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Initial Track Results

Nevertheless we tried to work with the combination. We got the car to the track for a baseline with the stock mass air sensor and 19lb injectors. The result was a very disappointing 13.46 at 103.7. We weren't quite ready to roll the car off a cliff, since we knew that the motor was not getting the proper amount of fuel.

We came back a few weeks later with the 24lb injectors back on the car (they tested out okay), a matching 76mm C&L, and an adjustable fuel pressure regulator (AFPR). We played around with fuel pressure and found the car produced the best ET with about 38lbs in the rails. We were now down to 13.29 with a trap speed of 105. Still running on very worn Nittos, the 60ft was far from optimal at 1.87.

Fuel System Upgrades
The stock 5.0L Mustang fuel system consists of an 80lph (liter per hour) in-tank fuel pump, nonadjustable pressure regulator, and 19lb. injectors. This is good enough to support 250-275 flywheel horsepower, or basically your typical bolt on modifications without heavy induction mods. Once you get into better breathing heads and a cam, around the 300-350 horse range, the fuel system must be upgraded to 24 or 30lb injectors. This means the fuel pump, injectors,mass air, and an adjustable fuel pressure regulator. You really can't do without all three.

  • Injector and AFPR installation
    We installed a set of good used 24lb. injectors (blue tops) and a regulator. Installation is straight forward. Depressurize the fuel rails by depressing the schrader valve. It is not necessary to disconnect the fuel lines from the injector rail.

    Next remove the upper intake manifold and associated vacuum lines. Now you can remove the four fuel injector rail screws and slowly pry the rail and injectors out of the manifold ports. Remove the old injectors, making sure not to leave any O-ring behind in the rail or the manifold.

    With the injector rail up and off the manifold, remove the three Allen screws which hold the stock regulator to the rail. Then install the new regulator and O-ring and secure with the same Allen screws.

    Put a little petroleum jelly or Vaseline on the new injector O-rings and place them into the rail ports. With all eight injectors on the rail, carefully line up the injectors in the manifold ports, and use light pressure to force the rail and injectors into place. Replace the rail retaining screw.

  • Fuel Pump Installation
    While we could get fuel pressure to 38psi. the car seemed sluggish at WOT, as if the stock fuel pump was not keeping up with the demand. So we made the $100 upgrade to a Walbro 190lph replacement pump.

    Installation of the pump is straight forward. Drive until the fuel level is at empty. Depressurize the fuel rails at the schrader valve, and disconnect the battery. Jack the rear of the car as high as possible, and remove the tank straps. Lower the tank carefully, disconnecting the electrical connectors and two fuel lines necessary to allow the tank to drop. Eventually you'll need to pull the tank off the filler tube. The pump assembly is accessed from the top of the tank, secured by a circular retaining ring. Use a brass punch to knock the ring loose and then pull the pump out.

Decision Point
At this point we were pretty much at a crossroad. On one hand we were leaning towards putting the stock cam back in. It would be the simplest

We obtained a good used (and partially polished!) Edelbrock Performer upper intake manifold. The difference between it and the RPM is the Performer features longer runners. Edelbrock rates its range from idle to 5500 rpm, whereas the RPM intake is rated at 1500-7000 rpm. Both models utilize the same lower intake. The runner length influences the resonant tuning effect of the intake charge, which effects the torque characteristics of the engine. The longer the runner the greater the low end torque.

The Performer we obtained is an older model, which features a cool ribbed "vintage" style plenum cover. However the older design utilizes a bolt inside the plenum to mount to the lower intake. A little patience and stubby wrench is required to tighten the bolt.
way to eliminate all the driveability problems. By the way, the other two criteria -fuel economy and emissions, were satisfied. Even with the idle and bucking quirks, the motor was delivering 17-18mpg over a typical weekly commute, and that would surely be around 20mpg on a sustained 300+ mile drive. With the catalytic h-pipe the car passed emmissions with flying colors, putting out nearly zero hydrocarbons! See the full test results in our article on the catalytic h-pipe. However not wanting to give up so quickly, the other option was to first get the driveability back by obtaining a Performer upper intake. Fortunately we located one locally and in a matter of hours we had the RPM upper removed and the Performer upper in its place. (The nice thing about the two Edelbrock intakes is that they share the same lower intake, making the swap a matter of minutes.)

