oaklandopen
Member
Im gonna chalk up roids posts to drugs or alcohol
Why can't this be the new MS3?
- Thread starter chief_wiggum
- Start date
Young Roids
Member
- :
- The pennies have been saved the MS3 is mine!
No, chalk it up to weak steriods that didn't work so good as they should have.
In the early 20th century, bigger engines existed, both in road cars and sports cars. Due to the absence of displacement limit regulations, manufacturers took increasing liberties with engine size. In order to achieve power over 100 hp, most engine builders simply increased displacement, which could sometimes achieve over 10.0 L. One of the biggest straight-4s of its time was De Dietrich 17,000 cc motor. Its cubic capacity is over twice the size of the Cadillac's 500 in3 8.2 L V8, which was considered the largest engine of its type in the 1970s. These engines ran at very low rpm, often less than 1,500 rpm maximum, and had a specific output of about 10 hp/L
here is a pic of another car big engine 15.4L
here is a pic of another car big engine 15.4L
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happy and angry
Member
Young Roids, I feel compelled to correct a lot of the things you are saying in this thread. A lot of people are telling you that you are wrong; I am going to tell you why you're wrong. So this is going to be a bit long because... uh... you're really wrong a lot. I'm going to try and keep things simple because it's kind of hard to delve into some of the stuff you are talking about in great detail without getting pretty technical.
Let's start with X-stroke engines. This is prompted by this comment here:
"Stroke" refers to how many times a single piston moves up and down in a cylinder per engine cycle. An engine cycle is composed of the entire combustion cycle starting with intake, compression, combustion, exhaust.
First, a typical four stroke cycle:
1. Intake stroke. The piston moves down the cylinder (away from the combustion chamber), sucking air into the cylinder from the intake valves.
2. Compression stroke. The piston moves back up the cylinder, compressing the air charge into the combustion chamber. Fuel is injected in this stroke, usually pretty late.
Fuel and air mixture ignition happens at or near the top of the compression stroke. Some motors ignite fuel a touch early, or a touch late, depending on spark timing.
3. Combustion or power stroke. The piston is moved down the cylinder by the force of combustion. This is where an engine gets its power.
4. Exhaust stroke. The piston moves back up, forces exhaust gasses out of the cylinder using the exhaust valves.
Repeat.
There, a very, very simple internal combustion engine cycle. You generate power on every second rotation of the crankshaft, in every cylinder.
A two stroke cycle combines the steps so instead of four strokes you have two.
1. Intake and compression. Air is pulled in and compressed on the same upstroke of the motor.
Fuel and air are ignited, again, at or near the top of this stroke.
2. Power and exhaust. The piston moves down the cylinder from the force of the combustion, and the exhaust gasses are expelled from the cylinder in the same stroke.
Repeat.
A very simple two stroke cycle. I'm not gonna get into the mechanics of it, you can look all that up on Wikipedia or how stuff works. I suggest you do, actually. It's pretty cool. The important thing to notice is that a two stroke makes power in each cylinder on every single rotation of the crankshaft, rather than every second rotation.
A diesel motor. Any diesel motor, actually.
Most conventional diesels are two strokes. They are mostly turbocharged because forced induction makes it easier to get air into the cylinder with forced pressure rather than just the movement of the piston alone like in a naturally aspirated gasoline motor. So go take a look at any truck running an 8 cylinder diesel. Probably a two stroke. I believe the V10 TDI they are putting in the Audi R8 is a two stroke diesel. This is actually one of the reasons why a diesel is torque heavy. Making power on every rotation of the crankshaft means you make more power per engine revolution. Torque is a measure of force, after all, and a two stroke can generate force twice as fast as a four stroke.
And of course we all know about the 8, 10, 12, hell, even 16 cylinder gas engines out there. They are all inevitably four strokes. Stroke has no relationship to the number of cylinders, simply the mechanics of how air gets in and out and where power is generated.
When you think of a motor, and you think of a piston moving up and down in a cylinder, you may not realize this but there is a lot of weight being thrown around. The strength of an engine component is finite. If you lengthen the stroke to drastically increase displacement, you do two things: you make the motor prohibitively deep in the cylinder which can make it hard to fit in an engine compartment, if you intend the block to be strong enough to withstand the heat and forces of combustion, and you make the connecting rod very long.
