higher coolant temps means less heat transfer (energy loss) to the coolant system and more energy available to do work on the piston.

One of the best of the hypermilers here, palemalasian, gets good economy in part due to living in a warm climate, and if I remember correctly he uses a block heater too.

There may be some small change in fuel atomization with warmer coolant, but it is nothingcompared to the gains possible when less energy is used to warm coolant. With cooler coolant, more energy is used to warm the engine that would have otherwise been used to push the piston down with more force.

So I would say it is less theory and more like a proven fact that a warm engine is more efficient thana cool engine, and less efficient than a hot engine. I've read an article here describing a crazy high efficiency engine that was severely insulated and heated the gas to a vapor. Will find the link when I get to the comp, using my phone right now.

[endurance]

Since I put on my grill block at the same time as I put in my SGII, I really can't say how much warmer my car is running or how much mpg was gained by the grill block alone. However, it does have a 180f thermostat and now routinely runs between 192-202 with routine excursions to 213f when climbing long, continuous grades. At the same time, I'm getting 25-30% better mpg this winter over last winter, using the same snow tires and same winter gas. I was up over 40% until winter got nasty over the last three weeks. While I believe the overwhelming majority of that gain has come from improved hypermiling technique, I have to believe that at least some is coming from the higher operating temperature, too.

I know, there's no science in any of that, but until warmer weather returns so I'm challenged with overheating issues, I'm not going to do any A-B-A testing.

[Ang84Indy]

I always run a 195 in all my cars. Also change them every few years, I don't wait for them to fail.

[watercat]

What would be a good target temp for the fuel line? if you warm the fuel will it be able to evaporate from the tank easier building pressure and getting past the fuel tank cap? I'm thinking of my veggie burner and that tank got fairly warm but we vent to the outside?

what about temps on the intake for the air? I have a geo with the factory cold air intake system which could be easily modified to draw warm air.

[stovie]

in my opinion the warm air intake is heating the wrong thing for example the temperature where i'm at is 38 degrees at night and thats how cold the fuel is in the morning so ya you can heat the air but the thing your trying to improve is the evaporation of the fuel that really sucks at 38 degrees. i have no return fuel line so i'm trying to see what happens when you heat the fuel line with the coolant line from what i've read so far i should be able to hit 180 degree fuel without vapor lock in the line.