Pretty much every day, a magazine or media outlet gets slammed for touting "cheap horsepower." There seems to be a disparity between what readers and the media define as affordable, so before we continue let's try to clear that up. Here at Mopar Muscle, something that is built on a budget is not going to be a grenade with the pin pulled, nor is it going to rely on some unobtainable tidbit we're relying on you to pull out of a mythical scrapyard. In our quest to build the Budget Sledgehammer—our 5.9L Magnum small-block—we faced the fact that most are going to head to the internet to order their parts new. The one exception to that is the basis for our build-up—the donor core 5.9L Magnum engine itself.

Of all the Chrysler V8s, no other engine is present in salvage yards in greater numbers, except perhaps the 5.7L Hemi. And while the Hemi might arguably be more numerous, the Magnum is certainly less expensive. In useable form, these can typically be picked up for well under $500—sometimes even less. The larger 5.9L version—which we're using here—is on the high end of that spectrum, and 5.2L cores can be had for as little as $100. Even if you have to go through two or three of them, the dollars pencil out about the same. At the end of the day, even if you have a pro do all the heavy lifting on an engine like ours, you're still buying a complete turnkey engine for less than the price of a bolt-on blower kit for a late-model Hemi. If you build it yourself, a good core and all the parts can be scored for around $4,000.

Cylinder Heads

The inspiration for our Budget Sledgehammer comes from EngineQuest's CH318B cylinder head. We detailed it in an earlier story [here], but in a nutshell these stock-appearing iron cylinder heads fix a number of problems inherent in the stock Magnum head, namely cracking and warping. When EngineQuest designed these heads for the reman market, they also endowed them with more flow and improved the pushrod pinch in the intake port. With a little work, these reman heads can outflow aluminum performance pieces. Companies like Hughes Engines and IMM Engines (who helped us with this build) have seized on that and brought their own versions to market, with our IMM-prepped pieces easily topping the 260 cfm mark at .600-inch lift.

To backtrack a little, the EngineQuest CH318B casting was designed to be used on a Magnum block, but it has the LA-series intake bolt pattern, so it can take any of the wonderful high-performance LA intakes (318/340/360) on the market. This increases the horsepower and keeps a cap on the cost. When IMM modifies the EQ heads, they open the valve pocket area, blend it into the throat, put a nice valve job on it, and put larger 2.02-inch intake valves in them. At $1,469 for a pair, it's easily the most expensive part of this build-up, but good heads are essential for making power. For those curious about using them with a Magnum intake, you'll be glad to know EngineQuest also offers the CH318A—an identical casting that retains the Magnum intake bolt pattern.

Induction

Pairing your cylinder heads with an intake manifold that's appropriate for the flow capability of the heads and the planned use is critical. This factory-based 5.9L Magnum is going in a 1973 Plymouth Duster that will see mostly street use with occasional drag action. Our 10.4:1 short-block, detailed in a previous story [here], has a Comp Mutha Thumpr hydraulic-roller camshaft with .556/.542 inches of lift (using 1.6 rockers) and 235/249 degrees of duration, ground on a 107-degree lobe separation angle. When talking about an engine for a hot street car, this is smack-dab in the middle of goldilocks territory. We'll be able to run on ordinary 91-octane pump gas without detonating, and the valve timing will provide enough flow to produce serious power without causing ill manners or bleeding off too much cylinder pressure.

Our compression, cylinder heads, and cam choice all point to using an intake manifold that will accentuate performance on the street with lots of off-idle grunt, a fat midrange, and a top-end that holds on until the limit of our modest valvetrain is reached—about 6,000 rpm. Going with anything bigger means spending a bunch more on everything from valvesprings and rockers, to big headers and a bigger fuel system. Mission creep is the biggest problem the DIY engine builder faces, so we firmly staked out our street territory with Edelbrock's Performer RPM AirGap intake. This piece is a third-generation dual-plane design that maximizes all the benefits of a dual-plane (wide powerband, good street manners, thermal management) while modestly stretching its capability into race territory.

While valvetrain options abound—including some very nice pieces from Hughes Engines which we plan to cover at a different time—we opted for a bare-bones approach here. Our cam lift being in the mid .500-inch range dictated the use of cost-effective beehive springs paired with 1.6 ratio Comp High-Energy roller rockers. We initially tried a ball-style rocker with a roller tip, but upgraded to the full rollerized High Energy rocker after discovering some binding. Fortunately, we were able to use a small-block Chevy part number, which kept the price in check. Likewise with the pushrods. Due to IMM's .035-inch longer Ferrea valves and the extra valve lift, we used a Ford-sized 6.900-inch chromoly pushrod, saving a little money there as well.

