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Discussion Starter · #1 ·
Can anyone post some actual 1/4 mile times for a '99 Cobra with the independent rear suspension? I can't get mine to break 14 s, and I was wondering if that is actually the best a '99 Cobra can do... wheel spin is my main problem. I even tried launching in second gear to overcome it. Just a moderate launch @ 2500 rpm in second, and I still spun out. Maybe there's something wrong with my car, I shouldn't be able to spin out when starting in second gear, and giving it only about a quarter trottle, should I?
 

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Warcat

What brand / type / dimension of tires do you run on the drag strip?
 

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Discussion Starter · #3 ·
Nittos

engineer76 said:
Warcat

What brand / type / dimension of tires do you run on the drag strip?
I haven't exactly hit the drag strip yet, but I've got one of those performance meters giving me my times. I haven't sprung for drag radials/ wheels just yet, but I'm thinking about it. So the tires that gave me the sorry times are the ones in my signature.
 

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I don't know how acurate the performance meters are.

Assuming they are, you probabely have a launching, shift point problem.

With the 410 gears and the 285 tires you should see some decent numbers.
Also check your shift points: Increase/decrease your shift points in 200 RPM increments and see wether your times drop or raise. Since you have 410 gears, you probabely have to shift a little earlier, to have the biggest HP average thru out one full gear.
 

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Discussion Starter · #5 ·
engineer76 said:
I don't know how acurate the performance meters are.

Assuming they are, you probabely have a launching, shift point problem.

With the 410 gears and the 285 tires you should see some decent numbers.
Also check your shift points: Increase/decrease your shift points in 200 RPM increments and see wether your times drop or raise. Since you have 410 gears, you probabely have to shift a little earlier, to have the biggest HP average thru out one full gear.
Thanks for the tip.
I'll give it a go. I've been shifting at the redline on every run (approx 7000 rpm). On the next few runs, I'll drop that to 6200, then raise it to 6400, 6600, and 6800, until I find the right combo.

Should I shift every gear at the same rpm, or is there a optimum shift point (rpm) for each gear?

As far as the launching problem, I guess the only thing I can do is practice. Would heating my Nitto's help any? I've read that burning out with radials doesn't help...
 

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Heating up radials doesn't really help a lot. The cleaning effect, get rid of dirt and dust on the rubbers, is much bigger. Don't go crazy, because to much of a burn out does the oposite because the tires overeat - less traction.

Since the steps in the transmission, from one gear to the next, are set up for driveability on streets, the shift points are actualy not the same.

You need to find out how much the RPM's drop from 1-2 at lets say 6000 rpm. Then you do the same with 2-3 gear and 3-4 gear.
With this information you can now have a look at your dyno chart.
Lets say your COBRA* peaks (280 RWHP) at 6000 RPM and has 260 RWHP at 6500RPM and also at 5500RPM you want to have your 2-3 shift done at 6500, to end up at 5500 RPM. This would equal with the highest average HP at the wheels. If the drop would be 1500 RPM you want to go a little higher in the RPM.

IN GENERAL: Since the gear ratio from 1-2 drops more than from 2-3 and 3-4, you want to shift earlier, the higher you go in gear.


*Don't know enough about Cobra dyno charts (but theory is universal)
 

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This chart might give you an idea what I tried to explain in words.

If you shift to early you dont have the full potential, if you shift to late you don't have the full Hp potential. See how the shift points slightly differ from 1-2, 2-3 and 3-4?

This chart is only fiction, based on the HP numbers of a 2V 4.6L

Have fun training!
 

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Maybe a little slower then a Mach 1 when stock ,because of the IRS , but the h.p. is there ! as long as it got the BIG FIX that is !

With some more time at the track , you could run low 13`s with the mods you have !
Car and driver ran around 13.5 with a `99 ! if I can find the issue , I will post the stats !
 

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Discussion Starter · #9 ·
ran260gt said:
Maybe a little slower then a Mach 1 when stock ,because of the IRS , but the h.p. is there ! as long as it got the BIG FIX that is !

With some more time at the track , you could run low 13`s with the mods you have !
Car and driver ran around 13.5 with a `99 ! if I can find the issue , I will post the stats !
It did get the big fix. The block has the green and black dots on it, and the PCM Reflash sticker. I know I've got the horses, I just can't control 'em yet. My trap speed in the 1/4 was 104 or 105 (with the G-Timer). Using some of the calculators I've found online, that should translate to approx 13.1 in the 1/4. But I'm a full second off of that, LOL. I'll keep trying.

Did you ever get your Mach w/ IRS to run what it was supposed to?
 

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You have pretty decent tires... If you're spinning that bad, you might also wanna think about some lower control arms, or some other suspension to get you some better traction... might be worth it. Your car should break 14's easily when it's stock, not to mention your mods.
 

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Why dont you try to go easy out of first kinda like you would driving off a light during normal driving conditions then floor it after clutch is fully engaged. i am having the same issues with ym GT, i cant hook worth a damn in 1st off the line if i get on it good. i used to be able to drop it at 2g in first go.. but now i can barely do it at 1G. I know from using my G-tech meter they start their timer/meter when it feels the jerk of the car kick in.

try to do that easy out of first then floor it.

definately like they said earlier you should be around 13.5 and less on average closer to 13 flat with those mods.
 
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