The longer a connecting rod is, the harder it is to make it strong enough to withstand the force of a piston moving up and down in a cylinder. Consider the length of the 2.3 MZR stroke: 97mm. Times 6000 RPM (revs per minute) times two (one stroke up, one stroke down, per engine rotation). 1164000 mm per minute, or 116400 cm, or 1164 meters of travel in a minute (that's about 20 meters a second, or about 45mph). Doesn't sound like much, but it's moving pretty fast. The connecting rod must resist the force of the much heavier piston moving up at the top of the stroke, and resist compression at the bottom of the stroke. There is a lot of force involved, a lot of force to resist for a little stick of metal. Make it longer, and you necessarily make it proportionally weaker if you do not design for extra strength. If you design for extra strength you make it heavier or more expensive or both. Plus if you make it longer you are now moving farther per stroke which means you are now moving the piston twice as fast at a given RPM than a motor half the size.
Take the other approach and increase bore, but then you have a much bigger cylinder. To double the bore you have to more than double the size of the piston, and more than double its weight. When the weight at the end of the rod is heavier (perhaps 3 times as heavy, I'm too lazy to do the simple volume calculation for you, but it's basically grade 10 or 11 volume problems with a cylinder) you again have to make the connecting rod heavier. Much heavier.
So, now that you have a much heavier weight at the end of the connecting rod (plus a heavier connecting rod), OR simply a longer stroke making each piston move much faster per cycle, you have increased the forces involved in a single revolution of the motor significantly. You probably can't safely rev the engine as high without exceeding the strength limits of the components without spending a lot of money on expensive high strength light-weight materials like they use in high performance engines. Not really a good idea if you want your car to be affordable or reliable. Balancing the engine becomes harder, and higher revs become essentially impossible.
You've also done something else. You've just increased the heat each cylinder generates. Heat is the great enemy of every motor. When metal gets hot, it gets weak, it starts to bend easier, and if it experiences enough heat cycles (extreme heat followed by cooling down followed by extreme heat, etc) you can make many alloys brittle. You are burning more fuel in each cylinder to get the extra power you want, plus you've increased friction in each cylinder quite a bit because now the piston is either much larger is circumference and thus rubbing more surface area against the cylinder wall, or the stroke is much longer meaning a smaller circumference is rubbing along a greater length of the cylinder wall. This is another thing limiting how high you can rev the engine: the higher the revs, the more friction, the more fuel burned, the more heat. And heat breaks things.
As a more general comment, engine design involves a lot of compromises. More power means you must burn more fuel, burning more fuel means more heat and requires more air. Without making engines simply too big to fit in a modern car, you can force air in (with a turbo) or add cylinders. There are physical limits in what you can do with bore and stroke while still making the engine affordable to produce and rev sufficiently high to generate enough horsepower to be reasonably efficient. You generally pick your engine design based on the size of the engine bay, the design of the drivetrain, and the desired power for the intended application of the vehicle. I'm not going to get into that as this post is long enough (maybe some other time), but the stuff you are talking about engines in general is sort of out there.
This is really long winded, and I'm trying to be polite, but you don't know what you're talking about. Go read about this stuff. The two stroke and four stroke articles on Wikipedia have some good pictures and animated gifs, and Howstuffworks.com is a good resource for these subjects too. Read them.
Let's start with X-stroke engines. This is prompted by this comment here:
First, I don't think there are five stroke motors. But let's explain two stroke versus four stroke first, so we can get into why.
"Stroke" refers to how many times a single piston moves up and down in a cylinder per engine cycle. An engine cycle is composed of the entire combustion cycle starting with intake, compression, combustion, exhaust.
First, a typical four stroke cycle:
1. Intake stroke. The piston moves down the cylinder (away from the combustion chamber), sucking air into the cylinder from the intake valves.
2. Compression stroke. The piston moves back up the cylinder, compressing the air charge into the combustion chamber. Fuel is injected in this stroke, usually pretty late.
Fuel and air mixture ignition happens at or near the top of the compression stroke. Some motors ignite fuel a touch early, or a touch late, depending on spark timing.
3. Combustion or power stroke. The piston is moved down the cylinder by the force of combustion. This is where an engine gets its power.
4. Exhaust stroke. The piston moves back up, forces exhaust gasses out of the cylinder using the exhaust valves.
Repeat.
There, a very, very simple internal combustion engine cycle. You generate power on every second rotation of the crankshaft, in every cylinder.
