how do transmission and engine interact ??

Bimmer Nerd · 03-06-2009, 12:21 AM

so i am trying to figure one thing out, why is it that when you shift from 1st or to the 2nd and the car goes faster, i know that the engine reached its maximum RPM range and it can't go any further so it needs to get to lower RPM's but if it already reached its maximum RPM where does it get the more hp from in order to accelerate and decrease the RPM at the same time, i searched the web like "how transmissions work, how engines work, SMG's but couldn't really locate the answer" here is my "theory" that i thought of when knocking my head on the table in order to figure it out. what is think is that in the 1st gear only 1 cylinder is working at its full potential and when you shift up the next cylinder kicks in and so on" but what about 12 CYL cars that have 6-7 speed transmissions ??

in the low gears are they shifting 2 cylinders at a time ??? i know it might sound like a dumb question to some of you but i would seriously love to know the answer to that question.

thank you ( hope i won't get flamed) FLAME SUIT ON

Amir87 · 03-06-2009, 12:51 AM

The best site ever: How Stuff Works

http://auto.howstuffworks.com/engine.htm - Engine

http://auto.howstuffworks.com/transmission.htm Transmission

http://auto.howstuffworks.com/dual-c...ansmission.htm DCT Transmisson

Look around and you will learn some cool stuff.

.:bHd:. · 03-06-2009, 01:35 AM

heres the simplest explanation ever. Your transmission has gears in it. Each have their own ratio or in simpler terms.. each go up to a certain speed. 1st goes up to 40mph, 2nd goes up to 65mph, so on. You can just have one gear that will go up to a 100mph, but that wont be efficient because it will take a very long time to reach that speed. So instead of having one gear, the engineers will split it between 3 gears. So now the engine could use all its potential power to go up 40mph, then change gears and use all its power to pull from 40 - 65, and so on. That way you pretty much split the load. That's why 18 wheelers have like a 15 speed transmission lol.

hope thats clear enough.

im spencer · 03-06-2009, 01:23 PM

with such a ridiculously high post count I'd figure you've got more knowledge than most certified engineers

Cloud9blue · 03-06-2009, 02:32 PM

...
the kid still has alot to to learn.

aut0sh0cker · 03-06-2009, 02:33 PM

gears are used to maximize the comparatively narrow band of engine efficiency

UncleJesse · 03-06-2009, 03:47 PM

Quote:

Originally Posted by im spencer

with such a ridiculously high post count I'd figure you've got more knowledge than most certified engineers

because knowledge on a topic always directly proportional to post count.

Crimson92 · 03-06-2009, 05:38 PM

i think its great that he asked rather than assume

Bimmer Nerd · 03-06-2009, 06:55 PM

Quote:

Originally Posted by AlpineCloud9

...
the kid still has alot to to learn.

yea i do, thanx Amir87 and .:bHd:. for trying to answer my question.

easyman · 03-06-2009, 08:12 PM

its like a bike with gears.

In the 1st gear its very easy to start the bike but your legs (engine in the car) reach a certain rpm and cant pedal and faster.

You must switch to the next gear

at the highest gear it is very hard to start the bike (impossible for the car) but it is the best gear to use when already going..

at the lowest gear it takes several cycles of the pedal (or a cars engine) to turn the drive wheelss one revolution

at the highest gear it takes less than one cycle of the pedal (or the cars engine) to turn the wheels

