2001 dakota 2wd 3.9L V6 with V8 throttle body as the only mod. Gears are 3.55 in the axle, 2.74, 1.54, 1.00, 0.69 in the trans. Tires are 265/65-16, about 1-1.25" taller than stock. (in other words, my ******* gear ratio is really high)

Soon to have 180 tstat, SCT tuner, 4.10 gears, and 1.7 roller rockers.

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Went to the track tonight to see how I am on the tree. Flickered the stage bulb every time, started out pretty good but once I had cars next to me, my lights started getting erratic. The 231 red light was just a stab at the tree, the 251 late, i let go on bottom bulb instead of halfway thru the middle bulb

I was bumping in around 800 rpm, went to 1200 once staged.

I'm having Sean program an SCT tuner for my truck, should get it at the end of this week. Hopefully I can have the tstat changed and computer fooled by next wednesday, and I can hit the wedneday night TnT and see what Sean got me.

I made 5 full pulls, then a single dump and a double dump in each lane.









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Much better than Sunday...amazing what tossing ~300 pounds of weight can do.

Couldn't hit the tree for **** tonight, but got 5 ET's in a row that would be good for a bracket race.

Average RT was .027. Average "reasonable" RT was .090

Brought my launching RPM up as well, to 1600 RPM.

I run our decal guy and his cummins 3500 at 1:41 http://www.youtube.com/watch?v=9AJAGtv5KMU

Best 60':

#11
.116
2.678
7.676
46.000
11.798
58.94

Best 330': Same as above

Best 660':

#14
-.043
2.707
7.699
46.190
11.795
59.32

 

This is more than likely not correct! No Guarantees!

So I did a google search for dakota time slips, and came across a certain site that has a very convenient timeslip database, some with pictures. I established that it basically takes a 2.20-2.30 60 foot to run low 10's. So I thought about that for a second.

On Wednesday night, I 60'd in the 2.70 even range.

60 feet divided by 2.7 seconds = average speed of 22.22 feet per second.

That divided by 2.7 seconds again is an average acceleration of 8.230 feet per second squared. (verify: 60 divided by 2.7^2 = 60/7.29 = 8.230)

60 feet divided by 2.3 seconds squared = an average acceleration of 11.342 feet per second squared.

How to make up that much acceleration?

Lets say the rolling radius of a tire is 15" (1.25 ft), first gear is 2.74, rear is 3.55.

T = Torque (Tau)
F = force
D = distance
R = radius
A = linear (tangential) acceleration
a = angular acceleration (alpha)
m = mass

T = F x D
F = m x A

T = m x A x D (yes, I know that spells MAD..but you have to be to enjoy this stuff!)

A = r x a

since R = D when talking Torque of a tire,

T = m x A x R

since A = R x a,

T = m x R x R x a

T = m x r^2 x a

Thus, Torque is directly related to Mass, Radius, and Angular Acceleration

To improve acceleration, we are to assume that mass will stay the same, and radius will stay the same. Thus, Torque must increase.

---

Hang with me here:

T = m x r^2 x a
T' = m x r^2 x a'

T/a = m x r^2
T'/a' = m x r^2

T/a = T'/a'

That's a basic ratio. I hope you're still with me. This won't be so basic.

Go back to this:

T = F x D
F = m x A

Force: 3400 pounds x 8.23 fps^2 = 3400 x 8.23 pound-feet per second squared = 3400 x 8.23 poundals

The tires are the only thing accelerating the vehicle, to the tires must be providing a tangential force of 3400 x 8.23 poundals

Torque is force times radius (distance)

T = 3400 x 8.23 poundals TIMES 1.25 feet (15" tire rolling radius)

T = 3400 x 8.23 x 1.25 poundal-feet

32.174049 poundal-feet = 1 foot-pound of torque

3400 x 8.23 x 1.25 = 34,977.5 poundal feet = 1,087.14 foot-pounds of torque

So that says that based on that guestimated weight, I'm making an average of about 1,087 foot-pounds of torque at the axle shaft.

Now let's bring the gears into the equation:

1,087 / 3.55 / 2.74 = 111 foot-pounds of torque.

I bet you're going, "That aint right!" And it's not- that's ignoring any torque multiplication going on in the torque convertor, plus I under-balled that weight. Even with being an average value, it shouldn't be that low. The V6 is supposed to be rated at 225 ft-lb of torque.

Anywho, everything in this world is relative anyways. So we'll go with it, and now work everything backwards with the new 4.10 gears.

111 * 2.74 * 4.10 = 1,246.974 foot pounds

1,246.97 * 32.174049 = 40,120.2025 poundal-feet (an improvement of 5,142.75 poundal-feet or 159.8 ft-lbs)

40,120.2025 poundal-feet divided by 1.25 feet (rolling radius) = 32,096.162 poundals

32,096.162 poundals divided by 3400 pounds = 9.44 feet per second squared (an improvement of 1.21 feet per second squared)

60 feet divided by 9.44 feet per second squared = 6.35 seconds squared.

square root of 6.35 is 2.52 seconds

So the gears alone will put me from a 2.7 to a 2.52 second 60 foot time.

Database says that a 2.52 will put me in the range of 10.86 to 11.01 1/8 mile time, leaned more towards the 10.95 range.

That's not accounting for the SCT tuner of 1.7 roller rockers, either.

 

Made some passes tonight. Only differences from last Wednesday is the 180 thermostat, Sean's SCT tune, and I had an empty fuel tank Wed night vs FULL tonight (so say I had an extra 100 pounds). One pass, I ran it out the back door to the old 1/4 mile mark that Kennedale ran to in the olden days. No idea on time of course, but I hit 5000 RPM at 70 MPH.

Best pass last time was an 11.795, worst was 11.92.
Best pass this time was an 11.574, worst was 11.77.

Safe to say that Sean got me 2 tenths on the eighth mile. Notice that the sixties are about the same, so the tuner was all down-range. The 4.10's should fix that significantly. Since the 60 didn't change, the math above still holds true to the point of a maximum gain of 2 tenths on the 60 ft time. The Downrange time is still a guesstimate, though. But with having made it to the high 50's and low 60's, I think breaking the 10's on a V6 is a very real possibility, after the 4.10's and 1.7 rockers.

If you look at the video, the engine is in absolute bog until 2500, then it takes off. If I can un-bog it with the 4.10's, there could be more to gain than I'm predicting.

total run count is 34 right now.

+.061, 2.684, 7.565@47.10, 11.574@60.30
+.039, 2.699, 7.597@46.97, 11.622@60.06
+.077, 2.719, 7.628@46.94, 11.657@60.02
+.098, 2.721, 7.635@47.07, 11.645@60.21
+.164, 2.751, 7.678@46.88, 11.710@59.97
+.577, 2.733, 7.654@46.95, 11.676@60.14
-.057, 2.748, 7.666@46.91, 11.685@60.18
-.009, 2.730, 7.640@47.05, 11.643@60.41
-.228, 2.746, 7.643@47.24, 11.655@60.54
+.542, 2.803, 7.743@47.03, 11.776@60.22 (pro tree)

http://www.youtube.com/watch?v=K5JtFyzkGvE

Some charts I found.