The 4.6L has been in the Mustang for 10 years now. The modular aftermarket has finally exploded with parts. While we still don't have a set of heads everything else is there to make serious power. These engines are pretty stout from the factory with the exception of the pistons. There are several 2v mustangs making upwards of 600 rwhp.? But if your new to the game here is a beginner's guider to Mustang performance.
Underdrive Pulleys- add approximately 6 to 10 hp and about the same amount of torque. They reduce the speed at which your accessories turn such as a/c, water pump, and alternator. Prices range from $99 to about $169 for top of the line Steeda pulleys.
High flow H or X pipe- one of these will add between 6 and 15hp on the top end of your 4.6. They help the car breathe better above 3000rpm by reducing backpressure. However the reduction in backpressure may cause a loss in low end torque. If you buy an offroad H-pipe then your "Check Engine" light will come on because the offroad pipes don't have catalytic converters. In order to resolve this you have two choices, buy MIL eliminators from Dallas Mustang Parts or get a chip burned to turn off the two rear catalytic converters. Either of these methods will make the "check engine" light go off. Prices range from $109 to over $400 for a Bassani X-pipe with high flow cats.
70mm throttle body- a larger throttle body will give you an additional 1 to 3hp. The car should feel a little more responsive. A new Ford SVO throttle body will run you $199.
Mass Air Flow Meter- a larger MAF meter can be worth as much as 12hp on modified cars. They allow the car to take more air which means more power. I would suggest you get the meter after you have made modifications to you car because they don't do much for stock 4.6's. They cost about $259 for either SCT or Pro-M. Many supercharged mustangs use the Lightning MAF.
Gears- gears don't add horsepower but they feel like it! They allow your car reach its powerband faster than with the stock rearend. The car will turn more rpms at highway cruising speeds. Getting gears that are too deep can give you bad gas mileage. A 96-98 4.6L 5spd should go for 3.73 gears. The newer 99 and up 5spd cars do great with 4.10 gears. This is because the newer cars have more useable powerband. All the automatic 4.6L's should go for 3.73 and a PI torque converter. This setup will outrun most 5spd cars. A new set of gears only costs $189 but you will need a professional to install them. Installation can run $250 or more.
K&N air filter- a K&N air filter should be the first mod that any Mustang owner makes. In some cases just adding the filter will give 1 to 3hp and plus it has a lifetime guarantee. They cost between $39 and $49.
Steeda timing adjuster- an old trick to get free hp was to advance the timing. Well, Steeda has made it easy to advance the ignition timing on 4.6L's with their timing adjuster. You can get as much as 10hp depending on your setup and low end torque will increase as a result. Steeda will let you have one for $169.
Catback exhaust- a catback exhaust replaces everything from the catalytic converters on back. They can add up to about 10hp but most people buy them for the sound. They cost between $229 and $699 for a stainless Bassani exhaust. If you only want that deep rumble then a set of mufflers will do the trick as the stock pipes are stainless and will last forever. A pair of 2-chamber Flowmasters will cost about $60 apiece. A new player in the Mustang game is SLP, a long time GM parts producer.
Ignition wires- a set of ignition wires will reduce the amount of resistance and provide a more powerful spark. These are only available for the 96-98 4.6's because the 99-00's don't have use ignition wires. A set of wires will cost you between $79 and $109.
Coil Packs- a set of high performance coil packs will deliver more energy to your spark plug. This will create a fatter more powerful spark. These should be used in conjunction with high performance wires in order to get the best results. Accel, MSD, or Performance Distributors are your only choices. They run about $100 for the set. Shown below are the Screamin Demon packs from Performance Distributors.
EEC/Computer- EEC
Intakes- Intakes
FRPP cylinder heads- the FRPP heads improve horsepower and torque from about 3000 rpm to the 6000 rpm redline. Out of the box they bring 35 additional ponies but if you get them hand ported they can be worth 50 to 60hp. A set of professionally ported FRPP heads with custom cams can be worth 65 to 80hp. The heads cost about $1700 from FRPP. The head porting will run you between $500 and $1200. A cheaper alternative is to bolt on the PI (power improved) heads from the current 99 and up 4.6L. The heads, intake and everything needed for the conversion will cost about $1200. An advantage to doing this is that you will gain a full point in compression and not to mention about 40hp at the rear wheels. However this is not a good idea for a blown car because after the headswap you will be running 10.5:1 compression.
