nickate

iTrader: (5)

And is the trans in the Northstar stronger than the one behind the LS4?

I just noticed they used two different powertrains in the GXP.

cherrygxp

i believe that the bonneville gxp was the only car that had the northstar. And they didnt make a 04 GP gxp.

98Jeep360Limited

x2, I was always under the impression that the Grand Prix GXP and the Bonneville GXP used the Northstar in 05, but it was just the Bonneville.

BuffaloSS

iTrader: (3)

Correct. The Bonne GXP got the northstar...the GPGXP got the LS4

06PIMPALASS

I'm pretty sure the first year for the LS4 in the IMP,GXP was 06,Supercharged 3800 in 05.As far as the transmissions go the 4T80E is stronger than the 4T65E by far,I build them for a living so trust me on this.

hexxLS4

iTrader: (1)

Yeah the first V8 in a GP or MC was the LS4...never a Northstar.

ChipC

Impala/MCSS LS4 production was for 06 (05 was supercharged). Grand Prix GXP started in mid-05 (as 05) and has always been LS4. Supercharged 3800 in Grand Prix was a GTP and/or a CompG in 05, became just a GT in 06-07, and dropped for 08.

And as said, 4T80E is stronger and physically larger.

Chip

nickate

iTrader: (5)

WHAT IS QUICKER/FASTER... The LS4 or the NORTHSTAR????

We all know what GXP cars they came in.

Sorry for the confusion and thanks for confirming my suspicions about the 80 series trans!

I thought the LS4 trans would be doomed reliability-wise having the crappy v-6 trans dealing with tons of grunt and with a boot--- TRACTION

Please lmk if you have a Northstar car and have run it!

cherrygxp

the LS4 is faster than the northstar. I test drove a bonnie gxp and it was not nearly as peppy as the GP GXP. i believe the northstar puts out about 270hp.

98Jeep360Limited

Yeah the Northstars do feel somewhat sluggish compared to the LS4, they definetly don't have that tire burning midrange snap. Although, I drove an 06 Cadillac STS with the more powerful Northstar in it ( VVT, 320hp) and that car felt considerably faster than a regular Northstar.

nickate

iTrader: (5)

Anybody know why they didn't use the 4T80E Behind the LS4?

germeezy1

Physical size is the reason, from what I have heard. With the LS4 the 4T65 was the best fit. The Northstar only comes with the 4T80E so its the same combo as comes in a Cadillac. The 4T80E is stronger but its heavily torque managed and comes with considerable drivetrain losses. 300 hp STS/DTS FWD's typically dyno under 220 whp.

nickate

iTrader: (5)

This is the same deal as the 4L60E vs. the 4L80E in the RWD world.

The LS4 NEEDS the stronger (but less efficient AND larger) trans especially when a 'lil aftermarket help is added.

GM goin' after fuel economy and not considering slicks. WHAT NIMRODS!!! lol

They should give you an option (remember those?).

Kazmaniac

Because the 4T65E is already in the parts bin from the V6, so they simplfied the parts management and reduced shipping costs.

Secondly you need to design in the mounting for the 4L80E.

And most of all, they didn't intend for you to be racing the car.

The General is just saving money ... budgets; cost reductions, etc. You're lucky they had enough money in the budget to give you a V8.

germeezy1

And the 4T80E still leaves alot to be desired, with incredibly tall gearing and the 50 mph dead spot like the 4L60E's have. What are you GP and MC guys dynoing right now? Because at 300 flywheel under 220 to the wheels is pretty amazing powertrain loss! Also the 4T80E won't live even behind a Northstar if you take away the torque management. I used to own a money pit that was an 00 STS with XMS/RSM Racing parts. It was a kings ransom to go a court jesters speed...