03-06-2009, 12:21 AM	#1
Bimmer Nerd Major General 519 Rep 7,789 Posts Drives: 6MT F80 Join Date: Jun 2008 Location: Santa Monica, CA iTrader: (12)	how do transmission and engine interact ?? so i am trying to figure one thing out, why is it that when you shift from 1st or to the 2nd and the car goes faster, i know that the engine reached its maximum RPM range and it can't go any further so it needs to get to lower RPM's but if it already reached its maximum RPM where does it get the more hp from in order to accelerate and decrease the RPM at the same time, i searched the web like "how transmissions work, how engines work, SMG's but couldn't really locate the answer" here is my "theory" that i thought of when knocking my head on the table in order to figure it out. what is think is that in the 1st gear only 1 cylinder is working at its full potential and when you shift up the next cylinder kicks in and so on" but what about 12 CYL cars that have 6-7 speed transmissions ?? in the low gears are they shifting 2 cylinders at a time ??? i know it might sound like a dumb question to some of you but i would seriously love to know the answer to that question. thank you ( hope i won't get flamed) FLAME SUIT ON
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03-06-2009, 12:51 AM	#2
Amir87 Gruppe Titan 262 Rep 2,839 Posts Drives: 08 E92 SG/Coral Join Date: Sep 2007 Location: NC iTrader: (37) Garage List 2008 E92 335i [10.00]	The best site ever: How Stuff Works http://auto.howstuffworks.com/engine.htm - Engine http://auto.howstuffworks.com/transmission.htm Transmission http://auto.howstuffworks.com/dual-c...ansmission.htm DCT Transmisson Look around and you will learn some cool stuff. __________________
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03-06-2009, 01:35 AM	#3
.:bHd:. Major 331 Rep 1,149 Posts Drives: E92 335i MT Join Date: Feb 2008 Location: So Cal iTrader: (0)	heres the simplest explanation ever. Your transmission has gears in it. Each have their own ratio or in simpler terms.. each go up to a certain speed. 1st goes up to 40mph, 2nd goes up to 65mph, so on. You can just have one gear that will go up to a 100mph, but that wont be efficient because it will take a very long time to reach that speed. So instead of having one gear, the engineers will split it between 3 gears. So now the engine could use all its potential power to go up 40mph, then change gears and use all its power to pull from 40 - 65, and so on. That way you pretty much split the load. That's why 18 wheelers have like a 15 speed transmission lol. hope thats clear enough. __________________
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03-06-2009, 01:23 PM	#4
im spencer Back in the f80 55 Rep 815 Posts Drives: 2016 F80 Join Date: Nov 2007 Location: Pasadena, CA iTrader: (1) Garage List 2007 328i [0.00]	with such a ridiculously high post count I'd figure you've got more knowledge than most certified engineers __________________ 2003 SS S2000 2016 MW F80 2018 BMW X3 X-Drive
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03-06-2009, 02:32 PM	#5
Cloud9blue Brigadier General 711 Rep 3,251 Posts Drives: around the potholes Join Date: Aug 2008 Location: NY/NJ/MA iTrader: (13)	... the kid still has alot to to learn. __________________ 09 BMW E92 335i: Top Mount EFR 7670 / Dinan / AP Racing / Wavetrac / TC Kline [Full Mod List] 07 BMW R1200S: Shine Yellow / Akrapovic / Ohlins 19 Volvo V90 T6: R-Design / Bowers & Wilkins / Polestar Optimization
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03-06-2009, 02:33 PM	#6
aut0sh0cker meh 123 Rep 1,756 Posts Drives: E92 335i, 997.2 C4S Join Date: Jan 2008 Location: 91362 iTrader: (2)	gears are used to maximize the comparatively narrow band of engine efficiency
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03-06-2009, 08:12 PM	#10
easyman Private First Class 3 Rep 157 Posts Drives: M2 Join Date: Feb 2006 Location: NY iTrader: (0)	its like a bike with gears. In the 1st gear its very easy to start the bike but your legs (engine in the car) reach a certain rpm and cant pedal and faster. You must switch to the next gear at the highest gear it is very hard to start the bike (impossible for the car) but it is the best gear to use when already going.. at the lowest gear it takes several cycles of the pedal (or a cars engine) to turn the drive wheelss one revolution at the highest gear it takes less than one cycle of the pedal (or the cars engine) to turn the wheels __________________ Current: M2 Previous: 87' 325i Vert, 02' 330i, 07' GTI, 10' TSX, 15' M235i Alpinweiss .
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