Camshafts- Aftermarket cams are beginning to show up for the 2v motor. Comp Cams, VT Engines, Livernois Motorsports, Crower, SHM, Crane Houston Performance, and Modmax are all offering billet cams. Modular 2V's real respond well to split pattern camshsfts. For good street cam I would recommend .530" 216 @ .050 intake and .550" 218 @ .050 exhaust. For a blown car I would go .550" 224@.050 intake and .550" 228@.050 exhaust. New valvesprings are needed with any cam over .531" lift. The Crower or Comp Cam springs can handle up to .600" lift. A few people have put regular PI cams in 96-98 heads and have gotten gains of 12-15 rwhp. The stock PI cams are about $145 each.
Roots blower- the roots type blower available from FRPP or Allen Engine Development is a quality piece. Full boost of 6psi is reached by 2000 rpm and holds all the way to the redline. This blower will give you some much needed low end torque. This kit will make your 281 feel like a 351W. Your car will throw you in your seat like never before. There is even a smaller pulley available to increase the boost to 9 psi. FRPP claims a gain of 55rwhp but it is more like 60-75rwhp and if you have mods it will be more than that. The blower will run you about $2000 plus $900 for the install kit. The Allen kit comes with an intercooler and it puts out around 9 psi of boost for a gain of roughly 90 rwhp and a bunch of torque. It is a little more expensive at $3500 for the kit. The big news in positive displacement blowers is the Kenne Bell 2V kit. You can get 6, 9, or 14lb pulleys and its intercooled. Folks this blower makes some big time power. Over 400 rwhp and 430 rwtq with the 9lb pulley.? Saleen also sells a lysholm twin screw kit for the 2v cars.
Centrifugal supercharger- centrifugal superchargers will give you a good midrange and awesome top end power. The more rpm you are turning, the more power they produce. Generally with 8psi and stock 96-98 4.6L will get a 100hp shot in the arm. The 99-00 GT's will get about 130hp from 8 psi of boost. The popular manufacturers are ATI, Paxton, Powerdyne, and Vortech. They cost between $2500 to over $4000. On a stock 4.6L you shouldn't go above 8psi unless you have an intercooler or aftercooler because the increased heat may cause detonation. Detonation will kill a stock 4.6L because the stock pistons and connecting rods are not forged and will break. The most important thing on a blown car is to have a safe tune. The air/fuel ratio needs to be below 12.0:1.
Headers- short tube headers may add about 3 hp to a stock 4.6L and more on modified cars. Longtube headers have been shown to add over 15hp and 20ft/lbs of torque. Installation is a real pain because you basically have to remove the motor to put them on or drop the K-member. A set of shortubes can cost from $299 to about $450 while the longtubes go for $349 on up. Hooker, BBK, and Mac are the popular manufacturers. Bassani and JBA have released new midlength headers that offer easier installation and almost as much power as longtubes. Hedman has gotten into the header game also, they offer a set of 2V longtubes for just over $210.
Nitrous- Nitrous offers the best "bang for the buck" of any modification. For around $500 you can have an additional 100hp. Most kits are adjustable between 50 and 125hp. I highly recommend that unless you have a Bullit or SVO intake that you run a dry kit. A wet kit will give more power but many people have blown up their plastic intake manifolds because of nitrous backfires. On a stock bottom end the most you should run is about a 150hp shot of juice. Holley's new NOS noszle kit is the safest wet kit on the market. It sprays nitrous and fuel directly into the combustion chamber bypassing the intake manifold.
5.0 Big Bore Block- New for 2003 is the FRPP 5.0L crate motor. It makes 425hp and 360lb/ft of torque. This engine is centered around a 5.0L modular block that has 3.7" bores rather than the stock 3.55" bores. This is done by taking an aluminum Cobra block and resleeving the cylinders to accept the bigger 3.7" bores. Several shops are selling these "5.0" shortblocks. Modular Performance, Livernois Motorsports, and SHM just to name a few. The bigger bore produces more power and torque across the board. Modular Performance even offers a stroker kit for the 5.0 big bore. It will increase the already potent motor to a whopping 5.3L and 324 cubic inches. SHM offers a similar package that displaces 5.2L or 318 cubic inches. Since they are fairly new they are still relatively expensive.
Stroker Kit- Much like the big bore block, a stroker kit increases power by increasing displacement. The stroker is basically what the name implies. So far there are a few companies offering 4.6L strokers. Most of them increase the displacement to 298 or 302 cubic inches. This is done with a longer 3.70" or 3.75" crankshaft. The stock unit only has 3.543" throws. All of the kits are available in stock bore or .020 overbore.
This is a test done in 1997 by Super Ford magazine. It shows the gains that the test car recieved with the FRPP parts. With FRPP heads and intake the GT has the same hp as a Cobra but more torque. 4.6L Cobras dyno about 255-265hp and 260-265lb/ft of torque. Notice how peak hp has moved up in the rpm range. With these mods a set of 4.10 gears would be perfect.
