KEEPING PACE, PART 2: 550HP VP44 RECIPE

The Blueprint For Making Your 24-Valve Cummins Relevant In Today’s High-Horsepower World

The second installment in this underdog diesel series brings us to the VP44-fueled, 24-valve 5.9L ISB Cummins that powered second-gen trucks from ’98.5-’02. Aside from the way it compared, stock, to the outgoing 12-valve it replaced in 1998, the 24-valve Cummins has never really received its due credit for horsepower potential. Sure you’re not going to squeeze 650hp out of a mild set of injectors and a turbo upgrade like you can on a common-rail, or unlock 100 extra ponies for free like you can with a P-pumped 12-valve, but the VP44-fueled 24-valve can still be made to turn out respectable horsepower. Case in point, many seem to forget how easy it is—especially in the modern era—to reach 500-hp with the 24-valve platform.

This time, we’re examining a 550hp part’s recipe we’ve seen play out on the dyno time and again. In a nutshell, it calls for a set of 150hp injectors, a hotrod VP44, a chassis-mounted electric lift pump system, a turbo upgrade, and the right tuning. For insurance, minor valvetrain upgrades and head studs are preferred, but other than that the path to making 550-hp (or more) is clear. Perhaps the best part is the fact that you don’t need to make any hard-part changes in the bottom end. The factory rotating assembly has zero issues tolerating 550 hp and 1,100 lb-ft on a regular basis. If you’re ready to effectively triple the horsepower of your ’98.5-’02 Dodge, the ultimate, daily drivable, 550-plus hp combination is presented here.

They are often ignored, skipped over, and deemed “not worth it” by many enthusiasts, but we’re here to remind everyone that the 24-valve Cummins is a viable candidate for making horsepower. Thanks to modern turbo technology, proven fueling enhancements, and the right tuning, 550 hp, and 1,100 lb-ft are achievable. But not only that, it can be daily-driven, doesn’t tax the 5.9L’s factory internals, and can be realized without breaking the bank.

From everything we’ve seen over the years, 150hp injectors represent the best route to getting your ’98.5-’02 Dodge into 550hp territory. While hole count and hole size can vary among 150hp injector nozzles, the versions produced by reputable builders such as Scheid Diesel, Industrial Injection, Dynomite Diesel Products (pictured), and Diesel Auto Power definitely deliver. Better yet, for $450 to $1,200 you’ll have an injector that’s easily capable of supporting your 550 hp goal.

SAC style nozzles (as opposed to VCO) tend to be more common in the mid-size injector realm, which includes 150hp units. SAC style nozzles offer more durability than VCO nozzles, but they are louder and can haze more at idle. Some of the more popular SAC style, 150hp injectors on the market are the 6x.012-inch Lightning 2’s from Scheid Diesel (six-hole nozzles, with each hole measuring 0.012-inches), the 7x.010-inch Race3 units from Industrial Injection, DDP’s 150hp sticks, and the budget-friendly 7x.010’s offered by Diesel Auto Power.

Fuel injector pop-off pressure can vary between 150hp injector builders, but 290 bar is about as low as you want it to be before atomization begins to noticeably suffer. However, a lower bar pop-off pressure does extend the duration, making for more fuel being injected per combustion event.

It’s not a given that a high output VP pump is required for 550 hp, and we’ve seen standard output Bosch VP44 support close to 600 hp and 1,200 lb-ft in the past. However, the majority of the ’98.5-‘02 trucks we see in the 550hp range are indeed equipped with an aftermarket VP44. The internal modifications performed inside these pumps help you get the most out of a set of 150hp injectors.

Both Scheid Diesel’s Lightning VP44 (pictured) and Industrial Injection’s Hot Rod VP44 enjoy reputations for durability while supporting high horsepower. Depending on injector size, either pump can add as much as 100 hp to a 24-valve truck’s bottom line. Even with smaller, 100hp injectors in the mix, Scheid’s Lightning pump adds at least 75 hp. With 150hp injectors, the full, advertised 100hp gain is realized, if not more.

For anyone piecing together their own tank-to-engine fuel system, FASS’s adjustable pressure lift pump can be purchased separately. Pressure is adjustable from 1 to 20-psi and the pump can flow 165-gph. As with any VP44-equipped 24-valve Cummins, a low-pressure fuel supply gauge is highly recommended to monitor pressure. Preset supply pressure should be available during cranking, at idle, cruising, or wide-open throttle.

