Ok......i have a 1998 mustang cobra convertible with the 4.6 32V DOHC engine....flowmaster catback exhaust and K & N filter....with 70,000 miles....no more mods so far. I raced my brothers new 2006 pontiac grand prix GXP that has a 5.3 liter engine putting out 303 horsepower and 323 ft. lbs. of torque. I know mine stock is 305 horsepower and 300 ft. lbs. of torque. He beat me by maybe half a car length...Why is my car so slow? I shifted at around 6700 RPM's through first and second and thought that my car ran strong. Could it be possibly the crappy low end of the cobras? I have ordered an h-pipe, JLT ram air........will these make it any faster? Or is it all about the gears?
The best bang for the buck is gears, 4.10s would put you ahead of him. The weight could also be a factor, verts are pretty heavy. You should notice an improvement in the mods you listed but the gears will be a more drastic increase. The way those DOHC motors like to rev I wouldn't even mess with anything less than 4.10s. A set of drag radials will also let you launch harder.
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DHG #01434 Bullitt - full JLT intake, MGW shifter, Accel coils (I wish I had 4.10s, o/r H, tune)
Black 89 LX(the drag car) best 8.75 at 80 mph in the 1/8
97 Mountaineer V8 AWD
thanks man........i am not really into taking it to the track.....just like to street race it every now and then and i have heard before to put 4:10's or 4:30's on the DOHC cobras. I dont want my higher RPM or gas mileage to suffer but you think its a waste for 3:73 gears? Also i guess when i get around buying my 18" chrome saleen or cobra r wheels that i will be slower again or will i be able to stay fast? I keep hearing slower accelaration will be felt with the 18's versus the stock 17's.
3.73's aren't a waste. Some people just go really aggressive with their gearing. It's not for everyone though. 3.73 is a good gear for a car that gets a lot of street duty.
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I had a guy with a new Monte Carlo SS with the same engine LS4 (303 hp fwd) pull up to my car and was revving, he sounded like he had flowmasters. This was pretty late at night and there was not other cars on the road. I got the launch on him and never looked back.. Went up to 60 and shut it down, was ahead by 1 1/2 cars. I think those cars are 3400 lbs.....but HP is pretty equal...plus the are FWD. they are not slow by any means.
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2006 Deluxe GT 5 Spd Manual Tungsen Grey with black painted stripes, 20 x 10 konig beyonds, kw V3 coil over kit, BMR Chomoly Panhard rod, BMR Boxed Subrames, BMR Upper Strut, BMR lower control arms, BMR Upper Control Arm, Eibach Sway bars, Prothane Eurethane bushing kit. Bassani cat back.w/ x-pipe + hi flow cats, Roush Rear Spoiler, Street Scene Body kit,Street scene grille, 3D carbon louvers, HID system, Raptor Shiftlight with Speed of sound pillar guage, C&L with Preditor 91 Custom Tune
I guess the torque has to do with alot of it too? Am i correct? His Grand prix has 323 ft. lbs........mine is only 300 ft. lbs. stock and i still have only the 3.27 gears......When i get my h-pipe and 3.73 or 4.10 gears i should beat him? I am just shocked how they are coming out with these new family sedans that are really fast.........hes got a 4 door grand prix with 18's..........come on now....thought it would be slow but i do have a convertible so the weight might be another factor.
I guess the torque has to do with alot of it too? Am i correct? His Grand prix has 323 ft. lbs........mine is only 300 ft. lbs. stock and i still have only the 3.27 gears......When i get my h-pipe and 3.73 or 4.10 gears i should beat him? I am just shocked how they are coming out with these new family sedans that are really fast.........hes got a 4 door grand prix with 18's..........come on now....thought it would be slow but i do have a convertible so the weight might be another factor.
Yeah, i think gears will help alot, and make sure you get the hole shot on him because you can launch your car better than a FWD car can. Then you've got him. As for power on new cars, yeah....just look at the HEMI cars, they are boats but they are pretty fast...esp the SRT8's with 425HP. All the new Chevy SS cars has the 303 HP motor now, and the Cadillac CTS-V has 400 HP and the STS-V has 470. Its crazy....people want fast and practical cars so it can double as the family cruiser too.
