HOT ROD to the Rescue
The Magnum Heads on Brian Ferguson’s 1997 5.9L Dodge Ram Truck Overheated.
When the 5.9L (360ci) Magnum EFI engine in Brian Ferguson’s 1997 Dodge Ram 1500 Sport 4x4 truck reached the end of its tether at 130,000 miles, it was completely rebuilt. The upper end was enhanced with Hughes Engine parts, including its EQ iron Ram HD Magnum heads with bronze guides, a hydraulicroller RV cam (0.523/0.533-inch valve lift with 1.6:1 rockers, 208/214 degrees duration at 0.050, 114 lobe-separation angle), and a single-plane EFI intake manifold. “I wanted more power without sacrificing 100,000-mile reliability,” Ferguson says. “It’s a toy, used to play off-road and tow my dirt bikes.”
“I had about 2,000 miles on the new engine,” Ferguson continues. “When I lost compression on cylinder No. 1, I took the heads over to Hughes for inspection. The valveguides were blown out. I hadn’t even towed anything yet. The engine had never run hot on the gauge or boiled over.”
Longtime Mopar specialist Dave Hughes had never seen such a failure in such a short time on an engine with such low miles. No one wanted a repeat, so HOT ROD and Westech Automotive—our go-to Chicago-area rescue shop—got involved to science-out the root causes of the perplexing problem.
As Brandes tells it, “Hughes told me the valveguides had literally melted, oblonged, and lost valve control. Hughes repaired the heads, but making sure it wouldn’t happen again was my bailiwick. We’d never seen so much heat in the head. We looked at the exhaust (the header flanges were blued), the cooling, fuel and ignition curves, and so on.
“We found the two air temp sensors were flaky and replaced them with new ones. The speedometer was reading high, which we traced to a wrong speedometer gear. At 40 mph, the ECU [electronic control unit] thought we were really doing 50. This caused the ECU to prematurely lock up the A518 overdrive automatic’s torque converter at only 1,400 rpm. Ferguson had swapped out the original long-runner Dodge factory ‘keg’ EFI intake for a short-runner single-plane. He was driving the truck in town at 35 to 40 mph. Combined with the early converter lockup, around town Ferguson was constantly lugging the engine. He was still running the original factory computer programming, so the confused ECU also leaned out the fuel mixture.
“It gets worse. The factorystyle oval-dish pistons were about 0.060-inch down in the hole at TDC. The high-swirl factory Magnum heads couldn’t generate good mixture motion with such a low piston deck height. At only about 8.7:1, the static compression ratio was way too low anyway.
“Put all this together and we had a lazy, slow-burning air/fuel charge that caused the chamber to retain too much heat. We might have been able to bandage the combo with some careful tuning and just changing the speedo gear, but we decided to really make this combo all it should be with a piston swap to raise the compression ratio as well as generate some mixture motion.”
THE FIX: SHORT-BLOCK
A piston change meant boring the already 0.030-inch over block another 0.010-inch (0.040over an original 360’s 4.0-inch bore size). On his own, Ferguson decided since the engine needed pistons anyway, why not step up to a 4-inch Scat cast stroker crank for 410.2 cubes? With less than 2,000 miles on the previous build, Brandes could reuse the existing, undamaged main and rod bearings.
Stroker crank in hand, Brandes selected a matching piston. He went with a UEM KB Pistons hypereutectic step-dish KB416 profile. “The step-dish gives you essentially a quench area on the open-chamber cylinder head,” he explains. “It forces the air/ fuel charge toward the valve and spark plug. This generates mixture motion and speeds up the burn. It made up for the fact the piston was still 0.050-inch down in the hole. The static compression ratio went up to 9.4:1.”
The pistons were ordered as a piston-and-ring kit that includes iron moly compression rings. Also ordered was an optional add-on to the basic piston:
KB’s newly available Line 2 Line abradable skirt coating. It’s sprayed onto the piston skirt, adding thickness to develop zero piston-to-wall clearance for reduced piston rock and quieter operation. While it benefits even tight clearance hypereutectic pistons, the coating really comes into its own with forged pistons (like UEM’s Icon piston line) that require higher initial skirt clearances. During initial engine run-in, the coating wear-mates to the cylinder, developing microscopic high/low spots that actually retain additional oil for reduced friction.
THE FIX: VSS ERROR
The speedometer and the ECU in late-model vehicles rely on electrical pulses from a vehicle speed sensor (VSS). In the 1997 Dakota, the VSS is a hybrid device that mounts into the side of the trans like an old-school speedo cable, but instead of connecting to a cable, the gear outputs to the VSS. Ferguson’s nonstock, 35-inch-tall, off-road tires and 4.56:1 rear gears had totally confused the speedo and ECU—easily corrected by installing a driven gear with additional teeth. (For more on speedo calibration, see this month’s Pit Stop column.)
THE FIX: ECU
With mechanical issues cured, the ECU was reprogrammed to work with the single-plane intake, higher compression, and added displacement. Chrysler “Jetronic” computers require a separate flash programmer for serious recalibration. SCT’s X3 DCX Power Flash unit (PN 3200) is the preferred solution. It plugs into the vehicle’s diagnostic port to transfer custom tunes. The device can store up to three separate custom tunes, retain the original factory tune in case it’s ever needed, read and clear trouble codes, and even data-log during a test drive. Although the X3 DCX isn’t prominently featured on SCT’s website, it’s still available new, targeted to hard-core custom tuner shops. As of early 2018, Summit Racing has them in stock.
