I'm talking about CdA(used in car mags) vs. Cd(used everywhere else) to describe drag.

You want to talk about L/D ratio go right ahead. It's a more important factor in wing design, but so are weight and cost, which are also not drag, and thus are also not what we were talking about...

-b

 

ive got a spreadsheet of each fillup for the past 10,000+ miles
i bicycle to and from work.
the S is used primarily on 200-300 mile city-to-city cruises in my flat home state.
i logged gas brand, average temp, driving style, top usage, etc

it would seem that i get better mileage (28 vs 26) cruising at higher speeds (80s vs 70s)

put your egos and formulae in the backseat... ill take my anecdote and run with it

in the end , ask yourself - whats a few mpg here or there?

 

Rings sort of hollow coming from someone whose so anal that he logs gas brand, average temp, top usage, driving style...

 

Let me relate a quick story. I flew in a small plane from Atlanta to Reno over 3 days. We had a constant 20-30 knot headwind. We were flying the plane slow to conserve fuel so we could make fewer stops. Our airspeed was a constant 155kts, but our groundspeed was only 120kts. the whole way back the wind was still with us, but this time our ground speed was 180kts because it was from behind. Both times the plane was being flown at the same fuel conserving rate, but the speed was different.

Imagine doing the same thing flying a couple of inches over the ground in your S. The wind at the ground is slower, but the effect is the same. The most efficient speed will be slower into the wind and faster with the wind. Even a light wind can make a huge difference if your comparing to-from trips that give you an alternating head and tailwind.

I don't doubt that some of you have gotten some great mpg out of your cars. I just think it's due to (primarily) wind.

-b

 

Haha, this thread is great. The greatest minds battling it out when it's already been proven (on days with no wind) that the reason most ap1's get better mileage doing higher speeds is because of the fuel map. It's fine if you don't believe it, but it's a fact that early ap1s ran extremely rich in the lower rpm range, and are much leaner as they approach vtec.

And yes, by the laws of aeronatics and physics a bumble bee should not be able to fly (wing size/shape compared to body weight in simple terms).

Yes a head wind has more effect than tail wind (in simple terms think about the tail wind having to only push on the sides of the car because it is moving slower than the car, where the headwind pushes against the side and the front)

Oh well back to your regularly scheduled physics fight.

 

[QUOTE]Haha, this thread is great. The greatest minds battling it out when it's already been proven (on days with no wind) that the reason most ap1's get better mileage doing higher speeds is because of the fuel map. It's fine if you don't believe it, but it's a fact that early ap1s ran extremely rich in the lower rpm range, and are much leaner as they approach vtec.

And yes, by the laws of aeronatics and physics a bumble bee should not be able to fly (wing size/shape compared to body weight in simple terms).

Yes a head wind has more effect than tail wind (in simple terms think about the tail wind having to only push on the sides of the car because it is moving slower than the car, where the headwind pushes against the side and the front)

Oh well back to your regularly scheduled physics fight.

 

I get equal to even possibly better gas mileage at roughly 80mph versus a slower 70ish mph. It surprised me the first few times, but I finally figured it had to do with the fuel mapping and the engine being closer to the torque peak. That negated the disadvantages of higher drag. I'm sure at a certain point, the mileage started dropping, but even driving 90+mph as fast as traffic would allow coming back from an all-highway 250 mile trip still netted 26+mpg. I was impressed.

 

Okay. I couldn't resist. Lets tear it apart piece by piece and barbeque it.

Yes, the engine will run more efficiently at some given RPM. Doesn't matter what that RPM is. That lever to your right with the knob on top? It's a gear shift. It's connected to a device called a transmission that was specifically designed to allow the engine to run at various speeds relative to the vehicle speed. Try it out. Shifting down from the 80's to the 60's will be MUCH more efficient.

http://www.sciencenews.org/articles/...1/mathtrek.asp

Repeating the bumblebee tidbit just proves you don't understand physics.

A head wind is the same as a tail wind with respect to drag, which is the predominant force at the speeds we are talking about. Imagine swimming in a pool of water. Now imagine that the pool of water is on a truck slowly moving backwards or forwards. The wind is like the truck. If you swim at a constant rate, then the truck's speed directly adds to yours. Not an insignificant contribution is it?

Enjoy your popcorn.

-b

 

curiosity and record-keeping is exclusive to frugality, brother

i also log every maintenance and upgrade. its a good habit from good ownership. give it a shot

 

Not sure what you mean by this?


I admit I should not have brought up the bumble bee again. Sure it is a bit of a myth, however one that is also used as a basic problem in physics classes. I am sorry.

I would say that if you can swim 80 mph, and the truck is moving at 5mph, then yes the difference is insignificant enough that the change in fuel consumption is not comparable to the difference of consumption caused by the fuel map.

55 vs 85 will most likely go to the 55mph. However how about trying 65 vs 75 in an '00 or '01 s2000?

No one disagrees that with an ideal fuel map that higher speed = less mpg. However it is a fact that in an early s2000 the fuel map is less than ideal (this was changed in '02-'03). So while it may take more energy or in case of a car horsepower to go faster, because of the fuel map, as you approach vtec there is a point where less increase of fuel = more increase of horsepower.