What is VTEC? - school project accuracy
05-31-2011, 08:34 PM
#1
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What is VTEC? - school project accuracy
hey this is a paper i wrote up for a project. i want it to be as factually accurate as possible.
plz tell me what you think! it's an optical illusion, its not actually as long as it looks and ill give you a free cookie
plz tell me what you think! it's an optical illusion, its not actually as long as it looks and ill give you a free cookie
Originally Posted by my massive brain and interweb research
VTEC is a largely misunderstood term among the informed and uninformed alike. There is almost as much misinformation circulating around the concept of VTEC as there is factual explanation, and a straightforward breakdown in simple terms is nearly unheard of. VTEC stands for Variable Valve Timing/Lift and Electronic Control. It was invented by Honda in 1983 to sidestep tax regulations affecting performance in Japan. Due to the number of vehicles in Japan at the time, new regulations were rapidly beginning to take effect on the new vehicles being produced. These tax regulations were based on engine displacement in an effort to keep pollution to a minimum in a crowded city. Honda realized that it was no longer fiscally possible to increase the size of their motors to provide the much desired performance characteristics that set their vehicles apart from other manufacturers.
Honda put some of their best scientists in the research and development division to work on creating a system that would allow their motors to operate more efficiently and deliver more performance without raising the physical size of the engines. After a few months, VTEC emerged from the labs and went into production. VTEC is actually a very simple system, when you picture what it is from a practical standpoint. A motor creates power by moving air and fuel through it, and harnessing the explosive energy of the two when ignited. Honda realized that instead of increasing the size of the explosion, they could increase the power it produced by introducing more air and fuel in the same volume. Raising the size of the combustion chamber was not an option, so they had to find a way to pack more air and fuel into a smaller space. Adding more fuel to the equation was not a problem, because by this point they already had complete control over the fuel delivery through electronic fuel injection. Adding air to the equation was a little more difficult, because the motor’s performance in relation to RPM fluctuated greatly.
The answer came from the valves and the camshafts. Honda realized that allowing the motor more air across all RPM would require a compromise between low and high RPM horsepower. As new camshafts were tested it became apparent that two different camshaft profiles were necessary for smooth power delivery throughout the powerband. At low RPM, the motors performed best with limited air in the fuel mixture. At high RPM, the motors were capable of flowing much more air and fuel, thus exponentially increasing the high RPM horsepower. Before this discovery, there was an intake and exhaust lobe on the camshaft, each controlling a separate rocker arm to actuate the respective valves to flow air through the motor. Honda introduced a third lobe to their camshafts, which had a higher lift and duration than the intake or exhaust lobes. This was called the VTEC lobe, and was capable of opening the valves further and for longer than the low RPM intake and exhaust lobes on the camshaft. In simple terms, when engaged – the VTEC lobe could allow the motor to flow much more air through the combustion chamber – provided it could keep up to the demand.
After tuning the ‘crossover point’ at which the valves were controlled by the high RPM camshaft lobe, Honda was able to effectively increase high RPM horsepower by increasing the airflow and adding more fuel to the mixture to compensate. This removed a major bottleneck in the powerband, and Honda went on to create higher revving motors to take full advantage of this new design. As for the technical side of things, the VTEC crossover point (at which the ECU switched camshaft profiles) is controlled by a number of factors. Most importantly, oil pressure, engine RPM, vehicle speed, and engine temperature. The mechanical working are a large source of confusion in the Honda tuning scene but the factual data stands as follows: Once the proper data is sent to the ECU, a signal is sent to the VTEC solenoid which uses oil pressure to operate a spool valve which hydraulically locks a pin through the rocker arms. This pin binds the low RPM rocker arms to the VTEC rocker arm, which follows the VTEC camshaft lobe, effectively taking control of the valves and altering their lift and duration for better airflow.
To put things simply, VTEC allows your motor to flow more air and fuel at high RPM, thus creating significant horsepower gains over non-VTEC motors.
Honda put some of their best scientists in the research and development division to work on creating a system that would allow their motors to operate more efficiently and deliver more performance without raising the physical size of the engines. After a few months, VTEC emerged from the labs and went into production. VTEC is actually a very simple system, when you picture what it is from a practical standpoint. A motor creates power by moving air and fuel through it, and harnessing the explosive energy of the two when ignited. Honda realized that instead of increasing the size of the explosion, they could increase the power it produced by introducing more air and fuel in the same volume. Raising the size of the combustion chamber was not an option, so they had to find a way to pack more air and fuel into a smaller space. Adding more fuel to the equation was not a problem, because by this point they already had complete control over the fuel delivery through electronic fuel injection. Adding air to the equation was a little more difficult, because the motor’s performance in relation to RPM fluctuated greatly.
