04 Grand Prix GTP vs. Bonneville GXP - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


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Old 09-21-2008, 08:41 AM   #1
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Default 04 Grand Prix GTP vs. Bonneville GXP

Anyone ever race these two cars?

GTP has the */C motor at 260HP, GXP at 275, but I'm sure the weight of the GXP would be it'* downfall.
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Old 09-21-2008, 12:02 PM   #2
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its not the weight (the GTP weighs almost the same as a Bonneville) that is the downfall its the HP and Tq ranges of the Motor. The L67 makes power down low, and pulls away quicker, and then the Northstar makes power Higher in the RPM'* and can gain in the back half

From a Dig the GTP wins
From a Roll the N* Wins
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Old 09-21-2008, 10:38 PM   #3
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Quote:
Originally Posted by 1993 SLE View Post
its not the weight (the GTP weighs almost the same as a Bonneville) that is the downfall its the HP and Tq ranges of the Motor. The L67 makes power down low, and pulls away quicker, and then the Northstar makes power Higher in the RPM'* and can gain in the back half

From a Dig the GTP wins
From a Roll the N* Wins

Found these stats on the net, Not sure how accurate.....

Gran Prix GTP
260-hp at 5,400 rpm and 280 lb-ft of torque at 3,600 rpm
curb weight 3583lbs.

Bonneville GXP
Horsepower : 275 hp @ 5600 rpm
Torque : 300 lb-ft @ 4000 rpm
curb weight 3790lbs

Peak HP is 200rpm lower and peak torque is 400rpm lower. It wouldn't seem that much more powerful on the bottom end.

Also, I wonder what the GXP makes in HP and Torque at the GTP'* peak rpms?

There is a 207lb difference. In a race, quite substantial, I think.
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Old 09-21-2008, 11:17 PM   #4
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i hang around Club GP quite alot and none of the 04+ owners have reported weights that light.

i would you would have to drive the cars to really experience it. I have been fortunate to drive all the cars that have been mentioned, plus many L67 cars both stock, lighly, and heavily modded.

there is a huge difference in the real world between the Northstar and the L67/L32
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Old 09-22-2008, 02:23 PM   #5
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I think that bottom line, the GXP is somewhat of an underperformer based on its specs. I don’t think it’* particularly weak off the line or super-strong on the top end. My 95 mph trap speed is about what I’d expect based on the ET. Since so few people have taken their GXPs to the track, and I don’t know if they were running premium, the car’* performance is still somewhat of an unknown IMO. I am the only one to run 14s as far as I know.
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Old 09-24-2008, 10:22 AM   #6
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Premium does make a big difference. As one who WOT'* all the time and run all the grades of gas often. I can see the difference easily. Also I think the PCM/ECM/TCM learn procedure can come into play. As well mastering a FWD launch and controlling torque steering well doesnt come easy. ( I'm doing better at getting the feel of gently nudging the car out of the heading for the rightside ditch than I am at keeping the front tires seated on the pavement when I spray nitrous.) The engine is also pushing a big tranny with the 4T80E. Great for longevity, but how much quicker would it be coupled to a 65. Alot of variables. Also as much as I want to believe the GXP airbox breathes adequately for not being able to mod it, Turbo'* gutting it and achieving the advertised 14.6 makes me wonder.

Turbocoupe, did gutting the airbox affect the MAF in any way in regards to daily driving? Did you leave the Screen on?

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Old 09-24-2008, 03:08 PM   #7
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Venom, I left the MAF screen on, and I will not be touching it. I feel it would almost certainly cause issues with daily driveability. Also, I don't think it is a bottleneck because the MAF inlet is very large, 3.75" ID. I cross-referenced it using the direct replacement MAF from Jet performance, and it is the same Jet part number as the 2004 CTS-V, therefore it ought to be plenty big for the GXP.

The gutting did not impact daily driveability at all. I could not detect any drop in low-end torque.

I have a few other ideas I will be trying in the upcoming months to attempt to gain some additional performance. I'll post those up in the performance and brainstorming section.
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Old 09-24-2008, 11:04 PM   #8
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I have ran the engine with the box top off and filter out and just to touch the maf screen and block say, two holes caused the engine to buck and adjust. It'* that sensitive and something I haven't wanted to "disturb"
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Old 10-13-2008, 07:09 PM   #9
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My brother bought the above mentioned 2004 Grand Prix GTP. Pic for your delight...


Name:  04GPGTP.jpg
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He took his car to the track and ran a best of 14.69 @ 93MPH (2.099)60ft. Bone stock

We decided to take our cars out, just to see who'* was quicker. We were not able to go
from a stop, but from a roll of 10-15MPH.

On "3" we both mashed it, dead even, slight wheel spin on both cars.
I slowly gained on him about a cars length by the time we hit 70MPH.

I was pretty happy and I think it was an outcome was something we both didn't expect.

I think my car will run mid 14'*. Maybe soon, I'll have to go to the track.

*Race occured on private property

Last edited by FrankAR15; 10-13-2008 at 07:13 PM.
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Old 10-13-2008, 09:04 PM   #10
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as i said, the N* wins from a roll
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