A/C and WOT

Zsteve · 07-25-2010, 10:20 AM

Quote:

Originally Posted by Zaggeron

"acceleration" means to change velocity over time. Unless your speed is increasing you are not accelerating.

Acceleration - Wikipedia, the free encyclopedia

You're confusing "pushing the accelerator" with acceleration.

no not at all. If I remember right, cars today use voltage as a means of determining acceleration (along with other things too). 0 to 5v. 0 volts is only when completely off the pedal, otherwise there is some voltage between .1 and 5V that will cause acceleration, it just varies. Even on a flat road a car will require some voltage to keep the car going at a certain speed and this will cause acceleration, but you might not go faster cuz its using that voltage just to keep from slowing down due to the weight of the car and some other factors like wind. KInda like going up hill you have to give it more gas just to keep the same speed, so you are increasing the voltage to do that but not going faster. If you kept the same voltage going up hill you would lose speed.

My main point is that a WOT cutoff is fine but anything else would mean the A/C is off most of the time and as you know, here in TX we want the A/C.

Zaggeron · 07-25-2010, 01:37 PM

@ZSteve. Last try ...

Frankly I don't know what sense you are using "acceleration". Acceleration in the normal sense doesn't have anything essential to do with how much gas you have to give the car to maintain forward motion. Acceleration is not the amount of power you put to the tires to move the car forward. Acceleration is an *increase* in speed. If you accelerate up to a specific speed then if you maintain that speed -- say 65 -- you are no longer accelerating.

Did you read that wikipedia link?

From Acceleration - Wikipedia, the free encyclopedia :

"In physics, and more specifically kinematics, acceleration is the change in velocity over time. Because velocity is a vector, it can change in two ways: a change in magnitude and/or a change in direction. In one dimension, i.e. a line, acceleration is the rate at which something speeds up."

There may be some word for what you describing, but it is not "acceleration" which has the specific meaning given above.

Perhaps you mean that since you can't really maintain an exact speed there is always a little bit of acceleration and deceleration going on. Or perhaps you mean that if the A/C shutoff were controlled by the voltage going into the ECU from the throttle it would be constantly shutting off whenever you give it some gas even if your speed remains constant. That's true, but it wouldn't be controlled by acceleration in that case. They could gate it by actual acceleration by rapidly sampling the MPH...

I agree with your overall point, but "acceleration" is not the phenomenon you are describing

Zsteve · 07-25-2010, 01:49 PM

Quote:

Originally Posted by Zaggeron

@ZSteve. Last try ...

Frankly I don't know what sense you are using "acceleration". Acceleration in the normal sense doesn't have anything essential to do with how much gas you have to give the car to maintain forward motion. Acceleration is not the amount of power you put to the tires to move the car forward. Acceleration is an *increase* in speed. If you accelerate up to a specific speed then if you maintain that speed -- say 65 -- you are no longer accelerating.

Did you read that wikipedia link?

From Acceleration - Wikipedia, the free encyclopedia :

"In physics, and more specifically kinematics, acceleration is the change in velocity over time. Because velocity is a vector, it can change in two ways: a change in magnitude and/or a change in direction. In one dimension, i.e. a line, acceleration is the rate at which something speeds up."

There may be some word for what you describing, but it is not "acceleration" which has the specific meaning given above.

Perhaps you mean that since you can't really maintain an exact speed there is always a little bit of acceleration and deceleration going on

exactly

book answers are fine and all but we all know when we say we are accelerating we mean we are stepping on the gas pedal. Im not trying to use every word to their exact meaning as most dont in here, we go by our slang for it. I guess the point Im getting at is, if there is voltage on the gas pedal wire that goes to the throttle body or whatever it goes to, the car thinks it is accelerating as it has no idea wether the car is encreasing speed or not due to the voltage applied by how much the pedal is pushed. Im not doubting the real meaning of acceleration, just using it the way we normaly do when talking about cars in here. Like I was saying about going up a steep hill, you have to basically go WOT to keep the car from losing speed and not necessarily increase speed, and in this sense we are accelerating the gas pedal but nit really the car. I think we are both on the same page just looking at it in a different angle.