A two stroke cycle combines the steps so instead of four strokes you have two.
1. Intake and compression. Air is pulled in and compressed on the same upstroke of the motor.
Fuel and air are ignited, again, at or near the top of this stroke.
2. Power and exhaust. The piston moves down the cylinder from the force of the combustion, and the exhaust gasses are expelled from the cylinder in the same stroke.
Repeat.
A very simple two stroke cycle. I'm not gonna get into the mechanics of it, you can look all that up on Wikipedia or how stuff works. I suggest you do, actually. It's pretty cool. The important thing to notice is that a two stroke makes power in each cylinder on every single rotation of the crankshaft, rather than every second rotation.
I've just explained to you what a four stroke versus a two stroke actually means. Now I'm going to show you how it has nothing to do with the number of cylinders. And I will do it with a simple example:
A diesel motor. Any diesel motor, actually.
Most conventional diesels are two strokes. They are mostly turbocharged because forced induction makes it easier to get air into the cylinder with forced pressure rather than just the movement of the piston alone like in a naturally aspirated gasoline motor. So go take a look at any truck running an 8 cylinder diesel. Probably a two stroke. I believe the V10 TDI they are putting in the Audi R8 is a two stroke diesel. This is actually one of the reasons why a diesel is torque heavy. Making power on every rotation of the crankshaft means you make more power per engine revolution. Torque is a measure of force, after all, and a two stroke can generate force twice as fast as a four stroke.
And of course we all know about the 8, 10, 12, hell, even 16 cylinder gas engines out there. They are all inevitably four strokes. Stroke has no relationship to the number of cylinders, simply the mechanics of how air gets in and out and where power is generated.
Interesting. A 5 liter inline turbo four. Okay. Now we're starting to get into the limiting factors of engine design and the economics of building a reliable engine.
When you think of a motor, and you think of a piston moving up and down in a cylinder, you may not realize this but there is a lot of weight being thrown around. The strength of an engine component is finite. If you lengthen the stroke to drastically increase displacement, you do two things: you make the motor prohibitively deep in the cylinder which can make it hard to fit in an engine compartment, if you intend the block to be strong enough to withstand the heat and forces of combustion, and you make the connecting rod very long.
The longer a connecting rod is, the harder it is to make it strong enough to withstand the force of a piston moving up and down in a cylinder. Consider the length of the 2.3 MZR stroke: 97mm. Times 6000 RPM (revs per minute) times two (one stroke up, one stroke down, per engine rotation). 1164000 mm per minute, or 116400 cm, or 1164 meters of travel in a minute (that's about 20 meters a second, or about 45mph). Doesn't sound like much, but it's moving pretty fast. The connecting rod must resist the force of the much heavier piston moving up at the top of the stroke, and resist compression at the bottom of the stroke. There is a lot of force involved, a lot of force to resist for a little stick of metal. Make it longer, and you necessarily make it proportionally weaker if you do not design for extra strength. If you design for extra strength you make it heavier or more expensive or both. Plus if you make it longer you are now moving farther per stroke which means you are now moving the piston twice as fast at a given RPM than a motor half the size.
Take the other approach and increase bore, but then you have a much bigger cylinder. To double the bore you have to more than double the size of the piston, and more than double its weight. When the weight at the end of the rod is heavier (perhaps 3 times as heavy, I'm too lazy to do the simple volume calculation for you, but it's basically grade 10 or 11 volume problems with a cylinder) you again have to make the connecting rod heavier. Much heavier.
So, now that you have a much heavier weight at the end of the connecting rod (plus a heavier connecting rod), OR simply a longer stroke making each piston move much faster per cycle, you have increased the forces involved in a single revolution of the motor significantly. You probably can't safely rev the engine as high without exceeding the strength limits of the components without spending a lot of money on expensive high strength light-weight materials like they use in high performance engines. Not really a good idea if you want your car to be affordable or reliable. Balancing the engine becomes harder, and higher revs become essentially impossible.
You've also done something else. You've just increased the heat each cylinder generates. Heat is the great enemy of every motor. When metal gets hot, it gets weak, it starts to bend easier, and if it experiences enough heat cycles (extreme heat followed by cooling down followed by extreme heat, etc) you can make many alloys brittle. You are burning more fuel in each cylinder to get the extra power you want, plus you've increased friction in each cylinder quite a bit because now the piston is either much larger is circumference and thus rubbing more surface area against the cylinder wall, or the stroke is much longer meaning a smaller circumference is rubbing along a greater length of the cylinder wall. This is another thing limiting how high you can rev the engine: the higher the revs, the more friction, the more fuel burned, the more heat. And heat breaks things.
