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  • 2007 Dodge Ram that Keeps its Wild Performance Under Wraps

2007 Dodge Ram that Keeps its Wild Performance Under Wraps

The Dictionary Uses a Picture of This Truck to Define "Sleeper"

Sep 30, 2015
Photographers: John Muldoon, Nick Kraft
John Muldoon is no stranger to diesel technology. "I was always intrigued by diesel as a kid," he says. "I've always been mechanical." After a few years of school and working as a heavy-duty and medium-duty mechanic, John jumped into the diesel-performance world and opened his own shop in 2014, Muldoon's Diesel Performance in Wilmington, Delaware. Aside from the occasional dalliance in performance Volkswagen TDIs, Fords, and GMs, his bread and butter is the Cummins diesel engine—which explains why his shop truck is a single-turbocharged '07 Dodge Ram 2500 monster.
Photo 2/13   |   John Muldoon's '07 Dodge Ram 2500 was an accidental project: Removing the cylinder head for some routine engine maintenance revealed a few too many marks in the cylinder liners for comfort. The solution? A full-on engine build, with transmission upgrades and tuning to match.
John inherited the truck from his late father, and he says it's the one final link he has to his dad. Shortly after taking possession of it, John pulled the head to do some minor modifications (new valvesprings, polished headwork, and such), but he found scoring in the cylinder walls from some improper maintenance. With that discovery, a full build was in order. From the time he started working on the project, the Ram has been fantastically reliable. "I'd rather overbuild it than underbuild it," John says about his ethos when building the truck.
Starting with the 5.9L 24-valve Cummins, John bored the block 0.020-inch over, ported the cylinder head, installed better valve seats, and tightened it all down with ARP head studs. The fasteners and valvesprings help keep everything together when the massive Fleece Performance billet S468 snail hits full boost. A Motorsport Diesel single CP3 injection pump supplies the stock fuel nozzles (honed to 80-percent-over) with a supply of clean diesel.
Photo 3/13   |   2007 Dodge Ram 2500 Driver Side Profile
Photo 4/13   |   The exterior gives you no clues as to the performance this truck is capable of. The subtle, blacked-out badging and discreet Cummins logo are the only hints that the Ram is a pavement-roaster.
The 48RE automatic transmission is understandably beefed up as well, with billet input, intermediate, and output shafts; mostly-billet internals; and a stock-stall, triple-disc torque converter. A Snow Performance water-methanol system provides lower intake temperatures, greater air density, and significantly reduced EGT, meaning a healthy boost in power.
Obviously, John did the engine and transmission builds and installs out of his own shop, but he gives lots of credit to Innovative Diesel for the ECU tuning. In full-race spec, the turbo puts out 60 psi of boost, which gives the Muldoon's Diesel Performance shop truck 1,600 lb-ft of torque and around 900 horses, extrapolated from its 10.94-second quarter-mile e.t. The Ram made a documented 842 hp on a loaded dyno, but ambient temperatures were more than 100 degrees, so John's power claim seems legit. A spool valve keeps turbo lag to a minimum, keeping the 'charger spinning even when the engine is running at light load.
Photo 5/13   |   2007 Dodge Ram 2500 Interior
Photo 6/13   |   Inside, the theme is subtlety, again. Black pillars, a suede headliner, and an aftermarket stereo look classy, but they don't tell one word of the performance story. To get that, you'd have to look at the transmission temperature gauge and programmer, mounted on the steering column. The best feature is the tuning switch, which hides in the cigarette lighter assembly.
One of our favorite features of John's truck is how subtle it looks. There are no traction bars, gaping air intakes, or low-hanging intercoolers—just a set of off-road tires and wheels. Even the bench-seat interior is mostly stock, with no A-pillar gauges or rollbars to betray the crazy performance. John went so far with the deception as to hide the tuner selector inside the cigarette lighter assembly.
In the future, John may swap out the single turbo for a compound setup, and the CP3 pump may get a companion to keep the diesel supply high enough for bigger power. His only regret with the build is not upgrading to Carillo rods, which right now may limit his progress to "only" 1,300 hp. We say bully; this Ram is perfect as-is, and the world would be a better place if every shop had a truck as cool as his.
Fast Facts
Year/Make/Model: '07 Dodge Ram 2500
Owner: John Muldoon
Hometown: Wilmington, Delaware
Odometer: 88,198 (and counting)
5.9L Cummins I-6 common-rail; bored 0.020-inch over; balanced rotating assembly; mild ported cylinder head; staked valve seats; O-ringed head; ARP New Age 625 head studs; composite head gasket; Inconel exhaust valves; Hamilton Cams 110-pound valvesprings, 188-220 camshaft and HD pushrods; SoCal Diesel ceramic-coated 0.020-inch-over Mahle pistons; ARP connecting rod bolts; and Fleece Performance coolant bypass kit
Photo 10/13   |   Underhood, John made sure the Ram looks as clean and fresh as possible. Classic, Cummins-Orange paint and top-shelf engine auxiliaries keep it looking like a much less complicated, vintage powerplant rather than the modern brute it actually is. A single turbo and fuel pump meet this Cummins' needs for air and fuel.
Motorsport Diesel 10.6mm CP3 injection pump, 80-percent-over-stock injector nozzles, AirDog 150-gph lift pump, T&C Diesel Performance 30,000-psi pressure relief valve, and tuning by Gordon Lindamood at Innovative Diesel
Fleece Performance billet S468 turbocharger, stock intercooler, Fleece Performance Mantake air intake, and Wilson Manifolds intake plenum and manifold
Steed Speed T4 24-valve exhaust manifold, Sound Performance diverter/quick-spool valve, Diamond Eye HX40 downpipe, and Flo-Pro 5-inch exhaust
Snow Performance MPG-Max water-methanol system
Photo 11/13   |   2007 Dodge Ram 2500 Snow Performance Water Methanol Injection System
Photo 12/13   |   Snow Performance water-methanol injection is one of the keys to the Ram's performance and reliability. John hid its tank in the bed underneath the toolbox, keeping it away from prying eyes and safe from sliding cargo.
Muldoon's Diesel Performance 48RE four-speed automatic; Diesel Performance Converters stock-stall, triple-disc torque converter; TRE Diesel Performance valvebody; BorgWarner internal clutches and kickdown band; TCS Performance billet aermet input, intermediate, and output shafts; GM governor pressure solenoid conversion; and PPE deep transmission pan
900 hp (estimated)
1,600 lb-ft
295/75R17 Nitto Terra Grappler
17-inch American Racing Mojave
Reverse-leveled KYB shocks, and rear polyurethane spring bushings
Photo 13/13   |   John's rig is the mascot truck for his shop, Muldoon's Diesel Performance, but it's not a trailer queen. He's driven it from his shop in Delaware to a supplier in Tennessee to pick up parts, and it usually gets pressed into daily-driver duty.
Rear Axle:
11.5-inch AAM axle; 3.73:1 Truetrac limited-slip differential
Fun Fact:
"I built it to be a street/strip/daily truck and then got bitten by the horsepower bug. It was my father's truck, and once he passed away, it remained one of the last links between us. It's just all around fun. My best time quarter-mile time so far is 10.94 seconds at 124 mph."