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Marvin
Dodge Dakota
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11/06/2002
09:42:34
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 Subject: Please explain litres
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I'm confused on engine size. As I understand it, 3.9 litres is the size of the piston bore,ie. 3.9 cubic litres: is this correct?
If so, why is a smaller engine more powerful?
Why is, say, a 2.2 litre more powerful than a 3.9?
My previous vehicle was a 4.3 litre v6 Safari van. It was very strong and great for towing my boat. When I bought my 3.9 Dakota I assumed it would be close to the GMC powerwise, but it's not even close. When I pull out to pass with my Dak, I feel like I'm towing my Safari behind me.
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Lattimer
Dodge Dakota
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11/06/2002
11:11:05
| RE: Please explain litres
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Liters are a measure of the volume of displacement in an engine. THis takes the number of cylinders x cylinder bore x crank stroke. Essentially, it is the volume of air your engine can move through the a cylinders when the piston goes from bottom to top of the stroke.
So, the 2.2 is smaller, the 3.9 is in the middle, and a 4.3 is bigger.
The 2.2 feels stronger for several reasons:
1. You are probably talking about a turbo charged engine.
2. The vehicle using the 2.2 is typically very small and light.
Comparing the 4.3 to the 3.9 is easier, but you must remember that the weight of the vehicle comes into play.
The 4.3 has approximately 20 more horsepower than a 3.9, and it makes its torque at a different RPM range than the 3.9. They are different engines, so they will feel different. However, rear end gears will also make a huge difference in perceived power. THat is probably the biggest reason you feel such a difference.
Shawn
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Lew
Dodge Dakota
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11/06/2002
11:21:06
| RE: Please explain litres
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Thanks Lattimer..That's sort of what I figured.
The way you explain it clears it up.
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Jon
Dodge Dakota
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11/06/2002
18:29:18
| RE: Please explain litres
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Generally the larger displacement of the engine the stronger it is, unless you are talking about turbochargers and superchargers like was said above. However there are hundreds of other factors that determine horsepower and torque output such as valve lift and duration, compression ratio, ignition timing, etc. For the small engines to make as much power as larger engines they usually have to increas compression and igniton advance which means you would have to run higher octane fuel.
Another thing that makes a huge difference is gear ratios. Maybe the Safari was geared lower, that way it could tow more and accelerate faster but it had a lower top speed and got slightly less gas milage.
-Jon
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dogliftsleg
Dodge Dakota
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11/07/2002
16:54:38
| RE: Please explain litres
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there is app. 60 cubic inches to a litre. the 3.9 has about 234 or so ci and the 4.3 has about 258 ci.
60 is very close but is not exact, if anyone knows exactly feel free to chime in as I know you will.
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Close
Dodge Dakota
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11/07/2002
23:06:04
| RE: Please explain litres
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Close dogliftsleg, it is actually 61.024 cubic inches = 1 liter
Only reason I know is because I keep having to do dam conversions in engineering classes.
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rednek
Dodge Dakota
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11/07/2002
23:17:11
| RE: Please explain litres
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the 3.9 is a 239 cid engine
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dogliftsleg
Dodge Dakota
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11/09/2002
06:48:05
| RE: Please explain litres
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I knew it was something close to what I posted, Thankyou! the liters to ci conversions I listed were based on my 60 ci to a litre rough figure. I work in a Die shop and we us .040 as a rough figure for metric to english conversion actual is .03937etc. It gets us close enough when cutting raw stock to length before making die parts.3.9X60= 235 yeah I know it is not right but I was going for close enough just to demonstrate the app. difference to numbers some might understand.
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dogliftsleg
Dodge Dakota
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11/09/2002
06:52:38
| RE: Please explain litres
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rednek re-read my post I said the ci numbers I posted are APPROXIMATE as I knew they are off.
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sadgjk
Dodge Dakota
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11/09/2002
07:01:16
| RE: Please explain litres
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I'd hate to be rednek's kid. I bet when his boy gets a bad grade in school, long after the teacher has rubbed his nose in it with a BIG RED "F" on the top of his paper that the teacher held up for the whole class to see and the kid is totally embarrased. ol rednek gives the kid he!!, beats his heiny and sends him to bed with no dinner. Hey red ol boy the guy already said '"long before you posted"' that he knew the figures were a bit off. all he did was litres by 60 not whatever you thought he did, and he said the engine ci figures was """ABOUT""" such and such a size. I bet when you walk in the bar everyone gives you wide room to roam not because you are bad but because you are an a$$. Boy talk about a Cliff Claven act alike!!!!!
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.......
Dodge Dakota
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11/10/2002
19:19:02
| RE: Please explain litres
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Message:
A S K A JAP
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shelly
Dodge Dakota
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8/16/2005
02:08:33
| RE: Please explain litres
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thanks, as I am a girl, and new to all this engine stuff (althought a pilot, PhD and now a race car driver (open wheel as well as premier late model), just trying to understand liters.
Now I know:
61.024 cubic inches = 1 liter....thanks guys.
shelly
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WTF?
Dodge Dakota
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8/16/2005
19:22:58
| RE: Please explain litres
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What is your doctorate in? You made it through 25 years of schooling and took flight training and you don't understand volumetric displacement or how to calculate it? You don't understand the SI Metric System? Worse yet, you post that glaring lack of knowledge on a web-board instead of hitting Google and finding the answers in about 5 minutes?
Shelly, do they give those doctoral degrees away with dog food now?
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