Unlike the 12-valve, tuning is a considerable part of the power-making puzzle with the 24-valve—and specifically, you want to pick a box that allows the VP44 to fuel higher than 3,200 rpm (which is the factory maximum). For nearly two decades, Edge Products’ Comp module has been used to alter the timing and increase fueling on ’98.5-’02 Dodges, and it’s still a favorite today. The real potential of the Comp is unleashed through hard-wiring the module (also known as “tapping the pump wire”). In the past, Edge’s Comp module has been combined with the Smarty S-03 with solid results.

It goes without saying that an aftermarket fuel supply system should be added to a VP44 Cummins, but with an aftermarket injection pump onboard, a 150 to the 165-gph system (at a minimum) is required. FASS’s 165-gph Titanium Signature Series system and the 165-gph AirDog II-4G are commonly used and have no problem maintaining 16 to 18 psi worth of fuel supply pressure to help keep the VP44 well lubricated and (especially) cooled.

With CAN-bus fueling, direct and improved VP44 fueling, injection timing, boost control, and built-in boost fooling, the Quadzilla Adrenaline is another well-known module for unlocking upper rpm fueling from the VP44. It too requires tapping the pump for best results and is said to provide for full fueling up to 3,700 rpm. As an added bonus, the iQuad version plugs into the Adrenaline module, allowing you to view engine parameters and change tunes with your iPhone or Android smartphone.

Although a factory HX35W can be nursed through the torment a set of 150hp injectors dish out, it will never support 550hp or more. While BorgWarner’s SX-E line of S300 frame turbochargers has all but reinvented the game (more on that next), it’s hard to argue with the original PhatShaft turbos from Industrial Injection. In particular, we’ve seen a 64/65/14cm2 version support 567 hp and 1,106 lb-ft on an ’01 Dodge 2500 that was daily driven, regularly towed with, and that ran bottom 13’s at the track.

It doesn’t get much more old-school than a Redline box from Blue Chip Diesel, but this remains the highest rpm module you can get your hands on for a VP44 Cummins. Full fueling up to 4,000 rpm made it a hot-ticket box back in the day (to our knowledge, it’s no longer in production), especially for truck pullers competing against 5,000-rpm P-pump trucks who were looking for as much ground speed as possible.

Edge’s Competition Juice with Attitude is another common find in 24-valve trucks that turn out respectable power. With its Power Level 7 capable of fueling up to 3,600 rpm combined with Edge’s industry-leading CS3 or CTS3 Insight monitor, we’ve seen it employed on countless 550 to 600hp trucks over the years.

Right out of the box, BorgWarner’s S363 SX-E is a near-perfect turbo for a ’98.5-’02 Cummins. The 63mm forged milled wheel charger provides quick spool-up, excellent low-speed drivability, and can support 550 hp or more. Bumping up to an S366 SX-E could easily push a 24-valve equipped with a hot-rod VP44 and 150hp injections close to 600hp territory.

Nothing is worse than an ECM pulling fuel due to excessive boost pressure. As was previously mentioned, boost-fooling is built into the Quadzilla Adrenaline, but that’s also the case with the aforementioned Edge Comp, Edge Competition Juice with Attitude, and Redline box. Note that any tuning that doesn’t handle boost fooling may require you to add a fooler under the hood.

Wastegate or not, peak boost for a 24-valve running on factory head bolts should be capped at around 45 psi. While a higher-mileage ’98.5-’02 Cummins’ bottom end likely won’t mind the excess boost and drive pressure that comes with making 550hp, an aged head gasket probably will. This is why head studs need to be on your short list of hard-part additions when pursuing this power level.

As is practiced on other engines, head studs can be installed one at a time on the 24-valve Cummins as a precautionary measure as opposed to a full-on head gasket repair. So long as the head gasket is good, replacing each factory head bolt with a stud one fastener at a time provides good insurance against lifting the head. It’s also game-on with boost after studs are in place.

Of course, throwing more boost at a high-mile cylinder head can be asking for trouble—so it’s no wonder why many support the act of pulling the head for inspection before installing head studs. It’s not uncommon to find a cracked head, or one that is in need of resurfacing, a valve job, new valve guides, and valve seats. By far, ARP is the name enthusiasts trust the most when it comes to head studs, and for a 550hp application, the company’s ARP 2000’s will suffice just fine (no need for Custom Age 625+ or fire-rings at this power level).

An engine build isn’t a prerequisite for making 550 hp with a 24-valve Cummins, but there are several top-end items that should be upgraded before you turn more fuel, rpm, and boost loose on your ’98.5-’02 Dodge. Stiffer valve springs are at the top of this list. To stop valve float at high rpm, valve creeps at high boost, and reversion during instances of high drive pressure, the 90-lb valve springs from Haisley Machine are a great addition, as are the 103-lb springs offered by Hamilton Cams.