Carburetion

In the universe of carburetors there are many great choices. Chances are, you have several in your garage that you'll probably dust off for a build-up like this, but if you do decide to buy new, one of Quick Fuel Technology's Street-Q units would be a sound choice. The Street-Q series is chock full of racer features and comes in a bunch of sizes (650, 750, 850, and 950 cfm). They are unbelievably inexpensive (our 650cfm unit costs just $482), they're offered with either vacuum or mechanical secondaries, and have the full range of tuneabilty. Ours was almost perfect right out of the box, only needing a slight drop in primary jet size to get our air/fuel ratio right in the 12:1 sweet spot. By having a square bore footprint and a modular Holley 4150 architecture, it's easy to dive right into a QFT double-pumper. With high-end features like adjustable high-speed air bleeds, four-corner idle mixture, two-circuit metering, large sight glasses on the bowls, adjustable secondary linkage, and downleg boosters, even the serious racer will feel right at home with the Street-Q.

Ignition

Driving our ignition system choice was a couple of things. Obviously, we wanted to keep the price down, but we also wanted a stock look. We arrived on the Pertronix Flame Thrower cast-look distributor for both of these reasons, but we also liked the fact that it had Pertronix's new Ignitor III ignition module mounted deep inside. This little jewel brings any vintage muscle car into the modern age with stuff like an adjustable digital rev limiter, multi-strike capability all the way up to redline, and five times more spark energy than a points system. Digging deeper, we liked the adaptive dwell, which like an HEI, expands the dwell time as rpm increases, meaning your coil will have plenty of juice—even at high rpm. It's a mean little distributor, and when paired with Pertronix's Flame Thrower III coil with 45,000 volts (at just 0.32 Ohms), makes for a power-packed combo. Carrying the sizzle to our NGK FR5 plugs was a set of universal 8.8mm Flame Thrower wires. All in, our Pertronix bill came to around $360, but given that we've seen marginal vintage ignitions cost as much as 50 hp on the dyno, it's a price we were willing to incur.

Headers

It's common practice for dyno operators to use the same set of headers on the dyno for the sake of simplicity. These are often large-diameter, long-tube step headers that easily clear the dyno apparatus, and that produce big numbers on the screen due to their optimized design. In practice, however, these dyno headers rarely fit into real cars like our 1973 Duster. For that reason, we ordered a set of Patriot 1 5/8-inch diameter long-tube headers with a block-hugging design (part No. H8206-1, $406.97 Summit). These are specifically for a Chrysler small-block being used in an A-Body, so their various twists and turns are designed to clear steering and suspension components without rubbing on sheetmetal. Being a long-tube design, they also boost horsepower and torque, widening the powerband in the process. An attractive ceramic metallic coating further ads to performance, and holds the inevitable corrosion at bay. We think the Patriot long-tubes were a good choice, producing nice power even though they weren't optimized for the dyno environment. The good news is that thanks to our Patriot long-tube headers, the numbers we got for the Budget Sledgehammer are representative of what we'll get once installed in our Duster.

Dyno

With our long-block assembled, loaded on the dyno, and filled with Torco 10w30, Brian Hafliger of IMM Engines ran a tuning loop on the Budget Sledgehammer, adjusting the total timing to 34 degrees and making a minor adjustment to the primary jetting. With everything up to temp and checking out, it was time to make a full power pull, first optimized with the 650cfm Street-Q carb. We had our sights set on a solid 430 hp—about what a similar vintage Vortech small-block Chevy might produce with similar equipment. What we got was a solid 461 lb-ft. at 4,500 rpm and 454 hp at 5,800 rpm. The little Street-Q blew us away, so we were understandably eager to try the 750.

Typically, a larger carb on an engine equipped like ours would be worth 5 to 10 hp more at key points in the power curve, but once we had optimized our jetting for the bigger 750, it turned out not to be so. That said, the big double-pumper produced 465 lb-ft of torque at an even lower 4,400 rpm (+4 lb-ft. ), and 455 hp (+1 hp) at the more elevated speed of 6,000 rpm. Average torque increased by 2 lb-ft and average power improved by just over 2 hp. That's pretty much a wash—not enough to really feel in the seat of your pants—but since the price difference is only $36, probably still worth the money.

Our big problem now? The Budget Sledgehammer has enough slam to break just about every part in our Duster's slant-six driveline, from the fragile factory 904 TorqueFlight, to the toothpick driveshaft and wimpy 7.5-inch rearend. We have some serious updating to do before we drop it in and bolt up some slicks, so stay tuned as we get underway with more wrenching on our Duster!

