Since I'll be getting the LS1 with a FMS 220/220 - 112 LSA or a FMS 224/224 - 112 LSA and Stage 2 5.3 heads, the shifts will be a few hundred rpms higher. Allen said in his e-mail that these cams would pull hard to about 6300 rpms. I think I've heard that heads would give it a little extra, I'm thinking around 6400-6500 rpms.

I saved a few charts off of a calculator I found a long time ago. It was showing exactly where I am currently shifting with the 3.42 gears and what mph I was shifting at. (This is with the 265/70/16 Firestones)

3.42 = 1-2 (50mph) & 2-3 (94mph) shifting at 5900 rpms

Which of these would work best with the motor set-up & a 2800-3000 stall?

3.73 = 1-2 (49mph) 2-3 (93mph) shifting at 6500 rpms

3.90 = 1-2 (47mph) 2-3 (89mph) shifting at 6500 rpms

4.10 = 1-2 (44mph) 2-3 (84mph) shifting at 6500 rpms

Just by looking at the charts, I'm leaning towards the 3.90s. What do ya'll think.

 

i like my 3.90's.

 

How big of a stall. Strictly speaking in performance terms, you want a higher gear for a higher stall if you want traction despite popular beleif intution. Also, steeper gears will "tame" the stall a bit. I really think you should concider the stall speed, vehicle weight and tire hieght in all of this. I still dont know what vehicle this is in, your silverado has an LS1 swap?

 

No, I just bought an LS1 and will be building it up over the next year or so. I was thinking of maybe a TCI 2800-3000 stall, but I might go with a Yank 3000 or 2600 at the least. I was told that more gear would lower the stall a couple of hundred rpms, that's why I was wanting to go with a little bigger of a stall. But, I really need some gears. I'm tired of punching it around 40mph or so and having to wait a second or two for it to kick in. I want my engine to rev faster, it takes for ever with the set-up I have now and think it would get a lot worse with a higher reving motor. That's why I was considering the 3.90 gears for more throttle response.

 

Go with 4.10s. Im shifting into 3rd at 76mph and top 3rd at @ 128mph. IMO perfect gears for the 1/4. And throttle responce is sweet.