On 12/28/05, msnbcnnbcbs@hotmail.com <msnbcnnbcbs@hotmail.com> wrote:
> Im currently doing about 220-240 miles before the low fuel light comes on [15
> gal tank]. I'm trying to to cut back on my fuel bill every month and was
> wondering, throwing caution to the winds on losing power, as I'm more
> interested on improving efficiency at this point :P if
>
> 1. Installing an electric fan would increase the engines fuel efficiency to
> warrant the hassle and cost and
I put a Black Magic 150 on my '99 318 4x4 and the results were less
than stellar. Fuel efficiency didn't change appreciably for me -
definitely not enough to pay for the fan, even considering I got it
cheap (used) from another list member. Throttle response improved a
tiny bit. But the biggest issue was heat. The BM 150 was barely able
to keep up with my engine's cooling needs in the upstate NY summer.
On any day over 80, I'd watch the temperature needle climb from under
195 to 210 at every red light, it even crept up some when traffic
slowed down.
You really need to run a bottle or two of "water wetter" in
conjunction with one of these fans, and bias your coolant more heavily
towards straight H2O (as you're in south Florida, an 80/20
water/antifreeze mix won't be a problem from the cold weather
perspective).
> 2. Returning the Tstat to the stock 195 would be prudent/usefull to improving
> the engines fuel efficiecy.
I also had a 180 T-stat in my '99 and, again, the fuel mileage didn't
change significantly. But, a cooler engine means running a little
richer. Remember that the T-stat's temperature rating isn't the
temperature it'll keep your coolant at - it's just the coolant
temperature that will trigger the T-stat to open. The actual coolant
temperature will usually be a little higher during normal operation.
> Now if I were to put an electric fan on this thing, wouldnt leaving the 180 in
> make sense? (Im assuming the engine would get warmer as the stock fan cools
> better?)
It would be safer, as it would give the fan more time to work on
cooling things off, and if you start with cooler fluid in the radiator
it'll have a better chance of maintaining that temperature.
> Or is an aftermarket Water pump enough to not risk any engine
> overheating? (Most of my driving is freeway, but this is South Florida so...:(
On the highway, the fan doesn't matter much anyway. You're moving FAR
more air through the radiator at 60 MPH than any fan you can mount in
the engine compartment could ever hope to push. When I snapped all
the blades off my fan in the mudpit one Daktoberfest, I still drove
the truck home and the temp. gauge stayed pegged at 180 the entire
time I was moving - that's basically with no fan at all. Sure, it was
55 degrees outside, and that helped, but you see my point I hope.
> If you reccomend an electric fan, please point one out to me, Im not sure what
> it is I need :(
Bernd was really the expert on this setup in a V6 2WD. He supposedly
had his set up well enough that he didn't have an overheating problem
even in those hot Texas summers.
There's a new Black Magic that's rated somewhere around 3300 CFM -
this is bigger than the BM 150 I had on my '99, and may work out.
It'll take a long time before the tiny fuel mileage improvement you
get by installing an electric fan finally pays off. Do you have a
tonneau cover on the bed? Are you running your tires at or slightly
above the correct pressure? Are you running a tire that has high
rolling resistance?
The only thing that produced a non-trivial, repeatable mileage
difference on my '99 was putting a tonneau cover on the bed. I think
Josh got a good mileage improvement when he lowered his truck.
It's a truck. Trucks generally get bad gas mileage. What are you
getting now, anyway?
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