Driving in "L" or "I"
Senior Member
Joined: 06-04-2008
Posts: 1,882
From: Toledo, OH
if im not mistaken, which i could be, all the auto hhrs have the same tranny, including the SS, the 4t45 is rated to 350 hp, the only difference is the SS manul tranny is different from the non SS models
Member
Joined: 03-25-2008
Posts: 69
From: Southern New Jersey
From http://media.gm.com/us/powertrain/en.../09car.htm#20L
2009 Hydra-Matic 4T45 Transaxle ( MN5 ) 3/18/2008
Type: four speed front-wheel-drive, electronically controlled, automatic overdrive transaxle with electronically controlled torque converter clutch
Engine range: 2.2L - 3.5L
Maximum engine torque: 221 lb-ft (300 Nm)
Maximum gearbox torque: 325 lb-ft (440 Nm)
Gear ratios:
First: 2.95
Second: 1.62
Third: 1.00
Fourth: 0.68
Reverse: 2.14
Final Drive Ratio: 3.05, 3.29
Maximum shift speed: 6900 rpm Sprocket Ratio Dependent
Maximum validated gross vehicle weight: 2220 kg (4884 lb)
6-position quadrant: P, R, N, D, I, L
2009 Hydra-Matic 4T45 Transaxle ( MN5 ) 3/18/2008
Type: four speed front-wheel-drive, electronically controlled, automatic overdrive transaxle with electronically controlled torque converter clutch
Engine range: 2.2L - 3.5L
Maximum engine torque: 221 lb-ft (300 Nm)
Maximum gearbox torque: 325 lb-ft (440 Nm)
Gear ratios:
First: 2.95
Second: 1.62
Third: 1.00
Fourth: 0.68
Reverse: 2.14
Final Drive Ratio: 3.05, 3.29
Maximum shift speed: 6900 rpm Sprocket Ratio Dependent
Maximum validated gross vehicle weight: 2220 kg (4884 lb)
6-position quadrant: P, R, N, D, I, L
Senior Member
Joined: 08-07-2011
Posts: 553
From: Montebello, CA
Launching in "L" gives you 1st till around 5500, then 2nd lags in, there is no jolt from 1st to 2nd, its almost a let down. However if you shift from "L" to "I" before the change from 1st to 2nd there is a tremendous amount of boost built up and the SS lunges foward without delay. Once in "I" it will hold 3rd, and 4th pretty well as long as your foot stays in it, and locks out the "OD" from the regular "D". The "L" and "I" in comp mode work OK for launches, but I have found that punching the pedal while above 40mph "D" is the only option.
Senior Member
Joined: 04-09-2010
Posts: 192
From: Northern Virginia
Most of the time I leave it in "D" but I am HPTuned, have changed the shift points up and down, and selected "Performance" mode. Doing a 20 mph rolling start with traction control ON it will light up the front tires (yes both) take off hit second light up the tires again and just fly. No 1st to 2nd dump. Great fun! I only use "I" when I am at speed for engine braking or quicker (much) throttle response. Get HPTuners or Trifecta tuned if you want your Auto to work well. It helps greatly when you stop the nanny from protecting your trans. 
Senior Member
Joined: 09-20-2009
Posts: 1,058
From: Hayward, Ca.
I'm Trifecta tuned, and I shift the trans like a manual almost all the time. I use I then L to engine brake slowing down. I take off in L and manually shift at almost redline[sometimes sooner in town]. When taking off in L and manually shifting into I, there is no lag, and at WOT, lights the tires in 2nd gear.
Manually shifing a auto trans will not hurt it, and helps saves brakes on engine braking. Autos also put the power down a little more consistant than a manual,[all things equal], and you can also use the brakes, to modulate putting the power down, especially under low traction situations, as in turns. "Moon"
Manually shifing a auto trans will not hurt it, and helps saves brakes on engine braking. Autos also put the power down a little more consistant than a manual,[all things equal], and you can also use the brakes, to modulate putting the power down, especially under low traction situations, as in turns. "Moon"