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2006 Deluxe GT 5 Spd Manual Tungsen Grey with black painted stripes, 20 x 10 konig beyonds, kw V3 coil over kit, BMR Chomoly Panhard rod, BMR Boxed Subrames, BMR Upper Strut, BMR lower control arms, BMR Upper Control Arm, Eibach Sway bars, Prothane Eurethane bushing kit. Bassani cat back.w/ x-pipe + hi flow cats, Roush Rear Spoiler, Street Scene Body kit,Street scene grille, 3D carbon louvers, HID system, Raptor Shiftlight with Speed of sound pillar guage, C&L with Preditor 91 Custom Tune
yeah thats what i was gonna say...........it seems like all the cars coming out today are getting more and more horsepower yet are more practical and some are even family cars...............keeping up with the sports cars.
You need to ask yourself how much do you want to put in the car. Then choose accordingly. Yes, full exhaust would be the best gain but headers are very pricey, maybe just add a mid pipe. You could also nickle and dime it with bolt ons or just get a base supercharger kit. Its all in what your after, total speed and bragging rights or a few bolt ons that complement each other nicely. If it was mine I would start with gears (4.10s), Off road mid pipe (if you don't have smog testing), and a shifter. These few mods with good driving will make that Cobra slither past a lot of competition. Good luck!
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DHG #01434 Bullitt - full JLT intake, MGW shifter, Accel coils (I wish I had 4.10s, o/r H, tune)
Black 89 LX(the drag car) best 8.75 at 80 mph in the 1/8
97 Mountaineer V8 AWD
Well, he's making more torque than you, (323 to your 300) hes making it lower in the rpm band, (4400 to your 4800) hes making he's peak hp numbers faster than you (at 5600 vs your 5800) and hes only off by 2 hp to match you. Not to mention he's is an auto so theres no quessing about where to shift or how fast, your car on the other hand is completely dependant on you which calls into play your driving skills. (He out weighs you by about 100lbs.)
The gears will give you better/faster launches from a dead stop, they wont do much for you once your rolling. Your current mods of flowmaster and k&n arent really adding anything other than good sound. Together with a full exhaust is a different story.
Stonecold.........I just got a JLT ram air intake and am getting a mac catted or offroad h-pipe......havent decided yet........will these help out or is it ultimately up to the gears? I installed the JLT ram air and must admit it pulls faster through the RPM's with this mod.......havent got the h-pipe yet.
Stonecold.........I just got a JLT ram air intake and am getting a mac catted or offroad h-pipe......havent decided yet........will these help out or is it ultimately up to the gears? I installed the JLT ram air and must admit it pulls faster through the RPM's with this mod.......havent got the h-pipe yet.
It will certainly help out. I would opt for an X pipe over the H though as they make a little more hp but some people dont like the higher pitched sound of an X as compared to the throaty growl of the H. The gears are whats going to get you out of the hole faster. (assuming you were to race from a stop.)
I know that the 96-98 GT's were bogged down by poor flowing heads. A popular swap is to change them out for PI heads which came in the 99+ cars. I dont know if this applies to the cobras of the same year though. It's something to look into though because for the GT's of those years its the real choke point. Maybe one of our 4.6 guys will provide the answer.
1. The 2 valve 4.6 and the 4 valve 4.6 are two completey different motors.
2. 3.73 gears work great for the 2 valve motors. You have a 4 valve and should use
4.10's if your scared and 4.30's if you want to go fast.
3. Gears will not affect your rpms or gas mileage that much.
4. Gears will help you out from a stop and a rolling start. They don't change when you gain speed. The reason they help so much is to multiply the torque and keep the engine in it's peak power band. They are the best mod besides forced induction.
5. If you have smog testing, get catted X, otherwise get off road X. X is better than H.
6. Like said earlier, get a good shifter. Our shift forks are weak and can be bent if abused.
7. Headers make good power but are expensive parts and labor wise. Before you buy the midpipe figure out if you are going to install headers because they will require a different midpipe.
8. Don't worry about the heads mentioned earlier. This was only on the 2 valve motors.
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97 Cobra #777 Blk/Blk
ProCharger P600B 7psi w/3 core intercooler, off road x-pipe, flows, pro kit, oil separator mod.
Why is my 1998 cobra so slow? 
