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Diesel Tech Questions

Top Tech

Bruce W. Smith
Mar 9, 2018
Photographers: Bruce W. Smith

Turbo for Towing

QUESTION: My truck is an ’08 Ram 2500 with a 6.7L Cummins engine and six-speed manual transmission. The truck has a South Bend dual-disc clutch and stock 3.42 gears. I want more midrange power for towing a trailer that weighs a little less than 10,000 pounds loaded. My plan is to have the stock turbocharger swapped for a BorgWarner S467.7 second-gen kit while keeping the stock fuel system. My question is related to the A/R of this turbo. Would it be better for my daily driver/light towing use to get a turbo with a .90 A/R exhaust housing or 1.00 A/R? Is there anything else I should consider?
Ron Belknap
via email
Photo 2/7   |   Although the difference between an A/R .90 and 1.00 may seem small, there is enough variance to justify picking one combination over the other when it comes to daily driving that includes towing trailers in the 10,000-pound range. While a 1.00 A/R on 400 Series turbochargers will allow more aggressive fuel delivery, it’s better suited to aggressive street/strip use (not towing) and isn’t going to perform at its full potential with the stock fuel system.
ANSWER: Although the difference between an A/R of .90 and 1.00 may seem small, there is enough of a difference to pick one combination over the other when it comes to daily driving that includes towing trailers in the 10,000-pound range. While a 1.00 A/R will support a bigger, more aggressive fuel delivery, it’s better suited to aggressive street/strip use (not towing) and isn’t going to perform at its full potential with the stock fuel system. It will also have a lot more lag and produce higher EGT than the stock turbo, especially when a trailer is in tow. We consulted with several experts, one being Bill Allen at Source Automotive in Clackamas, Oregon, who works exclusively on Cummins-powered Dodge Rams and does a lot of racing to boot. Bill recommends thinking smaller: “With towing and daily street driving in mind, the .90 is my recommended turbine housing. But I would lean more toward a BorgWarner S467/83/.90 with stock fueling, because it maintains good bottom-end driveability, EGT relief up top, and the drive-pressure relief from a larger turbine wheel and housing.” Keep in mind, the S467 turbo is designed for around 700 hp with a 6.7L engine and stock fueling and even with a race tune, it will not support that turbocharger. The turbo is dependent on drive energy from the exhaust gases in order to spool. If drive energy generated by the engine is too low (due to a lack of fuel), the turbo will not spool until the top end of the engine rpm, which eliminates the truck’s towing capability. We also spoke with Dan Kitzman of BD Diesel Performance on this subject. “Even with changing the A/R of that turbo, it’s not possible to compensate that much for a lack of fuel by changing [to a smaller] turbine housing,” Dan says. “A small A/R ratio on the turbine will keep the exhaust gases directed mostly at the turbine wheel, therefore keeping that turbine wheel spinning faster and creating boost at a lower engine rpm. With a larger A/R ratio, it will allow more of the exhaust gases to bypass the wheel, lowering the turbine wheel speed and extending the performance into a higher engine rpm.” He also suggests that if your heart is set on the big turbo, you need to invest in a set of bigger injectors and a high-output CP3 injection pump. However, understand that doing so will take away from your plan of keeping the rest of the fuel system stock. Now, if you want to retain stock fuel delivery, Dan suggests using BorgWarner’s S363SX-E turbo kit. “This system keeps the power band down in the lower rpm range where street-driven tow rigs need it.” The S363SX-E doesn’t have the S467.7’s 700hp capability on its own, but it will still create enough airflow to develop 550 hp with your setup, all the while giving your pickup strong low-end performance without EGT issues or excessive turbo lag.

Oh! My Six-Oh!

