2000 GMC FastBack AeroCap Project

[MetroMPG]

Originally Posted by bondo

My fuel efficiency numbers always tank in cold temperatures. The air is just denser and any aero modification is not as effective.

This notion seems to come up frequently, and I want to make sure it's not misinterpreted.

Aero mods on their own aren't less effective in cold weather.

But the overall efficiency of the truck as a collection of systems is reduced in cold weather.

So if one were to methodologically test a particular aero mod in cold vs. warm weather (A-B-A as controlled as possible on the road, or in a lab), you would see a similar result in both temperature scenarios.

[bondo]

I guess this notion was incorrectly instilled in my mind when I was a young man. I remember how the crop duster pilots would shut down and not fly in the heat of a late summer day. They told me they lost lift due to the thin air.

The link below tells of how the Phoenix airport can be shut down down due to unsafe flying conditions created by air at high temperatures, look under the transportation heading.

Again, thank you for correcting my statement about how a variance in air temperature might have an effect on the performance of a vehicle, aerodynamically.

Bondo


Impacts of Temperature Extremes

[aerohead]

Originally Posted by bondo

I guess this notion was incorrectly instilled in my mind when I was a young man. I remember how the crop duster pilots would shut down and not fly in the heat of a late summer day. They told me they lost lift due to the thin air.

The link below tells of how the Phoenix airport can be shut down down due to unsafe flying conditions created by air at high temperatures, look under the transportation heading.

Again, thank you for correcting my statement about how a variance in air temperature might have an effect on the performance of a vehicle, aerodynamically.

Bondo


Impacts of Temperature Extremes

Bondo,
I've grown fairly accustomed to the taste of my own foot now,as I've stuck it in my mouth on many occasions.
I certainly got the jist of your comment and am working diligently on the precision of my own comments.
If I was as diligent and as scientific as Darin,I'd be out doing A-B-A tests year round,and knowing the difference the seasons make.
And until that time,I also,will be mindful.
Appreciate your input and encouragement,always,PK

[bondo]

Originally Posted by MetroMPG

This notion seems to come up frequently, and I want to make sure it's not misinterpreted.

Aero mods on their own aren't less effective in cold weather.

But the overall efficiency of the truck as a collection of systems is reduced in cold weather.

So if one were to methodologically test a particular aero mod in cold vs. warm weather (A-B-A as controlled as possible on the road, or in a lab), you would see a similar result in both temperature scenarios.

Darin,

In a post you put up on metrompg.com back in 2005, you discuss reasons why fuel efficiency tanks in cold weather. Your reason number 9 sums up much better what I meant to say in the qoute of mine you refer to in the quote of yours I refer to now.

Here is the link to the metrompg.com post.

9 reasons why your winter fuel economy bites! - MetroMPG.com


This may be a good topic to discuss in a new thread, like the one you made for me on the open truck bed vs. conventional camper shells. The topic does relate to Chaz's thread but I do not wish to hijack his thread with discussion on another topic.

Thanks,

Bondo

[walteraxe]

cool

[ChazInMT]

Sooo, My outage season is over and I'm headed back to Montana from Vermont. I have have gotten 15.5 mpg at worst and 17.5 mpg for my best tank of gas over the past 3 months. Not real scientific but I never saw better than 15 mpg before I put the cap on.

[KamperBob]

Originally Posted by ChazInMT

Sooo, My outage season is over and I'm headed back to Montana from Vermont. I have have gotten 15.5 mpg at worst and 17.5 mpg for my best tank of gas over the past 3 months. Not real scientific but I never saw better than 15 mpg before I put the cap on.

Glad to see you got some return on your investment.
Good luck with Zephyr going West.
KB

[swede]

Chaz,

I had heard of your cap but hadn't found your thread till just now. I read through it all and couldn't help but be impressed by the craftsmanship. Looks good indeed, but I know what you mean when you mentioned that the camera really does it make it look better. I have found that the coroplast I covered mine in really loosened up when the temp went from 10 degrees C to 30 degrees C.

Just curious, how much does the wood rib construction that you and Fubeca have used weigh in at?

[swede]

Originally Posted by ChazInMT

I have have gotten 15.5 mpg at worst and 17.5 mpg for my best tank of gas over the past 3 months. Not real scientific but I never saw better than 15 mpg before I put the cap on.

It sure sounds like a small improvement until you do the math though, doesn't it. Still puts you well ahead percentage wise, unlike those same 1-2 mpg gains would on a car that already gets 50+mpg.

I guess that's one of the blessings/curses of having a vehicle with the aerodynamics of a barn door to start out with

[ChazInMT]

Weight, Just guessing at around 55-70 Lbs. I can lift it myself fairly easily, but handling it is a real bear without 2 people. My 9yo son sometimes is the second "Man" on the job to help move it.

Yeah, on some hot days, my shrinkwrap grows a lot, looks really baggy. But as soon as I start driving it cools and shrinks back up so it isn't ever flapping in the breeze.

Good news on my trip back home, yesterday I got a 18 MPG tank of gas!!! Wooo Whoooo. At highway speeds through WI & MN (68 mph Avg I'd guess). So psyched. I have 3 more tanks to get a reading on before I'm home. Going through ND & MT today (75 mph speed limits) we'll see. Hoping for 16.5 mpg tanks.