View Full Version : any idea (help)

09-14-2003, 07:04 PM
my frind have mustang cobra 1996 with the following mods,

-vortech S-trim
-aluminum probe piston with compretion 8.5
-aluminum flywheel
-centerforce cluth stage 3
-3.55 end gare
-flowmaster 2 chamber muffler

the problem is
the car did not go as it has to,1st and 2nd shift ,no problem.but
when he shift to 3 gare the car dead, i think that mustang gt
can beat him in 1/4 mile.
so, did u guys have any opinion or addetional mods he has to
put to wake up his 4-V engin, and run fast ...

09-15-2003, 12:09 AM
I'll try to help out as much as I can. First, let me make sure I read that right. The supercharged cobra falls on it's face once you get into 3rd gear?? Or the car died?

Anyway, if the car is running alright, then you should be so far ahead of a stock GT by the time you hit 3rd gear it wouldn't be a problem. Anyway, If this car hasn't been on a dyno then it needs to be. Dyno's do alot more than just read horsepower and torque. Make sure you get the wideband 02 on it so you can see the air to fuel ratio. I may be wrong, but it kind of sounds as if the IMRC's aren't opening. This will really choke off the car when it really needs it the most, high rpms. There are two cables right in between the intake and the fire wall. Grab ahold of them with the car off, and pull them pretty hard. You should feel spring tension. The cable should move, and you should hear a click. If not, then they are probably not working as advertised. Now, start the car, and with the hood popped, rev the engine up. Watch the cables behind the intake. If they move (you'll be able to tell if they're working), then I don't know what to tell ya. Fuel filter, spark plugs, etc.


09-15-2003, 07:38 AM
NO the car in 3rd shift run but with slow rpm when compared
with 2nd shift.

09-15-2003, 04:23 PM
Well, naturally, at higher speeds, and taller gear ratio (2nd gear vs 3rd gear), it will pull slower. You've got to think that the faster you are going, the more wind resistance you are going to have. Going by seat of the pants feel is hard to do unless there are some major problems. Get it to the track or a dyno and see if you are just hoping for more pull than what you've got, or if there's something wrong. I don't know what else to tell you. I know my car pulls pretty damn hard in 3rd, but I always wish it would pull harder. Get to a track and see if you can hit the traps at over 110 mph. If the car won't do it, then it has problems.

09-15-2003, 05:25 PM
i think the problem with piston with compression 8.5 and with
stock injucter and fule system..

any one agree with me or has diff. idea

09-15-2003, 07:01 PM
If 1st and 2nd are pulling fine and you notice the problem in 3rd it sounds more like a drivetrain issue than a piston/compression issue. You should be having those problems in every gear.

The '03 Cobra comes with 8.5:1 compression ratio so if your friend has his car tuned right and everything that isn't going to be a problem especially in the upper rpms (you may notice a lot of torque loss down in the lower rpms with that compression ratio).

Stock is 9.85:1 but a few do drop the compression when they rebuild (though you need to add more boost to make up for the loss of power).

I think you need to get his car on the dyno and make some pulls to see what it's making......and make sure A/F readings are done with a wide-band meter. Right now we are just guessing...we need more information.

09-30-2003, 08:48 PM
If the car was starving for fuel, it would do so in every gear at higher rpms. I too think you are just feeling the gear ratio difference.