Compression VS Displacment??
Aug 22, 2006 | 11:19 PM
#21
Pro Rider
Joined: May 2004
Posts: 1,936
Likes: 2
Compression VS Displacment??
Well I would say, if money is no object, then give me the biggest motor you can, with medium compression, that flows a ton.
Remember, for every action, there is a complete and opposite reaction, atleast I think thats how it goes. But what I mean is, compression is great for acceleration, once accelerated, does nothing but hurt hp. The tighter sqeeze then becomes harder to compress. So if your building a motor that comes to power right at the last moment, then you are wanting all the compression you can get, since you are accelerating the whole time. But if you are setup to get up to speed and hold it, then you will want to weight how much compression that gets you from point a to b the fastest.
My personal taste....I like a big hp producing engine. I can gear around a lack of torque, and on the hills that I run, I can get up to speed before the hill, so its pulling peak hp on the hill. I might loose a little on the bottom, but thats how it goes If I was building an all motor engine, I would have more compression than I do.
So now that I have jumped all over the fence, with out taking a stand on one side or another[img]i/expressions/face-icon-small-happy.gif[/img], j/k, depending on what I was racing, would determine the build.
I am cheap, so I went with the stock bore/stroke build, and will take it till I have it as fast as it can possibly be. But if I had alot more money to spend, I would have to biggest thing known to mankind.
Remember, for every action, there is a complete and opposite reaction, atleast I think thats how it goes. But what I mean is, compression is great for acceleration, once accelerated, does nothing but hurt hp. The tighter sqeeze then becomes harder to compress. So if your building a motor that comes to power right at the last moment, then you are wanting all the compression you can get, since you are accelerating the whole time. But if you are setup to get up to speed and hold it, then you will want to weight how much compression that gets you from point a to b the fastest.
My personal taste....I like a big hp producing engine. I can gear around a lack of torque, and on the hills that I run, I can get up to speed before the hill, so its pulling peak hp on the hill. I might loose a little on the bottom, but thats how it goes If I was building an all motor engine, I would have more compression than I do.
So now that I have jumped all over the fence, with out taking a stand on one side or another[img]i/expressions/face-icon-small-happy.gif[/img], j/k, depending on what I was racing, would determine the build.
I am cheap, so I went with the stock bore/stroke build, and will take it till I have it as fast as it can possibly be. But if I had alot more money to spend, I would have to biggest thing known to mankind.
Aug 22, 2006 | 11:24 PM
#22
Extreme Pro Rider
Joined: Mar 2003
Posts: 3,828
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Compression VS Displacment??
Originally posted by: 650VIPER
Well I would say, if money is no object, then give me the biggest motor you can, with medium compression, that flows a ton.
Remember, for every action, there is a complete and opposite reaction, atleast I think thats how it goes. But what I mean is, compression is great for acceleration, once accelerated, does nothing but hurt hp. The tighter sqeeze then becomes harder to compress. So if your building a motor that comes to power right at the last moment, then you are wanting all the compression you can get, since you are accelerating the whole time. But if you are setup to get up to speed and hold it, then you will want to weight how much compression that gets you from point a to b the fastest.
My personal taste....I like a big hp producing engine. I can gear around a lack of torque, and on the hills that I run, I can get up to speed before the hill, so its pulling peak hp on the hill. I might loose a little on the bottom, but thats how it goes If I was building an all motor engine, I would have more compression than I do.
So now that I have jumped all over the fence, with out taking a stand on one side or another[img]i/expressions/face-icon-small-happy.gif[/img], j/k, depending on what I was racing, would determine the build.
I am cheap, so I went with the stock bore/stroke build, and will take it till I have it as fast as it can possibly be. But if I had alot more money to spend, I would have to biggest thing known to mankind.
Well I would say, if money is no object, then give me the biggest motor you can, with medium compression, that flows a ton.
Remember, for every action, there is a complete and opposite reaction, atleast I think thats how it goes. But what I mean is, compression is great for acceleration, once accelerated, does nothing but hurt hp. The tighter sqeeze then becomes harder to compress. So if your building a motor that comes to power right at the last moment, then you are wanting all the compression you can get, since you are accelerating the whole time. But if you are setup to get up to speed and hold it, then you will want to weight how much compression that gets you from point a to b the fastest.
