My first real drag race

[Jay 02 TA ws6]

You have the MN6 T-56 six speed transmision in your car. It has the following gear ratios:

1st: 2.66:1
2nd: 1.78:1
3rd: 1.30:1
4th: 1.00:1
5th: 0.74:1
6th: 0.50:1
Reverse: 2.90:1

So according to the math using a 275/40/17 (25.66") tire, if you were doing 45 MPH in 1st gear and the tach was showing roughly 5,500 RPM, that would equate to a 3.51 rear gear ratio. 50 MPH in 4th with the tach showing 2,400 RPM would equate to a 3.67 rear end.

Now obviously there are no such gear ratios available for the 10 bolt, but there are a 3.55 and a 3.73 available. You gave your indicated RPM's in likely rounded down numbers, so it's likely that your engine speed was actually a little higher which could be closer to a 3.55 or 3.73 rear end. It sounds to me like you may have an aftermarket ring and pinion with a numerically higher gear ratio.

We gotta talk about this...

I'm going to bed, but I'll try to do the math tomorrow. That doesn't seem right to me.

[Nightrage]

I have 245's all around. Not sure if or by how much that puts the math off.

[Z Ya Later]

You have the MN6 T-56 six speed transmision in your car. It has the following gear ratios:

1st: 2.66:1
2nd: 1.78:1
3rd: 1.30:1
4th: 1.00:1
5th: 0.74:1
6th: 0.50:1
Reverse: 2.90:1

So according to the math using a 275/40/17 (25.66") tire, if you were doing 45 MPH in 1st gear and the tach was showing roughly 5,500 RPM, that would equate to a 3.51 rear gear ratio. 50 MPH in 4th with the tach showing 2,400 RPM would equate to a 3.67 rear end.

Now obviously there are no such gear ratios available for the 10 bolt, but there are a 3.55 and a 3.73 available. You gave your indicated RPM's in likely rounded down numbers, so it's likely that your engine speed was actually a little higher which could be closer to a 3.55 or 3.73 rear end. It sounds to me like you may have an aftermarket ring and pinion with a numerically higher gear ratio.

Could it also be the guages were slightly off? Its not like its that uncommon for our cars. I've read the PCM and had it show the car is idling at 800 RPM yet the tach only shows about 700 at most. Say there's a 100 rpm error, then it would be 45 MPH at 5400 RPM, which is right where the car should be with a 3.42 rear gear ratio. As for the second sample, it would be 50 MPH at 2300, which is roughly 1 MPH under what it should be for a 3.42 rear. It sounds to me like your guages are slightly off, which wouldn't surprise me. As for the redline RPM in first on stock gearing, its 48 MPH with a 3.42 rear. Who's running 53+ in first stock?

[Jay 02 TA ws6]

I have 245's all around. Not sure if or by how much that puts the math off.

Depends on the rest of the size... 245/xx/xx ???

[fastTa]

I have 245's all around. Not sure if or by how much that puts the math off.

That puts you closer to the 3.42's that you more likely have.

[Jay 02 TA ws6]

You have the MN6 T-56 six speed transmision in your car. It has the following gear ratios:

1st: 2.66:1
2nd: 1.78:1
3rd: 1.30:1
4th: 1.00:1
5th: 0.74:1
6th: 0.50:1
Reverse: 2.90:1

So according to the math using a 275/40/17 (25.66") tire, if you were doing 45 MPH in 1st gear and the tach was showing roughly 5,500 RPM, that would equate to a 3.51 rear gear ratio. 50 MPH in 4th with the tach showing 2,400 RPM would equate to a 3.67 rear end.

Now obviously there are no such gear ratios available for the 10 bolt, but there are a 3.55 and a 3.73 available. You gave your indicated RPM's in likely rounded down numbers, so it's likely that your engine speed was actually a little higher which could be closer to a 3.55 or 3.73 rear end. It sounds to me like you may have an aftermarket ring and pinion with a numerically higher gear ratio.

Shouldn't have doubted your math.

Now that I've done the math, I get the same thing. 46 mph at 5500 assuming 3.42 rear, and 275/40/17 tires.

I don't think he has a numerically higher ratio. Sounds dead-on to me.

5500 RPMs would equate to the following speeds in each of the six gears:
46.15525705
68.97358637
94.44075673
122.7729837
163.6973117
245.5459675