Ford Modular Engines

Frequently Asked Questions


Modular FAQ

Q: I recently installed an off-road h-pipe on my car and now I get a Check Engine light, what's wrong with my car?

A: The stock catalytic h-pipe comes with 4-6 converters from the factory. There are 4 o2 sensors that tell the computer if the cats are doing their job. The first set looks at emissions and then compares to the rear set to see if the converters are doing their job. When you run an off-road pipe the readings never change so the computer senses something is wrong and trips the "Check Engine" light. There are several ways to fix this problem. First you can go with a set of MIL eliminators. These plug into your rear o2 sensors and basically fool the computer into thinking everything is OK. Option 2 is a custom burned chip. The chip can be programmed to turn off the rear o2 sensors among other things. This will also remove the light. Keep in mind with either modification, power must be disconnected for them to work.

Q: I want to change to bigger injectors, is there anything else I need to buy?

A: When you decide to change injectors to a 50# or smaller high impedance injector, you also have to have your mass air meter recalibrated to work with the injectors. On a Pro-M this requires sending it in for re-calibration. On a C&L it requires a sample tube change. Anything larger than 50# injectors will require an injector driver and most likely an aftermarket stand alone computer to function properly.

Q: I swapped gears in my Mustang, how do I correct the speedometer?

A: For 96-98 cars you can replace the speedometer gear with a higher tooth gear to correct for gear changes. Please see the speedometer gear chart on page 72 of our catalog for the proper speedometer gear for your car. For 99+ cars you will need to use a speedo recalibration box (Part # SGRB) which electronically recalibrates your speedometer.

Q: What is the biggest size slick I can run on my car without cutting?

A: On the 94 and up Mustang GTs you can run a 15x10 rim with 6.5 BS and clear the brakes and wheel wells. This wheel will also fit a Cobra, but grinding of the caliper for clearance will be necessary. The biggest slick for those rims would be a 28x10.5x15 MT ET Drag. This will barely clear the wheel wells. Most naturally aspirated street cars will only need a 26 inch drag tire to hook up where power adder and higher HP NA cars will benefit from 28 inch slicks.

Q: What size rim do I need for skinnies, and do I need spacers too?

A: On a GT you can run a single 7/16 spacer and a 15x3.5 in front skinny. The Cobra is a lot more involved. You need to run 2 spacers and put longer studs on for the skinnies to clear the calipers. The only manufacturer to make bolt on skinnies for 96+ Cobra is Bogart Racing Wheels. Bogart welds a legal spacer onto the rim during production. Long studs are highly recommended when using any spacer.

Q: What are pulleys and why do they make horsepower?

A: Underdrive pulleys do exactly what the term implies, they slow down the speed at which the accessories drive. They accomplish this by using different size pulleys on the crank, water pump, and alternator. The alternator and water pump are run at slower speeds while the crank spins more freely. Think of switching gears in your 10 speed bicycle from the big gear in front and the little gear in back to the little gear in front and big gear in back. This slows down the tire and makes it easier for you to turn the pedals. This allows the engine to rev up much more freely and is usually good for 8-10 horsepower.

Q: Why do I need an aftermarket shifter?

A: The T-45 transmission used in the 96-00 Mustangs is on the weak side and the sloppy stock shifter doesn't help matters any. The Tremec 3650 and T-56 used in 01 and up Mustangs are a lot stronger then the T-45s, but still will benefit from a good aftermarket shifter. A good aftermarket shifter will feature positive stop bolts that will prevent you from breaking a shift fork on a good hard shift. They also use better materials to give the shifter a much firmer feel.

Q: What is the difference between progressive and specific rate springs?

A: Progressive rate springs have a variable spring rate. What this means is that the spring gets firmer as it gets compressed. The harder you push into a corner the stiffer the spring becomes. A specific rate springs features the same rate all the time, it does not matter what pressure is applied on the springs. Progressive rate springs tend to have better characteristics on the street where as a specific rate spring shines on the track.

Q: I want to replace my T-45 transmission with something stronger, what options do I have?

