best gear for tci 4l80 6 speed

gp471

Not-quite-so-new-guy
Jan 15, 2022
32
8
hi all
would like to hear real world info about gears used in their g bodys.buiding an 87 grand prix with a 471 455 pontiac fuel injected engine.the tci is near $10k.plan to use a ford 9in maybe with a 3.00 or 3.25 ratio.
thanks

Using the latest developments in drivetrain technology, TCI® has developed an innovative automatic transmission for Pro Touring, street and all-out race vehicles. Designed for Pontiac applications, this 4L80E-based TCI® 6x Six-Speed Automatic Transmission is a fully programmable transmission that gives you six forward gears (2.97, 2.23, 1.57, 1.18, 1.00, 0.75) for quicker acceleration and increased fuel economy at cruising speeds. Capable of handling up to 850 horsepower, this versatile transmission from TCI® features a compact design, allowing it to work in a variety of performance applications.

from another thread

6X is a close ratio automatic transmission. 2nd - 5th gear is similar to manual M20 close ratio tranmission. RPM retension between shifts is unmatched by any A4 automatic. Notice the drive ratio in each gear with 3.55 rear gear and what rear gear a T56 6 sp manual car would need to match the 6X ratio wise in 4th gear as well as come close in 2nd & 3rd. T56's 1st gear is it's only gear with better mechanical advantage than 6X, but it may be a little to much advantage as RPM lost between 1st to 2nd gear is huge even with perfect shift, taking engine out of it's power band. My 64 still has a 3.54 1:1 5th gear for a little more top end.
6X has average lost of 1600 RPM between shifts. Shift at 6500 RPM and engine RPM only falls back to 4900 +/- 100 RPM. Less converter stall needed, that may hurt 60" time when drag racing at strip, but sure doesn't hurt street fun factor...LOL
TCI 6X
2.97
2.23 -- 76.10% (high) RPM Retention -- 23.90% RPM DROP
1.57 -- 70.40% (high) RPM Retention -- 29.60% RPM DROP
1.18 -- 75.16% (high) RPM Retention -- 24.84% RPM DROP
1.00 -- 84.75% (high) RPM Retention -- 15.25% RPM DROP
0.75 -- 75.00% (high) RPM Retention -- 25.00% RPM DROP
TCI 6X, 3.55 rear gear
1st gear2.97
3.55​
10.54​
2nd gear2.23
3.55​
7.92​
3rd gear1.57
3.55​
5.57​
4th gear1.18
3.55​
4.19​
5th gear1.00
3.55​
3.55​
6th gear0.75
3.55​
2.66​
T56 man
1st gear2.66
4.19​
11.15​
0.60​
2nd gear1.78
4.19​
7.46​
-0.46​
3rd gear1.30
4.19​
5.45​
-0.13​
4th gear1.00
4.19​
4.19​
0.00​
5th gear0.74
4.19​
3.10​
-0.45​
6th gear0.50
4.19​
2.10​
-0.57​
Car only has 360 Peak HP at rear wheels, Converter is stalled at 2800 RPM so not much more flash than stock. You can hear engine rpm drop very few RPM between 1st/2nd and 3rd/4th shifts. When car shifted into 5th near top of the hill it was doing 132 MPH per tuners data logger. Use of Old School mechanical advatage to help make up for not having a lot of HP.

seems relitive to me
 
Last edited:

DRIVEN

Geezer
Apr 25, 2009
7,566
113
*CENSORED*
You'll have all kinds of torque so I'd probably go with the 3.00s.
 

Max Headroom

Master Mechanic
Sep 8, 2011
398
63
Could you list the trans gear ratios, your anticipated shift rpm by gear and the anticipated power band of the motor?
I'm writing a digital program for street cars and could use some real world numbers.
Thanks
 

gp471

Not-quite-so-new-guy
Thread starter
Jan 15, 2022
32
8
Could you list the trans gear ratios, your anticipated shift rpm by gear and the anticipated power band of the motor?
I'm writing a digital program for street cars and could use some real world numbers.
Thanks
i just inserted the tci proganda that shows the ratios.my old 455 with a turbo 400 shifted at 5600.this closer ratio i suspect shifting about 5000.
 

Max Headroom

Master Mechanic
Sep 8, 2011
398
63
i just inserted the tci proganda that shows the ratios.my old 455 with a turbo 400 shifted at 5600.this closer ratio i suspect shifting about 5000.
Could you possibly get me the rest of the stats?
I would really appreciate and will send you a print out of what I come up with.
The output is not like anything I have seen in other software.
I will send you a copy of the output and would like your opinion on whether you think it has any value.
 

gp471

Not-quite-so-new-guy
Thread starter
Jan 15, 2022
32
8
Could you possibly get me the rest of the stats?
I would really appreciate and will send you a print out of what I come up with.
The output is not like anything I have seen in other software.
I will send you a copy of the output and would like your opinion on whether you think it has any value.
these are from tci.transmission gives you six forward gears (2.97, 2.23, 1.57, 1.18, 1.00, 0.75)my engine is pontiac 455strked to 471 cu in.cam is at.50 230i and 236e.edelbrok heads and proflo4 fuel injection 27 in tires.what stats due you also need?
 

Max Headroom

Master Mechanic
Sep 8, 2011
398
63
Could you give you shift point in rpm and your engine's power band?
I ran the transmission gears you posted and figure a 5500 rpm shift for first gear and shifting a little short on the rest to make up for the extra pull on the motor due to the taller gear.
I figured a power band of 3000 rpm to 5500 rpm, once again raising the bottom of the band to account for the extra work of the taller gears.

The idea is to see where your shift rpm ends up after each gear and to be sure your transmission leaves you in the power band after the shift.

Any feedback would be welcome.



I
Capture.JPG
figured
 
Oct 14, 2008
8,040
113
Melville,Saskatchewan
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.
 

gp471

Not-quite-so-new-guy
Thread starter
Jan 15, 2022
32
8
Could you give you shift point in rpm and your engine's power band?
I ran the transmission gears you posted and figure a 5500 rpm shift for first gear and shifting a little short on the rest to make up for the extra pull on the motor due to the taller gear.
I figured a power band of 3000 rpm to 5500 rpm, once again raising the bottom of the band to account for the extra work of the taller gears.

The idea is to see where your shift rpm ends up after each gear and to be sure your transmission leaves you in the power band after the shift.

Any feedback would be welcome.



I View attachment 190416 figured
max you seem to be about right but i dont see the rear gear you are working with.the cam i am installing says at least a 2200 stall but the extra cubes at 471 cu in i think tend to negate that.butler performance says it will make good enough vacuum for power brakes and i suspect the cam will start making power at 3100 and stay till at least 6000 rpm.hope this helps max
 

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