| From | Message |
Alt-Tab
Dodge Dakota
11/16/2001
20:59:58
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 Subject: 3.9 specs
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Message:
Hey everyone, I just got my Dakota a week and a half ago, and I'm already getting into it. I previously owned a 1992 Mazda MX-3 (which I loved dearly) and decided on a truck for something different. The more I drive this truck, the more I like it. But I'd like to get a little information about some things. If you don't feel like answering all my questions, but you can show me where to find the answers, that would be GREAT.
1995 Dodge Dakota Sport Regular Cab
3.9L V6 Automatic transmission 2wd
Here's what I need:
Displacement (cc):
Horsepower @ ?rpm:
Torque @ ?rpm:
Compression ratio: ?:1
Gear Ratio 1st:
Gear Ratio 2nd:
Gear Ratio 3rd:
Gear Ratio 4th:
Final Drive Ratio:
I appreciate any replies, and I apologise if these are stupid questions, or have been covered before. Soon I'll be able to post something intelligent. :-)
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Alt-Tab
Dodge Dakota
11/17/2001
00:04:18
|  RE: 3.9 specs
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Message:
Is this right?
"3.9-liter V6 with 175 horsepower and 225 pound-feet of torque"
What rpms are those measured at? Is this rwhp or bhp? I need the info for some comparisons I'm doing. Thanks in advance for any replies.
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bernd
*GenIII*
11/17/2001
01:14:01
| RE: 3.9 specs
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Message:
Displacement = 3.9L (that's 3900cc or 239CID)
HP and TQ are as Alt-Tab posted
Compression ratio is: 9.1:1
I've got the auto and manual transmission ratios in a spreadsheet in the Tips and Tricks section of SpeedTweaks.
1997 Dodge Dakota SLT - V6
Supercharged/Intercooled @ 10# w/Nitrous
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Alt-Tab
Dodge Dakota
11/17/2001
02:29:26
| RE: 3.9 specs
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Message:
Thank you VERY MUCH! That's just what I needed.
Displacement (cc): 3888
Gear Ratio 1st: 2.74
Gear Ratio 2nd: 1.54
Gear Ratio 3rd: 1.10
Gear Ratio 4th: 0.69
Final Drive Ratio: 4.55 ??? Is this right?
How is the final drive ratio calculated? When I add the 4 gear numbers I get 6.07...Where does 4.55 come from?
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bernd
*GenIII*
11/17/2001
02:49:35
| RE: 3.9 specs
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Message:
Let me explain the metric system to you:
3.9 Liters = 3900 Cubic Centimeters = .0039 Cubic Meters (it's all based on x10).
3.9L actually equates out to 237.9926 Cubic Inches.
1997 Dodge Dakota SLT - V6
Supercharged/Intercooled @ 10# w/Nitrous
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Alt-Tab
Dodge Dakota
11/17/2001
02:58:25
| RE: 3.9 specs
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Message:
Then why would the spreadsheet you sent me to say 3888 cc? I always thought that the 3.9L was a rounded number BASED ON the cc. 3.888L V6 would sound mighty stupid.
For example, my previous car, a 92 Mazda MX-3 had a 1844cc V6, translated to a 1.8L V6. (The world's smallest mass produced V6.)
I knew the number would be very close to 3900cc but wanted to know the exact number.
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bernd
*GenIII*
11/17/2001
03:20:00
| RE: 3.9 specs
IP: Logged
Message:
The spreadsheet is taking the CID and converting to CC's (rounding up or down as required). It's doing this based on exact Bore and Stroke measurements. (One could say that it's slightly more accurate), but much more complex.
Here's the formula:
((0.7853982*(((BORE*25.4)^2)*(STROKE*25.4)*CYLINDERS))/1000)
It's easier to just deal with the factory rated engine size. (No one's actually heard of a 3.908L anyway. ;)
1997 Dodge Dakota SLT - V6
Supercharged/Intercooled @ 10# w/Nitrous
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Alt-Tab
Dodge Dakota
11/17/2001
03:24:27
| RE: 3.9 specs
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Message:
Thanks for the help.
Confusion cleared, I think.
Mental note: "Memorize that formula."
Wow, to think...the stuff you don't learn when you have an Import.
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Alt-Tab
Dodge Dakota
11/17/2001
03:25:36
| RE: 3.9 specs
IP: Logged
Message:
Oh, btw, what about the final drive ratio? Where does that number come from?