Bingo! The first 100 yards of driving confirmed our suspicions that the Performer intake, rated at idle to 5000 rpm, is a better match for our engine combination. The off-idle torque was now abundant, and suprisingly we noticed no significant top end loss. The idle and bucking were not improved, lending more support to our theory that the stock mass-air voltage transfer functions in the EEC must be modified to the match the load of the new engine combination. (The EEC processor contains tables which correlate voltage from the mass air sensor to air-flow in kg/hr. We were stunned with the improvement in driveability. Fifth gear passing on the freeway was now possible, whereas with the RPM intake we found ourselves having to downshift into fourth in order to avoid a spongly, responsless, throttle until the tach hit 3000 rpms.


More Track Results
Of course the ass-meter has failed us many a times in the past, and the only way to corroborate our feelings for the Performer would be to get

In line with keeping the car a daily driver, we went with Nitto drag radials (245-50R16). At 30psi they function as well as a radial on the street. At 15-18psi at the track they hook as well as a cheater slick. Besides, it's nice to sip a Coke in the pits while your buddies are sweating to get their wheels swapped!

back to the track. So we did... The first run of the day was a gut wrenching 13.80 at 106 mph. No need to panic though, the numbers told the secret. Wheelspin, or a slipping clutch, resulted in a horrible 2.16 60ft. Yet the mph was over 1mph higher than our previous best with the RPM intake. There was potential in those numbers.

We lined up again, reducing the pressure in the Nitto drag radials to 17 psi and bringing the launch down to 3000, this time a 1.80 short time flashed the board, soon followed by a 8.33 1/8th mile ET. As the driver of the car I can tell you that when you see an 8-tenths reduction in ET just at the halfway point, it's easy to lose concentration and screw up the 3-4 shift. Fortunately I didn't, and the timeslip confirmed the joy, as we just knocked off a 12.97 @ 107.8

Two more runs followed and we ended up improving to 12.85 @ 108.2 on 1.76 60ft!


So where are we at now?
The Performer intake was hands down the key to the performance puzzle here. The latest track results show a clear gain in power across the board. Without getting the car on the dyno it is hard to say how much power the Performer makes versus the RPM, but we are pretty confident that what we'd see is the RPM making perhaps a few more peak HP at a higher rpm, however the Performer will have a flatter, broader torque curve, which calculates into more average horsepower...and that is what counts in a street car.

The driveability issues are still not completely resolved. In order to live with this cam in a daily driver we must resolve the low speed bucking, and choppy idle, problems. A custom chip, or perhaps playing around with one of several aftermarket EEC tuning software, will make this engine the perfect all around street-strip daily driver.


Project 5.0L EFI Track Results
Date Run 60ft 1/8et 1/8mph 1/4et 1/4mph major change/comments
2-9-02 11 1.75 8.24 85.75 12.85 108.2 ~70deg.air temp.
  10 1.80 8.33 85.01 12.97 107.8  
  9 1.77 8.28 84.42 12.93 107.3  
  8 2.16 9.09 82.91 13.82 105.9 Performer intake. 24lbs@38
       
 12-01 7 1.99 8.75 80.91 13.53 104.6 24lb@36psi
  6 1.89 8.59 82.77 13.37 104.8 24lb@40
  5 1.87 8.52 81.07 13.29 105 24lb@38 --view video--
  4 1.96 8.77 81.84 13.79 100 Performer RPM. 24lb inj. 76mm MAF. (missed 3rd)
 
 11-01 3 2.016 8.84    13.67 102.2 19lb@40psi
  2 1.925 8.67   13.46 103.7  
  1 2.19 9.02   13.83 103.29 19lb inj. stock MAF. (missed 2nd)

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Posted by prw512, 09/10/11 09:01pm:
your problem is the cam 112 ls is bad you sould try 114 ls



Fuel System Upgrades
The Walbro 190lph kit includes new connector, filter, hose, and rubber tank seal. The kits are universal fit, meaning there are minor mods to make. For one, don't use the tank seal since it's a square cut and the stock one is round. The square cut will leak. Secondly, the rubber hose needs to be shortened to match the stock hose (shown in lower pic.) Finally the stock connectors are simple spade lug style, they will need to be transferred over to the new pump.

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
   

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