Better fuel mileage in the pouring RAIN ??? ***

[japar]

I have noticed that my F350 seems to get better mpg in the rain. I made the same delivery to Conn for years and when it was raining I seemed to get more miles per tank. When I checked my fuel mileage I would average 13-15 mpg. Well yesterday I made a run to NH in the pouring rain before the return trip I topped off. 11.5 gals I went 191 miles so I got just over 16 mpg. I never ever got over 15 mpg ever. My truck is a 94 factory turbo CC dually 5 speed 4.10's. I purchased the the truck with 200K it now has almost 300K and has some blowby. With 300K and blowby I should be gettin less mileage, I did put in new G code injectors maybe 40K ago but still run the same pump and haven't changed rear tires in years. Does the diesel engine turn the mosture into super heated steam or something? Anyone else ever notice this

 

[92F350CC]

The only thing I can think of is colder air.

 

[jasonhughes]

Colder denser air plus roads have a little less friction. Imagine how it would be with an intercooler now.

 

[icanfixall]

All the above plus the air is wet so that makes better combustion. Its almost like water injection creating steam in the combustion area.

 

[GOOSE]

Maybe you are inattentively driving slower in the rain. Rain creates extra friction for the truck to push through.

 

[HammerDown]

Maybe you are inattentively driving slower in the rain. Rain creates extra friction for the truck to push through.

Water on the road surface 'may' increase rolling resistance...some...but then again, the wet road surface may cool the tire/rubber some actually helping rolling resistance. But then again, will 'cooler tires' not build pressure from heat thus hurt rolling resistance?
> driving in the rain vs dry roads...as long as tires are properly inflated, I think any difference is (for lack of better words) splitting hairs.

 

[japar]

I have owned this truck since 2005 put almost 100K on it. When I made deliveries to CT it was like 220 Miles round trip I would fill 1 tank run 200 miles and switch tanks then it was easier to caculate mileage. In the winter was the worst like 13 the few time I hit 15 it was in the rain in the summer then I was pulling in outside air. Recentlly I was testing glow plugs and changed the relay I didn't connect the plastic intake that goes to the rad support. This last trip to NH in the rain sucking in hot air from under the hood I pull over 16MPG which is a first and personal best what gives? I used to drag race a Camaro with a BBC I know about tempeture barametric pressure, altitude and humidty and yes my Camaro made more power with cool dense air but this truck is a different animal. This last run I ran 60-65 and alway try to run 2500RPM or less which is pretty much how I always drive on the highway

 

[HammerDown]

I have owned this truck since 2005 put almost 100K on it. When I made deliveries to CT it was like 220 Miles round trip I would fill 1 tank run 200 miles and switch tanks then it was easier to caculate mileage. In the winter was the worst like 13 the few time I hit 15 it was in the rain in the summer then I was pulling in outside air. Recentlly I was testing glow plugs and changed the relay I didn't connect the plastic intake that goes to the rad support. This last trip to NH in the rain sucking in hot air from under the hood I pull over 16MPG which is a first and personal best what gives? I used to drag race a Camaro with a BBC I know about tempeture barametric pressure, altitude and humidty and yes my Camaro made more power with cool dense air but this truck is a different animal. This last run I ran 60-65 and alway try to run 2500RPM or less which is pretty much how I always drive on the highway

Consider this...going down the highway even without the plastic vent running to the rad support...how much "hot air" is really in the engine compartment? I would think not much at all > but more so driving local, stop-go traffic.

 

[79jasper]

When I drove from tulsa, ok to Kansas city, I got 16 MPG. Which it was raining the way up there.

That was with the heavier leeland gin pole/winch bed.

Now I have a real light j & l flatbed. But who knows the mileage now, since I can't keep the damn thing going....