Top Speed Differences Between 3 55 and 3 07 Gears

[06SRTCoupe]

Greetings!

I did a search but could not find an answer to my question. Like the title says, how does going from a 3.07 to a 3.55 effect top speed in Gen 3 and Gen IV Vipers? Also, does anyone have the max speed in each gear with a 3.07 vs a 3.55? Thanks a bunch!

Regards,
-Brent

[Shooter]

Gen 3 & 4 Viper's reach their "top speed" in 5th gear. 6th is a .50 ratio and is considered an overdrive. 3.55 will help acceleration more then top speed. Better to get the 2010 gen 4 ACR 5th & 6th transmission ratio's then just c/o the final drive imho.

[Steve M]

The answer depends on a lot of variables. For a stock-ish Gen 3 car, I'll assume a 6,200 RPM rev limit, stock 345/30/19 tires, and a 0.75 5th gear ratio:

Theoretical top speed (5th gear):

3.07s: 217 MPH
3.55s: 189 MPH

You'll never get to 217 MPH with the 3.07s because you will be drag limited. If you have more power, you can overcome at least some of that.

For the Gen 4, we'll assume a 6,400 RPM rev limit (it was increased over the Gen 3), stock 345/30/19 tires, and a 0.75 5th gear ratio (stock in the 2008-2009 cars):

Theoretical top speed (5th gear):

3.07s: 224 MPH
3.55s: 195 MPH

Again, with the 3.07s, you won't get there due to drag.

And the final iteration is with the addition of the 0.80 5th gear in the 2010 cars, all else the same:

Theoretical top speed (5th gear):

3.07s: 210 MPH
3.55s: 183 MPH

[06SRTCoupe]

Thanks for the info Gents! Appreciate it!

[06SRTCoupe]

The answer depends on a lot of variables. For a stock-ish Gen 3 car, I'll assume a 6,200 RPM rev limit, stock 345/30/19 tires, and a 0.75 5th gear ratio:

Theoretical top speed (5th gear):

3.07s: 217 MPH
3.55s: 189 MPH

You'll never get to 217 MPH with the 3.07s because you will be drag limited. If you have more power, you can overcome at least some of that.

For the Gen 4, we'll assume a 6,400 RPM rev limit (it was increased over the Gen 3), stock 345/30/19 tires, and a 0.75 5th gear ratio (stock in the 2008-2009 cars):

Theoretical top speed (5th gear):

3.07s: 224 MPH
3.55s: 195 MPH

Again, with the 3.07s, you won't get there due to drag.

And the final iteration is with the addition of the 0.80 5th gear in the 2010 cars, all else the same:

Theoretical top speed (5th gear):

3.07s: 210 MPH
3.55s: 183 MPH

Quick question Steve. Wouldn't the 2010 5th gear ratio allow for a high top speed since it's a higher number? Or do I have that backwards because my brain is already fried from work this week? :D

[Stealth78]

Quick question Steve. Wouldn't the 2010 5th gear ratio allow for a high top speed since it's a higher number? Or do I have that backwards because my brain is already fried from work this week? :D

I'll answer for him, your brain is fried. Sorry couldn't help myself. In all seriousness Steve is correct and you my friend have your numbers backwards. Also to note, GenIV's with either an Arrow tune or HPT setting the Rev limiter to 6,600 rpms allows for the car to accomplish 201mph in 5th gear while retaining the factory 08, 09 5th gear ratio, which I thought was .74. This has been done, so yes it is factual.

[Stealth78]

I'll answer for him, your brain is fried. Sorry couldn't help myself. In all seriousness Steve is correct and you my friend have your numbers backwards. Also to note, GenIV's with either an Arrow tune or HPT setting the Rev limiter to 6,600 rpms allows for the car to accomplish 201mph in 5th gear while retaining the factory 08, 09 5th gear ratio, which I thought was .74. This has been done, so yes it is factual.

Sorry.... This was with the swap to 3:55's!!!

[Steve M]

I'll answer for him, your brain is fried. Sorry couldn't help myself. In all seriousness Steve is correct and you my friend have your numbers backwards. Also to note, GenIV's with either an Arrow tune or HPT setting the Rev limiter to 6,600 rpms allows for the car to accomplish 201mph in 5th gear while retaining the factory 08, 09 5th gear ratio, which I thought was .74. This has been done, so yes it is factual.

I've seen both 0.75 and 0.74 quoted - if someone could get me the actual tooth counts, I could make the calculation more accurate. I'm referencing a spreadsheet I built, which is essentially the Excel version of this website: https://xse.com/leres/ss/calculator.html

I did some research and actually got what I think are the correct tooth counts for the rear ring and pinions to make that portion a little more accurate. From what I found, "3.55s" use a 46 tooth ring gear and a 13 tooth pinion, which gives you a ratio of 3.54 (or 3.5385). The difference is slight, but it does make a difference.

[Stealth78]

I've seen both 0.75 and 0.74 quoted - if someone could get me the actual tooth counts, I could make the calculation more accurate. I'm referencing a spreadsheet I built, which is essentially the Excel version of this website: https://xse.com/leres/ss/calculator.html

I did some research and actually got what I think are the correct tooth counts for the rear ring and pinions to make that portion a little more accurate. From what I found, "3.55s" use a 46 tooth ring gear and a 13 tooth pinion, which gives you a ratio of 3.54 (or 3.5385). The difference is slight, but it does make a difference.

Impressive research Steve. I apologize, I know you has asked me to provide you with those numbers before. This has been the busiest winter I have ever had and I still have not even opened the boxes for anything I bought last year.

[Steve M]

Impressive research Steve. I apologize, I know you has asked me to provide you with those numbers before. This has been the busiest winter I have ever had and I still have not even opened the boxes for anything I bought last year.

No worries - I've been equally busy over here. I need to replace my clutch, but haven't even gotten around to ordering one yet.

[06SRTCoupe]

Thank you for the research Gents! Yes, my brain is definitely fried haha.