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Building a 450hp, Blown or Nitrous'd, Daily Driver 5.0
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Everyone wants a daily-driveable street car that hauls. Even the fastest track-only Pro 5.0 drivers, or all-out autocross guys, want a driver that doesn't disappoint. But we can't tell you how many times we have been at an event and seen a shuddering, ill-idling daily driver. It may be quick (likely in the 12s), but it surely can't be fun to drive. Using today's technology, we'll show you how to build a 450hp,11-second combination that is both streetable and durable.
We'll assume that you are starting with a stock-block-based 302. Since a stroker short-block (or stroker kit) is not needed to break into the 450hp level, we'll consider it an unnecessary expense. If you've already got a 351W or 347ci stroker, you're likely shooting for something a little hotter than the combinations that we are building. If you have questions about the durability of your short-block, check out the "Blow Me Up, Scotty" sidebar at the end of this article.
The key element in the 450 puzzle is airflow, and your cylinder heads are the main ingredient in getting a boosted (or nitrous'd) air mixture into your engine. You're likely to be confused about the many cylinder heads on the market, so we'll do our best to give recommendations on the most popular aftermarket street castings and any required porting or polishing.
Although it used to be very popular, porting stock or 351W heads and installing larger valves is really a waste of time and money, given the quality of the available heads. GT-40 iron heads, the mainstay of the budget racer for years, are no longer available. In their place, however, lies a wide selection of excellent castings intended for street-going 5.0s. The most popular are the TFS Twisted Wedges, Brodix Track 1s, Dart Windsors, Canfields, Avengers, Edelbrock Performers, and aluminum GT-40s.
An entire story could be dedicated to comparing and contrasting these heads, but we'll quickly gloss over the details. Any of the above heads can easily accomplish (and eclipse) the 450 hp mark. Of those listed, the smaller, more street-oriented heads would be the GT-40 aluminum (in both standard and "X" versions), Edelbrock Performers, and Dart Windsor Jr's. To clear the 450hp hurdle (even with a power adder) we'd recommend light porting--something like a port-matched intake and exhaust, bowl work and light combustion chamber reshaping.
The larger heads in our group are the Dart Windsor Sr's, Canfields, Avengers, and Brodix Track 1s. They generally will have larger intake ports (in both volume and cross-sectional area) and will adequately support more horsepower, rpm, and a power adder--but they will give up some torque on the street down-low and in the mid-range. Porting on these castings isn't necessary at this power level, although you might want to consider a polishing job to clean up any flash or roughness in the castings. The benefit to choosing the larger heads, over the more street-oriented castings, is the future power potential when you decide to step things up.
Something else to think about when purchasing a set of heads for your 450-hp power-adder street car is combustion chamber volume. Chamber size directly affects the compression ratio, so choose wisely. The stock 5.0 cylinder head has a combustion chamber of approximately 62- to 63cc, which produces about 9.0 to 9.2:1 compression--depending on production tolerances and the exact year of your cylinder heads and block. The aftermarket cylinder heads we've listed have varying chambers available from 54- to 64cc. That's a significant range that could result in anything from a 10:1 compression ratio on down to 8.8:1. Generally, for naturally aspirated/nitrous street performance, 9.5:1 compression is a good target, and about 9:1 for supercharged engines. Discuss the proper combustion chamber volume and compression ratio for your specific application with your engine builder.
Big cams are sexy--have been ever since the hey-day of the '60s when big 3/4-race cams, lope-lope idles, and solid lifters were the fad--but they don't necessarily make the most horsepower or sense for a street-oriented 'Stang. The first thing we need to do is outline what type of power adder is being used--the huffer (supercharger) or the juice (nitrous oxide).
Boost is a wonderful solution for a 450-plus hp street combination because you don't have to worry as much about a big camshaft (or, for that matter, a big intake or cylinder head). The boosted air/fuel mixture is forced through the intake port and past the intake valve, and the engine doesn't have to rely as much on opening the valve higher (lift) and longer (duration) to help get air into the engine. A set of 1.7 roller rockers is about all you need in an 8- to 10-psi blown application. That will increase valve lift on the stock cam from .444- to .471-inch lift and will boost horsepower up to about 430 to 450. An aftermarket cam is capable of making more power, naturally, but be careful with your selection. The bigger the cam, the more you'll hurt driveability.
