noob MT question
Nov 27, 2007, 01:01 PM
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noob MT question
Wide open throttle (WOT) refers to an internal combustion engine's maximum intake of air and fuel that occurs when the throttle plates inside the carburetor or throttle body are "wide open", providing the least resistance to the incoming air. In the case of an automobile, WOT is when the accelerator is depressed fully.
At WOT, manifold vacuum decreases. Ideally, to preserve driveability and fuel economy, manifold vacuum should not fall any lower than 1" (mercury).
At WOT, manifold vacuum decreases. Ideally, to preserve driveability and fuel economy, manifold vacuum should not fall any lower than 1" (mercury).
Ok so Im reading up on how MT saves gas over AT, and Im not really getting one of these points:
Driver control. Certain fuel-saving modes of operation simply do not occur in an automatic transmission vehicle, but are accessible to the manual transmission driver. For example, the manual-transmission vehicle can be accelerated gently, yet at wide open throttle (WOT), by means of shifting early to a higher gear, keeping the engine RPM in a low power band. By contrast, in an automatic transmission, the throttle position serves as the indicator of how fast the driver wishes to accelerate. If the accelerator pedal is floored, the transmission will shift to a lower gear, resulting in high engine RPM and aggressive acceleration. The thermodynamically efficient combination of open throttle and low RPMs is unavailable to the automatic transmission driver.
If I am going at say around 25km/h and I shift directly from 2nd gear to 5th gear, and floor the pedal, even though the revs are really low and Im accelerating really slow,
1) wikipedia is telling me is that the car saves more gas, while
2) our car is telling me that im getting low gas mileage becase im flooring the pedal which = lower gas efficiency.
wikipedia says that for MT in that situation saves gas, but the definiton of wide open throttle refers to maximum intake of air and fuel. How does that save gas, even if it reduces drag?
Nov 27, 2007, 09:17 PM
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wikipedia does not have accurate info i could go on there and say it rains cream soda but it doesnt mean its true so watch where you get your info from ur best bet is to ask a mechanic or some 1 who really knows kuz im not to sure about that whole thing but shifting from 2nd to 5th i would imagine is not the best thing for your motor but who knows lol
Nov 28, 2007, 01:32 PM
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To the OP: WOT will eat fuel weather you're driving with a standard gearbox or an automatic...what your car is telling you is correct. A standard gearbox will only have an MPG advantage if you don't drive and shift like a doofus (i.e. going from 2nd straight to 5th gear and then flooring it).
Nov 29, 2007, 06:41 AM
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ok thanks for the answers guys~ i also got this response from another board:
it makes sense to me now 
At WOT, air/fuel mixture system are in demand and does not save gas a bit even in any gear because when the TPS is a 100%, it will tell the PCM to spray more fuel from the injectors to the combustion chamber, and of course more ram air is in demand. At 5th gear from 2nd, the engine will accelerate slower which means demand for fuel is low., and engine rotates slower so fuel burns longer that saves fuel. But putting in high gear with low speed will but load into the transmission gears.
Never skip gears!!!! That just hurts the transmission, the only time you should ever do that is when you're playing arcade games.
Nevertheless, don't worry about all the technical stuff and readings.
Just remember, try to use as much power to start the car off, and as low RPM as you can. Too little power, would mean more work for the car to get the car moving, you know what would happen. So it's all a matter of balance between power/energy and lower RPM. If you change from start off gear, 1st or 2nd, to 3rd too early, that stresses the tranny and the engine. Too late, would mean high RPMs, would stress your wallet.
Nevertheless, don't worry about all the technical stuff and readings.
Just remember, try to use as much power to start the car off, and as low RPM as you can. Too little power, would mean more work for the car to get the car moving, you know what would happen. So it's all a matter of balance between power/energy and lower RPM. If you change from start off gear, 1st or 2nd, to 3rd too early, that stresses the tranny and the engine. Too late, would mean high RPMs, would stress your wallet.
Nov 30, 2007, 06:48 AM
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So you're saying that article was fake??? Great...all that time growing beans for nothing.
To the OP: WOT will eat fuel weather you're driving with a standard gearbox or an automatic...what your car is telling you is correct. A standard gearbox will only have an MPG advantage if you don't drive and shift like a doofus (i.e. going from 2nd straight to 5th gear and then flooring it).
To the OP: WOT will eat fuel weather you're driving with a standard gearbox or an automatic...what your car is telling you is correct. A standard gearbox will only have an MPG advantage if you don't drive and shift like a doofus (i.e. going from 2nd straight to 5th gear and then flooring it).
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