Has anyone used 3.31's on a TS car?

[Jmurrz]

I recently blew up my differential and am rebuilding it with a Eaton TrueTrac and gears but I am wondering if people have tried a 3.31 rear gear. I am making ~600 to the wheels with my 2.3 Whipple and I love the top end pull that some of the lower geared cars have. I do like to track the car and I know my ET's will drop a little bit but is there a tire that I could run to make it work for the track? I am running 26" slicks right now and they hook pretty well. I know that a 3.73 would be perfect for my power level with a 28" slick but I am worried about losing the top end pull.

Feel free to chime in, I am really stuck. The car will be about 70% street 30% track. I know this should be in Driveline but I wanted a little more exposure in Terminator Talk.

Thanks in advance guys!

 

[tt335ci03cobra]

I ran a 3.08 before when I had a 5.4 and 57's. I loved the traction, but hitting 100mph in 2nd at about 6500rpm was pretty boring.

I did my new combo with less torque/higher rpm torque/power and am running a 3.73. It's much easier for stop and go traffic, and more enjoyable in town.

Since you have a torque rich 2.3 vs a more linear torque 2.8+, you can pull off 3.31's or 3.27's but it will feel decidedly doggish. At most id step down to a 3.55 honestly. Is it worth the money? Arguably yes since it's opened up but if it wasn't getting opened up I would leave the 3.73 in it.

You'll get better freeway mileage with the 3.27 or 3.31 by a hair or two and would likely spin about 1850rpm in 6th at 70 vs 2050 in a 3.55 or 2250~ in a 3.73 setup.

In general, I've seen too much torque necessitates tall gearing and tires to hook up. It's quick at the track but not so fun on the street. The taller you go, the more it feels like a 2 or 3 spd vs a 6 speed.

There's a website called Wallace racing (Google Wallace racing calculator) that has a MPH gear calculator. I'd plug and play with that to see if a 3.31 or 3.27 is where you want to be.

Edit:

http://www.wallaceracing.com/calcmph.php

(Worst case copy and paste that^)

For quick reference the factory tire is 25.6" and the average 315/30/18 or 315/35/17 is about 25.75". Most 26" slicks grow to a 27" by the traps, 28"'s grow to 29's. Slicks get taller down the track, regular tires not really.

1st 2.66
2nd 1.78
3rd 1.30
4th 1.00
5th .80
6th. .63

Final drive is 3.55 factory, 3.31 is your thought, 3.73 is your current

RPM is self explanatory. Pick an rpm you'd like like say 2000rpm cruising, 6500rpm at the top of a gear or the traps, etc.

Good luck.

 

[Brutal Metal]

I still have the 3.27's but the 1st gear in the T-45 is 3.35. Op I'd use 3.55's

 

[selbyvince]

I had 3.27 gears in my old comp orange cobra. Car made right under 700 hp with a 2.2 and e85. Car was just a street car, only seen 2 passes at the track. I had put the 3.27s in as I was initially going turbo with the car and changed my mind afterwards. Before I had driven the car I ordered a set of 3.55s to replace them with, but after driving the car a little I just ditched them and kept the 3.27s. I actually liked them.

 

[tt335ci03cobra]

I had 3.27 gears in my old comp orange cobra. Car made right under 700 hp with a 2.2 and e85. Car was just a street car, only seen 2 passes at the track. I had put the 3.27s in as I was initially going turbo with the car and changed my mind afterwards. Before I had driven the car I ordered a set of 3.55s to replace them with, but after driving the car a little I just ditched them and kept the 3.27s. I actually liked them.

That sounds like a great combo from e85 to a 2.2 ect.

I'm get tuning the idea that smaller more efficient blower applications (very torquey compared to big blower setups) like a taller gear to balance out the initial punch.

Quick question, what's you're freeway rpm like? 1800@70?

Cool car man, great combo.

 

[Jmurrz]

I ran a 3.08 before when I had a 5.4 and 57's. I loved the traction, but hitting 100mph in 2nd at about 6500rpm was pretty boring.