Blower cams are a tricky business. Most people use the Ford Motorsport E303 cam (emissions-legal in 50-states) because of its proven ability to make decent power in a wide variety of applications. But, because the E-cam is a single-pattern cam (intake and exhaust duration are the same) on a narrow 110-degree lobe separation, it isn't optimum for a supercharged combination--though it does work fine on nitrous. With a boosted intake charge helping get the air/fuel mixture in, a blower cam doesn't need an aggressive intake lobe. Although, it should have a bigger exhaust profile to help get the exhaust out of the engine--hence, the dual-pattern cam.
Lobe separation is another area that is important for a supercharged camshaft. Wide lobe separation (114 degrees or more) spreads the intake and exhaust lobes farther apart, reducing overlap and preventing boost from blowing out the exhaust. Crower, Comp, Lunati, and other cam companies offer custom grinds that will satisfy all your basic blower cam requirements. Generally, on a street- oriented 5.0 blower cam, aim for an intake duration of 210 to 220 degrees at .050-inch lift, an extra 5 to 10 degrees exhaust duration (over the intake duration), and a 114-degree lobe separation.
If you're planning to use nitrous to make your 450 hp, the camshaft will be a critical part of your parts package. The stock cam isn't going to cut it. Even though the nitrous adds an additional punch to the intake charge, it doesn't increase port flow at lower valve lifts (and durations) like the blower does. With nitrous, you need a camshaft that opens the valves quicker, longer, and higher to help get the nitrous/air/fuel mixture in and out of the engine with the greatest possible power production. Nitrous camshafts are similar to naturally aspirated camshafts, but we would still recommend a slight intake-to-exhaust duration split. The Motorsport cams (E303, X303, F303) work well on nitrous, but your local 5.0 speed shop, engine builder, or cam manufacturer should be consulted for advice on your specific combination.
EFI or Carb?
Electronic fuel injection revolutionized the street performance market from a variety of angles. Streetability, durability, tunability, power production, and smog-legality are all areas in which fuel-injected 5.0s. Just the same, you can't beat the simplicity and cost of an old-fashioned carburetor. That presents quite a dilemma for those seeking 450-plus hp. The solution for the year 2000 is clearly the EFI setup, though.
For an EFI intake, any of the popular long-runner manifolds will work fine (Edelbrock Performer, GT-40, or Cobra) and won't require any porting or polishing. Throttle body size is another debate; but, you can't go wrong with a middle-of-the-road 70mm throttle body, available from BBK, Edelbrock, and Accufab. The mass air sensor (or MAF) should at least be the size of the throttle body or larger. C&L Performance offers 73- and 80mm sizes, and Pro-M (Best Products) sells 75-, 77- and 83mm models for a variety of applications. Just remember to order your mass air sensor in a size corresponding to your fuel injector size.
Carbs are making a resurgence in the 5.0 ranks due to their lower cost, ease of tuning, and healthy power potential. Using a centrifugal supercharger with a carb is a sticky mess (although some have done it), so we'll just advise on nitrous use. Try a dual-plane intake, such as the Edelbrock Performer RPM or Weiand Stealth, which won't require any porting. Carb size is another matter, and really depends on your entire induction, head, and camshaft combination--so, again, please consult with your local 5.0 shop. As a general guideline, an engine will make more power with a 650- to 700-cfm double-pumper carb, but won't get nearly the fuel-efficiency as with a vacuum secondary.
Giving your powerplant the proper amount of fuel is one of the most difficult areas for the beginning 5.0 enthusiast. Fortunately, at the 450hp mark, we can use most of the stock components. So, the margin for error is much greater than if we had to design an entire fuel system from start to finish. For EFI applications, you'll need to add a larger in-tank pump (190-lph or 255-lph) and an external pusher pump--maybe from Bosch, Vortech, or BBK.
The stock fuel rails will work fine with an adjustable regulator at 450 hp, but the fuel lines are questionable. At this level, we'll be right on the edge of requiring a larger 1/2-inch feed fuel line. You won't need a larger return line because you can use your old 5/16-inch feed line as your new return. Even though you may be able to get away with using the stock line, we'll go on record as recommending you install the 1/2-inch braided steel line (you'll need about 20 feet). Ground Pounder makes the fuel rail adapters for attaching the braided line to the stock fuel rails.
