When it comes to tearing down an engine and building it back up, whether for performance or reliability, it is critical to have a clear goal in mind. The goal can be as simple as a rebuild that will last 200,000 miles, or a larger undertaking like building a 1,000 horsepower engine to last 200,000 miles.
The key is to have a clear goal in mind to help you select the parts you need to achieve that goal. The tradeoffs could be cost, performance, or reliability.
To lay out a clear goal, you need to identify how the truck is going to be used. In the case of this engine, it is going into a truck that will be driven daily. It will see a wide range of uses from driving to the local convenience store to hauling a trailer loaded with 10,000 pounds across the country. The truck will also operate under a wide range of altitudes and temperatures. It will also occasionally hit the drag strip and a dyno event. With all of that laid out, we can set clear goals for the engine:
- Mid 500 horsepower on fuel only
- High 600 to low 700 horsepower with nitrous (part 2 of this build)
- Good low end power for towing
- No major maintenance on the engine for 2 years. (This may seem odd to state, but when choosing parts, reliability can come into play.)
- This engine should last for at least 200,000 miles
- 16.5 mpg combined (same as before the engine was built)
Reason For Teardown
The engine we are rebuilding is from a 2004 Ford Super Duty that has been used as a test mule for many years. By test mule we mean the engine was used to test a wide range of components being developed by multiple companies over the years and after all was said and done, the engine went through a number of different configurations. The engine has seen close to 75 different sets of injectors, a wide range of turbocharger configurations (single and compounds), has made over 100 visits to the dyno, and at one point the truck was used for sled pulling. In addition to the abuse listed above, the engine has logged over 150,000 miles, which by itself isn’t much for a diesel, but when factoring in all the engine had been through, that is a fair amount of miles.
While driving cross-country one day, after a short stop, the engine barely started, and when it did, there was a distinctive popping sound coming from the intake. That type of popping sound was a sign that the exhaust valves weren’t opening in one of the cylinders. The most obvious causes of that problem are from a bent push rod, broken rocker and/or damaged lifter.
Instead of diving into the engine and trying to repair the issue, Editor Chad felt it was probably time for a complete overhaul. After years of abuse, the odds that this was the only issue that would come up in the near future were pretty slim.
In order to pull the engine out of the front of the truck, the turbocharger, up pipes, and intake manifold were all removed. Upon removing the intake manifold it was obvious that cylinder number one was having the issue. The heads had been upgraded years earlier, all the EGR equipment removed, and the intake manifold cleaned. As a result, all of the intake runners were clean except for cylinder one. Cylinder one had soot lining the runners, a clear sign of the exhaust being pushed past the intake valves.
With the engine removed, the oil pan was pulled off and the rear cover removed. Then the engine was set on blocks. The right side valve cover and oil manifolds were removed to further inspect what was causing the issue. The 6.0-liter Power Stroke uses a single rocker arm to actuate two valves, via a bridge that sits on top of the valves. The ’04 and later model engines feature rockers that actuate on a plastic pivot. It appears that the pivots broke on the number one exhaust rocker arm. In addition, the rocker arm tip broke. The combination of the two caused the exhaust valves not to open. The popping sound was caused from the pressure that was built up in the cylinder after it fired being relieved through the intake valves as they opened.
As tear down continued, additional issues started showing up signifying that it was a good choice to rebuild the engine instead of fixing it. Pieces of plastic and metal were found on top of the right head. When the head was pulled off, cylinder three and five had debris on top of the pistons, and a number of the coolant passages were blocked.
The left side showed no issues as the disassemble went exactly like one would expect tearing down a 150,000 mile engine. The remainder of the engine was the same as well. Only the right side showed any issues initially.
For machining, the block, cradle, heads, crank, rods and pistons were taken over to H&H Machine in Haltom City, TX. H&H Machine, generally builds sprint car engines and other performance engines, but they do work on the occasional diesel.
Upon initial inspection, it was determined that the heads needed to be decked, the block would be in good shape after boring the cylinders 0.030-inches over, but the crank needed to be replaced. There was a deep groove where the oil pump gears were (most likely from debris being pumped through the oil system) and H&H wasn’t comfortable re-using the stock crank.
Time to start ordering parts
With a good idea of what needed to be done to the engine, Westfall started planning and ordering parts. Here is where having a clear goal is key. Westfall didn’t need to buy a new crank because he had multiple 6.0-liter core engines. He took one of the other cranks to H&H Machine. For rods, there are two thoughts. Spend the money and get a good set of rods that will hold substantially more power than the engine would probably ever make or reuse the factory rods.
“I don’t plan on spraying the engine very often and I really don’t beat on my vehicles. For me, I didn’t see a need to upgrade to a set of premium rods when there are hundreds of stock bottom end trucks running in this power range. With the engine cradle and horsepower limitations the 6.0’s have, the stock rods are sufficient,” explained Westfall.
With the cylinders being bored 0.030 inches over, the factory pistons had to be replaced. The options are oversized stock forged replacements, and/or a custom piston.
