Low MPG?

Does driving a total of 18 miles down a steep mountain in low gear (instead of burning up my brakes) use more fuel than driving 18 miles on level ground?
 

CliffBeer

CURRENTLY BANNED
Will be helpful to know what kind of fuel atomization system you have - EFI, carbs (Holley or Webers or ?), etc....
 

Russ Noble

GT40s Supporter
Lifetime Supporter
Why???

Forget about the brakes and the fuel consumption. Just see how quickly you can cover the distance up and down on such a neat road! :-) That'd be much more interesting.

Cheers
 
Russ Noble said:
Forget about the brakes and the fuel consumption. Just see how quickly you can cover the distance up and down on such a neat road! :-) That'd be much more interesting.
It's a very scary road, no guard rails, just trees at the lower elevation and boulders at the higher elevations. I have little interest in descending that road at 9m/s/s. I was driving a Toyota Tundra (the tow vehicle).

On the other hand, my father was making timed runs up the mountain (from 1,500' to 4,500' in 4.8 miles). The goal of the event was not to be the fastest car to the parking lot 3/4 of way up, but to have the least difference between your two timed runs. The first place finisher did it in less than 0.4 seconds. My father did it with less than a 4 second difference between his two runs (this was his first time on the mountain). For both runs he had to come to a complete stop because the clouds obscured the road.

http://www.climbtotheclouds.com/
 

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Either way it make's no CENTS. I would be happier to arrive at the bottom with the brake pad's fried. Hell it would be fun to do it in neutral. Wouldnt wear out the trans or cost anything for fuel. There is an idea for you, Call it the GT 40 trolley derby, no motors allowed. !!! There are probably more GT40's around the US without motors than with.

Jac Mac
 
jac mac said:
Either way it make's no CENTS. I would be happier to arrive at the bottom with the brake pad's fried.
If you use your brakes all the way down long mountain roads like that, it can cause your brakes to get hot enough to fade, or even catch fire.

One of the guys who drives a shuttle van at the mountain mentioned that there's a spot were you can see a car-sized piece of new blacktop on the road, and the trees above it are burned. A car burned to the ground at the spot (but the people were not injured).
 
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Ian Anderson

Lifetime Supporter
Ben
Sensible question
I remember a TV program where it was stated that with a current EFi setup the engine will not be fuelled on overrun. Supposedly the brain will only fuel with what is required to turn the engine at the required revs at the current load.

So driving down in a low gear should be a very much better consumption than the same distance on a flat road.

But if you were in a carb model I would expect lower gear = more revs per mile and thus more air drawn through and mixed with fuel so probably the same as or more fuel used than on the flat.

Ian
 

Russ Noble

GT40s Supporter
Lifetime Supporter
What a great road Ben! Thanks for the interesting link.

Is it sealed all the way up?

It's not unlike a lot of our sealed mountain passes here, which are great fun for high speed driving, and the massive drops just give you more incentive to stay on the road :-)

I know what you mean about cooking the brakes. I think most NZ enthusiasts will have experienced that at some stage on our passes. Pumping the pedal frantically as it goes to the floor as a tight corner looms up, then toss the whole lot sideways to try and scrub off some speed and avoid impending doom. Realistically there's usually a slight warning before the brakes go away completely so you can generally manage the problem. It's not so bad if you're driving but it can be a bit un-nerving if you're a passenger! Passengers tend to look at the drops, the driver is only concentrating on the road!

My road car has the hardest pads I can buy, they don't work particularly well when cold around town but boy are they good on the high speed downhill when it really counts. If you drive quickly and frequently over these passes it's also important to run top (race) quality brake fluid and change it annually otherwise it will become contaminated and boil at a much lower temperature.

Our roads here also have that same cloud/visibility problem which can come in at any time. Also, even in summer snow can come in with virtually no warning and motorists can be temporarily stranded.

The photo you posted of that road is just crying out for a GT40 thundering up it :-) And uphill is easy on the brakes:-)

What sort of car did your father compete in?

Cheers
 
Russ Noble said:
What a great road Ben! Thanks for the interesting link.

Is it sealed all the way up?
They just used the first 4.8 miles of the road which are sealed (paved). After that the paving comes and goes. There are some great photos showing of past races when it wasn't a vintage race. Some of the cars are going around the corners with the front wheels pointed the wrong way on a dirt section of the road. Back then they used the full 8 miles of the mountain road, all the way to the top.

I know what you mean about cooking the brakes. I think most NZ enthusiasts will have experienced that at some stage on our passes.
I haven't been to NZ (except once to change planes, but that doesn't count), but I've heard that once you head inland, the roads are interesting.

Our roads here also have that same cloud/visibility problem which can come in at any time. Also, even in summer snow can come in with virtually no warning and motorists can be temporarily stranded.
We didn't have any snow this year, but it is possible. The record low for Mt. Washington in July (our summer) was 24 dF (-4 dC) in 2001.

The photo you posted of that road is just crying out for a GT40 thundering up it :-) And uphill is easy on the brakes:-)

What sort of car did your father compete in?
I wouldn't recommend driving a GT40 on the road, some sections of the paved road are rougher than the dirt sections. My father was driving a Lotus Mk XI, and he kept scraping the bottom of his car on the road. Next year he's thinking of bringing a car with a higher ground clearance.

Four or five of the cars entered this year were old Sprint cars, which have high ground clearances (there were also a bunch of MGs (TA/TC/TD) entered).
 
Today's Boston Globe newspaper has an article about a Mt. Washington road race

http://www.boston.com/sports/other_sports/running/articles/2006/07/26/only_one_big_hill/

Only one (big) hill

Runners finish on top of the world at Mount Washington Road Race

By Stan Grossfeld, Globe Staff | July 26, 2006

MOUNT WASHINGTON, N.H. -- John J. (the Younger) Kelley, the 1957 Boston Marathon champion, gets serious when he recalls battling 90-mile-per-hour gusts during the 1961 Mount Washington Road Race.

"There's awe and fear of that mountain," Kelley said. "You could easily get blown off by that swirling wind at one of those high mountain curves and die. You see those memorials like, 'On this spot three hikers perished in 1938.' That doesn't do anything to fire you up."

Mount Washington demands respect. The highest wind gust ever recorded, 231 miles per hour, was recorded here in 1934 . In mid June, there are still snowfields near the summit, and below the tree line there are black flies that love flesh more than flying. The summit is shrouded in clouds two-thirds of the year, with June temperatures hovering around freezing.

[...]
 
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