Thinking Outside the Box With Dart’s SHP Short Blocks and Top End Kits

When it comes to building an engine, the last mistake anyone wants to make is pairing a nice short block with a bad set of heads, or vice versa. It would be like drinking a bottle of vintage Château Lafite from a paper cup with Cheez Whiz on saltines; a total waste.

The rising popularity of crate engines can be traced back to the appeal of getting a matched, proven package that doesn’t require a lot of research from the buyer. But when buying a complete crate engine, your choices are limited to what the company selling it thinks you might want. Great, if you just want to order up engine A, B, or C and take it home, but there’s no room for special requests or individuality when you’re buying straight off the shelf.

Dart Heads understands that desire to make your engine your own, and in recent years they’ve added even more options to their ever growing SHP line of street engines and top end kits. They offer these choices so that you, the consumer, can still have a say in what goes under the hood. Rest assured that Dart is backed by 40 years of Pro Stock racing knowledge.

Special High Performance is what SHP stands for, and it’s the umbrella under which Dart has designed a host of engine packages to choose from. “Richard Maskin came up with the idea for the SHP block as a way to support the aftermarket manufacturers and give local engine builders a way to be competitive with factory crate motors,” says Jack McInnis of Dart. “The local engine builders and mom and pop speed shops built the performance aftermarket through hard work and innovation. Without them you would have no other choices than a factory crate motor, and that would not be a good thing for performance enthusiasts.”

These aren’t 2,000 horsepower Pro Street motors they are building, but then again you don’t need a Pro Street budget to get Dart quality. Instead, what they’re putting together is a line of engines that are designed specifically for street/strip guys. That doesn’t mean you’re giving up big horsepower potential though – our in-house SHP small block Chevy has put out over 700 hp!

The Foundation – Dart’s Chevy and Ford SHP Blocks

A lot of budget-conscious builds start with a used block to keep costs in check, but this inevitably leads to additional costs in machining and checking the block to make sure it is still good. With a fresh, new Dart SHP block, all you need is a final hone before you start installing. Also, when you’re buying a Dart block, you’re not just buying a stock factory core; they use much of the same technology that they implement into their race blocks for their street blocks. Below are some of those benefits:

Dart’s SHP blocks incorporate performance upgrades you just won’t find in a factory core.

Priority Main Oiling – In the eyes of many racers and professional engine builders, this is the most crucial improvement over a factory block. A stock 350 block sends oil to the cam before making its way to the main bearings. As a result, there is a pressure loss due to the complex route the oil has to take before it gets to the mains. Dart reconfigured the oil passages so the mains are fed with the higher pressure oil and the secondary passages are created for the cam.

Siamesed Cylinder Bores – Instead of cylinders being separated by water jackets, the cylinders are connected by shared material in the adjacent walls. This, in turn, ties the whole block together. The extra support keeps the cylinder bores round and less likely to go oval under extreme temperature and pressure conditions.

Rigid Deck and Blind Holes – Up top, a thicker-than-stock deck ties the block together as well. The SHP .625” minimum deck thickness also plays a huge role in keeping the cylinders round. In addition, typical stock block design leaves the bottom of the head bolt holes open to the water jacket, but the SHP’s blind bolt holes keep the bottom of the studs dry and eliminate a potential sealing issue.

Stroker Crank Clearance – With a stock block, when using a stroker crank, clearance for the big end of the rods has to be gained with a die grinder. Dart, however, notches the cylinder barrels at the bottom of the SHP block to clear up to a 3.75” stroke. Main bearing bulkheads are also machined for counterweight clearance.

The SHP block’s splayed 4-bolt main caps and thick main webs are far stronger than the typical factory block.

Bare Block Options

Small Block Chevy

The Chevy SHP small block comes with a 9.025″ deck height with the ability to handle a maximum size of 434ci, although Dart recommends staying under the recommended 408-cube 4.165” x 3.750” sizing. It comes standard with 4-bolt inner and two bolt outer ductile iron main caps, but you can opt for aluminum caps. They come finished in either a 4.000” or 4.125” bore.