Dyno Results

5.9L Magnum Small-Block

QFT 650cfm Carb QFT 750cfm Carb RPM: TQ: HP: TQ: HP: 4,000 453.9 345.7 449.6 342.4 4,100 458.1 357.6 458.2 357.7 4,200 460.2 368 461.8 369.3 4,300 460.8 377.3 462.6 378.8 4,400 461.3 386.5 465.8 390.2 4,500 461.7 395.6 465.2 398.6 4,600 460.3 403.2 464 406.4 4,700 459.4 411.2 460.4 412 4,800 456.6 417.3 458 418.6 4,900 451.6 421.3 451.5 421.2 5,000 447.7 426.2 455 433.1 5,100 444.8 431.9 450.3 437.3 5,200 440.6 436.2 445.1 440.7 5,300 435.2 439.1 431.3 435.3 5,400 426.5 438.5 432.3 444.5 5,500 421.1 441 426.4 446.5 5,600 411.9 439.2 420.9 448.8 5,700 413.6 448.9 415.4 450.8 5,800 411.7 454.7 410.1 452.9 5,900 402.3 451.9 404.6 454.5 6,000 397.9 454.5 398.6 455.4 Average: 439.9 416.5 442.2 418.8 Show All

Read More!

Find out how we got this far in our 5.9L Budget Sledgehammer Magnum small-block build-up with these two previous stories!

EngineQuest CH318B cylinder head build-up and flow test:

Make Big-Power Magnum 5 9l Mopar Heads

IMM Engines short-block build-up of 5.9L Magnum donor engine:

Build 500hp Capable 360 Magnum Short Block Cheap

See all 26 photos Our Budget Sledgehammer short-block is a mostly stock 5.9L Magnum, except for a set of stock-weight forged pistons from Icon, new bearings, and a ball-brush hone job. Except for press-fitting the 10.4:1 Icon pistons on the stock rods and new cam bearings in the block, all of the assembly can be done at home. Here, Fred Hafliger of IMM Engines in Indio, CA pours Torco break-in oil directly into the lifter valley.

See all 26 photos Modern hydraulic roller lifters can be reused with no problem on a stock rebuild, but in a performance street application like ours, new ones are good insurance. These set of 16 Mopar Performance lifters (part No. P5249862, $129.97 from Summit) are getting a shot of assembly lube before being dropped in. They're being paired with a hydraulic-roller Comp Mutha Thumpr cam (.556-/.542-inch lift with 1.6 rockers, 235/249 degrees duration at .050 inch lift).

See all 26 photos Links bars insure that the roller on the lifter is aligned parallel to the surface of the cam lobe. The stock ones can be reused as shown here.

See all 26 photos The lifter link bars are locked in place by the link bar spider (reused from the original core). It bolts to the centerline of the block in three places.

See all 26 photos These iron EngineQuest CH318B Magnum heads were prepped by IMM Engines and are designed with an LA-series intake bolt pattern. IMM has machined them for larger 2.02-inch intake valves, given them a larger throat diameter, and they've been hand-blended in the bowl area. They cost $1,469 (pair) and flow around 266 cfm at .600-inch lift.

See all 26 photos Since we began our Budget Sledgehammer series, we've discovered that Hughes Engines also offers several cool versions of the EngineQuest CH318B cylinder head, including a Super-Prepped Ram CNC head ($2,300.20, pair assembled), which comes with 2.02-/1.62-inch stainless valves and bronze valve guides. The added CNC work has the potential to push output well above 500 hp, depending on compression, fuel octane, and camshaft specs.

See all 26 photos The IMM-prepped EQ Magnum supports flow for over 400 hp with larger stainless Ferrea 6000-series 2.02-inch intake valves. The exhaust valves are smaller-diameter 1.60-inch semi-tulip Ferrea valves, which pick up flow everywhere compared to the larger 1.625-inch stock nailhead valve in the stock Magnum head. Both valves are .035-inch longer than stock to maximize valvetrain geometry with the higher-lift cam. IMM cuts the spring seat pocket to an additional depth of .100 inch for a 1.325-inch diameter beehive spring with a 1.75-inch installed height.

See all 26 photos A set of FelPro 1008 head gaskets (.039-inch compressed height) was used with the cleaned-up stock fasteners torqued to 50, then 105 ft-lbs (twice) using 30-weight oil on the threads and under the bolt heads. Start your torque pattern at the center and spiral out for the most even clamping load.

See all 26 photos Unlike LA-series heads that use a pedestal-style rocker arm arrangement, the Magnum series V8 has stud-mount rocker arms and guideplates to stabilize valvetrain motion. We're using Comp guideplates (part No. 4825-8, $19.41, Summit) and hardened 5/16-inch screw-in studs (part No. 4504-16, $61.99, Summit). These get torque to 25 ft-lbs. with 30 weight oil.

