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Old 01-31-2006, 03:37 PM   #1
Djs94stang
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Default 99 Cobra vs 99 GT

What is different with the engine that allows the Cobra to make 320 hp vs the GT 260? I'm not familiar with the 4.6 that much. I was thinking that in the future I'd replace my SN95 with the later model and was considering installing a Procharger and figured the Cobra had more hp to offer to begin with and maybe it's built better to handle the extra power.

Also any other specs for this model would be helpful or tell me the best place to find them will help too...such as stock rear axle, type trans, etc.

Thanks
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Old 01-31-2006, 03:40 PM   #2
blackbetty01
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Default RE: 99 Cobra vs 99 GT

Cobra= 4v, GT=2v
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Old 01-31-2006, 04:19 PM   #3
Djs94stang
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Default RE: 99 Cobra vs 99 GT

So the bottom end (crank/rods/pistons) are the same. It's only the induction that is different?
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Old 01-31-2006, 04:36 PM   #4
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Default RE: 99 Cobra vs 99 GT

First, let me state that 1999 Cobras had a recall because they weren't producing the right power numbers:
The recall addressed this with:
--New lower intake manifold
--New cat-back exhaust
--Computer reprogramming

Valves:
1999 Cobra has 4 valves per cylinder (30mm exhaust x2, 37mm intake x2)
1999 GT has 2 valves per cylinder (36mm exhaust, 44.5mm intake)
--This is the single most important difference between the two.

Block:
1999 Cobra: Aluminum (86lbs)
1999 GT: Cast Iron (154 lbs)

Compression:
1999 Cobra: 9.85:1
1999 GT: 9.30:1 (in 2000 they went to 9.74:1 compression)

Crank:
1999 Cobra: Forged
1999 GT: Cast Iron

Pistons:
1999 Cobra: Hypereutectic cast alloy shallow skirt with friction reducing coating on sliding surfaces
1999 GT: ???

Rods:
1999 Cobra: Sinter-forged alloy, fracture-split big ends
1999 GT: Stamped iron

Flywheel:
1999 Cobra: Nodular Iron 8 Bolt
1999 GT: Nodular Iron 6 Bolt

Heads:
1999 Cobra: Dual Overhead Cam. Main Chains to exhaust cams, Secondary Chain to intake cams behive shaped valve springs.
1999 GT: Single Overhead Cam, weaker valve springs.

Redline:
1999 Cobra: 6500 RPMs
1999 GT: 5800 RPMs

Intake manifold:
1999 Cobra: Cast Aluminum
1999 GT: Plastic

Throttle Body:
1999 Cobra: 57mm twin bore
1999 GT: 66.8mm (2000-04 had 65mm)
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Old 01-31-2006, 04:54 PM   #5
Dan04COBRA
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Default RE: 99 Cobra vs 99 GT

Good post.
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Old 01-31-2006, 05:56 PM   #6
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Default RE: 99 Cobra vs 99 GT

wow I learned a lot about the cobra and the GT. Do you think this could help as being a sticky?
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Old 01-31-2006, 06:22 PM   #7
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Default RE: 99 Cobra vs 99 GT

all good info except the rods on the 99 GT are stamped, not cast.
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Old 01-31-2006, 06:25 PM   #8
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Default RE: 99 Cobra vs 99 GT


Quote:
ORIGINAL: MikeHawke

all good info except the rods on the 99 GT are stamped, not cast.
Thanks, that's why I had the ?? I'll fix it.
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Old 01-31-2006, 06:45 PM   #9
MikeHawke
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Default RE: 99 Cobra vs 99 GT


Quote:
ORIGINAL: Fallstar01


Quote:
ORIGINAL: MikeHawke

all good info except the rods on the 99 GT are stamped, not cast.
Thanks, that's why I had the ?? I'll fix it.
LOL, I saw your ???, that's why I threw in my 2 cents

That's some good info. I will throw a sticky on this.
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Old 02-24-2006, 08:30 PM   #10
2VNA
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Default RE: 99 Cobra vs 99 GT

I was reading that there is a cooling problem on the 4.6 heads, causing 7 & 8 to over heat. It's a flow problem and can be resolved but they said you have to pull the trans to do it. I would post the link but it's on another board and I don't think that would be to cool.
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Old 02-24-2006, 08:30 PM
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