What trans and gear ratio is best?

[1BAD351 21]

Here is a spreadsheet I made comparing the Ford and GM versions of the Tremec T-56 transmission that will hopefully make its way into my car in the near future. I am not worried about 5th and 6th gear acceleration as the car is going to be mainly a street car and a weekend 1/4 mile car. So I want it to have the most get up and go I can get. The car makes its peak tq at 4400 rpm and peak hp at 5700. The one I was leaning toward was the cobra with a 3.55 rear, because the gears seem to be decent speeds and after shifts they land right before peak tq and rpm's in each gear are very close together. 1st gear isnt to short, and 6th gear doesn't turn high rpm's on the highway. Anyway what do you guys think?

 

[stangme428 33]

1BAD351

nice spreadsheet.... plug my numbers in when you have a moment...:tongue_smilie: i ended up with a early viper trans with the .50 6th and 3.77 gears. long story .. i sent my 9" 31 spline center to moser for a daytona pinion support and 3.73 gears ... they didnt have any 3.73 in stock at the time and made me a deal on some 3.77 that someone backed out on ... so it worked out. sent my stock axles to them also to measure for the new 31 spline axles... no guessing if i measured it out the correct way.

 

according to compcams dynomation software with my stroked 408W, AFD 2V canted valve heads and 304HR cam, single plane intake, Cam RPM range is 3000 to 6500 with peak torque @ 5000 rpm and peak HP @ 6500.

wheels are 16x8 with soon to be 245. 45. 16 on all 4 corners...

 

Viper T56

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

i hope to have my 69 on the road by the end of this month... april 09.... :punk:

[1BAD351 21]

Thanks, it took me a while to make that thing, but it really gave me a good look as to what I was dealing with. At first I wanted the trans you had because it had the .5 od, but then I was looking and realized the cobra trans had better gearing. I could run 3.55 or 3.73's and get the same as a gm with 3.91 or 4.10's so it all balanced out. I am really debating between the 3.55's and 3.73's with the cobra trans. They drop me a little lower in the rpm band and might actually be better because it drops me a little bit more before my tq peak. I'd have a little more get up and go too and that's always good. Running right around 2k rpm at 70 mph might give me a little bit more power in 6th gear so I don't have to downshift as much.