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Dart SHP Sport-Block Engine Build
We Combine A Dart SHP Short-Block And Top-End Kit To Produce 476 Hp Without Breaking The Bank.
Bailout. Bonus. Budget. The first two terms are reserved for one percent of the population. But the third, budget, is something that we can control when building our Mustangs and Fords for high performance.
If you haven't noticed, for the past year or so MM&FF has placed a larger focus on cost-effective ways to go fast. It's no secret the country is in a recession, and we're here to help you find the best and cheapest ways to modify your car. Some of the more notable engine builds we've done are the Recession Special and Stock-Block Stroker. Both are outstanding ways to increase power using the reliable 5.0L engine package.
In keeping with the low-budget theme, this month we stopped by Dart Machinery (Troy, Michigan) to get a glimpse of its popular Special High Performance (SHP) line of parts. We followed along as the fabled high-performance manufacturer brings a reasonably priced engine to the small-block Ford legacy. This engine build is still budget-oriented, but a bit more powerful than the aforementioned projects.
Over the years, Dart has been known for its Windsor Sr. and Jr. cylinder heads, which have been a staple in the 302 and 351 arena since the early '90s, but were more recently replaced by the Iron Eagle and Pro1 line of heads. Those who are NHRA fans might recognize the Dart brand from its exploits in the Pro Stock ranks. Owner Richard Maskin has been the power behind 3 Pro Stock championships and over 60 national event wins in the category. To say he and his team know horsepower is an understatement--Pro Stock engines are approaching 3 hp per cubic inch in naturally aspirated trim! The technology trickles down from the in-house Pro Stock program to the consumer products, as Maskin and his team are involved in every aspect of the Dart parts line. In fact, the two engine builders who handle all of the short-block assemblies are the same guys who build the Pro Stock engines. That's a claim not many manufacturers can tout.
Dart offers cylinder heads and engine blocks for the small-block Ford market, and the company has recently upped the ante with short-block assemblies and prepackaged top-end kits. It brings new meaning to mail-order horsepower. In one afternoon, an enthusiast can add heads, a camshaft, an intake, an oil pan, and the other parts and pieces to make a ready-to-run engine capable of some serious horsepower.
At the time of our visit, Dart offered its SHP short-blocks in only the Sportsman engine block, but by the time you read this, the company will have released its new SHP block. The SHP block is said to be cheaper, as Dart cut out more features to help reduce the price. It's stronger than a stock 5.0L block, including the rare Mexican 302 stock-block, but not the level of its Sportsman and Iron Eagle offerings.
The SHP short-block we followed from bench to dyno features the Sportsman block, which is a lot stronger than most people realize. The Sportsman moniker can be mistaken for weak--that is not the case, as we have seen (and built in this magazine) many supercharged and turbocharged engines producing up to 1,000 hp with the Dart Sportsman block. Longevity is not an issue at those power levels. It's a suitable foundation for a stout street or strip engine package. It's not as sturdy or durable as the Iron Eagle block from Dart due to its outer caps being two-bolt main caps (the inner main caps are four-bolt caps), but the bore size can be safely taken out to 4.125 inches without sweating it, meaning more cubic inches from the 302-style block.
We ordered one of the cheaper versions of the SHP short-block. It still came with the Sportsman block, but we opted for the cast-steel crankshaft rather than the forged one. We also selected I-beam rods instead of the pricier H-beam pieces, but the pistons are the same forged slugs as in all of the SHP short-blocks. One option we chose was the larger 4.125-inch bore (rather than the 4.030-inch standard). The larger bore increases the cubic inches from 347 to 363. For those keeping track, Dart builds all of its 302-based engines with 3.400-inch crankshafts.
According to Dart's website, the short-block retails for a mere $3,939 with the optional 4.125-inch bore. A fully optioned short-block comes to the party at $4,814 (363ci, forged crank, H-beam rods). The base 347ci short-block is available from Dart's website for just $3,475. Other components include coated Clevite bearings, coated cam bearings, and Hastings moly rings. Dart includes forged flat-top pistons, and when combined with a 62cc chamber and proper thickness head gasket, the compression ratio is 9.7:1. Our engine could be run on 91-octane fuel, making it compatible on pump gas in California and some states in the middle of the country. Dart offers in-house coatings on pistons and any other engine part for an additional cost.
The thing we like about the Dart product offerings is that the short-block is shipped in a box, ready for a top-end and oil pan. The top-end kit comes in similar fashion--one big box that includes all the parts and pieces.
Our goal with this engine build was to assemble an above average combination without breaking the bank. With that goal in mind, we selected a Ford Pro1 top-end kit, with larger 195cc aluminum cylinder heads and a single-plane Professional Products intake manifold. At our request, Dart ordered a hydraulic roller camshaft (from Comp Cams). The stick is mild and perfect for the street/strip crowd. The top-end kit comes with assembled cylinder heads, intake, cast-aluminum valve covers (ours had optional sheetmetal), intake gaskets, head gaskets, exhaust gaskets, NGK spark plugs, and head bolts. Valvetrain components are available from Dart, but they aren't included in the top-end package.