Properly sized fuel injectors are critical with an EFI system, and we could write an entire book about the topic. The size of injectors you need will be determined by whether you are running nitrous or a blower. Let's go on the assumption that our motor will produce 450 hp. With a wet nitrous system additional fuel for the nitrous will be added separately, so go with 24-pound-per-hour squirters, which are fine for naturally aspirated performance. A dry nitrous kit needs to add the fuel through the injectors (the dry kits ramp up the fuel pressure to help push additional fuel through), so usually a 30-pound injector is a good starting point.
With a supercharger, you'll need to juggle injector size with the calibration setting of your fuel management unit (FMU). An FMU ramps up the fuel pressure in a ratio that is proportional to boost. A supercharged combination is tuned by adjusting the FMU, base fuel pressure, and injector size. 30- or 36-pound-per-hour injectors will work well in the 450hp range.
With a carburetor, you'll need to re-do the whole fuel system--especially considering that you now need to supply the engine and the nitrous system as well. For naturally aspirated applications, a dead-head type fuel system (in which there is no return line) works fine. A return-style system is highly recommended when using nitrous, though. The easiest way to accomplish this is to purchase a fuel pump that features an internal-bypass (Barry Grant, Weldon, or Holley VoluMax), or use a return-style fuel regulator.
A 1/2-inch fuel feed line (-8) should tie into your fuel pump, which needs to pump a minimum of 110 gallons per hour. If you plan to increase the power of the nitrous system beyond 150 hp, or have total horsepower over 500, you will need to step up with a completely separate fuel system for the nitrous--including fuel line, pump, and regulator.
Huff or Juice?
From Pro-Mod to Pro 5.0, the blower versus nitrous debate rages on. We aren't going to tell you which is better (because that will always be up in the air), but we will outline some basic information about each as it applies to the 5.0 Mustang.
Going the supercharged route has a high initial cost, with the most popular centrifugal blower kits (Vortech S-trim, Paxton NOVI ST, Powerdyne, and ATI) in the range of $2,500-$3,100. However, unlike nitrous, the maintenance required of this power adder is next to nothing.
In order to achieve 450 hp, count on adding from 8 to 10 pounds of boost. The most popular kits are generally capable of producing as much as 18 psi in racing cog-belt applications. For our goals, the standard as-shipped 8- to10-rib serpentine systems are fine. At low- to mid-rpm levels, the boost curve results in low boost levels with a centrifugal blower. The max boost figures (8 to 10 pounds) are only seen in the very highest reaches of the tach. On a recent Paxton Novi ST installation, we saw little-to-no boost below 2,500 rpm.
While you won't get a big-block or stroker feel with a blower, it deserves mention because it's great for drivability, smog, and fuel economy. Low-rpm, and off-idle torque, while well appreciated in a street car, won't get any help from most centrifugal huffers. Another option is the Kenne Bell series of Whipplechargers (screw-type blowers). These superchargers offer great off-idle and mid-range boost production.
Nitrous is a completely different animal from the supercharger--specifically, it is only active when you hit that little happy button. You don't have to deal with it during your daily commute to work. And, if it isn't working properly, it doesn't hamper you from cruising. If you have a fuel-injected 5.0 beast, there are three kinds of nitrous systems: a wet nozzle, a dry nozzle, and a wet plate-type system. The dry nozzle system is injected before the throttle body and fuel is added through the injectors. Nitrous Oxide Systems (NOS) offers both dry nozzle and wet plate systems (for GT-40, Edelbrock, and stock intake). Wet nozzle systems inject fuel and nitrous through a nozzle mounted before the throttle body. Compucar, The NitrousWorks, and Nitrous Express offer this variety. A wet plate system is your only choice with a carburetor.
All of these systems have proven to be dependable and highly capable of providing up to a 150hp shot of the go-juice. To decide which is right for you, talk to the fast nitrous 5.0 guys at your local track and get their advice. They may help you avoid problems--like melted engine parts. Any of the plate designs are more than capable of spraying 150-hp-worth of nitrous. Just remember, as with any nitrous kit, start out your tune-up very conservatively, with very little timing and lots of extra fuel.