The answer came from the valves and the camshafts. Honda realized that allowing the motor more air across all RPM would require a compromise between low and high RPM horsepower. As new camshafts were tested it became apparent that two different camshaft profiles were necessary for smooth power delivery throughout the powerband. At low RPM, the motors performed best with limited air in the fuel mixture. At high RPM, the motors were capable of flowing much more air and fuel, thus exponentially increasing the high RPM horsepower. Before this discovery, there was an intake and exhaust lobe on the camshaft, each controlling a separate rocker arm to actuate the respective valves to flow air through the motor. Honda introduced a third lobe to their camshafts, which had a higher lift and duration than the intake or exhaust lobes. This was called the VTEC lobe, and was capable of opening the valves further and for longer than the low RPM intake and exhaust lobes on the camshaft. In simple terms, when engaged – the VTEC lobe could allow the motor to flow much more air through the combustion chamber – provided it could keep up to the demand.
After tuning the ‘crossover point’ at which the valves were controlled by the high RPM camshaft lobe, Honda was able to effectively increase high RPM horsepower by increasing the airflow and adding more fuel to the mixture to compensate. This removed a major bottleneck in the powerband, and Honda went on to create higher revving motors to take full advantage of this new design. As for the technical side of things, the VTEC crossover point (at which the ECU switched camshaft profiles) is controlled by a number of factors. Most importantly, oil pressure, engine RPM, vehicle speed, and engine temperature. The mechanical working are a large source of confusion in the Honda tuning scene but the factual data stands as follows: Once the proper data is sent to the ECU, a signal is sent to the VTEC solenoid which uses oil pressure to operate a spool valve which hydraulically locks a pin through the rocker arms. This pin binds the low RPM rocker arms to the VTEC rocker arm, which follows the VTEC camshaft lobe, effectively taking control of the valves and altering their lift and duration for better airflow.
To put things simply, VTEC allows your motor to flow more air and fuel at high RPM, thus creating significant horsepower gains over non-VTEC motors.
05-31-2011, 08:51 PM
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Re: What is VTEC? - school project accuracy
You are a little off,Actually Vtec is this little black box in the back of the block that contains a sample of chuck norris round house kick.That is partially released at a set rpm level.
On another note lol,good paper very detailed
On another note lol,good paper very detailed
06-01-2011, 08:29 AM
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Re: What is VTEC? - school project accuracy
if you want it to be accurate, you need to stop using the term motor when you're talking about an engine.
06-01-2011, 10:24 AM
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Re: What is VTEC? - school project accuracy
Unless the teacher and all the students are motorheads nobodys going to know wtf you are talking about so prepare for questions like..
"what is a camshaft?"
Good paper tho!
"what is a camshaft?"
Good paper tho!
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06-01-2011, 03:36 PM
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Re: What is VTEC? - school project accuracy
lol much better than the first guy to explain it to me
first honda I looked at buying, the guy told me he has work on multiple hondas, 20+. So I ask him what exactly is VTEC...his words..."ummm, it makes it go faster". Needless to say I did not buy his car.
first honda I looked at buying, the guy told me he has work on multiple hondas, 20+. So I ask him what exactly is VTEC...his words..."ummm, it makes it go faster". Needless to say I did not buy his car.
06-01-2011, 05:51 PM
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Re: What is VTEC? - school project accuracy
http://en.wikipedia.org/wiki/VTEC
Should have everything you need for the paper, if you want any additional information.
And careful with
Honda's first vehicle, a mid engine truck, made peak power at 8,500 RPM (I can't find redline in a quick search).
Hondas first car revved to 10,000 RPM.
I imagine that in the 60s it must have been quite the spectacle to hear a production car wind up like that. But either way, Honda cars revving high up has been going on for nearly 50 years now...
Should have everything you need for the paper, if you want any additional information.
And careful with
This removed a major bottleneck in the powerband, and Honda went on to create higher revving motors to take full advantage of this new design.
Hondas first car revved to 10,000 RPM.
I imagine that in the 60s it must have been quite the spectacle to hear a production car wind up like that. But either way, Honda cars revving high up has been going on for nearly 50 years now...