Earlier we mentioned Dart's experience in NHRA Pro Stock and how it lends a hand in the R&D of Dart's mainstream products. The Pro1 cylinder heads benefit from wet-flow technology. As we all know, the flowbench is the cylinder-head porter's best test tool, much like an engine dyno is the ultimate tool for developing a complete engine package.
Dart has taken flowbench testing to the next level with its custom wet-flow bench. The wet-flow technology was derived as a result of Maskin looking to gain an edge in Pro Stock. The basic concept is, why flow only air through a cylinder head's port when in the real world there is air and fuel moving through it? The answer is a flowbench that moves air and liquid to simulate fuel through the cylinder head ports to test the results in a real-world scenario. The Pro1 was developed with this technology at the fingertips of the R&D team.
The 195cc Pro1 heads are made of 355-T6 aluminum and have all the features that most enthusiasts are looking for in a head. The intake port flows 285 cfm at 0.600-inch lift using 28 inches of water. On the exhaust side, the port moves 185 cfm at both 0.600-inch and 0.700-inch lift measurements. The intake port increases flow to 288 cfm at 0.700-inch lift. The combustion chamber measures 62 cc, which is pretty standard in most aftermarket small-block Ford cylinder heads. The intake valves measure 2.02 inches, while the exhaust is released through 1.60-inch valves. The Dart team selected a Comp hydraulic roller camshaft (PN XE282HR-12) for this engine, and it enters our realm boasting 0.565/0.574-inch lift and duration readings of 232/240 at 0.050-inch, intake and exhaust, respectively. Lobe separation is 112 degrees, giving this engine a nice rumble at idle.
Tony McAfee and Jeff Lake assembled our engine and performed the dyno testing with Dart's in-house engine dyno. Over the course of two days, the engine was built and tested, along with a few carburetors and two sets of headers. Our initial dyno pulls were made with a Barry Grant Demon 650 carburetor and a pair of Kooks dyno headers. The fuel utilized in all dyno testing was a high-octane ERC fuel. We didn't run this engine on pump gas because Dart uses the dyno for Pro Stock engine testing and the team prefers to keep fuel changes to a minimum so the system doesn't get contaminated.
McAfee and Lake found that 30 degrees of timing was optimal; they tried a bit more and a bit less, which resulted in losses in horsepower. Dart claims this combination should make around 475 hp, and we almost hit that mark on the first run with the engine making a peak of 468 hp at 5,900 rpm. The promotional literature shows 475 hp with a 750-cfm carburetor, but we wanted to see how far we could push the 650 carb. The team grabbed a wooden 1-inch spacer and installed it--power increased to 476 hp and peak rpm was raised to 6,000.
Dyno testing is fun--it's very easy to make changes, and we had a Demon 750 carb waiting in the wings. McAfee and Lake felt the spacer is required for this combo, so it was left on when the 750 carb made its way on to our 363. Lake was quick to comment during the carb swap, "Bigger isn't always better." He was right: The peak dropped to 465 hp, but as McAfee pointed out, "We picked up 10 hp in some areas around 5,500-6,500 and had 8 more average horsepower through the entire pull." The guys swapped to a set of smaller headers (from 2-inch to 1 7/8) and the power dropped off. The Kooks headers were the hot ticket with larger primary tubes and 3-inch collectors.
"I would run the 650 over the 750," commented Lake. "The 650 is a little more driveable than the 750 as you tip into the secondaries. You aren't going to see or feel the small difference in average power, but the 650 would be a better carburetor for this combination on the street." At this point, Maskin was watching over the dyno runs and said, "This engine will make that power all day long and last over 100,000 miles on the street."
McAfee and Lake also threw in a few comments about fuel injection. "We just played with a small-block Chevy with the Motorvation fuel injection, and it picked up a little bit over the carburetor," said Lake. They were quick to say that adding fuel injection shouldn't hurt power, and in some cases, it might pick it up. The testing on the Chevy was accomplished with a carbureted intake converted to fuel injection and a carburetor-looking throttle body. It picked up average horsepower and didn't hurt the peak numbers.
We were trying to keep tally of the parts needed to complete the Dart short-block and top-end. For those who are buying it all new, save some budget money for the valvetrain (cam, lifters, pushrods, and rocker arms), carburetor, 28-ounce balancer, timing chain and cover, distributor, spark plug wires, water neck, water pump, and oil pan and pump. If you want a reliable and reasonably priced 363ci or 347ci that makes upwards of 476 hp, just order it from Dart or one of its dealers (listed online). Soon the company will offer CNC ported heads, and with that combo, the 363 could eclipse 500 hp.
The Dart 363ci could power a street/strip 3,200-pound Mustang to high 10-second times with ease. That is without a power adder and with street amenities like A/C and heat. Now if you add the H-beam rods and a forged crankshaft, a little hit of nitrous could carry your Mustang into the 9-second zone.
Step By StepView Photo Gallery
On The Dyno
- 363ci (4.125 bore x 3.400 stroke)
- Dart Pro1 195cc Cylinder Heads
- Single-Plane intake manifold
- Kooks 2-inch headers
- Demon 650 with 1-inch spacer
- 9.7:1 compression
- Hydraulic Roller Camshaft