Dart offers Ford SHP blocks in both 302/8.2″ deck height (shown here) and 351W/9.5″ versions.

Short and Tall Deck Small Block Ford

The Ford SHP block gives you the choice of an 8.200” 302 or a 9.500” 351 base. Both blocks are offered in 4.000 or 4.125 finish bore, and both use the 351-style 1/2” head bolts for strength. The 302 and 351 also come with their respective main bearing sizing. Again, Dart recommends staying under 4.185 on the bore but they’ve seen successful 369ci combinations from the short deck and 454ci with the tall deck SHP block.

Dart’s SHP Assembled Short Blocks

Another new venture for Dart is their short block assembly. The SHP block has sparked enough interest to have full-time engine builders in-house at Dart putting together these Ford and Chevy short blocks. But these engines aren’t built on an assembly line; each SHP short block built at Dart is crafted by the same guys that build their championship-winning Pro Stock engines.

“What we’re finding is that a lot of our engine building dealers were losing money to the OEM crate motor engine business,” said McInnis. “The custom engine builder couldn’t compete with that. Our idea was to create a pre-assembled short block and bundled top end kit so the local engine builder or do-it-yourselfer could build a custom engine that was better than the OEM crate motor offerings while still being affordable.”

Dart is not trying to compete with fully-custom engine builders on these short blocks, which is why they are offering them only in limited configurations. A 372 or 400ci small block Chevy, 454ci big block Chevy, 347 or 363ci 8.200” Ford, and 9.500” 351-based short blocks will be available mid-year.

Our 400ci small block Chevy SHP short block.

Dart assembles these short blocks with affordability in mind, using a cast steel crank, hypereutectic pistons (Ford short blocks come standard with forged pistons), and forged I-beam rods. Depending on your budget and goals, Dart offers upgrades for all these internal components, like a forged 4340 crank, forged pistons, and forged H-beam rods.

Dart’s Top End Kits

As we’ve already mentioned, Dart offers a wide variety of short block combinations, but they’ve recently added matching head-and-manifold packages to their in-house options. “We have been doing top end kits for a long time through the catalog companies. With the addition of the SHP line, it made sense to make it more widely available,” said McInnis.

For their top end kits, they offer many options depending on the goals of your engine build. The kits for both Ford and Chevy are broken down between Iron Eagle (cast iron) and Pro1 (aluminum) heads. Outside the obvious weight difference between the head’s material is the fact that the Pro1 comes CNC bowl-blended.

The heads are offered in a wide range of combustion chamber and intake runner sizes to accommodate different engine configurations. Also, in the small block applications, you get a choice of a single or dual plane intake manifold.

“Picking between a single plane and dual plane really depends on the size of the engine, cam used, and RPM the engine will be operating in,” explained McInnis. “If it’s a primarily street-driven car, they are usually going to be more happy with a dual plane; it will be more enjoyable and make better low end torque. They are probably leaning more toward the single plane if it is something that will be either big cubic inches or if they are taking it mainly to the track.”

Dart’s Pro1 top end kit for small block Chevy.

Top End Kits Include:

• A pair of assembled heads (Iron Eagle or Pro1)
• Intake manifold (single or dual plane)
• Valve covers
• Intake manifold, exhaust manifold, valve cover, and head gaskets
• ARP head bolts
• Spark plugs

Intake Port Sizing Options (Pro1 and Iron Eagle Vary)

• Small Block Chevy – 180cc, 200cc, 215cc, 230cc, CNC 227cc
• Big Block Chevy – 308cc, 325cc, 345cc, CNC 335cc
• Small Block Ford – 170cc, 180cc, 195cc

Dart Pro1 small block Ford, Iron Eagle small block Chevy, and Pro1 big block Chevy.

A Top End Kit Taken One Step Further – Dart’s Horsepower in a Box

For those looking to take the guesswork out of valve train selection, Dart offers a wide range of packages designed to match their top end kits. Through building hundreds of engines and customer feedback, Dart was able to put together a few camshaft options that suit a wide range of performance applications.

