best gear for tci 4l80 6 speed

[gp471]

Neat sounding transmission. What speed do drive on the highway? The cruise rpm is important as well. I get 1700 rpm with the 3.00 and 1850 rpm with the 3.25 both a 60 mph. That is the converter locked up and a 27" tall tire. It sounds like a lot of fun for a drivetrain.

dont know yet.im still spending money building the 471.i want to get the rear end installed now to make headway.suspect i will not have engine ready till late sume between parts and machine work and money.would like to get imput on bst gear to start.close to 10 k for this 6 speed monster from tci.my old car ran great with a 3.43 gear but worry this thing will be outta first gear in no time.butler per says the 471 will hit about 525hp and 575 torque.

 

[Max Headroom]

gp,

While rear gears have great effect on how fast and quick the car is, it doesn't change during the run or while driving, so it can be considered a constant and can be excluded from the calculation.
What does change during the run are the rpm and the transmission gears.

The code calculates the rpm drop based on engine speed and the change in trans gear.
The second part compares where the revs dropped to and what the entered low end of the power band is.
If the box is green, you are still in the power band.

Once you become familiar with using it you can do a couple of helpful things with it.
It can help determine optimum (or at least better) transmission gears for your specific application and it can also help you tailor your shift rpm.

When I first used it, I picked just over a 10th in the quarter by shifting 150 rpm sooner out of first and 200 rpm sooner out of second.
I was running out of motor on top and shifting sooner dropped my after shift revs deeper into the power band.
That let me get further down the track before making second and I still had a little motor left at the end of the track.
I also found out that by shifting that little bit earlier, I was coming out closer to peak torque.
It really made a difference.

With respect to your 3.43s, I think you have to balance running out of motor in first with how quickly you can get the car moving fast enough to create enough forward inertia for the car retain as much velocity as possible on the shift to second..
The mechanical advantage of your first gear ratio is a lot higher than second.
The faster the car is going before the shift, the easier for the taller second gear to accelerate further/faster.

What kind of speed do you want in the 1/4?

 

[64nailhead]

No need for 6 gears with an auto that the lockup can be programmed for unless you’re cruising over 90 mph.

And it’s impossible to recommend an optimal gear without knowing the tire size and the engine info that Max is asking for.

FWIW, I’m running a 4l80 unlocked around 140 at the stripe at 7100 rpms, but I have the converter unlocked and slippage is about 12%. That’s with a 28” tire. I swap to 26” tires for street driving and I turn 2700 at 80 locked up and about 2350 at 70.

It’s very difficult to pick a rear end ratio without tire size, max rpm at the stripe and what is the desired cruise rpm.

You want to cruise at the very bottom of the torque curve- a BB usually can handle high teens (1800ish) pretty easy unless the cam is way big and/or the compression is in the tank.

 

[olds307 and 403]

I say the 3.25 for Highway rpm, unless you drive 70 mph everywhere. I think 1700 rpm will be a bit low for that cam. What stall converter are you running? Either rear gear will be a smoke show off the line in first. Obviously suspension work and drag radials will be needed for a good launch.

 

[64nailhead]

dont know yet.im still spending money building the 471.i want to get the rear end installed now to make headway.suspect i will not have engine ready till late sume between parts and machine work and money.would like to get imput on bst gear to start.close to 10 k for this 6 speed monster from tci.my old car ran great with a 3.43 gear but worry this thing will be outta first gear in no time.butler per says the 471 will hit about 525hp and 575 torque.

You don’t need anything more than a stock 4l80 with a build for sub 600 crank hp. Save your money.

 

[gp471]

You don’t need anything more than a stock 4l80 with a build for sub 600 crank hp. Save your money.

i do thank your concern about my money but like fools they soon part.didnt want to leave it to anybody anyway...lolbut i like the fact that first to second does not make such a large jump in ratio.i think i like starting out like a i have a 4.11 but still have room for cruise.think i will start at a 3.25 as worse case it will work with a turbo 400.
thanks