My personal taste....I like a big hp producing engine. I can gear around a lack of torque, and on the hills that I run, I can get up to speed before the hill, so its pulling peak hp on the hill. I might loose a little on the bottom, but thats how it goes If I was building an all motor engine, I would have more compression than I do.
So now that I have jumped all over the fence, with out taking a stand on one side or another[img]i/expressions/face-icon-small-happy.gif[/img], j/k, depending on what I was racing, would determine the build.
I am cheap, so I went with the stock bore/stroke build, and will take it till I have it as fast as it can possibly be. But if I had alot more money to spend, I would have to biggest thing known to mankind.
Aug 22, 2006 | 11:42 PM
#23
Pro Rider
Is Oldmanracing! Also the inventor on the DS650 carb Mod!
Is Oldmanracing! Also the inventor on the DS650 carb Mod!
Joined: Jan 2006
Posts: 408
Likes: 0
Compression VS Displacment??
Horsepower is defined as how much cfm can flow through the head.
If both motors have the same balance, then hp will be very simular.
Torque is increased by compression or displacement.
Thus for this subject, bottom power for both motors will feel alike.
The 650 will have to be geared to allow it to rev alittle higher.
The big bore advantage is that its VE is higher and thus will be a better trail and dune machine.
Plus it can run on street gas.
OMR
If both motors have the same balance, then hp will be very simular.
Torque is increased by compression or displacement.
Thus for this subject, bottom power for both motors will feel alike.
The 650 will have to be geared to allow it to rev alittle higher.
The big bore advantage is that its VE is higher and thus will be a better trail and dune machine.
Plus it can run on street gas.
OMR
Aug 22, 2006 | 11:45 PM
#24
Thread Starter
|
Pro Rider
Joined: Apr 2004
Posts: 1,739
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Compression VS Displacment??
Originally posted by: OMR
Horsepower is defined as how much cfm can flow through the head.
If both motors have the same balance, then hp will be very simular.
Torque is increased by compression or displacement.
Thus for this subject, bottom power for both motors will feel alike.
The 650 will have to be geared to allow it to rev alittle higher.
The big bore advantage is that its VE is higher and thus will be a better trail and dune machine.
Plus it can run on street gas.
OMR
Horsepower is defined as how much cfm can flow through the head.
If both motors have the same balance, then hp will be very simular.
Torque is increased by compression or displacement.
Thus for this subject, bottom power for both motors will feel alike.
The 650 will have to be geared to allow it to rev alittle higher.
The big bore advantage is that its VE is higher and thus will be a better trail and dune machine.
Plus it can run on street gas.
OMR
Aug 23, 2006 | 12:09 AM
#25
Pro Rider
Is Oldmanracing! Also the inventor on the DS650 carb Mod!
Is Oldmanracing! Also the inventor on the DS650 carb Mod!
Joined: Jan 2006
Posts: 408
Likes: 0
Compression VS Displacment??
Volumetric efficiency (VE) is used to describe the amount of fuel/air in the cylinder in relation to regular atmospheric air. If the cylinder is filled with fuel/air at atmospheric pressure, then the engine is said to have 100% volumetric efficiency. On the other hand, super chargers and turbo chargers increase the pressure entering the cylinder, giving the engine a volumetric efficiency greater than 100%. However, if the cylinder is pulling in a vacuum, then the engine has less than 100% volumetric efficiency. Normally aspirated engines typically run anywhere between 80% and 100% VE. So now, when you read that a certain manifold and cam combination tested out to have a 95% VE, you will know that the higher the number, the more power the engine can produce.
Basically, volumetric efficiency is effected by your carb, intake manifold, headers, and cam specs. All of these items effect how much fuel/air will flow into the cylinder. But remember, the more fuel/air that gets into the cylinder, the more power the engine will produce.
Answer to your question - Yes.
Basically, volumetric efficiency is effected by your carb, intake manifold, headers, and cam specs. All of these items effect how much fuel/air will flow into the cylinder. But remember, the more fuel/air that gets into the cylinder, the more power the engine will produce.
Answer to your question - Yes.
Aug 23, 2006 | 12:14 AM
#26
Pro Rider
Joined: May 2004
Posts: 1,936
Likes: 2
Compression VS Displacment??
