[commonsense]

Any GM engineers out there? Guys who have built a Sky/Solstice, with an automatic, to 400 HP? I need to know how much power a 5L40E Automatic will reliably take before I think about upping the horsepower. I'm probably at about 320 hp/300 ft lbs of torque right now which, according to some information at Wikipedia, is more than the designed 250 ft lbs of torque it is supposed to take. The article does say for cars weighing up to 4000 lbs and, of course, the Sky/Solstice is way under that. But I'm concerned if I boost power to around 400 hp, the transmission won't take it. Anyone have any engineering information on this or real world experience with a Sky/Solstice automatic around 400 hp? Thx. I'll copy the Wikipedia article into the next posting.

 

[commonsense]

5L40-E

The 5L40-E was designated in either "M82" (rear-wheel drive) or "MX5" (all-wheel drive) versions for service in BMW vehicles from 2000 model year until the design was superceded by (for BMW) the 6l45e and (for all others) the 6l50e series electronic automatic transmissions in 2007 . It is designed for service in vehicles up to 4000 lb (1814 kg) GVWR and in service was mated to a selection of final drive ratios 3.42:1, 3.73:1, or 3.91:1 depending on the carline. The 5L40-E had been designed for 1.8–3.6 L engines with a maximum of 250 ft•lbf (340 N•m) of torque. A notable failure mode of the assembly is lifetime overtorque in the heaviest carlines wherein the unit is matched with a significantly higher torque-rated powerplant; the transmission is well known for failing between 150,000km and 200,000km in the 5 series E39 and X5 BMW'S equipped with their inline 6-cylinder and V-8 powerplants, due to insufficient or contaminated lubrication during operation in cruise overdrive range, and service loads beyond the engineered maximum rating of the unit. Despite this apparent mismatch, and since carmaker BMW does not manufacture the extremely sophisticated 5l40e, BMW customers have reported that Authorized BMW Service will not repair this type of transmission, instead offering to install fully assembled units as replacement (a common practice which entails significant cost to the consumer.)[citation needed] An aftermarket preventive package exists to curtail early failures but is designed to alleviate very specific symptoms and generally is not a prescribed remedy for a manufacturer mismatch.
Gear ratios:
1 2 3 4 5 R
3.42 2.21 1.60 1.00 0.75 3.02
Applications:
3.42:1 M82
2004–2006 Cadillac CTS (RWD)
2005–2006 Cadillac STS (RWD)
3.73:1 M82
2004–2006 Cadillac SRX (RWD)
3.91:1 M82
2006 Pontiac Solstice
2007 Saturn Sky
2.92:1 M82
2004–2006 Holden WL Statesman/Caprice (RWD)
2004–2006 Holden VZ Commodore (RWD)
2005–2009 Chevrolet Omega (RWD)
2006–2009 Holden VE Commodore (RWD)
2008–2009 Pontiac G8 (RWD)
3.42:1 MX5
2004–2006 Cadillac CTS (AWD)
2004–2006 Cadillac STS (AWD)
3.91:1 MX5
2004–2006 Cadillac SRX (AWD)
BMW 3 Series (E46)[1]
BMW 5 Series (E39)
BMW Z3
BMW X5 (E53)
[edit]5L50

The 5L50 is engineered to handle the stresses from vehicles weighing up to 5000 lb (2268 kg) GVWR. Final drive ratios include 2.93:1 and 3.23:1. The 5L50 can handle up to 311 ft•lbf (422 N•m) of torque.
Gear ratios:
1 2 3 4 5 R
3.42 2.21 1.60 1.00 0.75 3.02
Applications:
2.93:1 M22
2004–2006 Cadillac XLR
3.23:1 MV3/M22
2005–2006 Cadillac STS
2004–2006 Cadillac SRX

The Hydra-Matic 5L40E/50E automatic transmissions have some unique operating characteristics with which customers may not be familiar. They have been designed to provide more of a manual transmission feel than other Hydra-Matic automatic transmissions.


Normal Mode Operation
During normal mode operation, drivers may notice increased powertrain braking after releasing the accelerator pedal. The vehicle will not coast freely when the accelerator pedal is released but will start to gradually slow down as if the brakes were lightly applied. This feels very similar to releasing the accelerator pedal on a vehicle equipped with a manual transmission.

