angelrx7HEAVEN

go with 200r4 auto tranny, shift kit, valve body mods, etc, u will never miss a **** and shift harder then the stick....look for at least a .25 sec decrease

Nihilanthic

So, 4 gears and 3 shifts is just the magic number of being closer to the asymptote while balancing the shift time, huh...

Im gonna build a autocrosser/street toy/track racer so Id be happier with a T-56. Autos are great for cruising or dragging but I hate trying to make them get in the gear i want for cornering. Id be happy doing some light dragging with a T-56 more than getting serious about it and trading off the fun factor and better (for me anyway) cornering ability of having a manual for a lower ET.

LT1-10AE

There are two problems with hitting 5th in a race.

1. 5th is not a very strong gear and doesn't like being slammed on.
2. The gear drop from 4th to 5th is massive.

1st rockets you out of the hole, 2nd continues that same feeling, 3rd starts to pull like a frieght train, 4th feels like a frieght train going full bore downhill and 5th feels like you just dumped 1000lbs on the car.

4.10s are a perfect around town gear, autocross and 1/8th mile gear. For the highway, 1/4 mile or top speed runs, a 3.55 would be perfect.

FYI: With a 26" tall tire and the .50:1 6th gear and 4.10s, you'll be turning around 2200RPM at 70MPH. I imagine it would be high 2k, low 3kRPMs doing the same in 5th or 4th in an automatic.

You do know Edelbrock and MSD have teamed up to make an ignition system and carbureted intake for the LS1, right? It makes tons of power on the stock cam. A local friend has one in an '88 Camaro and runs 7.30's with it in the 1/8th.

turbogarrett

iTrader: (1)

Last year shifting to 5th cost me ~2mph vs. hitting the rev limiter in 4th (6800).

wingsfan

You sure about theat? I would turn around 1800 with 25.7" (275/40/17) tires and the 4.1s, which is around the teorteical calculation

http://www.geocities.com/z_design_st...ion_z28_6.html

With slightly taller tires I'd expect to turn a few less RPM for the same speed (maybe 500 RPM less).

wingsfan

About 65 mph, the redline was set at 6400.

LT1-10AE

Yup. I'm running 275/40-17s with my LT1/T56 and it hits dead on at 2200RPM @ 70MPH.

wingsfan

Something wrong with your tach or speedometer then? That doesn't jive with any of the calculators I've seen, or my personal experience.

What year t56? The .62 6th gear from a '93 would put you ~2300 rpm @ 70 with that tire combo.

LT1-10AE

Nope. The speed was checked via GPS and the RPM was checked with Datamaster.

Cars don't usually follow calculator results very well. I've noticed this with theory of nose heavy V8 RX-7s. Mine also breaks this rule by being 60lbs heavy to the rear.

razorback

ok since this kinda got turned into a trans debate, what should i look for in an auto trans? i already plan on rebuilding my dodge 727 with a shift kit in it. and i keep getting told that its gonna blow with the 4.10 gears

wingsfan

I've had mine verified by both radar and my local Sheriff.

Mine seems to follow the link I posted really well. 2200 RPM would put me over 80. Ask me how I know (see above)

My93rx7

iTrader: (1)

Check out www.hinsonsupercars.com for a ton of info on the ls1/lt1 swap i just got mine done its well worth it.