QUESTION: I’m a little stressed because my ’07 Ford truck’s 6.0L Power Stroke engine suddenly quit. There were no warning signs, sounds, or diagnostic trouble codes when it shut down. It just died. The engine cranks but doesn’t fire. There’s no oil flowing to the filter or the oil-pressure-relief valve. The ICP, IPR, and FICM numbers appear to be OK as far as I can tell, per the values noted in the service manual. (ICP is zero when the engine is cranking, the IPR reads 86 percent, and the FICM is at 48 volts.) I haven't started any disassembly. I’m hoping you guys might know of something else I can check before breaking out the big tools and pulling off the cab to try and diagnose what’s wrong.
Bruce Milton
via the Internet
Photo 3/7   |   When there’s no oil pumping into the filter housing of a 6.0L Ford Power Stroke engine, a probable cause is the gerotor oil pump has taken a fatal hit from debris originating at a failed rocker. Most of these engines have high mileage that can make owners think twice about investing in a rebuild, so the cabs are pulled off, and the old engines are replaced with a complete long-block.
ANSWER: We’re afraid your stress regarding your Super Duty’s ailing 6.0L engine is justified. We reached out to several of our Six-Oh experts around the U.S. on this one and here’s what they say. Kenneth Tripp at Tripp Trucks in Rock Hill, South Carolina, says he has seen the crank-driven gerotor oil pump grenade on these engines and completely trash the front and pump covers. He has also witnessed the oil pump fail with less catastrophic results. Kenneth suggests pulling the oil pump for inspection. “The most common cause of an oil pump failure usually goes hand in hand with a camshaft failure of some sort. Most 6.0L engine replacements are caused by a failed lifter, usually when a roller breaks off a lifter, damaging the camshaft. At the same time, the roller’s needle bearings get picked up by the oil pump, damaging the pump and covers, and leaving the engine in a No Start condition.” Another potential cause for a failed oil pump is an injector’s upper-seal clip coming apart and its pieces getting sucked into the oil pump. When you inspect the oil pump and find it chewed up, look for evidence of foreign material (like the injector clip) that may have caused the failure. If you find imprints of small needle bearings, you know right away a roller rocker came apart and took out the camshaft and the oil pump. Anthony Youngblood from Super Duty Service in Grain Valley, Missouri, concurs: “Put a pencil magnet in the bottom of the oil-filter housing. If it gets covered with metal shavings, either roller lifters are letting go or the rotating assembly is failing somewhere. I have seen quite a few spun rod bushings in the small end cause this.” Anthony says if you need to run the truck for a “very short term,” pull the harmonic balancer and the low-pressure oil pump to clear the obstruction if the pump isn’t already destroyed. The consensus: These engines typically have higher mileage than most customers want to bother with rebuilding.
Photo 4/7   |   Top Tech My Six Oh Ford 6 0 Shop Mechanic

Numbers Not There

QUESTION: We put together a 24-valve 5.9L Cummins engine just like the one you guys did in the magazine in 2016 (“Big Three Blend”) with an Industrial Injection Diesel Performance PhatShaft 62/70 turbocharger, 120hp nozzles, a VP44 injection pump, and 200-gph lift pump. It’s not making the power we anticipated. It rolls some coal early, comes on strong for a few seconds, then feels like it just falls down as soon as she reaches about 2,700 rpm. The dyno numbers we got put it at 321 hp and 730 lb-ft of torque. We were expecting closer to 425 hp and 850 lb-ft. We’re hoping you can provide some suggestions to get us closer to our goal.
S. Ridgeway
via telephone
Photo 5/7   |   Getting early 24-valve 5.9L Cummins engines to make 450 hp is challenging, because the stock ECMs and VP44 injection pumps will not deliver the fuel volume, duration, and timing needed to create those numbers. A good workaround is using a custom tune and interface to bring out the increased power of aftermarket upgrades, such as bigger injectors and turbos that would otherwise be left on the table.
ANSWER: Making 450 hp with early 24-valve 5.9L Cummins engines can be a challenge because the second-generation Dodge Ram ECM needs a lot of programming to make the stock VP44 deliver the added fuel volume, duration, and timing needed to make that kind of power. (We know from firsthand experience!) That era of smog-friendlier engines was the first generation to merge electronics with mechanical fuel pumps to control fuel flow, and pre-programmed, off-the-shelf tuners do a good job overriding the stock ECM settings to make a 100 to 125 hp and 200 lb-ft of torque above the H.O. engine’s 245/505 numbers. However, to reach the 425 to 450hp range, you need more than a generic tune to tap into that extra power. That’s where someone who knows the intricacies of custom PC-based UDC (User Defined CaTCHER) software and the appropriate hardware to control the VP44 comes into play. There are many sources and options available through diesel-performance shops across the U.S. If you don’t want to go the “custom tunes” route, some diesel fuel-injection experts suggest replacing the stock VP44 pump with a remanufactured performance model that has internal upgrades that will help an early 24-valve produce an additional 80 to 100 hp. The downside of using a hopped-up VP44 is the added expense of the pump, along with the possibility of needing bigger injector lines. As a note, one of our inside tech sources tells us the typical refurbished stock VP44 should be able to handle 500 hp, as long as there’s a 150- or 200-gph lift pump behind it. And the setup still might need a custom tune. Spend the money on the electronics side first, as it is the best route to attaining your power goals.