Chrysler tuner Dale Matthews was brought in to work his magic on the X3. According to Matthews, “I raised the idle speed from 600 to 720 rpm, then advanced the base timing to 16 degrees BTDC to hold a smoother and better burning cylinder at idle. To adjust for the added cubic inches, in the main spark table, I added from 3 to 7 degrees of timing to certain areas of the map, mostly in the higher rpm/load range. I set the max advance at WOT [wideopen throttle] to 36 degrees. The
added cubic inches require more fuel. The oxygen sensor controls the air/fuel ratio in closed loop below 3,000 rpm; once that threshold has been crossed, the Speed Density–based system defines the air/fuel ratio from the table. Targeting the WOT A/F ratio to 12.5–12.8:1, I ended up adding an additional 15-percent fuel over the stock table.” Flowing 21.1 lb/hr at
43.5 psi, the Ram’s existing fuel injectors proved up to the task.
Last Thanksgiving, liter- ally seconds after some final tweaks on Westech’s chassis dyno, Ferguson hopped in the truck, left southern Wisconsin, and drove crosscountry to his new home in San Bruno, California—about a 2,300-mile drive. He went through Denver and the Rockies on I-70, climbing as high as 11,158 feet. Did we mention he was towing a 500pound trailer—and running 87-octane gas? “I’m super happy!” Ferguson says. “It’s just got so much more effective power everywhere. I’ve had no major problems since.”
You could say the wrong speedo/VSS driven gear was the straw that broke the camel’s back, but without higher compression and good mixture motion, the existing truck would still have remained lazy on the bottom end. This points out the need for totally matching your desired end goals and usage when planning your rebuilt engine combination.
12–13] Next, it’s over to the grinding wheel to carefully clearance the rods’ pin ends ( 12). Most material was removed from the formerly square pin-end corners ( 13).
“They didn’t hear any detonation, so they figured everything was OK!” — Norm Brandes
16–18] Chrysler speedo-driven gears come in both long- or short-stem versions ( 16). The long stem has a 3-inch shaft length and fits cable-driven speedos; the short stem’s 1.5-inch shaft is for late-models like the Ram truck and work with a slip-in...
Hughes’ $5 adjustable slip collar keeps the distributor from walking up and down in the block as it meshes with the helical cam drive gear. Gear-walk causes timing variations and can degrade sequential injector timing. Adjust collar-to-gear clearance...
08–11] The stock Magnum rod’s small end must be ground to clear the bottom of KB’s stroker piston. To find out how much to shave off the rod, insert two pins (one through each piston pin-hole) until they nearly touch, leaving just enough gap for a...
Amazon.com 04] Scat’s affordable ($382 at Amazon) cast 4-inch stroke crank plus a 4.040-inch bore yields 410.2 ci—plus massive torque potential. The crank can be neutralbalanced (it may take some Mallory), but Brandes elected to balance it for a...
Marlan Davis 05] The stock flat-top pistons ( left) make for a lazy, slow burn that kept too much heat in the open-chamber Magnum heads. The KB416 piston for 4-inch stroker cranks and Magnum heads ( right) has a step dish that creates quench by...
06–07] Brandes special-ordered the hypereutectic pistons with KB’s new Line2Line abradable skirt coating that reduces piston rock as well as friction. It wear-mates to the cylinder, safely achieving zero piston-towall clearance. But with a...
02–03] The stock long-runner “keg”-style intake ( 02) works best in the 1,800–2,000-rpm range, but then runs out of breath. Ferguson had replaced it with a Hughes F1 single-plane ( 03), whose under-plenum air gap is said to cool the charge as much as...
01] The wrong speedo gear messed up the ECU: It thought the truck was traveling much faster than it was. It responded by leaning out the fuel curve and advancing the spark. This caused heat buildup in the combustion chamber, melting the valveguides....
[ ECU tuning plus a speedo gear swap were only a partial answer. The full big-torque fix ultimately involved building a 4-inch stroker motor.
[ The ECU went “lean,” melting down the valveguides. Norm Brandes ( shown), Dave Hughes, and Dale Matthews sleuthed out the problems.
[ After final tweaks on Westech’s chassis dyno, Ferguson drove the truck from Illinois to California across the Rocky Mountains.
[ A good ECU program and the right speedo gear weren’t enough! Ferguson’s original goal was more downstairs torque. But the engine’s top-end mods helped mainly midrange and higher rpm performance, so Brandes turned the 360 into a 410. Fel-Pro standard...
[ Ferguson says, “I use my truck as an off-road toy and to tow a trailer with my dirt bikes. I wanted more low-end power—and reliability.”
[ Source of the chain of failure: The 30-tooth speedo driven gear wasn’t right for the 4.56:1 axle ratio and 35-inch tires, confusing the ECU.
[ Owner Brian Ferguson wanted enough power and reliability for off-road fun and games, but the initial rebuilt engine and tune had issues.
19] SCT’s X3 DCX Power Flash programmer was used to dial-in the Ram’s 410ci engine. Geared toward hard-core tuners, it comes with no preloaded tunes, but there are lots of predefined tunes you can download—or construct or modify any tune on a PC, then...
20] There’s a motor in there somewhere. Back in the truck and fully tuned, the fresh 410 is nearly ready to head west.