Tranny + gears... synergistic effects?

2k3gt

New Member
Apr 20, 2003
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York, ME
Alright guys, heres the deal. I'm thinking a bit in advance and trying to plan what I'm gonna do with the ride... and I've decided that I'm gonna get a power adder as soon as im done with the basic worthwhile boltons. Theres a problem though.. I'm auto, and I'd like to swap to a 5, maybe 6 speed. A lot of work to do, I know. But what would be the best combination for a twin screw, or maybe even twin turbo app?

I've heard 3.73's are best for FI cars... but if I get a 6 speed does that mean I'll need a steeper gearset for the same effect? Would 5 gears be enough for 4.10's and a 8-9# blower or turbo, or is the 6 speed really necessary? And on the side.. are forged internals absolutely necessary for a street-only car, to the point where a failure is inevitable?

Broad questions, I know. But I possess only a very rudimentary technical knowledge of cars in general. Any advice would be very helpful.
 
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I have 4.10 gears with a 5 speed tremec 3650 transmission @ 90 MPH I tack 3000 RPM'S. I dont have a supercharger. I have heard that if you are going to supercharge dont go higher than 3.73 gears.
 
Yeah, I read that alot from the 4.6 forum... but would it be okay to get 4.10's with the cobra 6 speed and a power adder, or would it still be too much?

How would the stock rearend hold up to ~400rwhp?