Originally posted by: sandbomber
[img]i/expressions/face-icon-small-happy.gif[/img] could I borrow some money now!!!!
Originally posted by: 650VIPER
Well I would say, if money is no object, then give me the biggest motor you can, with medium compression, that flows a ton.
Remember, for every action, there is a complete and opposite reaction, atleast I think thats how it goes. But what I mean is, compression is great for acceleration, once accelerated, does nothing but hurt hp. The tighter sqeeze then becomes harder to compress. So if your building a motor that comes to power right at the last moment, then you are wanting all the compression you can get, since you are accelerating the whole time. But if you are setup to get up to speed and hold it, then you will want to weight how much compression that gets you from point a to b the fastest.
My personal taste....I like a big hp producing engine. I can gear around a lack of torque, and on the hills that I run, I can get up to speed before the hill, so its pulling peak hp on the hill. I might loose a little on the bottom, but thats how it goes If I was building an all motor engine, I would have more compression than I do.
So now that I have jumped all over the fence, with out taking a stand on one side or another[img]i/expressions/face-icon-small-happy.gif[/img], j/k, depending on what I was racing, would determine the build.
I am cheap, so I went with the stock bore/stroke build, and will take it till I have it as fast as it can possibly be. But if I had alot more money to spend, I would have to biggest thing known to mankind.
Well I would say, if money is no object, then give me the biggest motor you can, with medium compression, that flows a ton.
Remember, for every action, there is a complete and opposite reaction, atleast I think thats how it goes. But what I mean is, compression is great for acceleration, once accelerated, does nothing but hurt hp. The tighter sqeeze then becomes harder to compress. So if your building a motor that comes to power right at the last moment, then you are wanting all the compression you can get, since you are accelerating the whole time. But if you are setup to get up to speed and hold it, then you will want to weight how much compression that gets you from point a to b the fastest.
My personal taste....I like a big hp producing engine. I can gear around a lack of torque, and on the hills that I run, I can get up to speed before the hill, so its pulling peak hp on the hill. I might loose a little on the bottom, but thats how it goes If I was building an all motor engine, I would have more compression than I do.
So now that I have jumped all over the fence, with out taking a stand on one side or another[img]i/expressions/face-icon-small-happy.gif[/img], j/k, depending on what I was racing, would determine the build.
I am cheap, so I went with the stock bore/stroke build, and will take it till I have it as fast as it can possibly be. But if I had alot more money to spend, I would have to biggest thing known to mankind.
You betcha. If I borrow you 1 grand................will you borrow me 10 in return?
[img]i/expressions/face-icon-small-happy.gif[/img]
Aug 23, 2006 | 02:19 PM
#27
Pro Rider
Joined: Nov 2003
Posts: 668
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Compression VS Displacment??
Originally posted by: ERBEDS650
Ok, just for some fun here in chat, you have the same cams, carb, pipe, headwork, valves, CDI, 1 quad with 14 to 1 compression stock sized cylinder VS a quad with a 720/730 displacment at 11 to 1 compression? I hears some of both sides chat in here on this but not on the same page as of yet.
Love to hear everyones thoughts, Even DSnuts
Ok, just for some fun here in chat, you have the same cams, carb, pipe, headwork, valves, CDI, 1 quad with 14 to 1 compression stock sized cylinder VS a quad with a 720/730 displacment at 11 to 1 compression? I hears some of both sides chat in here on this but not on the same page as of yet.
Love to hear everyones thoughts, Even DSnuts
this has been a very constructive post without all the silliness, and I like the question and answers.
There are some key words in the question that need examined: "same cams, carb, pipe, headwork, valves, CDI,"
You will get 180 degree opposing answers from different people, yet they may all be right "in their experience" using the same cams, carb, etc.... Why?
222
Aug 23, 2006 | 02:32 PM
#28
Pro Rider
Joined: Nov 2003
Posts: 668
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Compression VS Displacment??
Originally posted by: maxxedouty
another way to put it is that the longer the stroke the more the torque, however the best combo would be a squared as 4"stroke & a 4" bore.
another way to put it is that the longer the stroke the more the torque, however the best combo would be a squared as 4"stroke & a 4" bore.
222
