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 > first report new springs with a surprize result

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Harvard

51.6N 114.7W

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Posted: 11/20/19 09:19am Link  |  Quote  |  Print  |  Notify Moderator

pianotuna wrote:

The wheels had been aligned less than 1000 miles ago.


If the wheel base were 158 inches, raising the rear end by 2.5 inches would reduce the front end caster by about 1 degree.

pianotuna

Regina, SK, Canada

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Posted: 11/20/19 11:55am Link  |  Quote  |  Print  |  Notify Moderator

It is 176 inches.

At 65 mph am getting 8.1 mpg. Day one is 585 miles to get out of the snow zone. I'll camp here tonight 43.763924, -93.316532


Regards, Don
My ride is a 28 foot Class C, 256 watts solar, 556 amp hours of AGM in two battery banks 12 volt batteries, 3000 watt Magnum hybrid inverter, Sola Basic Autoformer, Microair Easy Start.

Chum lee

Albuquerque, NM

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Posted: 11/20/19 01:36pm Link  |  Quote  |  Print  |  Notify Moderator

Just guessing. Did you, by chance, fill your tank with non-ethanol fuel or go from summer to winter blend fuel?

Chum lee

philh

Belleville MI

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Posted: 11/20/19 05:42pm Link  |  Quote  |  Print  |  Notify Moderator

JaxDad wrote:

On he contrary, any improvement in the aerodynamics of a ‘brick’ result in pretty substantial gains. Bear in mind also that as speed increases the drag does NOT increase proportional to the gain. According to Bernoulli's equation, drag is proportional to the SQUARE of THE speed.

Look up “AirTabs” and the gains that can be made by just adding some little plastic stick on tabs to a ‘brick’ and changing the vortices that form BEHIND it.


It's a FREAKING BRICK

There is NOTHING you can aerodynamically change to a FREAKING BRICK to get a 20%+ fuel economy improvement, NOTHING.

Bernoulli at 65MPH? Seriously? We're not talking about radical changes to trailing airflow, you're suggesting a slight change to turbulent airflow underneath will have a 20% improvement in fuel economy.

pianotuna

Regina, SK, Canada

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Posted: 11/20/19 11:15pm Link  |  Quote  |  Print  |  Notify Moderator

Phil,

It is NOT 20% improvement. I regularly got 9 mpg. Now I'm getting between 10 and 11 *if* I drive 49 mph. (not lie-o-meter, real measurements)

I do have air tabs--but never noted any difference in mileage, except with a tail wind--where they lowered fuel consumption a bit (measured by a lie-o-meter). They helped with cross winds--and large trucks. They helped with noise levels in the cab.

However today I was for some time driving 75 mph. The lie-o-meter was reading about 5.2. At 70 that was 5.8 and at 65 6.4. about 1/2 the trip was at 65 mph.

There was a head wind but not much of one.

I drove 585 miles and consumed 77 US gallons. That works out to 7.59 mpg. My RV weighs 13750 lbs.

drsteve

Michigan

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Posted: 11/21/19 06:42am Link  |  Quote  |  Print  |  Notify Moderator

That sounds like a heck of a change just from some aerodynamic tweaking. OTOH, when I bought a new TT my mileage decreased by about 1.5 mpg. The new trailer is virtually the same weight and a bit shorter, but it has 6-7 inches more ground clearance, and the box itself is taller.

I'd say gather some more data before drawing any firm conclusions.


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philh

Belleville MI

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Posted: 11/21/19 09:21am Link  |  Quote  |  Print  |  Notify Moderator

pianotuna wrote:

Phil,

It is NOT 20% improvement. I regularly got 9 mpg. Now I'm getting between 10 and 11 *if* I drive 49 mph. (not lie-o-meter, real measurements)

I do have air tabs--but never noted any difference in mileage, except with a tail wind--where they lowered fuel consumption a bit (measured by a lie-o-meter). They helped with cross winds--and large trucks. They helped with noise levels in the cab.

However today I was for some time driving 75 mph. The lie-o-meter was reading about 5.2. At 70 that was 5.8 and at 65 6.4. about 1/2 the trip was at 65 mph.

There was a head wind but not much of one.

I drove 585 miles and consumed 77 US gallons. That works out to 7.59 mpg. My RV weighs 13750 lbs.


9 --> 11 is a 22.2% improvement

pianotuna

Regina, SK, Canada

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Posted: 11/21/19 03:06pm Link  |  Quote  |  Print  |  Notify Moderator

Wise advice--and once I'm back to "normal" I'll do just that.

Today 450 miles driving at the speed limit. Totally out of the snow zone but I still need to do pedal to the limit.


drsteve wrote:



I'd say gather some more data before drawing any firm conclusions.


wopachop

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Posted: 11/21/19 06:52pm Link  |  Quote  |  Print  |  Notify Moderator

What a fun thread. I have some guesses.

1. New springs and airbags improved aerodynamics and reduced bouncing which might equate to less tire drag friction.


2. Maybe a rear brake pad or e-brake was dragging slightly and freed up from work done to the rear wheel area.

3. You were in snow and driving to Florida. Maybe that first gas tank was mostly downhill?

4. Fuel truck guy accidentally put the high octane into the low octane bladder.

philh

Belleville MI

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Posted: 11/22/19 09:22am Link  |  Quote  |  Print  |  Notify Moderator

wopachop wrote:

4. Fuel truck guy accidentally put the high octane into the low octane bladder.

High octane fuel has lower Btu energy. Additional power is made up from higher compression.

But you raise a good point, quality of fuel (including age) can have a huge effect on performance.

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