See all 26 photos Chevy rocker arms (Comp part No. 17002-16, $172.97 Summit) and 6.900-inch long Ford pushrods (Comp part No. 8313-16, $200.99 Summit) make for odd bedfellows in a Dodge engine, but the extra lift from the 1.6 rocker ratio and the extra pushrod length means more flow and better valvetrain stability. Combined with LS beehive springs, you can see the combo clears with room to spare at full valve lift.

See all 26 photos A new or remanufactured water pump can be had from Summit or Rock Auto for $20 - $30 and will depend on your accessory drive and vehicle. This long-snout unit should work in our 1973 Duster with a v-belt drive.

See all 26 photos When setting preload on a hydraulic roller valvetrain, take all the slack out of the rocker with the lifter sitting on the heel of the cam, tighten the polylock one turn, then lock it in with the Allen wrench.

See all 26 photos Now is a good time to prime the lube circuit and check the supply of oil to the valvetrain. A cordless drill with a hexagonal drive extension fits into the oil pump drive and a simple mechanical oil pressure gauge monitors pressure. We saw a strong 60 psi on the gauge with a steady stream of oil dribbling from the pushrod weep holes. Now's the time to investigate and fix any lube problems before you put fire in it.

See all 26 photos The beauty of the EngineQuest CH318B cylinder head is that it allows us to use a common LA-series intake manifold on a later Magnum engine, which means you'll need LA-series intake manifold gaskets (Felpro part No. 1213, $23.60 Summit). Cyclo Ultraweld High-temp RTV sealer goes around all water passages.

See all 26 photos After setting the intake gaskets in place on the RTV, put more on the top side of the gaskets around the ports, water passages, and on the ends of the block. You won't want to wait long before setting your intake manifold on top.

See all 26 photos Edelbrock's Performer RPM AirGap dual-plane intake (part No. 7576, $327.52 Summit) is hard to beat for a hot street machine. In fact, it's the main reason we wanted to use the EQ cylinder head with the LA-series intake bolt pattern in the first place.

See all 26 photos After loosely snugging all the manifold bolts, tighten them up after an hour once the RTV has had a chance to firm up. This will improve the seal over going full torque while the RTV is still wet.

See all 26 photos The Edelbrock AirGap intake includes several pipe plug fittings that need to be installed using liquid Teflon (sparingly) and an Allen wrench.

See all 26 photos The oil pump drive is installed next. Apply assembly lube liberally to the distributor gear before dropping it in and indexing it with a thin pair of needle nose pliers.

See all 26 photos This Magnum build is getting Pertronix's stock-look Flame-Thrower distributor (Part No. D7144600, $249.97 Summit). It's got an Ignitor III ignition module with a built-in rev limiter and multi-strike capability right up to our redline of 6,000 rpm. With a great price, lots of fire power, and a vacuum advance, it's perfect for our '73 Duster street machine.

See all 26 photos We went up-scale with a pair of ribbed and polished cast-aluminum valve covers from Mopar Performance (part No. P5007618, $239.97 Summit). They have the Magnum bolt pattern, plenty of room for our larger valvetrain, and fit our 5.9L perfectly.

See all 26 photos Firing our NGK FR5 plugs (one heat range hotter than stock) is a set of universal 8.8mm Flame-Thrower ignition wires from Pertronix (part No. 808280, $57.97 Summit). We opted for a custom set so that we can avoid arcing as we route our wires around a set of Patriot long-tube block-hugging headers.

See all 26 photos For our dyno test, we wanted to check out a pair of double-pumper carbs, both of them Street-Q Series units (650- and 750cfm) from Quick Fuel Technology. QFT's Street-Q series packs in a ton of features at a super low price (SQ-650, $481.95; SQ-750, $517.95). We tested both with a 1-inch plastic carb spacer from Summit (part No. SUM-G1408, $16.97).

See all 26 photos The beauty of a build like this is that you can do most of the assembly work yourself and save a bundle. That route is going to cost about $4,000 using mostly new parts with the exception of the 5.9L Magnum core engine. If you'd rather IMM build one for you, it will run between $6,000 and $6,500, depending on options. This would include parts, Magnum donor core, labor, machine work, dyno testing, and tuning.

See all 26 photos Our final job was to dyno test the Budget Sledgehammer Magnum on IMM's DTS dyno. Here IMM's Brian Hafliger sets the ignition timing at 34 degrees total. After an initial warm up and doing a tuning loop consisting of some minor jetting to the QFT Street-Q primaries, the 650cfm fuel mixer put out 454.7 hp (at 5,800 rpm)—well above our 430hp target. Swapping over to the larger 750cfm Street-Q, we saw a modest gain to 455.4 hp (at 6,000 rpm). More noticeable was the bump in torque from 461.7 lb-ft. (4,500 rpm) to 465.8 lb-ft. (4,400 rpm), giving the 750cfm Street-Q the slight edge both on the street and at the track.