Stronger pushrods, such as the extreme duty versions from Hamilton Cams shown here, work well in conjunction with stiffer valve springs. Their 0.120-inch wall thickness is thicker than competing products and they’ve even been tested in 3,000hp engines. While it might be considered overkill, it’s worth reminding everyone that even in a 550 to 600hp application the cylinder pressures that are on tap can bend the stock pushrods much easier than you think.

It may not add much in the way of horsepower, but a reputable aftermarket intercooler will make the quality of life much better for the turbo and engine. The On 3 Performance intercooler (sold by our friends at Haisley Machine) and Cool-It units offered by BD Diesel have always yielded sound results—namely in the form of 200 to 300-degree F reductions in peak EGT, which is huge.

Depending on your turbo selection, an exhaust manifold upgrade might be required. In those instances, it’s hard to beat the products offered by Stainless Diesel, Steed Speed, or BD. The polished T4 Stainless manifold shown here features a ¾-inch thick center section, incorporates high-flow, 1.650-inch diameter inner runner sizes throughout, and also has two ports drilled, tapped, and ready to go for your EGT and drive pressure readings.

Last but not least, a free-flowing exhaust adds the exclamation point—in both terms of flow and noise. The common, HX40 style downpipe (shown) will suffice in most applications, as will a 4-inch diameter system. As a general rule of thumb, a 5-inch system will be audibly deeper but may also drone more. Mufflers, resonators, and exit styles (be it conventional, dual, axle dump, etc.) are left to personal taste.

It goes without saying that the 47RE automatic will need a few reinforcements to hold up to a 550hp, 1,100 lb-ft effort day in and day out. At a bare minimum, a billet input shaft should be part of your four-speed build, and billet intermediate and output shafts would be great insurance, too. Then comes a billet flex plate, triple-disc torque converter, high-pressure valve body, additional direct and overdrive clutches, and various other weak link solutions.

If you’re in the manual transmission camp, you’ll likely only need a clutch upgrade to prep your hand-shaker for handling 550 hp. This will likely mean a little overkill in the form of a dual disc unit. For the NV4500 five-speed, the larger input shaft upgrade—where the shaft’s outer diameter is increased from 1-1/4-inch to 1-3/8-inch— is worth considering for added insurance.

A Proven HP Recipe

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It doesn’t get any more real world than this: the dyno sheet produced by a 130,000-mile, ’02 Dodge 3500 with a built 47RE behind a stock bottom end 24-valve Cummins. For fuel, the truck was treated to Dynomite Diesel Products’ 150hp injectors, Industrial Injection’s Hot Rod VP44, and a 150-gph FASS system. For air, the old-school 64.5mm Super B Special from BD Diesel got the nod, along with a BD exhaust manifold and a Spearco intercooler. Tuned by way of an Edge Juice with Attitude with the “Hot Unlock” level 6 active, the second-gen Cummins put down the 551 hp and 1,110 lb-ft numbers you see here.

’02 Dodge Ram 3500

Engine: 5.9L Cummins 24-valve with ARP 2000 head studs

Fuel: Dynomite Diesel Performance 150hp injectors, Industrial Injection Hot Rod VP44, FASS 150-gph fuel system

Air/Exhaust: BD Super B Special turbo (64.5mm), Spearco intercooler, Flex-a-lite electric fans, stock air box, and intake elbow, BD exhaust manifold, 4-inch turbo-back exhaust system

Transmission: Goerend 47RE with triple disc torque converter, billet-steel input, intermediate, and output shafts, BD billet flex plate

Tuning: Edge Juice w/Attitude with Hot Unlock

SOURCEs

AirDog
208.810.0590
airdogliftpumps.com

ARP
800.826.3045
arp-bolts.com

BD Diesel
800.887.5030
us.bddiesel.com

Blue Chip Diesel Performance
888.472.7373
bluechipdiesel.com

Diesel Auto Power
801.927.4600
dieselautopower.com

Dynomite Diesel Products
208.209.3214
dynomitediesel.com

Edge Products
801.476.3343
edgeproducts.com

FASS
636.433.5410
fassride.com

Haisley Machine
877.948.3164
haisleymachine.com

Hamilton Cams
512.355.9101
hamiltoncams.com

Industrial Injection
800.955.0476
industrialinjection.com

On 3 Performance
614.439.0057
on3performance.com

Quadzilla
801.872.5472
quadzillapower.com

Scheid Diesel
812.466.7202
scheiddiesel.com

Stainless Diesel
574.358.0456
stainlessdiesel.com

Steed Speed
250.807.7212
steedspeed.com