2 questions - Fuel Economy, Hypermiling, EcoModding News and Forum

manguela · 08-06-2011, 10:25 AM

Hello,

Everyday i do some Hypermiling while working, i've reached interest numbers, but i have some remaining questions:

1. It's better AC on than Windows down. How about if I only open the windows 2 inches? Is it still better AC on?

2. The recomend RPM in highway is between the highest torque and 200 or 300 RPM forward?

Many thanks!
(sorry for my poor english)

Daox · 08-06-2011, 01:24 PM

Welcome to the site.

Windows up/down really depends on speed. If you're going 25 mph windows down is probably better. However, at higher speeds windows down and A/C on is probably going to be better. Obviously windows up and fans on full speed is the best, but if heat doesn't allow for it I usually just turn the A/C on, temperature all the way to cold, and keep the fan speeds as low as is comfortable.

Highway rpm really isn't adjustable, so the general rule is slower is better.

manguela · 08-06-2011, 03:59 PM

Quote:

Originally Posted by Daox

Windows up/down really depends on speed.

Off course, sorry, i forgot to refer that is in highway speeds

Quote:

Originally Posted by Daox

If you're going 25 mph windows down is probably better.

I agree.

Quote:

Originally Posted by Daox

However, at higher speeds windows down and A/C on is probably going to be better.

Windows down and A/C on?! Its a mistake, right?
You mean windows close and A/C on.
Do you realy think the windows only 2inches down is wrost than A/C on?

Weather Spotter · 08-06-2011, 04:33 PM

I use the windows 99% of the time. the drag is less then the penalty of the AC in my car. but all cars are different.

manguela · 08-06-2011, 05:07 PM

Quote:

Originally Posted by Weather Spotter

I use the windows 99% of the time. the drag is less then the penalty of the AC in my car. but all cars are different.

But you dont open the windows all the way down, right?

Weather Spotter · 08-06-2011, 06:09 PM

I do what is needed to keep me cool.

Weather Spotter · 08-06-2011, 06:10 PM

the cooler I am the more I ecomodd. if I over heat the nut behind the wheel gets loose.

Kodak · 08-06-2011, 06:51 PM

Manguela, you have a good point.

If windows down are better at slow speeds, and AC is better at high speeds, there must be a point where the two intersect and are identical.

Moreover, there may be a point where windows partially down is the same at AC on. I suppose you want to know what that point is. Good thought; sorry I can't be more helpful, but I think that Weather_Spotter is right and it will vary greatly by car.

By the way, your English is pretty good.

manguela · 08-06-2011, 07:47 PM

Quote:

Originally Posted by Kodak

Manguela, you have a good point.

If windows down are better at slow speeds, and AC is better at high speeds, there must be a point where the two intersect and are identical.

Moreover, there may be a point where windows partially down is the same at AC on. I suppose you want to know what that point is. Good thought; sorry I can't be more helpful, but I think that Weather_Spotter is right and it will vary greatly by car.

By the way, your English is pretty good.

Yes, I think both of you are right.
I will make some extreme test so i can have some conclusions.
When I have any news I will reply here.

Weather Spotter · 08-06-2011, 07:54 PM

I have not done any ABA testing of it but I do know that when I turn on the ac in my car the SG readings drop 2-5 MPG. the windows down has little to no impact at speeds up to 55 MPH, from 55-70 MPH its a toss up (not sure with my tail have not been that fast when it has been hot out). over 70 MPH the AC starts to be better.