Dr Jamie Meyer
May 1, 2004
Contributers: Brian Herron Of Apten Performance Photos By: Brian Herron Of Apten Performance

Horse Sense:
As with so many cottage businesses making a go of it on the Internet, we hadn't heard of Apten Performance until we saw message-board posts about its modified blower for '03 Cobras. We discovered that not only does the company offer products for Mustang Cobras, Bullitts, Mach 1s, and GTs, but it also addresses such niches as Thunderbirds, Explorers, Rangers, and Sport Tracs. Apten's modified stock blower makes power in an interesting way That's a jump of 36.4 rwhp and 9.6 rwtq with a supercharger swap that no one can detect

We're having a great time adding parts to the new king of all musclecars-the '03 SVT Mustang Cobra. This thing rocks from the second you fire it up, and it only gets better when you add a few hot-rod parts. So far we've given you the skinny on cold-air kits, performance exhaust systems, shifters, pulley swaps, computer chips, and a few other tips along the way. Just opening up the inlet and exhaust sides of the raucous factory-blown 4.6 four-cammer is enough to make your hair stand on its end. But when you add a supercharger pulley for more boost and then top it all off with a good tune, this sucker gets up and begs like only one or two percent of all performance cars ever built.

Along the way, our friends at Paul's Automotive Engineering have acted as hosts and judges of some of the best aftermarket companies in the country with their in-house chassis dyno and talented Ford performance technicians who have assisted us with installations and evaluations. This time around, we're going to dig a little deeper into that marvel of technological torque under the hood with the addition of a ported stock Eaton M-112 supercharger from Apten Performance, which we'll pair with a more efficient heat exchanger from AFCO Racing Products.

AFCO has been making heat exchangers for the SVT Lightning for several years, and as does much of the Cobra technology, this is an area that borrows from successful Lightning products. The factory system circulates an antifreeze mixture through the intercooler mounted under the Eaton supercharger and through the heat exchanger located in the front of the car. There is a reservoir located under the hood to allow owners to maintain the fluid levels in their intercooling systems. The AFCO unit ($429) replaces the stock heat exchanger behind the front bumper and increases surface area for heat exchange by more than 30 percent. And, we can't stress enough how simple it is to swap this unit into the car. You don't have to remove the bumper or any of the other factory gear. The AFCO unit bolted into our car in less than 10 minutes, and it worked like crazy to keep inlet temperatures down, especially in our heat-soaked, three-back-to-back-run test.

We first heard about Brian Herron's Apten Performance-modified stock Eaton supercharger on one of several different Web sites that cater to factory-blown SVT Cobras. The word was that Brian could take your stock blower and for a reasonable fee ($599) work it over to result in appreciable gains on the chassis dyno and-more importantly-the seat of your pants.

Our photos will detail what the difference is once Brian has worked his magic. For us, it is an awesome modification that we highly recommend. Perhaps the most important reason we like this modification is that no one knows it's there. There is a slight sound difference, but other than actually removing the blower, no one can tell you've tweaked the car. The results are well worth the coin and effort. We easily saw the advertised 30-plus horsepower increase at the tires, and the majority of that is across the entire rpm range. There is also a noted increase in torque.

Apten's modified stock blower makes power in an interesting way. In stark contrast to swapping the blower pulley (the most obvious and dramatic way to increase power on an '03-'04 SVT Cobra), there is no increase in boost. Instead, the Apten modifications make the supercharger more efficient by decreasing the amount of power it takes to turn the blower itself as well as decreasing inlet temperatures by more than 10 degrees. As you can see in our photos, the outlet side of the blower is modified in such a way as to open up a larger surface area of the blower to the stock intercooler, thus decreasing inlet charge temperatures. Again, boost and engine rpm will stay the same, but you will see a jump of 30-40 rwhp in the car across the powerband.

While we took advantage of Brian's skills with the Superchips Custom Tuning software that he knows so well, it is important to point out that you will not need to have the car retuned if you just swap on the Apten. This is because the efficiency of the engine-not the boost-is increased. Also, Brian pointed out that his blower, combined with a 2.8 pulley, a cold-air intake, an AFCO heat exchanger, and a good exhaust system, will put the average '03 Cobra over the 500rwhp mark and right at the point where a custom fuel system and retuned mass air should be considered. Of course, at this point you will have a 500-rwhp car that acts just as it did stock-until you drop the hammer.

Joining Brian at Paul's Automotive Engineering was his friend and NMRA SSO superstar Jason Cohen.

We began with a baseline of our car, which came up to 433.9 hp and 471.3 lb-ft of torque at the rear wheels. This was with our custom Amazon Racing tune-up, a K&N FIPK, a Billet Flow pulley set featuring a 2.76-inch upper with idler, a Bassani X-pipe with cats, and a Bassani after-cat exhaust system. We were noticeably down on power and blamed it on the 100-percent humidity and terrible weather conditions. Even the Dynojet chassis dyno had trouble correcting for the horrendous relative elevation reading (4,500 feet). Still, the test would remain a good evaluation of the parts in question since we had everything swapped out well before the rains stopped.

