highonpsi

I've had a few different cars, lots of modded turbo Eclipse/Talons, a 2002 Altima 3.5SE manual 5spd, Monte SS and now a Grand Prix GXP. I thought the FWD and 5.3L V8 would make for a highway monster but it feels very slow on the highway, the FWD should have made the least loss to the wheels and it isn't too heavy for the power (3600lbs). My 2002 Altima 3.5SE 5 speed manual was MUCH faster on the highway and I wanted something either the same or faster. So my question is, will the HP tuner tune make a big difference on the highway? I just installed flowmastedr mufflers, and the car feels great from a stop, but on the highway it feels like a V6 (or worse). Could this be the limitations of the 4 speed tranny? To the people who got a tune, LMK what the improvement was on the highway.

Thanks

Heslekrants

My tune was a big boost to the top end.


I have no problem pulling from Mustang GTs especially at the higher speeds where traction is not a factor.

CenTexSS

iTrader: (2)

When you shift to 3rd it falls on its face. If you tune it to hold the gear longer it'll help out a lot.

98Jeep360Limited

I dunno, I never had a tune in my ( besides making the shifts firmer) but with my mods it was pretty darn quick on the highway, 70mph 2nd gear downshift it would pull to 120 in a short amount of time.

Sittingmongoose

iTrader: (1)

it pulls hard through 135 and it still pulls a little until my drag limited 157. You have to use manual mode and leave it in 3rd. If it shifts into 4th you wont go anywhere. Auto mode loses a huge amount on the high end.
This is off topic but how fast is your gc?

LS4SPEED

iTrader: (3)

Pulled to like 120 in second? Mine shifts at roughly 100 mph to third! What did you have done to yours to make it pull through second to 120? Maybe I'm missing something?

Sittingmongoose

iTrader: (1)

ya mine shifts around 105ish into 3rd maybe it was a mistype?

StealthV8

iTrader: (1)

Maybe your 2002 Altima 3.5SE 5 speed felt faster but i have easily beat those things on the highway.

highonpsi

lol

It had a CAI, and some exhaust mods. My buddy has a 2007 Altima 3.5SE 6 speed sedan and when we raced from a roll on the highway he was beating me in my '02 Altima pretty much the same every time (about 1-2 car lengths) Then when I had my '06 Monte Carlo SS with resonator deleted we went at it again and he was beating me by about 3-4 car lengths from a roll. Now I have a Grand Prix GXP and thought the tapshift made it a little faster on the highway but it feels pretty much the same as the Monte SS (haven't raced him with the GXP yet though) I'm just trying to find out if the tune makes a significant change to the powerband (I want to know if it is worth the money) Not trying to say my Altima was the fastest thing on the road LMFAO.

StealthV8

iTrader: (1)

if he can beat your gxp from any gear by 4-5 cars you need to sell that thing cause something is wrong. I get this old guy in a altima 3.5L always try to race me from first gear i walk him and from highways its still a steady pull.
And yes a tune and pretty much any engine mod helps the ls4 with top end.

highonpsi

99% of the 3.5se's on the road are automagics, the manual is much faster. My buddy did 14.18 @ 100 + mph, so I think it will be tough to beat him on the highway because his car is a couple of hundred pounds lighter and already traps pretty high before the weight really starts to matter.

StealthV8

iTrader: (1)

i've seen stock gxps do 100-102 mph in the 1/4 many a times. But ya his was a auto forsure. Other than that one old guy most of the 3.5's have teenagers driving their parents car packed full of their friends trying to find a race so the weight doesn't play in lol.. If you go from 1st gear you will win forsure, may be close like you say with the manual.

TonyGXP

my GXP routinely ran 13.6-13.8 @ 102+. sorry had an 06 Maxima and yeah the manuals are quicker but I highly.... highly doubt it's taking the GXP from any speed for any amount of time.. The GXP pulls effortlessley like your not moving out but in fact you are, strange for a small block GM, but I think it's the gearing that makes it that way.. best of luck with your car..

TiredGXP

iTrader: (2)

I agree. The gearing in the 4T65E-HD probably has a lot to do with the perception. First gear is done in less than 5 seconds, but the relatively tall second gear takes another 8.5 - 9 seconds. Seems like forever....

GM screwed the pooch by not putting a close ratio six speed in these vehicles.[/whine]

Panther427

The tune should help alot. I picked up alot of midrang power all the way to redline with my car. midrange about 30HP extra top end 20hp. It made a nice differance. ANd the gearing makes the car seem slower that it is. IF u ever rebuild the trans and put in even 3.2X gears the car would feel so much faster.

07carlocrusader

shoot my top end is great!!
no tune either!!

98Jeep360Limited

lol, I had a feeling some would get confused by this. I mean it would downshift to 2nd at 70, shift to 3rd at 100ish and pull pretty good till whenever I let off. I figured everyone would know that a 3rd gear shift would happen at some point or another haha.

98Jeep360Limited

And I gotta wonder whats up with the OP's car, because my buddies 350Z with a few mods couldn't even outrun me on the highway, and yes he can drive.

LS4SPEED

iTrader: (3)

I kinda figured that's what you meant. But it wasn't quite clear. I didn't know if you had done rockers, springs, and cam. If you did that with a trans tune and shift points and rev limiter set around 6500 rpm, you could prolly get a 2/3 shift around 120mph! Just asking, thanks for clarifying.

R.E.double.D.

Depends on the tune