06-01-2011, 07:40 PM
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Re: What is VTEC? - school project accuracy
I'm going to assume this is for some sort of technical paper and go a little OCD...
1) If it's misunderstood by both the informed and the uninformed.... then who's left?
2) You say there is a lot of misinformation, but you never describe it until one sentence at the end of the paper.
3) Don't end a sentence with a preposition.
4) As stated, use "engine" instead of "motor".
5) I'd say "without raising their physical size" to stay consistent with the sentence structure.
6) Where did you get "after a few months"? Do you have a source or did you just guess that it took a few months?
7) Don't use the word "very".
8) The comma isn't needed after "system".
9) The fuel is what delivers the energy in an engine (not a motor), and it's not released via an explosion. It burns (in an exothermic reaction).
10) VTEC doesn't really increase peak volumetric efficiency that much. It just makes the VE curve more broad. In your paper, you describe this as "introducing more air and fuel in the same volume", so I'd change the wording a bit.
11) Increasing combustion chamber volume would reduce power because it lowers the compression ratio of the engine. It has a minimal effect on trapped air mass.
12) "Raising the size of the combustion chamber was not an option, so they had to find a way to pack more air and fuel into a smaller space" is a logical fallacy. If you change "a smaller space" into "an equal volume" or something like that, then it'll work.
13) "Adding xxxx to the equation" is basically slang. There is no actual equation.
13) "the motor’s performance in relation to RPM fluctuated greatly" <- How so? What aspect of performance? Can you quantify "greatly"?
14) "RPM" is a unit for engine speed.
15) "At low RPM, the motors performed best with limited air in the fuel mixture." <- This implies the engine ran best with a richer mixture, which is probably not what you meant.
16) Was the power gain actually exponential? Can you quantify it?
17) This wasn't really a discovery for them. The effect of cam profile on the torque curve had been well known, but integrating multiple cam profiles into the same camshaft was the new technology.
18) There were multiple intake and exhaust lobes on each camshaft.
19) ", and was capable" should be ", and it was capable".
20) I'd use a comma instead of a hyphen.
21) How much more air is "much more air"?
22) What is the demand? In what conditions could it exceed this demand?
23) The crossover point is the point at which the VTEC lobe begins to dictate valve motion, not the only point at which it dictates valve motion. Your wording is a little misleading.
24) If possible, say how much airflow increased and how much power increased.
25) I keep stumbling over "bottleneck in the powerband". Bottleneck isn't really the right word to use there.
26) Don't say "As for the technical side of things".
27) "Most importantly, oil pressure, engine RPM, vehicle speed, and engine temperature." is not a complete sentence.
28) "a signal is sent to the VTEC solenoid which uses oil pressure to operate a spool valve which hydraulically locks a pin through the rocker arms" <- There are multiple pins used. This is also a pretty wordy sentence.
29) "allows your motor" <- Only mine?
That's what I found at first glance. It seems like a lot, but your writing is still a lot better than most of the stuff I read online.
Hope that helps (and isn't too late).
1) If it's misunderstood by both the informed and the uninformed.... then who's left?
2) You say there is a lot of misinformation, but you never describe it until one sentence at the end of the paper.
3) Don't end a sentence with a preposition.
4) As stated, use "engine" instead of "motor".
5) I'd say "without raising their physical size" to stay consistent with the sentence structure.
6) Where did you get "after a few months"? Do you have a source or did you just guess that it took a few months?
7) Don't use the word "very".
8) The comma isn't needed after "system".
9) The fuel is what delivers the energy in an engine (not a motor), and it's not released via an explosion. It burns (in an exothermic reaction).
10) VTEC doesn't really increase peak volumetric efficiency that much. It just makes the VE curve more broad. In your paper, you describe this as "introducing more air and fuel in the same volume", so I'd change the wording a bit.
11) Increasing combustion chamber volume would reduce power because it lowers the compression ratio of the engine. It has a minimal effect on trapped air mass.
12) "Raising the size of the combustion chamber was not an option, so they had to find a way to pack more air and fuel into a smaller space" is a logical fallacy. If you change "a smaller space" into "an equal volume" or something like that, then it'll work.
13) "Adding xxxx to the equation" is basically slang. There is no actual equation.
13) "the motor’s performance in relation to RPM fluctuated greatly" <- How so? What aspect of performance? Can you quantify "greatly"?
14) "RPM" is a unit for engine speed.