For trucks making up to 1000 hp and still being used as a daily driver or work vehicle, cast pistons are the best choice. — Craig Lancaster, MAHLE Motorsports
That made choosing a piston pretty easy. A set of 0.030 over MAHLE cast pistons were ordered. While the engine may be sprayed with nitrous every now and then, there is really no need at this performance level to worry about lowering the compression ratio or doing anything fancy with bowl design. The only other aspect to decide on is whether the pistons need valve reliefs.
The rocker ratio and camshaft determine if valve reliefs are needed or not. “The camshaft in a 6.0-liter engine is designed to help the engine reach its performance characteristics. These characteristics include not only horsepower and torque requirements, but emissions. Due to the emission aspect of the design, the operation of the valves is pretty limited, resulting is much less energy available for the turbocharger than a non-emission engine. This is one of the reasons why the 6.0-liters use a variable geometry turbocharger,” explained Westfall. Colt Cams reground the factory camshaft to give it a more favorable profile. The profile isn’t just a performance profile. It will help free up some extra energy for the turbo on the big end, but it will also help low end spool up, which improves fuel mileage, and towing.
The factory camshaft has profile of 0.225”/0.229” (intake/exhaust) at 0.050” lift. The Stage 1 regrind from Colt Cams bumps the profile to 0.251/0.245 inches. This equates to about a 0.035-inch of additional lift which doesn’t tell the whole story. The factory intake is open for 167 degrees and the Stage 1 opens the intake valves for 178 degrees. This is where the majority of the intake increase is coming from. To provide the extra exhaust energy, the exhaust goes from 176 degrees to 195 degrees (almost 20 degrees of additional duration). All of this additional valve lift and the cam is still a direct drop in replacement/upgrade (meaning no valve reliefs needed).
The most troubling aspect of the 6.0-liter Power Stroke was next to be decided upon, the heads. Many years ago, The factory heads were replaced with a set of ported and polished heads from Elite Diesel Engineering. These heads didn’t provide a huge performance gain on the dyno, but did reduce boost pressure and EGTs. In an application like this, this might be overkill but since the heads were still good, there was no reason to replace them.
Holding the heads down is a set of ARP2000 studs from ARP. The engine previously had studs and while the studs are re-useable, it is just a little extra insurance to have a new set. “When in an engine this far, sometimes it is a cost worth incurring just for the extra insurance. If were planned on running spray a lot of really pushing the engine, I probably would have opted for the Custom Aged 625 studs for the extra insurance,” explained Westfall.
Since the engine failure came from a plastic piece within the rocker arm assembly, there was no way the same style of rockers were going back in. Luckily, the guys at Diesel Dynamics happened to have a few sets of used ‘03 6.0-liter rockers lying around. The early ’03 engines used a metal pivot instead of the plastic pivot found in the later generations.
With all of the machining done and the parts gathered over the course of a few months, the engine was taken over to Diesel Dynamics in Joshua, Texas, for assemble. They build a few hundred engines every year and are extremely well versed with the Power Stroke engine assembly.
“We rebuild a lot of these because people don’t do proper maintenance and keep their programmers on high when towing like 15,000 pounds,” said Crede Young, Owner of Diesel Dynamics. “When we rebuild the 6.0-liter engines, we always use new oil coolers, EGR coolers or EGR deletes, update the HPOP pumps, and replace the rod bolts. At one point in time, we started seeing a lot of rebuilt engines from a competitor coming in that had broken rod bolts. No matter what performance level you are seeking, always replace the rod bolts,” continued Young.
Jerry Young (a.k.a. Papa) was kind enough to let us follow him through the process of assembling the engine. Almost immediately, he noticed that the oil pump had scores from debris running through the oiling system. Upon further inspection, the front cover showed similar scores. After finding good used replacements, Young finished assembling the short block. One thing Young did mention was that the front cover should not be tightened until the oil pump was installed and there was even space around the pump.
After years of replacing injectors many of the threads for the valve covers and oil manifolds were stripped out and needed to be fixed. Young drilled all of the threads out in the rocker boxes and installed Helicoils. This would ensure years of trouble free use.
On the top end, Young, also, replaced the lifters. “It isn’t the cheapest item to replace, but needle bearings don’t last forever. We replace them on every engine we rebuild and strongly recommend people replace the lifters even if the same camshaft is going back in,” said Young. With how the 6.0-liter is designed, if one went bad, the engine would need to be torn down to a short block in order to replace them.
When it comes to installing the oil cooler, Young opted for a new one instead of re-using the low mileage one that was in there. “We replace the oil cooler on every engine we rebuild. You have to be really careful with oil coolers. There are cheap brands out there that are known for having failures. We always buy the premium brands when it comes to oil coolers. Also, make sure you replace the high pressure oil screen,” mentioned Young.
The last major item to be installed in the engine was the damper. The stock damper works fine, but when increasing the power level of an engine, the harmonics within that engine change. The stock damper uses an elastomer for damping the harmonics. These only work within a narrow frequency range. A viscous type damper damps throughout the entire RPM range. With the objective of this build being a trouble free, low maintenance engine, a Fluidampr was installed. The extra damping may make the difference down the road.
