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Old 03-13-2005, 10:42 PM   #1
namtar
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Need to know

I wanna know what's the basic stats of an engine.
I know about cylinder that's okay.
But I'd like to know what 1.8L or whatever the number of L means...
is it reliated to the cylinders?
And what it improves or makes worse?
Does it have an impact on the fuel you use?
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Old 03-13-2005, 11:26 PM   #2
88GrandPrixSE
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Quote:
Originally Posted by namtar
I wanna know what's the basic stats of an engine.
I know about cylinder that's okay.
But I'd like to know what 1.8L or whatever the number of L means...
is it reliated to the cylinders?
And what it improves or makes worse?
Does it have an impact on the fuel you use?

That's related to the displacement of the engine.

Okay, there are 1000cc's (Cubic centimeters) in 1L. So, your 1.8L, that means you have 1800cc's of displacement. Since there's 4 cylinders in a 1.8L motor, 1800/4 = 450cc per cylinder. That is how much each cylinder has for displacement.

Displacement if you don't already know means how much the piston moves up and down, how much volume it's moving.

Having a bigger engine say a 350ci (5.7L) will generally last longer than a little 2L engine, because, while the 350 is running at 1500RPM, the little 2L is running at 2500RPM, so it's doing a lot less movement, but it also has a lot more parts to it that can fail so it pretty much evens out.

The bigger the engine the more fuel it uses, the smaller, the less (to an extent, if you under-power a vehicle it will use more fuel than a bigger engine). Take the Mustangs for instence, the new ones. The GT's have a 4.6L motor and probably get about 25mpg (highway) while the V6's 4L, get probably closer to 30mpg (highway) and the 4L will be way better in the city too, it's the city where the mileage gain is most noticeable in smaller engines.
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Old 03-13-2005, 11:32 PM   #3
osborste
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nicely done
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Old 03-23-2005, 02:40 AM   #4
Zepplin89
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Quote:
Originally Posted by namtar
And what it improves or makes worse?
Does it have an impact on the fuel you use?
you can improve your displacement by having the cylinders bored out (usually like .030") but you will need new cylinders and rings so it can get kinda expensive. some times the compression will go up depending on how much you bore, which will mean higher octane fuel.
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Old 03-23-2005, 02:54 AM   #5
88GrandPrixSE
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Quote:
Originally Posted by Zepplin89
you can improve your displacement by having the cylinders bored out (usually like .030") but you will need new cylinders and rings so it can get kinda expensive. some times the compression will go up depending on how much you bore, which will mean higher octane fuel.

You mean you'd need new pistons and rings.

Boring out the cylinders doesn't raise the compression, compression remains the same, only a few things will increase compression such as:
1) Different Crankshaft
2) Longer Rods
3) Pistons that sit higher on the rods
4) Turbo/Supercharger (Won't increase the compression ratio, but will increase kpa)
5) Different Head
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Old 03-23-2005, 03:07 AM   #6
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Quote:
Originally Posted by Zepplin89
you can improve your displacement by having the cylinders bored out (usually like .030") but you will need new cylinders and rings so it can get kinda expensive. some times the compression will go up depending on how much you bore, which will mean higher octane fuel.


Like I said in another thread...
Quote:
Engine displacement is calculated simply by multiplying the radius of the bore squared by Pi and multiplying that by the stroke travel of the piston and that figure times the number of cylinders in that engine.

Let's take a Chrysler 383CID V-8 as an example.

Bore = 4.25
Stroke = 3.38 (rounded, actually it is 3.37.5 but noone usually goes by that figure)

The radius, half of the bore, is 2.125.

2.125 X 2.125 (bore radius squared) X Pi X 3.38(piston travel, stroke) X 8(# of cylinders)

- That up there cleaned up is 2.125 X 2.125 X 3.1416 X 3.38 X 8 = 383.59 Cubic Inches.

Take that bore radius and say... add in .030 for boring .030 over. The radius becomes 2.125 + .015 (half of .030) which equals 2.14. So now we have:

2.14 X 2.14 X 3.1416 X 3.38 X 8 = 389.03 Cubic Inches.


This doesn't cause compression to "go up." You don't get "new cylinders" but rather new pistons.
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Old 03-24-2005, 12:33 AM   #7
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Quote:
Originally Posted by 88GrandPrixSE
Displacement if you don't already know means how much the piston moves up and down, how much volume it's moving.

So do both engines in your example, the 4.7L and 4L will move the same volume but the 4.7L has to do less RPMs? So I am guessing there is a point where the larger engine can displace a large volume whereas the smaller engine won't be able to perform the equivalent RPMs to displace that volume...is this correct?
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Old 03-24-2005, 12:43 AM   #8
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Quote:
Originally Posted by boothe
So do both engines in your example, the 4.7L and 4L will move the same volume but the 4.7L has to do less RPMs? So I am guessing there is a point where the larger engine can displace a large volume whereas the smaller engine won't be able to perform the equivalent RPMs to displace that volume...is this correct?

The displacement you measure is for one stroke of each piston, so the 4.7L will move more than the 4L per stroke.

But yes, to "move" the same volume, the larger engine does less rpm. Although this is a little bit backwards, because power and torque aren't really dependent directly on the amount of displacement. It's not like 4000L of displacement per minute = 200hP.
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