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5.0 Engine Buildup
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.
Cylinder Heads
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.
Camshaft
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.
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.
Cylinder Heads
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.
Camshaft
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.
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