03-04 Cobra Tuning Packages

Custom Tuning with Xcalibrator2 or Livewire

1If your Cobra has an intake and cat-back exhaust you can still benefit greatly from a custom tune.  03 cobras suffered from poor factory tunes that were pig rich and had poor starting and drivability problems.  As part of the custom tune we re-flash your pcm to the latest and last 04 Cobra pcm code (AMZ2) that Ford offered with all the drivability updates.  All vehicles also have an emissions feature called “cat overtemp protection”.  That means with the stock tune when you go to wot throttle the pcm will start dumping fuel to help cool the cats.  This will bring you’re a/f ratio down into the 10’s on any wot run other than a short one.  We disable that function as well as tune the a/f for max safe power as well as timing for 91 or 93 octane.2

 

Pulley Upgrade with Custom Tune
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One of the least expensive massive horsepower and torque gains in the history of any car is the pulley upgrade on the Cobra.  The stock boost on the cobra is about 9psi, well, we all have known for quite some time that this motor will tolerate a lot more boost than that.  Up to 21psi or more on pump gas!!  This motor is so strong that 600+ rwhp is achievable with no durability issues.  The first graph is the most basic upgrade you can do with the stock fuel system. 

 

This includes:

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Not only did this Cobra gain 43rwhp and 92lb-ft with these simple mods look at the midrange tq and hp gain at 4800rpm’s!  A staggering 85rwhp and 96lb-ft!!
Is your stock supercharger worth porting?

There is a lot of misconception to whether it’s worth porting your stock supercharger.  Many people don’t believe it’s worth it or think they gain boost by doing it.  Well, here’s the scoop.  The stock Eaton supercharger was never designed for more than 9psi of boost.  When you pulley the blower and boost it to 15psi the efficiency drops.  That’s why you’ll typically see more midrange gains than peak, at high rpm’s the blower is not efficient and will actually lose boost.  Porting the blower makes it more efficient at higher levels up to 15psi.  That will allow the boost to hold at high rpm’s.  It’s still no where near as good as a KB or Whipple but it’s still a big step ahead of the stock blower.  Typically you’ll need to upgrade your MAF, injectors and install a KB Boost-a-Pump for the additional fuel requirements.  Here’s some results.
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As you can see, the higher the rpm’s the more the gain.  That’s because at 3000 rpm’s the boost is equal, with the stock blower, though, as the rpm climbs the boost starts to nose over, the ported blower pull holds the boost better and therefore you’ll see more hp and tq.  Looking at the peak numbers you see only a 13lb-ft increase but look at the difference at 5500 rpm’s.  It’s about 50lb-ft, you’ll feel that!  So the final answer is YES!!

How about a 4lb Lower pulley?

The only drawback to a 2.76” upper pulley with stock lower is the belt will always slip a little under boost.  The best way to cure this is to change the lower pulley to a 4lb with a 2.93” upper.  This will produce the same 14-15psi like the 2.76” upper but with less belt slip.  Your supercharger uses about 40-50 hp to turn it when under full boost.  That’s why there is belt slip.  Here’s a graph to show the difference between the 2.76” upper only and the 2.93” upper with 4lb lower:
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Although the peak hp numbers are very close, look at the midrange hp gain.  There’s a difference of 35rwhp at 4000rpms.  So what’s the best setup with the stock blower?  Definitely the 4lb lower with 2.76” upper on a ported blower.  You will see a total gain of over 100 rwhp and up to 150 lb-ft of torque!!  I’ve done numerous Cobras with these combinations including my own which in the end put down 510hp to the wheels!  Want to use one of the “big” national tuning companies?  That’s fine but just remember.  Every car is a little different, unless you’re car is on a dyno with a wideband a/f readout you can’t verify if your tune’s not safe, nor can they.  That’s why I don’t sell mail-order tunes, only in house custom tunes!