“The Horsepower in a Box kit was the next logical step to help simplify a guy’s life that is trying to build an engine,” McInnis said. “Anyone can go through a catalog and pick parts that look appealing, but those might not be the parts that are going to work best together. Our thinking was to bundle these appropriately. Then someone can take advantage of Dart’s and Comp Cams’ expertise on parts that will work well together.”

They are currently offered in small block Chevy and small block Ford applications in both hydraulic roller and hydraulic flat tappet configurations. The lift on the Comp Cams camshafts range from .462/.469 up to .519/.523, and durations from 218/224 up to 230/236 at .050. Lobe separation on these cams is suited for naturally aspirated or light nitrous applications at 110 degrees. The total package includes:

• Hydraulic roller or hydraulic flat tappet lifters
• Hydraulic roller or hydraulic flat tappet Comp camshaft
• Dual roller timing set
• Front cover gasket

Dart adds the option of a power-matched hydraulic cam, lifters, timing set, and front cover gasket.

Our SHP Test Mule Number 1 – 400ci Small Block Chevy

The first SHP engine we received from Dart was from their original SHP branded block, the SBC. Choosing the larger displacement 400ci option, we also went with the total forged internal upgrade offered from Dart. This consisted of an internally-balanced, forged 4340 crank, 4340 H-beam rods, and flat top forged pistons. We capped the engine with a 215cc Pro1 top end kit with single plane intake manifold. These heads have a 72cc combustion chamber, which netted us a final compression ratio of 10:1.

Our Dart SHP small block Chevy short block features upgraded forged internals.

SHP 400 CI Short Block Standard Features:

• 4.125″ bore x 3.750″ stroke
• Internally balanced
• Plate honed
• Cast steel crank
• Hypereutectic flat top pistons with floating pin
• Forged 4340 I-beam rods with 3/8″ cap screws
• Hastings moly rings
• Clevite bearings
• Coated cam bearings

Our Upgrades Included:

• Forged 4340 steel crank
• Forged flat top pistons
• Forged H-beam rods

For the valve train, we stuck with Comp Cams for their Pro Magnum rockers, OEM tie-bar style hydraulic roller lifters, and a moderate street camshaft with 242/248 duration and .540/.562 lift. A Zex perimeter plate nitrous kit and Holley 830cfm HP carburetor topped it all off.

We added Pro Magnum rockers and OEM-style hydraulic roller lifters from Comp Cams to complete our top end.

We turned to Westech Performance to help us mate the Dart SHP short block, top end kit, and Comp Cams valve train. In a matter of four hours, Steve Brule had our small block screwed together and headed to the engine dyno cell.

The engine performed flawlessly out of the gate. It made 523 horsepower and 496 ft/lbs, while singing to the tune of 6,500 RPM. By 2,500 RPM, the engine was already making over 400 ft/lbs.

With grins on our faces and a few clean baseline runs in the book, it was time to hook the big purple bottle onto the engine for some 150-shot pulls through our Zex system. With the bottle warmed up in the custom made Westech warmer and 950 PSI on the gauge, we were ready for our first nitrous hit.

Again, everything worked perfectly and we netted a total gain of 145 horsepower and 143 ft/lbs, making a total of 668 HP and 639 ft/lbs. Not bad for a budget street build, but we weren’t done yet. Steve felt that the air/fuel ratio was still a little on the conservative side, and he decided to warm the bottle up another 100 PSI, bringing the gauge to 1,050.

On the engine dyno at Westech Performance, we made both N/A and nitrous pulls.

We were finally ready for our last pull of the day, which was the most impressive. Leaning out the nitrous hit with higher bottle pressure added another 34hp and 45 ft/lbs, breaking the 700-horsepower barrier. Here’s the scorecard at the end of the day:

Naturally Aspirated Power: 523 horsepower and 496 ft/lbs
Nitrous Assisted Power at 950 psi: 668 horsepower 639 ft/lbs
Nitrous Assisted Power at 1050 psi: 702 horsepower and 684 ft/lbs

This motor now resides in our Project “Riced Rat Rod” 1991 Nissan 240SX and is backed by a Tremec TKO-600 5-speed transmission. The first time we took it to Irwindale’s eighth-mile drag strip, shod with 235-wide Mickey Thompson drag radials, we launched the 240SX very softly and came back with a timeslip showing 7.915 @ 98.19 MPH with a 2.120 60-foot, naturally aspirated.

