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Rear Flap & MPG

Yahoo Message Number: 40641
I just read on another RV forum that a DP owner removed his rear mud flap and increased his MPG from 7.7 to 8.5.

I'm not particularly fond of my flap. Didn't have one on my last coach and never had a problem with the toad because the flaps behind the wheels were sufficient.

I have flaps behind the wheels of my Inspire that should also do the trick.

Anyone else heard about this or have opinions? It sounds a little far fetched but who knows?

George

'04 Inspire 51061

Re: Rear Flap & MPG

Reply #1 –
Yahoo Message Number: 40643
Hi George. I have not heard of that outcome and like you have my doubts.
Of course you could do a test. Take it off, determine the MPG and let us know if it makes a difference. Just a thought.

Lee

Lee Zaborowski, Jeanne Bortz

2007 Country Coach Intrigue #12153 Branson, Missouri
http://jeanneleez.blogspot.com

Re: Rear Flap & MPG

Reply #2 –
Yahoo Message Number: 40649
Hey George,

I am like Lee on this. Very dubious. A 9% improvement would be huge! Our coaches are like big bricks pushing the air out of the way so that we can slip through. The turbulent airflow in the rear of the coach is obviously evidenced by the collection of dirt and debris deposited there while driving through rain and mud. Not very aerodynamic to say the least! Race cars use air dams in the front to improve the flow and reduce turbulence and the resulting drag under their cars. However their interest is in speed and handling characteristics at 200+ MPH. Apha "See Ya" has a decorative front air dam. The air dam produces negligible improvement in air flow and is not very practical. If you examine many of them you will notice that they have been damaged by road conditions or driveways. A good friend of mine recently had a f/glass shop cut off several inches of his because he was constantly scraping obstructions.
IMHO, by the time the air rushes past six or more wheels mud flaps, tranny, exposed engine under parts and all of the other stuff under our coaches it is already so confused and turbulent that it hardly would even notice the flap! However, like Lee, I am open to the results of a scientific test.
BTW, I have noticed a substantial reduction in stone chips appearing on the front of my low slung Chev sedan toad vs. some other coaches that I have owned in the past that did not have the flap. So, meanwhile, I am leaving my flap hanging there!

Daron 98 Allure 30226

Re: Rear Flap & MPG

Reply #3 –
Yahoo Message Number: 40651
Daron,

On a 2005 Intrigue, I removed the rear mud flap and noticed a reduction in engine and transmission temp of about six degrees. This test was performed in temperatures ranging from 90 to 105 degrees, in a distance of about 2,000 miles. I never paid much attention to the mpg.

Joe - 2006 Intrigue 12054

Re: Rear Flap & MPG

Reply #4 –
Yahoo Message Number: 40652
Well it looks like I'm going to have to give this a try.
Will keep you posted.
George
'04 Inspire 51061

Re: Rear Flap & MPG

Reply #5 –
Yahoo Message Number: 40675
My rear flap is large, heavy and weighted to stay down while driving. It works well as protection for toad from rock damage but possibly increases dirt on toad. I had considered moving flap to just behind rear tires to reduce drag, to increase transmission cooling, to decrease dirt to engine & radiator, to hide it and to reduce fan high speed running.
I figured rear tires are source of rocks and most of dirt so flap would still be protective mounted just behing rear tires.
I figured air would be blocked by tires before flap, so drag might decrease and air trapped by tires & flap could flow over flap to cool transmission.
I figured low pressure area bdhind flap is where engine fan pushes air into, so need for fan would lessen.

Oh, that alligator that ruined my air filter was unhindered by flap being after air filter. Had the flap been moved forward, perhaps alligator would only have blackened paint.

Plenty of reasons I should have bothered to move flap forward years ago.
Possibility of less fuel use by moving flap forward or removing flap, might be enough motivation to get it done.
What a year. 6 months on TX coast enjoying big water birds and watching for the local 6+ foot alligator. Then I go to IL and in less than a month an alligator damages my coach and a great heron nearly crashes into my side of wind shield. Only 8 more days to survive in IL before I leave!

God Bless You,

Eric Lee Elliott

870.613.1398 or 800.827.5038

PMB 6755, 167 Rainbow Drive, Livingston TX 77399-1067
eric@...http://eric-elliott.com

Re: Rear Flap & MPG

Reply #6 –
Yahoo Message Number: 40680
Last year I cut 4 inches off the bottom of the rear flap and moved the CC name etc. up above the cut. I have improved fuel consumption, but not sure how much was the flap, an additive and driving slower. 8 miles to the gallon was what I have seen which included pulling some heavy grades from Arizona to Oregon. This was while towing our 2004 Honda CRV. John
2002 Allure
#30702

Quote from: Eric Lee Elliott\[br\
] >

My rear flap is large, heavy and weighted to stay down while

driving. It

Quote
works well as protection for toad from rock damage but possibly

increases

Quote
dirt on toad. I had considered moving flap to just behind rear

tires to

Quote
reduce drag, to increase transmission cooling, to decrease dirt to

engine &

Quote
radiator, to hide it and to reduce fan high speed running.
I figured rear tires are source of rocks and most of dirt so flap

would still

Quote
be protective mounted just behing rear tires.
I figured air would be blocked by tires before flap, so drag might

decrease

Quote
and air trapped by tires & flap could flow over flap to cool
transmission.

Quote
I figured low pressure area bdhind flap is where engine fan pushes

air into,

Quote
so need for fan would lessen.
> Oh, that alligator that ruined my air filter was unhindered by flap

being

Quote
after air filter. Had the flap been moved forward, perhaps
alligator would

Quote
only have blackened paint.
> Plenty of reasons I should have bothered to move flap forward years

ago.

Quote
Possibility of less fuel use by moving flap forward or removing

flap, might

Quote
be enough motivation to get it done.

What a year. 6 months on TX coast enjoying big water birds and

watching for

Quote
the local 6+ foot alligator. Then I go to IL and in less than a

month an

Quote
alligator damages my coach and a great heron nearly crashes into my

side of