Big Ask

QUESTION: My wife and I bought a ’17 GMC Sierra 2500HD, and we have our eye on a used 38-foot fifth-wheel trailer that weighs close to 14,000 pounds empty. From what I have read on some forums, the maximum load for our GMC is 18,500 pounds. Being this close to the towing limit, should I invest in airbags or will the truck still handle well? This will be our first big travel trailer and we want to make sure all is well before heading out for our trip from the Gulf up to Minnesota.
Ben Lomax
via email
Photo 6/7   |   Instead of maxing-out a ¾-ton single-rear-wheel pickup’s towing capacity by pulling a 14,000-plus-pound fifth-wheel/gooseneck trailer, look at the vehicle manufacturer’s “fleet” website to find the true tow ratings of different trucks, then choose a vehicle that has a capacity 2,000 to 3,000 pounds greater than the loaded trailer you want to tow.
ANSWER: Don’t believe everything you read on forums when it comes to towing and tow ratings. If you want the true tow ratings for any of the Big Three’s pickups, head to each company’s “fleet” website and search for the towing guide. GMC’s consumer site lists the maximum for the 2500HDs as being 18,100 pounds. That’s true. But what it doesn’t show is the tow rating applies to only one model: longbox two-wheel drive. The fleet website’s towing guide clearly lists towing limitations for all the makes and models. Your Duramax-powered Crew Cab 4x4, for example, tops out at 13,500 pounds for towing fifth-wheel/gooseneck trailers with a standard bed, and 12,400 pounds for the longbox model. There’s another weight that also needs to be added into the formula: Trailer cargo. The typical “wet” weight of an RV trailer the size you are talking about can easily add another 2,000 pounds in cargo and water to the “dry” weight. You should also pay close attention to the pin weight to make sure it doesn’t exceed the manufacturer’s limit. GM makes note of this in its GM Fleet Guide to Trailering & Towing: “Fifth-wheel or gooseneck kingpin weight should be 15% of total loaded trailer weight. The addition of trailer kingpin weight cannot cause vehicle to exceed Rear Gross Axle Weight Rating (RGAWR) or Gross Vehicle Weight Rating (GVWR). These ratings can be found on the certification label located on the driver door or doorframe.” Exceeding the manufacturer’s maximum tow ratings and pin weights creates serious safety and liability issues for the driver/owner of the vehicle. Our suggestion is to either find a trailer that fits within the towing limits of your new pickup or keep your eye on that monster RV and step up to a 3,500 longbed dualie, which is capable of towing it safely and efficiently with a 22,700-pound tow rating. As for helper springs, they are a great addition to any pickup that’s towing close to the maximum weight.