With the AFCO heat exchanger swapped on, the car was measured at 437.8 hp and 473.4 lb-ft. We weren't expecting a power increase, even though there was a slight amount found. We were more interested in street performance. To test this, we ran the car with three back-to-back pulls with the stock heat exchanger and then again with the AFCO unit. The results speak for themselves in our graph. As you would predict, we didn't lose power with the AFCO unit as we did with the stock heat exchanger. You also have to realize that the AFCO piece is doing a good job of warding off detonation at heat soak when you're out there during a long summer's night of street racing.

Next up, we swapped on the Apten Performance-modified stock supercharger. Working with Tom Honsaker and Mike Wilson of Paul's Automotive Engineering, Jason had the blowers swapped in less than two hours, which included a sizeable pizza break. We jumped from 437.8 hp to 474.2 and from 473.4 lb-ft to 483.0. The torque is seen across almost the entire powerband, while the horsepower begins picking up gradually at 3,000 rpm and increases to a maximum at around 6,500 rpm, well after you should shift the car. That's a jump of 36.4 rwhp and 9.6 rwtq with a supercharger swap that no one can detect.

To further test the blower, we backed the blower pulley size down to a more common 2.93 inches. This resulted in a pull of 461.2 hp and 464.8 lb-ft-a nice gain with a safer boost level. As noted, Brian tuned the car with a Superchips flash, but that was after the testing was over to clean up a few spots on the curve and to perfect the driveability. We want to stress that this was done because Brian was at the dyno with datalogging equipment in hand, and he was willing to put his tune in the car. The Amazon Racing/Diablo chip that was in the car worked wonderfully throughout the test.

We had one other interesting test that day, and it involved an '03 Cobra with an open-element air filter, a 2.76-inch pulley, and a mail-order Amazon Racing chip. The car baselined at 419.3 hp and 461.2 lb-ft. With the car still on the rollers, the guys swapped the Apten Performance Eaton onto the Cobra, and it picked up to 456.6 hp and 470.9 lb-ft with no tuning whatsoever. We'd say Apten has a certified winner with this piece.

Photo Gallery

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Apten Install
These are the steps to remove and reinstall the supercharger on your '03 Cobra. With a cool car, it will take two people anywhere from one to four hours to complete the entire job, depending on experience. While it may seem to be a difficult task, the instructions are lengthy only because we tried to include every step and make note of every possible shortcut. Torque specifications are not included, so check your shop manual.

Required Tools

  • 8mm socket
  • Deep socket 10mm
  • Standard socket 10mm
  • Open-end wrench 10mm
  • Deep socket 13mm
  • Standard socket 13mm
  • Open-end wrench 13mm
  • 3/8-inch extension
  • Torx bit (for MAT sensor removal)
  • Two fender covers
  • Pry bar to pull down tensioner and remove belt
  • One quart of intercooler fluid
  • One friend to help you complete steps 17 and 19 on the removal and steps 5 and 6 on the install
  • Double the 10mm and 13mm standard sockets if you have two workers

Supercharger Removal
1) Put a cover on each fender. You will be leaning into the engine bay, and you do not want to scratch the paint.

2) Disconnect the throttle cable and cruise-control cable from the butterfly. Remove the two bolts from the throttle cable bracket connected to the supercharger. Pull the throttle cable bracket out of the way.

3) Unplug the ISC and TPS sensors. These are the two black sensors that are on the inlet right behind the throttle body.

4) Unclamp the black plastic intake tube and pull it away from the throttle body.

5) Remove the four 13mm nuts holding the inlet to the supercharger and carefully slide it off. You do not want to damage the gasket because you will reuse it.

6) Remove the pulley cage if it is still on your vehicle.

7) Remove the supercharger belt.

8) Unscrew the black bracket on the passenger side that holds the boost bypass and several other sensors. There are two bolts on the side of the supercharger and one nut on the back of the EGR bracket that hold this on. Once you have removed those connectors, unplug the sensors and vacuum lines necessary to pull it clear. Be sure to note which wires you have disconnected and where they go.

9) Disconnect the EGR tube from the EGR assembly. The EGR assembly is black and round and located on the back of the supercharger. There will be a large nut holding the EGR tube to the EGR assembly.

10) There are two bolts that hold the EGR to the supercharger, once the EGR tube is off. Remove these two bolts and the entire black, round EGR valve will come off the back of the supercharger. Take it off carefully and save the gasket because you will reuse it.

11) Remove the vacuum lines from the back of the supercharger. There are a total of three lines, with one additional vacuum line that goes to the driver-side valve cover that may need to be disconnected.

12) Unplug the MAT sensor. This is on the driver side at the back on the supercharger. Look right below where the EGR was and slightly forward and you will see it.

13) Unbolt the two fuel rail bolts on each side of the supercharger. These 10mm bolts come right off. There is no need to remove the fuel rail or the injectors.

14) Remove the 10 lower intake manifold bolts. They are a gold color.

15) Remove the two black intercooler hoses from the front fittings. There is a hose clamp on each one, and after you slide the clamp back, the hose will come off. This step will result in some intercooler fluid leaking on your floor.