I don't know that a large displacement 4 cylinder would only rev to 3k, but it certainly won't rev as high as a 2.5L 4 cylinder. And 4 cylinders overheat for the same reasons any other motor does. When you start having them blown and dumping more fuel in them, you increase heat per engine cycle. Our car, for example, runs pig rich to keep things cooler and avoid heat damage. What I am saying to you is at 2.3L of displacement and with a moderately sized turbo MAzda engineers are already taking extra steps to manage heat to keep it from being a problem.
You aren't bringing much truth.
The stroke is not necessarily longer just because it is a diesel. The 2.0 TDI has a stroke of 95.5 mm, which is actually slightly less than ours. The bigger reason why diesels rev lower is because the components are heavily overbuilt to deal with the stresses inherent in a diesel motor. Compression is higher and diesel makes more energy by volume than gas which translates to more force and more heat, so the block must be thicker, the rods bigger, the piston stronger. This means more weight, and as discussed earlier, this means it's harder to balance and revs are kept lower to improve reliability. As a result, diesels are more expensive.
As a more general comment, engine design involves a lot of compromises. More power means you must burn more fuel, burning more fuel means more heat and requires more air. Without making engines simply too big to fit in a modern car, you can force air in (with a turbo) or add cylinders. There are physical limits in what you can do with bore and stroke while still making the engine affordable to produce and rev sufficiently high to generate enough horsepower to be reasonably efficient. You generally pick your engine design based on the size of the engine bay, the design of the drivetrain, and the desired power for the intended application of the vehicle. I'm not going to get into that as this post is long enough (maybe some other time), but the stuff you are talking about engines in general is sort of out there.
This is really long winded, and I'm trying to be polite, but you don't know what you're talking about. Go read about this stuff. The two stroke and four stroke articles on Wikipedia have some good pictures and animated gifs, and Howstuffworks.com is a good resource for these subjects too. Read them.
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Young Roids
Member
- :
- The pennies have been saved the MS3 is mine!
no there are not five stroke motors. That's why I don't want five cylinders.
john blutarski
Member
- :
- 2004 Subaru WRX STI
wow
happy and angry (bow)
happy and angry (bow)
happy and angry
Member
Okay did you read what I wrote, or are you just ******* with me or what?
The five cylinder motor in the new Focus RS is a four stroke. Not 5, not 3, not 17 and a half, 4. The number of cylinders in a motor has zero relationship to the number of strokes in each cycle of the motor.
Nliiitend1
Member
He's honestly not even worth the keystrokes at this point...(braindead
oaklandopen
Member
actually fuel enters with the air in the intake stroke, and the fuel/air mixture compresses together.....but the rest of you explaination is pretty sound
and is there a smiley for digging yourself a deeper hole? lol
just stop roids!!
ed: sorry...don't know about direct injection, but everything else that has fuel before the valve enters with the intake.
happy and angry
Member
Yea, I guess I ended up describing the DISI stuff from our car. Not so "straightforward" an example, I guess. But the idea is there.
the only thing I can think of that roids is trying to state is that the a 4 cylinder has 2 pistons moving up at the same time, 2 pistons moving down at the same time. I think he is trying to proove the 4 cylinder 4 stroke is inherently more balanced than a 5 cylinder 4 stroke. I don't know in what manner the pistons move in a 5 cylinder and if it is more balanced/efficient/etc
Yeah they used to have issues with the odd number cylinder engines due to balance, but that was a long time ago.
This thread has gone so far off topic it's not even funny. Some of the things this guy said were down right rough, not to mention incredibly insulting.
Though some great reading came from it, it's probably time fo a lot of this to stop.
Back to the topic...
I would love to have that car in my arsenal as well as my MS3. I want to buy american, but man they make it tough. This, for certain, would be the first american car I'd buy.
Gmac
This thread has gone so far off topic it's not even funny. Some of the things this guy said were down right rough, not to mention incredibly insulting.
Though some great reading came from it, it's probably time fo a lot of this to stop.
Back to the topic...
I would love to have that car in my arsenal as well as my MS3. I want to buy american, but man they make it tough. This, for certain, would be the first american car I'd buy.
Gmac