Up until now, all of the parts selected really don’t make major power. The two biggest items that determine how much power the engine will make and the driving characteristics are the fuel injectors and the turbocharger.
With rare exception, there starts to be a diminished return as the injectors start reaching 190cc.-Chad Westfall, Diesel Army
“With rare exception, there starts to be a diminished return as the injectors start reaching 190cc. If you look back at previous dyno sheets over the years, you will notice that 225cc injectors don’t yield much more power than 205cc which is only slightly more than 190cc. There are some exceptions like hybrids but that is a different animal and outside of the scope of this type of rebuild,” explained Westfall.
The size of the injector plays a big role in making power, but it, also, plays a role in smoke production and EGTs. This engine is going in a truck that resides in Texas. Texas is a state that reaches triple digit heat during the summer. In addition, with towing all over the country the truck will encounter a variety of different elevations. “The Maryland Performance Diesel 190cc injectors are very drivable. Especially with proper tuning from guys like Eric at Innovative Diesel, EGTs can be controlled and smoke production can be kept to a minimal amount when stuck in traffic,” mentioned Westfall.
Over the past ten years, 190cc injectors seem to max out on fuel only somewhere in the 570 to 590 horsepower range with the proper sized turbocharger. In addition, there are quite a few trucks that have landed in the 700 horsepower range with nitrous. A big determining factor to how much fuel only horsepower the truck will make is the turbocharger size.
“When it comes to selecting a turbocharger, you need to be very cautious. Too many people either deal with someone that doesn’t understand your situation or they select the largest charger chasing the big power number, not realizing they are giving up their low end. I went to BD Diesel Performance and had a few long conversations with them about what I was trying to achieve and what I was looking for,” explained Westfall.
The turbocharger ended up being an S300 BorgWarner turbocharger with a 64mm compressor wheel, 65mm turbine, and split volute 0.70 A/R wastegated turbine housing. Now for you turbocharger guys out there, you may realize an issue with this combination. In a 6.0-liter Power Stroke, a 64mm won’t support 570 to 590 horsepower and the 65mm turbine wheel is pretty small for that range.
This is where having a clear goal in mind is important. “I need to be able to tow with this truck. If I opted for a 66mm or something larger then I would gain the power but lose my bottom end. I would rather have a little less power on top and a truck that is fun to drive, then a truck that is all top end,” explained Westfall.
The 6.0-liters are notorious for having extremely high drive pressure and the wastegate will help to reduce that. In addition, the wastegate will help to keep from over-spinning the turbocharger. To help with additional low end spool up, a BD Diesel Performance diverter valve was installed. The diverter valve is pretty important on a 6.0-liter. By diverting the exhaust into half of the turbine housing, the charger comes on much quicker. “Depending on the tune I’m running, the engine will make 8 psi of boost while cruising down the highway at 1,800 rpm,” said Westfall.
The entire turbocharger kit is mounted on a BD Diesel Performance turbo kit and is fed with an upgraded set of y-pipes that feature high strength bellows. The factory bellows can fail with high EGTs and this is a perfect time to upgrade the y-pipes.
Once the engine was installed into the truck, a SCT Livewire TS was installed. The Livewire TS is the latest generation of the Livewire. It has a 4-inch color touch screen that can display a ton of information that is available via the OBD-II port. Initially, the performance tune was downloaded to the truck and the Livewire was mounted to the windshield. The truck actually performed pretty good with the “canned” tune. Outside of some excessive low rpm smoke the only issue was the transmission tuning. The “canned” tune shifts into overdrive around 50 mph and the engine speed drops to 1,300 rpm. Even with 2 to 5 psi of boost, the EGT’s would rise quickly and the truck would lug.
To take care of this issue, Eric Eldreth at Innovative Diesel Performance was called for custom tuning. Eldreth needed to know the VIN number of the truck and the serial number of the Livewire. Outside of that, he needed to know what modifications were made and what types of tunes were needed. Eldreth nailed it on the first try. While the truck may not make quite as much boost at low rpm, the EGTs are lower, the engine is smoother, and the smoke is very low (unless you floor it).
After about 2,000 miles of driving and working out the bugs with the truck, it was taken back to Diesel Dynamics to be strapped down to the dyno. Before each pull, the truck was allowed to come up to operating temperature (185 to 190 degrees oil temp and 190 degrees coolant temp) and the truck was manually shifted with Diesel Dynamics WDS (World Diagnostic System) to keep the truck from downshifting or upshifting.
The truck was brought to 2,200 rpm with no load and then the load was applied. The RPM was then dropped down to 1,750 rpm and then would make a pull. We tried a few times to bring the RPM down to 1,500 but the EGTs would reach 1,600 degrees before we would break 2,000 rpm. There is no reason to push the truck that hard to achieve max torque on the dyno. All said and done, we managed to lay down 528 hp and 1,364 lb-ft of torque. While this is slightly lower than our goal of mid 500s, the tradeoff we made with the turbocharger was well worth it for a truck that can tow and is very drivable.
That being said, we were blown away with the nitrous dyno results. Stay tuned!