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bernd
*GenIII*
11/17/2001
03:58:43
| RE: 3.9 specs
IP: Logged
Message:
The Final Drive Ratio is calculated from the overdrive gear ratio and actual axle ratio.
(Axle Ratio*OD Gear Ratio) = Final Drive
.69 (5th gear) * 4.10 (My gears) = 2.829 (or 2.83)
Then, there's effective ratio...this is where you can figure out the difference of the actual gear ratio in relation to tire size (are we confused yet?). ;)
1997 Dodge Dakota SLT - V6
Supercharged/Intercooled @ 10# w/Nitrous
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Alt-Tab
Dodge Dakota
11/17/2001
18:15:23
| RE: 3.9 specs
IP: Logged
Message:
Hmm, yeah, I think I'm more confused than I started out.
How do I know what my axle ratio is?
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CW
GenIII
11/17/2001
18:34:13
|  RE: 3.9 specs
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Message:
Are you having fun with this poor guy Bernd?
2001 4.7 5sp RC 3.91 sport plus
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bernd
*GenIII*
11/17/2001
19:09:49
| RE: 3.9 specs
IP: Logged
Message:
CW: Not trying to...it was REALLY late for me and got a little bit "punchy". ;)
1997 Dodge Dakota SLT - V6
Supercharged/Intercooled @ 10# w/Nitrous
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Alt-Tab
Dodge Dakota
11/17/2001
19:16:55
| RE: 3.9 specs
IP: Logged
Message:
Heh, maybe I should find another Import...all this American stuff is confusing me.
So, what's my final drive ratio? '95 3.9L V6 auto
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bernd
*GenIII*
11/18/2001
03:41:53
| RE: 3.9 specs
IP: Logged
Message:
Final drive is calculated like this:
(Axle Ratio*OD Gear Ratio) = Final Drive
1997 Dodge Dakota SLT - V6
Supercharged/Intercooled @ 10# w/Nitrous
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Alt-Tab
Dodge Dakota
11/18/2001
13:11:04
| RE: 3.9 specs
IP: Logged
Message:
You already told me that.
What's my axle ratio?
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CW
GenIII
11/18/2001
13:24:17
| RE: 3.9 specs
IP: Logged
Message:
Look on your glove box there is a sticker there listing options and diff ratio. There is also a tag on the rear diff that should show you the ratio. Bernd is giving you the right info for final drive but that is not the same as axle ratio.
2001 4.7 5sp RC 3.91 sport plus
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cbmoose
Dodge Dakota
JOIN HERE
2/09/2003
08:12:51
|  RE: 3.9 specs
IP: Logged
Message:
Here's the scoop, from the 1993 Mopar Service Manual: 238 c.i., 9.1:1 comp ratio, forged steel connecting rods (good for high revs), nodular cast iron crank, "Fast Burn" design cylinder heads, Aluminum Alloy w/Strut pistons. 3.91 bore, 3.31 inch stroke. Same as the 318.
Now, here's some interesting stuff. A 360 has a 4.0 bore, 3.58 stroke. The 340 has a 4.04 bore, 3.31 stroke. The valve sizes on the 340 are 2.02 intake, 1.60 exhaust. The 3.9 sizes are 1.916 intake, 1.624 exhaust. Less here, more there. The 3.9 camshaft is a hydraulic roller. Good for high revs, folks used to pay big bucks for those back in the day. Now, it's standard. Valve rockers are 1.6:1 ratio. I have no lift spec on the cam, but the intake closes 50 deg ABC, opens 10 deg BTC, 240 deg duration, 26 deg overlap. The exhaust closes 16 deg ATC, opens 52 deg BBC, 248 deg duration. By comparison, a Comp Cams #CCA20-225-4 lists 240/246 duration.
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tony grzyb
Dodge Dakota
JOIN HERE
4/25/2003
17:02:42
| RE: 3.9 specs
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Message:
what is the trans ratio in 5 gear on the 1997 to the 2003 dakota sport are they the same?
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eric
Dodge Dakota
JOIN HERE
5/15/2003
22:22:32
| RE: 3.9 specs
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Message:
I would like to know the gas mileage for a 2003 3.9L with the 3.92 axle ratio.trying to compare it to the 3.55 axle ratio. City/hwy Thank you
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josh
Dodge Dakota
JOIN HERE
3/20/2005
20:21:13
| superchargers
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hi i have a 2000 3.9 dakota and i wanna supercharge it if anyone know where and how i can get one please e mail me and let me know at mopar_man20@yahoo.com
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