Zaggeron · 07-25-2010, 01:57 PM

Quote:

Originally Posted by Zsteve

I guess the point Im getting at is, if there is voltage on the gas pedal wire that goes to the throttle body or whatever it goes to, the car thinks it is accelerating as it has no idea wether the car is encreasing speed or not due to the voltage applied by how much the pedal is pushed. Im not doubting the real meaning of acceleration, just using it the way we normaly do when talking about cars in here. Like I was saying about going up a steep hill, you have to basically go WOT to keep the car from losing speed and not necessarily increase speed, and in this sense we are accelerating the gas pedal but nit really the car. I think we are both on the same page just looking at it in a different angle.

Yea, before your last post I had edited my last post to bring up the possibility of that being what you mean. What confused me is that when most people talk about their car accelerating, they mean it in the book sense -- their car is increasing in speed.

wilsonp · 07-25-2010, 03:44 PM

No one cares about accelerating the gas pedal, and the throttle sensor is certainly not the only way to tell if the car is accelerating, not even the only sensor the car currently has.

Currently the VDC has to determine traction and wheelslip by measuring and comparing tire rotational speed at all corners. What if we turn off A/C when ever there is a 10% increase in tire rotational speed over the measurement period and the tires are all the same speed (i.e. not turning)?

Zaggeron · 07-25-2010, 03:53 PM

^
Still don't want it.

Zsteve · 07-25-2010, 07:20 PM

Quote:

Originally Posted by Zaggeron

^
Still don't want it.

ditto that just turn the thing off

07-25-2010, 01:37 PM	#77 (permalink)
Zaggeron A True Z Fanatic Join Date: Jan 2010 Location: Austin, TX Posts: 1,951 Drives: '10 370ZR '13 BRZ Rep Power: 18	@ZSteve. Last try ... Frankly I don't know what sense you are using "acceleration". Acceleration in the normal sense doesn't have anything essential to do with how much gas you have to give the car to maintain forward motion. Acceleration is not the amount of power you put to the tires to move the car forward. Acceleration is an increase in speed. If you accelerate up to a specific speed then if you maintain that speed -- say 65 -- you are no longer accelerating. Did you read that wikipedia link? From Acceleration - Wikipedia, the free encyclopedia : "In physics, and more specifically kinematics, acceleration is the change in velocity over time. Because velocity is a vector, it can change in two ways: a change in magnitude and/or a change in direction. In one dimension, i.e. a line, acceleration is the rate at which something speeds up." There may be some word for what you describing, but it is not "acceleration" which has the specific meaning given above. Perhaps you mean that since you can't really maintain an exact speed there is always a little bit of acceleration and deceleration going on. Or perhaps you mean that if the A/C shutoff were controlled by the voltage going into the ECU from the throttle it would be constantly shutting off whenever you give it some gas even if your speed remains constant. That's true, but it wouldn't be controlled by acceleration in that case. They could gate it by actual acceleration by rapidly sampling the MPH... I agree with your overall point, but "acceleration" is not the phenomenon you are describing __________________ 2010 Platinum Graphite 370z Roadster:Touring/Sport 2013 Subaru BRZ Limited Last edited by Zaggeron; 07-25-2010 at 01:53 PM.

07-25-2010, 03:44 PM	#80 (permalink)
wilsonp A True Z Fanatic Join Date: Jul 2010 Location: Virginia Posts: 1,134 Drives: 2009 Touring Sp Nav Rep Power: 16	No one cares about accelerating the gas pedal, and the throttle sensor is certainly not the only way to tell if the car is accelerating, not even the only sensor the car currently has. Currently the VDC has to determine traction and wheelslip by measuring and comparing tire rotational speed at all corners. What if we turn off A/C when ever there is a 10% increase in tire rotational speed over the measurement period and the tires are all the same speed (i.e. not turning)? Last edited by wilsonp; 07-25-2010 at 03:45 PM. Reason: Typo

07-25-2010, 03:53 PM	#81 (permalink)
Zaggeron A True Z Fanatic Join Date: Jan 2010 Location: Austin, TX Posts: 1,951 Drives: '10 370ZR '13 BRZ Rep Power: 18	^ Still don't want it. __________________ 2010 Platinum Graphite 370z Roadster:Touring/Sport 2013 Subaru BRZ Limited