16) With the two intercooler hoses removed, you can see the fittings they connect to on the manifold. This is actually a cap on the intercooler. In the next step, you will remove the cap. This takes two people.

17) Have one person tilt up the entire supercharger and intake assembly. When this is done you will have access to the four bolts that hold the intercooler cap to the intake manifold. With the intake tilted, unbolt three 10mm bolts and one 8mm bolt from the intercooler cap. Once the bolts are removed, pull the cap off the intake manifold. It will leak more intercooler fluid, and two fittings will come out with the cap. If only one of the fittings comes out, gently pull on the other one and it will also pop out.

18) Set the lower intake back down, making sure you do not incorrectly position it and smash the lower intake gasket while doing so. You will reuse the lower intake gasket.

19) Once the intake is set down, unbolt the 10 10mm bolts holding the supercharger to the intake manifold. After you have removed all the bolts, the supercharger will lift directly up.

20) Use rags or towels to soak up all the coolant that is sitting in the bottom of the intake. You want this to be completely dry.

21) Now that you have the supercharger out of the car, remove the black MAT sensor from the supercharger. Save this along with the two bolts. You will install it on your unit when it is replaced.

22) Remove the bypass valve from the supercharger. This is the black valve on the driver side and is held on by two bolts.

23) The last step before sending your supercharger to Apten is to remove the intercooler. Carefully unbolt all 10 bolts that hold the intercooler to the bottom of the supercharger. If one bolt becomes difficult to unscrew, thread it back in and then try again. You may have to perform this sequence several times on each bolt to get them out without breaking. If you do break a bolt, Apten can remove it for you, but it costs $20 to have each one backed out.

24) Now you are done. To ship the supercharger to Apten, package it carefully in a box that is at least 12x12x26 inches. If you cannot come up with a suitable box, Apten can send you one. The supercharger should be packaged so there is at least 1 inch of padding between it and any part of the box. Newspapers work well, as do foam sheets and padding. Foam peanuts do not work as well because the supercharger can shift around while being transported. The shipping weight should be approximately 35 pounds.

Reinstallation
1) Now that you've disassembled everything, reinstallation is a backward process.

2) First, install the intercooler back on the supercharger. You should use red RTV and put a bead around the mating surfaces on the supercharger. Also, use red Loctite on each of the intercooler bolts. Do not torque them down too tight or you will break them.

3) Reinstall the black MAT sensor on the supercharger.

4) Reinstall the bypass valve on the supercharger.

5) Now you will put the supercharger back in the car. Inspect the supercharger gasket on the top of the intake manifold and make sure it's still good. If so, carefully set the supercharger on top. You will feel the dowel pins slide in and the supercharger will fall into place. Install the 10 bolts on the supercharger that hold it to the intake manifold. These are the silver 10mm bolts.

6) Now that the supercharger is bolted down, you will need a second person for the next step. Tip up the entire intake manifold so you can place the water cap back on the intercooler. Make sure that both water tubes are installed and popped into both the intercooler and cap. When they fit into place, you will feel a clean, crisp pop as they go together. Once they are in, reinstall the three 10mm bolts and one 8mm bolt that connect the cap to the lower intake manifold.

7) Carefully drop the front of the supercharger so the intake manifold sits in place. It's important that the intake manifold sits correctly on top of the intake manifold gasket. When you set the manifold down, give it a little nudge back and forth to make sure it feels lined up. You can also look down the intake manifold bolts and verify that the holes are lined up with the gasket.

8) Install the 10 intake manifold bolts. These should be torqued in the typical intake-manifold installation pattern. Begin with the middle bolts, reversing sides, and work your way out to the ends.

9) Making sure all the fuel injectors are still installed tightly, bolt down the fuel rails. If the injectors are not down all the way, the bolt holes for the fuel rail will not line up correctly.

10) Connect the wiring plug for the black MAT sensor on the driver side near the back of the supercharger.

11) Connect the three vacuum lines to the back of the supercharger, and install the vacuum line to the driver-side valve cover if you removed it earlier.

12) Install the EGR valve back on the supercharger. There are two bolts that hold it on and a gasket that goes behind it.

13) Reconnect the nut that holds the EGR valve to the EGR tube.

14) Reinstall the black rail with the boost bypass and accessories. Be sure to reconnect every vacuum line and every sensor plug that you removed.

15) Reinstall the inlet to the supercharger. Be sure to use the gasket, and tighten down all four 13mm bolts.

16) Plug in the IAT and IAC sensors.

17) Install the throttle cable bracket on top of the supercharger. Connect the throttle and cruise cable to the butterfly.

18) Reinstall the rubber intake tube and tighten down the clamp.

19) Install the supercharger belt.

20) Install the pulley cage, if you still use it.

21) Check all connections, and make sure you have no bolts left over. If you have any questions, call Apten at (314) 276-9608 before starting your vehicle.

22) Unscrew the intercooler reservoir cap and start the vehicle. After 20 seconds of operation, you will need to top off the reservoir with more intercooler fluid as the pump kicks in. - Brian Herron,Apten Performance