A: There are several options for replacement transmissions for the T-45. The most popular is a swap to a 5-speed Tremec Trans. You will need the following to do this: Tremec 3550 trans, Lakewood or McLeod modular bellhousing, Tremec specific shifter, and a drive shaft yoke from a 5.0 car since the 3550 was designed as a T-5 replacement. If you choose the stronger Tremec TKO trans you will also need a TKO specific clutch though the TKO comes with its own driveshaft yoke. Another option is the Tremec T-56 6 speed conversion. The 6 speed is becoming more popular because the extra overdrive gear allows for more aggressive rear gearing while keeping highway RPM at a minimum. You will need the following for the T-56 conversion: Tremec Mustang specific T-56 trans with bellhousing and a Pro 5.0 six-speed shifter. You will also have to have your driveshaft shortened one inch. The stock 4.6 yoke will work since the trans was designed for mod motor use. You will also have to slightly modify the trans mounts or order one from Energy Suspension. These are the most common swaps although some more serious racecars have gone to LenTech automatics or C4 automatic trannies. A newer option for the modular cars is a G-Force trans swap. The G-Force trans is designed for the serious racer and will require several modifications to work in a modular application. Please call our sales department for more details.

Q: What is the difference between shorty and long tube headers? Which should I buy?

A: Both shorty and long-tube headers are available for GTs and Cobras. Short tube headers make more power than stock manifolds but less than a long tube header will. The short tubes are the same size as the stock manifolds so you can use the rest of your existing exhaust system. Longtube headers make more torque and power, but installation is much more involved. The headers extend down to the transmission and require a specific short matching h-pipe. If you are looking for every last pony availible, get the longtubes. They will increase your torque and HP more than shorties will, but they will cost more to purchase and install.

Q: Is a cat back worth the money? How much HP will I gain?

A: Cat back exhaust systems are usually better engineered and fit and look better than stock parts. They will also give your car a much better sound. HP gains vary by models but expect anywhere from a 5-20 hp gain.

Q: What are lower control arms and why should I replace my stock ones?

A: Lower control arms are one of the parts that connect the rear of the car to the chassis itself. Their main duty is to keep the rear from swaying and plant the tires. Aftermarket arms such as Maximum Motorsports, Steeda, BBK, Ford Racing and others use better bushings and stronger materials to plant the rear tires during straight-line acceleration and cornering.

Q: What does the quad shock do, and should I buy new ones when I change my regular shocks?

A: Ford began installing quad shocks years ago to stop the rear from hopping during hard acceleration. Just about all the major suspension companies offer a replacement quad shock. Many racers simply remove the quad shocks because their aftermarket control arms do such a good job of controlling axle hop. Home Install tip: when swapping quad shocks the visible top nut will not turn. This nut is welded to the frame. Reach under and you can remove the bolt from the rear.

Q: Can I install gears myself?

A: While it is possible, this is a modification we highly suggest you leave to a qualified mechanic. Gear installation requires specific shimming of the parts to make sure the rear wears properly and does not make noise.

Q: When I owned a 5.0, the best free mods included bumping timing to 14 degrees, the mod motors don't have distributors though. How can I advance my timing?

A: This is as simple as a call to our sales department. Steeda offers a timing adjuster that fits on the crank of both GTs and Cobras. You simply loosen the 2 set screws and turn it to the proper setting on the indexed trigger.

Q: At what point do I need an ignition system like the MSD or Jacobs boxes?

A: Most people do not run an aftermarket ignition unless they run a power adder of some kind or a hard-core NA race car. The ignition provides additional spark for a hotter burn in the cylinder. This will usually result in more power, especially in a power adder car. With a power adder there is more pressure in the cylinders so the added spark is a good idea to avoid spark blowout. You can also add other accessories such as a 2-step which are a great help for a drag car. The 2-step limits engine RPM while holding down an interior mounted switch. This is perfect for consistent rpm launches at the track.

Q: What flywheel do I use for my 4.6?

A: All 4.6 Cobras use an 8 bolt flywheel, FMS # M6375G46 for Billet. GT's are a little different. You will need to check the VIN # of the car. If the 8th character in the VIN is the letter X, the motor is a Windsor and will use the same 8 bolt flywheel as the Cobras do. If the 8th character is the letter W, the motor is a Romeo and uses a 6 bolt flywheel.

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* Please be advised that this information is for suggestion only and is based on prior experience. We at CJ Pony Parts can not be held responsible or liable for any mistakes or injuries connected with the topics covered.