Power Comparison

QUESTION: The second 351ci engine in my ’84 Ford F-150 has finally given up the ghost after nearly 240,000 miles. I’m the original owner, and my baby has been garaged its whole life. Because everything except the engine has been redone, I’d like to convert to diesel this time around to get more towing power and better fuel economy than I’d get by rebuilding the 351 or dropping in a 460. I’m leaning toward the Cummins R2.8L or 5.9L. Which one would you recommend? How do they compare in power to the V-8s?
C. Walton
via the Internet
Photo 7/7   |   Top Tech Power Comparison
ANSWER: As you’ve probably researched, there’s an abundance of diesel-engine choices and conversion parts to make the gas-to-diesel swap fairly easy. The Cummins R2.8L crate engine is a superb transplant candidate for many different applications. The turnkey powerplant’s 161 hp and 267 lb-ft of torque are good for repowering Jeeps, small SUVs, and compact pickups such as Ford Rangers and Chevrolet S-10s. However, you will probably be underwhelmed by its performance in your 4,200-pound F-150. Yes, the 2.8L Cummins will get impressive fuel economy. But towing and off-roading power won’t be much better than that of the 4.9L I-6 that was your pickup’s base engine. In general, a vehicle’s performance related to pulling power and acceleration—all other factors being equal—can be measured by the horsepower-to-weight ratio and torque-to-weight ratios. Torque is the big deal, because that’s what gets weight moving through the power band until horsepower in the upper rpm takes over. The higher the TWR, the better the pulling power. Vehicle weight aside, you get a good idea of an engine’s efficiency in the same manner. Your F-150’s 5.8L gas engine has a HWR of about .40:1, and a TWR of .64:1. A 7.5L (460ci) big-block engine is close to a .38:1 HWR with a .62:1 TWR. The R2.8L Cummins comes in a lot lower than both at .32:1 and .53:1, respectively. The high-output 24-valve 5.9L Cummins, which would be our choice of the inline diesels, is nearly the same as the R2.8L with a HWR of .28:1 and TWR coming in at .53:1. Remember, diesel engines are nearly twice as heavy as gas V-8s. So dropping in a 5.9L, with some very minor power modifications, will have more pulling power and probably 30 to 40 percent better fuel economy than a 460. Here’s another consideration: Wait a while longer to see if Cummins adds the 5.0L diesel V-8 to its crate-engine program this year. We’ve heard rumors it may be coming. The 5.0L engine’s 310 hp and 555 lb-ft of torque give it a HWR of .39:1 and TWR of .69:1, better power ratios than the gas V-8’s while potentially delivering 20 to 25 mpg. We think those kinds of performance numbers make the 5.0L Cummins the perfect diesel for repowering any fullsize ½-ton pickup.

Runaway Frankenpump

QUESTION: I have a Toyota rockcrawler with a ’99 Volkswagen TDI 1.9L engine, and its original injection pump went south. I took out the head, plunger, and cam plate and put them in a pump from a 1.6L TDI that was on my used-parts shelf. After putting the “franken” TDI pump back on the engine, it started fine but instantly ran up to about 3,500 rpm with zero throttle control. Has anyone ever experienced this before? Are there any other modifications that need to be done to the pump internally that I might have missed besides swapping in the 1.9L parts?
Cecil Wilkes
via email
ANSWER: Bolting on a Land Rover Defender 2.5L pump and forgetting about building the hybrid is a better move, as it’s much easier, less costly, and overall a better-performing alternative. For the frankenpump you now have, if it’s spinning up uncontrollably, the most likely reasons are: 1) Orientation of the governor lever on the shaft isn’t correct; or 2) The maximum-fuel screw is adjusted too far in. Try removing the lever and turning it one notch counterclockwise in relation to the shaft. If that doesn’t bring back throttle control, then reverse the fuel screw two full turns.

Funky 47RE

QUESTION: I have recently rebuilt a 47RE four-speed automatic transmission in a ’99 Dodge 2500 pickup. I also modified the valvebody with a TransGo reprogram kit, installed an ATS Diesel Performance Five Star torque converter, and added a new governor-pressure solenoid kit and sensor. The rebuilt transmission has a good 1-2-3 shift, but the engine overrevs before it changes to Fourth gear, and then the converter immediately goes into lockup. With very little throttle pressure, the converter comes out of lockup at highway speeds (65 to 75 mph), and the transmission does a lot of searching at 45 to 47 mph before finding a gear. Could the overdrive solenoid and torque-converter-clutch solenoid be the problem? Or am I overlooking something?
Bill Ivey
via email
ANSWER:The best way to diagnose these problems is with a scanner while someone is driving your truck. Gary Haslip, owner of Geezer Garage (Coburg, Oregon), says to look out for: 1) TPS voltage. It should be around .7 V at idle +or- and get close to 4.0 V at wide-open throttle. The volts should increase smoothly with little variation and are best watched on the "scope" side of the scanner. 2) Always check the throttle-valve linkage and adjustment. With someone holding the throttle wide open, check the TV arm at the transmission. Normal adjustment is to have an additional 3/16-inch movement to "bottom out" the TV arm. 3) Testdrive the rig with scanner data showing only Desired and Actual governor pressure, output-speed sensor, current gear, TCC solenoid (On-Off), and Overdrive solenoid (On-Off). Both Desired and Actual governor pressures should match, starting at 0 psi and smoothly rising until around 45 mph, when Desired should jump to more than 100 psi. Actual will be less, but also still increasing. “Another item I pay close attention to is the brake position (Open or Closed),” Gary says. “A maladjusted brake switch can cause the TCC to go Off while driving, or cycle On-Off. A bad alternator or dirty battery cables will also cause TCC cycling.”



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