Sport Mode Operation
Typically, Sport mode delays upshifts. The Sport mode simulates the performance driving of a manual transmission. Under certain conditions, the vehicle will maintain specific gears longer than a traditional automatic would. When driving in Normal mode in 5th gear, depressing the Sport button causes an immediate 5-4 downshift, which will be maintained for ten seconds. In any other gear, no downshift takes place when Sport is engaged. In Sport mode, the vehicle has firmer shifting and increased performance, and the transmission may remain in a gear longer than it would in Normal mode.

Driver Shift Control (DSC)
The driver manually overrides the automatic gear selection. Various mechanization options for input device and degree of override are allowed.

Performance Algorithm Shifting (PAS)
PAS overrides normal automatic gear selection during closed throttle high lateral acceleration maneuver. Lower gear is accompanied by near synchronous engine speed control for quick response upon re-opening throttle (enable threshold bias in Sport mode).


Performance Algorithm Liftfoot (PAL)
PAL prevents liftfoot upshifts while maintaining engine braking during repeated aggressive cornering.

Winter Mode
The vehicle launches in 2nd or 3rd gear instead of 1st, to avoid wheel spin in snow or ice, if selected by the driver.

Shift Stabilization
Shift stabilization is used to minimize shift business, or hunting between ranges. Based on several inputs and a map of engine torque at various RPM and throttle position, the TCM determines before making an upshift whether the engine will be able to maintain vehicle speed in the next higher range. If it calculates that it cannot maintain speed, it will prevent the upshift from occurring.

Downgrade Detection Brake Assist
Shift to lower gear with braking on downgrade based on fuzzy logic rules calculated from a thermal brake model, terrain detection, desired acceleration, vehicle speed, and mass detection.

Adapts
Adapts continually compares actual shift times to desired shift times. The transmission controls make hydraulic adjustments to assure the actual shift times approach the ideal shift time the next time the shift is made for similar operating conditions of vehicle RPM, engine load, and road load conditions. The adaptive shift process continues for the life of the vehicle to provide consistent and optimized shifts.

 

[kwtoxman]

Search the forum for info and use both search engines.

 

[juspimpin]

Search the forum for info and use both search engines.

That is not helpful.

Next time, don't post anything. It is easier for you and better for the thread.

I do not have any answers to the OP but I too am interested. I am at about the same as you currently. More is always better. I need tires first tho. cannot put all the power to the ground yet with the stockers. I had a manual and sticky 275s but they are chrome and I now have polished...lazy too I guess.

 

[kwtoxman]

That is not helpful.

Next time, don't post anything. It is easier for you and better for the thread.

LOL, I guess it isn't helpful to take some initiative and search the forum history for that information, at least as a start while waiting for replies, because... that would be too much work and you need to be spoon fed.


Of interesting note the the OP, the GMPP tune for the 2.0 auto cars is rated at a lower tq value than for the manual cars, so it seems as though GM was careful at what it fed the auto even in that tune.

 

[Shadofax]

LOL, I guess it isn't helpful to take some initiative and search the forum history for that information, at least as a start while waiting for replies, because... that would be too much work and you need to be spoon fed.


Of interesting note the the OP, the GMPP tune for the 2.0 auto cars is rated at a lower tq value than for the manual cars, so it seems as though GM was careful at what it fed the auto even in that tune.

Actually I've commented on this in the past, and believe this is not true, but rather GM gave the same dynamics to the tune, regardless, and the result is just showing that an auto is less efficient in torque transfer vs. a manual. Manual is simple gearing, auto is gearing, plus the auto shift "brains", plus auto tranny fluid which doesn't just relieve heat, much more complicated. Not knocking the auto though because on the flip side, if you like straight line speed, and consistency, the auto will probably edge the manual most runs. This is opinion.

Another opinion is that this auto still is not a wise choice for someone looking for around 400hp, but then again, you also are looking at potential rear axle issues too. As mentioned, given our weight, it probably will hold up with a 2.0 pushing less than 350hp.

By the way commonsense, how do you figure your tq rating is less than your hp rating? With a GMPP tune the engine rating is 290hp/325tq automatic. I've always figured that with a change in tune, IC upgrade and maybe free flow cat I might be in the realm of 310-320engine HP and around 345tq.

 

[oneforall]

i have also read up on this topic. I think you are safe with about 300Hp and 325tq. That is with that figure, the auto trans will be as reliable and last as long( with proper care) as the stock 260HP and 260tq. More that that, one need a better IC plus maybe more frequent trans fluid changes in order to keep the auto trans going. Just my thought on this matter.