We are confident that we can get some low-7-second eighth mile times with a little bit of practice, which will put it into the low 11/high 10 second range in the quarter mile. Keep in mind that we’re driving the car to and from the track, and it already has over 3,000 flawless road-driven miles on it.

Test Mule 2 – A 363ci Small Block Ford for a 1985 Fox Body Mustang

The premise behind our 363 small block Ford was to show the every day Mustang enthusiast that within a couple weekends, a moderate do-it-yourselfer could build and install a powerful small block in place of a tired 5-liter.

The 363 utilizes the standard Dart SHP Ford short block with cast crank, forged I-beam rods, and forged pistons. The top end utilizes a Dart Horsepower in a Box kit with Pro1 195cc heads, a dual plane intake, and a hydraulic roller valve train. Currently this project is still under construction, but we are looking to make close to 400 HP to the rear wheels.

Whether it’s an SHP short block or a custom 2,000-horsepower race motor, every engine gets the same attention to detail at Dart.

Engine Specs – Ford Short Block

• 4.125″ bore x 3.400″ stroke
• Externally balanced
• Plate honed
• Cast steel crank
• Forged flat top pistons with floating pin
• Forged 4340 I-beam rods with 3/8″ cap screws
• Hastings moly rings
• Clevite bearings
• Coated cam bearings

Our SHP Ford short-block gives us the confidence of building an engine around a new casting rather than a possibly compromised used factory piece.

Horsepower in a Box Kit

• Pro1 195cc aluminum heads
• Dual plane intake manifold
• Valve covers
• Intake manifold, exhaust manifold, valve cover, and head gaskets
• ARP head bolts
• Spark plugs
• Comp Cams hydraulic roller camshaft and OEM-style lifters
• Timing set
• Front cover gasket

Dart’s 372ci SHP Chevy Short Block

On Dart’s website you will see that they paired a totally standard 372ci small block Chevy SHP short block with their affordable Iron Eagle S/S 165cc heads. Finishing off the build was a 650cfm carburetor and dual plane intake manifold.

“When most people think about stroking a 350 they are thinking a 383, and that came about because you are limited on bore size for an OE block,” McInnis mentioned. “That was originally a 400 crank with the mains turned down to 350 size and a .030-over block. But because our block will go to 4.185 bore, we went the other route with a bigger bore, as it unshrouds the valves and breathes better, and ends up really costing the same as a 350ci.”

The results were 400 horsepower at 5,200 rpm while making over 400 ft/lbs of torque from 2,400-5,200 RPM! With one of the least expensive kits you can buy from Dart, you can still see that impressive horsepower can be harnessed.

Build Your Own Unique Engine With Dart’s Power Proven Packages

While crate motors have certainly gotten a lot of otherwise-idle project cars back on the street, many enthusiasts want to be more involved than just ordering straight off the shelf. Being able to create an engine combination that fits within your budget and horsepower requirements is key. By providing an array of short blocks and top end kits, Dart gives you the keys to a great street/strip engine combination. Make sure to come back and visit us as we will be finishing up the build of our 363ci small block Ford and stuffing it in our Fox Body Mustang!

About the author

Mark Gearhart

In 1995 Mark started photographing drag races at his once local track, Bradenton Motorsports Park. He became hooked and shot virtually every series at the track until 2007 until he moved to California and began working as a writer for Power Automedia. He was the founding editor for its first online magazines, and transitioned into the role of editorial director role in 2014. Retiring from the company in 2016, Mark continues to expand his career as a car builder, automotive enthusiast, and freelance journalist to provide featured content and technical expertise.
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