15) "At low RPM, the motors performed best with limited air in the fuel mixture." <- This implies the engine ran best with a richer mixture, which is probably not what you meant.
16) Was the power gain actually exponential? Can you quantify it?
17) This wasn't really a discovery for them. The effect of cam profile on the torque curve had been well known, but integrating multiple cam profiles into the same camshaft was the new technology.
18) There were multiple intake and exhaust lobes on each camshaft.
19) ", and was capable" should be ", and it was capable".
20) I'd use a comma instead of a hyphen.
21) How much more air is "much more air"?
22) What is the demand? In what conditions could it exceed this demand?
23) The crossover point is the point at which the VTEC lobe begins to dictate valve motion, not the only point at which it dictates valve motion. Your wording is a little misleading.
24) If possible, say how much airflow increased and how much power increased.
25) I keep stumbling over "bottleneck in the powerband". Bottleneck isn't really the right word to use there.
26) Don't say "As for the technical side of things".
27) "Most importantly, oil pressure, engine RPM, vehicle speed, and engine temperature." is not a complete sentence.
28) "a signal is sent to the VTEC solenoid which uses oil pressure to operate a spool valve which hydraulically locks a pin through the rocker arms" <- There are multiple pins used. This is also a pretty wordy sentence.
29) "allows your motor" <- Only mine?
That's what I found at first glance. It seems like a lot, but your writing is still a lot better than most of the stuff I read online.
Hope that helps (and isn't too late).
06-02-2011, 05:42 AM
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06-02-2011, 03:12 PM
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Re: What is VTEC? - school project accuracy
Devices converting heat energy into motion are referred to as engines,[3] which come in many types. A common type is a heat engine such as an internal combustion engine which typically burns a fuel with air and uses the hot gases for generating power. External combustion engines such as steam engines use heat to generate motion via a separate working fluid.
Another common type of motor is the electric motor. This takes electrical energy and generates mechanical motion via varying electromagnetic fields.
Other motors including pneumatic motors that are driven by compressed air, and motors can be driven by elastic energy, such as springs. Some motors are driven by non combustive chemical reactions. Molecular motors like myosins in muscles generate useful mechanical motion in biological systems by chemical reactions like ATP hydrolysis."
pulled straight from wikipedia. beside who really cares which term? does it confuse you on if he has a converted hybrid car? and yes i know the technical differences
06-02-2011, 03:37 PM
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Re: What is VTEC? - school project accuracy
06-02-2011, 05:54 PM
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Re: What is VTEC? - school project accuracy
06-02-2011, 05:57 PM
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06-02-2011, 06:25 PM
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Re: What is VTEC? - school project accuracy
What class is this? Haha, I feel like you could just use a bunch of big words and engine components to make this seem like a very informative paper even if its all just bs haha
06-02-2011, 08:31 PM
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Re: What is VTEC? - school project accuracy
That's why I asked what class it was for. If it's just some random writing assignment, then it probably won't matter. If it's for some sort of physics/engineering class, then he'd get chewed out.
06-02-2011, 10:37 PM
#21
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Re: What is VTEC? - school project accuracy
While this description is pretty good, the OP needs to correct it. The VTEC described says it affects both intake and exhaust valves.. Unfortunately, until very recently, vtec only affected the intake valves and it was one vtec lobe for both intake valves not one lobe for intake and exhaust valves. Obviously the VTEC implementation has evolved but what is being described in the OP, I'd imagine is for the original implemenation. Otherwise I think it's an acceptable writeup.
06-03-2011, 03:19 AM
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Re: What is VTEC? - school project accuracy
While this description is pretty good, the OP needs to correct it. The VTEC described says it affects both intake and exhaust valves.. Unfortunately, until very recently, vtec only affected the intake valves and it was one vtec lobe for both intake valves not one lobe for intake and exhaust valves.
06-03-2011, 06:11 AM
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Re: What is VTEC? - school project accuracy
I believe that is a true statement sir.
About the engine or motor thing, all engines are motors but not all motors are engines. So while it is correct to refer to an internal combustion engine as a motor, its a little more specific to refer to it as an engine.
As someone else mentioned, if this isn't for a technical class I doubt it matters.
About the engine or motor thing, all engines are motors but not all motors are engines. So while it is correct to refer to an internal combustion engine as a motor, its a little more specific to refer to it as an engine.
As someone else mentioned, if this isn't for a technical class I doubt it matters.
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