I did my new combo with less torque/higher rpm torque/power and am running a 3.73. It's much easier for stop and go traffic, and more enjoyable in town.

Since you have a torque rich 2.3 vs a more linear torque 2.8+, you can pull off 3.31's or 3.27's but it will feel decidedly doggish. At most id step down to a 3.55 honestly. Is it worth the money? Arguably yes since it's opened up but if it wasn't getting opened up I would leave the 3.73 in it.

You'll get better freeway mileage with the 3.27 or 3.31 by a hair or two and would likely spin about 1850rpm in 6th at 70 vs 2050 in a 3.55 or 2250~ in a 3.73 setup.

In general, I've seen too much torque necessitates tall gearing and tires to hook up. It's quick at the track but not so fun on the street. The taller you go, the more it feels like a 2 or 3 spd vs a 6 speed.

There's a website called Wallace racing (Google Wallace racing calculator) that has a MPH gear calculator. I'd plug and play with that to see if a 3.31 or 3.27 is where you want to be.

Edit:

http://www.wallaceracing.com/calcmph.php

(Worst case copy and paste that^)

For quick reference the factory tire is 25.6" and the average 315/30/18 or 315/35/17 is about 25.75". Most 26" slicks grow to a 27" by the traps, 28"'s grow to 29's. Slicks get taller down the track, regular tires not really.

1st 2.66
2nd 1.78
3rd 1.30
4th 1.00
5th .80
6th. .63

Final drive is 3.55 factory, 3.31 is your thought, 3.73 is your current

RPM is self explanatory. Pick an rpm you'd like like say 2000rpm cruising, 6500rpm at the top of a gear or the traps, etc.

Good luck.

Wow, lots of good info there. Thanks for that!

I still have the 3.27's but the 1st gear in the T-45 is 3.35. Op I'd use 3.55's

I think I am now in between the 3.55 and 3.31, it seems like a 3.27 would be a tad too low for me to use with my current level but a 3.31 might be a nice mix of out of the hole power and giving me that longer pull I am looking for.

I had 3.27 gears in my old comp orange cobra. Car made right under 700 hp with a 2.2 and e85. Car was just a street car, only seen 2 passes at the track. I had put the 3.27s in as I was initially going turbo with the car and changed my mind afterwards. Before I had driven the car I ordered a set of 3.55s to replace them with, but after driving the car a little I just ditched them and kept the 3.27s. I actually liked them.

With ~600 I think that the 3.27 would be too low for my HP range, but maybe a 3.31 would work better for me. How much difference was there when you went to the track between the 3.27 and the 3.55? I think I would like that long pull as well, I rode in a C6Z06 and I really love how long they pull between shifts.

Right now I am leaning towards the 3.31

 

[selbyvince]

That sounds like a great combo from e85 to a 2.2 ect.

I'm get tuning the idea that smaller more efficient blower applications (very torquey compared to big blower setups) like a taller gear to balance out the initial punch.

Quick question, what's you're freeway rpm like? 1800@70?

Cool car man, great combo.

:beer: thanks man, It was def a setup id do again. 6 lb lower, 3.1 upper ~20-21 psi on a gen 1 2.2L. supporting mods and e85 yielded 679/677 on the 1st dyno session. And it was somewhere in the 69x/68x on the 2nd dyno session (single blade throttle body and the newer JLT high boost intake.) As for the RPM, its been 3 years since ive drove that car, so I don't really remember. But it was somewhere in that vicinity.

With ~600 I think that the 3.27 would be too low for my HP range, but maybe a 3.31 would work better for me. How much difference was there when you went to the track between the 3.27 and the 3.55? I think I would like that long pull as well, I rode in a C6Z06 and I really love how long they pull between shifts.

Right now I am leaning towards the 3.31

Car never made it to the track with the 3.55s. Hell, I never drove the car with 3.55s in it. I bought it as a shell and put it together, so for me, it had 3.27s since day 1. And the only two passes I had with it were horrible. Weather wasn't ideal, I couldn't get it to hook, and I missed 3rd on one pass. Lol, so no helpful info for you in that aspect.