High Tech Turbo’s Airflow For Tow Cummins Package

The 2003-2007 5.9L Cummins became known as a true workhorse in the light duty truck market. While Dodge/Ram has moved on to the larger 6.7L powerplant, it doesn’t mean the common rail 5.9L 6BT can’t continue to get the job done dragging heavy loads. In fact, the 2003-07 Cummins is still one of the most popular trucks out there when it comes time to tow that heavy equipment from one jobsite to another.

Third gen Dodges with the common rail 5.9L represent much improved and refined vehicles all the way around. They sport improved interiors, full four-door cabs and of course the switch from the VP-44 injection pump to the more reliable CP3 common rail injection system. Dodge also made changes to the turbo system in 2003 by switching from the somewhat outdated Holset HX35 technology to the HE351 turbocharger family, which offered tighter turbine sections to help with emissions and low-end response.

While the HE351 turbocharger does work quite well in factory form, once free-flowing exhaust systems, cold air intakes and performance tuners are added to the mix, the factory HE351CW starts to show its shortcomings rather quickly. While the chosen turbine wheel and turbine housing allow for quick spool-up, exhaust back pressure can get much higher than Cummins intended once more fuel is added through performance ECM programming.

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Extreme drive pressures not only hurt overall performance, but can negatively affect exhaust gas temperatures, causing the engine to run much hotter than known safe limits, which forces owners to back out of throttle and stare at a pyrometer gauge over every mountain pass. These extreme EGTs can lead to premature parts failure, like warped and cracked exhaust manifolds or even to go as far as melting the aluminum pistons, which means a complete engine overhaul could be needed.

Airflow for Tow Package

To help overcome some of these known issues in the turbocharger system on mildly modified 5.9L CR trucks, High Tech Turbo of Salt Lake City, Utah, developed their Airflow For Tow package, which includes a replacement high-flow intercooler, stainless steel exhaust manifold and 64mm Stage 2.5 HE351CW turbocharger. The system is based on the fact that to combat high EGTs and exhaust back pressure in the Cummins engine, less restriction is needed on both the intake and exhaust side to improve the system’s efficiency. For guys already running a free-flow performance exhaust system, cold air intake and performance tuner, but not looking to get into additional fueling changes like CP3 pump upgrades and larger injectors, the Airflow For Tow package could be just the answer to allow full use of the power already on hand without belching heavy black smoke or running nuclear EGTs.

HT TURBO Intercooler

The HT Turbo intercooler system uses a much thicker and taller core when compared to the stock piece and is built to fit all Ram truck models from 2003 to 2009. Using thick cast-aluminum end tanks, the robust cooler is pressure tested to 100 psi and bolts directly in place of the factory cooler in less than 45 minutes with basic hand tools. HT Turbo says they recommend a performance intercooler to reduce restriction in the charge air system for just about any application, but especially those running larger than 64mm turbochargers. Even if EGT isn’t an issue, the restriction of airflow through the factory core with those high-flowing turbochargers can really hinder the engine’s ability to perform as it should. Certain model years were equipped with plastic end tank intercoolers, which are prone to failure from boost pressure and extreme duty use; all the more reason to look into a performance replacement like the polished unit supplied in the Airflow For Tow package.

Exhaust Manifold

On the exhaust side of the engine, the factory cast iron exhaust manifold is extremely prone to warping and cracking under the extreme temperature changes it undergoes, mile after mile. While it may not be something you can plainly see with it bolted on the engine, should you ever have reason to remove the manifold, in most cases once it’s laying on a flat surface with no bolts holding it tightly, they’ll start to show their warpage, which will become an even more frustrating part when it comes time to reinstall it and get all the mounting holes to line back up with the cylinder head.
HT Turbo has been casting their own line of stainless steel exhaust manifold for both the second and third generation trucks for quite a few years now and includes their T3 3rd Gen manifold as part of this kit. While still being a one-piece manifold like the factory manifold, the stainless material it’s cast from is much more durable and resistant to warping and cracking, holding up much better to the hot exhaust gases that continually flow through it. The HT Turbo manifold kit will also include new gaskets for both the cylinder head mating surfaces and the turbo charger exhaust inlet.

HT TURBO Modified Turbo

The true heart to the airflow package lies within their massaged stock turbo that comes outfitted with a larger 64mm compressor wheel and upgraded 10-blade turbine wheel. Using factory turbochargers that are completely torn down, cleaned and rebuilt with OEM repair kits, technicians at HT Turbo machine out the factory compressor cover and turbine housing to accept the larger wheels, which helps to increase air being fed to the 5.9L engine and expelled out the exhaust side.

1 The new Airflow For Tow package from High Tech Turbo is built and marketed towards the 2003-2007 5.9L Cummins crowd already running basic bolt-on parts like a tuner, intake and exhaust. The package looks at eliminating known restrictions in the turbo system with their performance stainless steel exhaust manifold, cast end tank intercooler and new Stage 2.5 64mm HE351CW turbocharger.

2 Based off the factory HE351CW turbocharger, HT Turbo’s new Stage 2.5 comes equipped with a larger high-flowing cast 64mm compressor wheel mated to a 10-blade high-flow larger that stock turbine wheel. This combination of wheels offers what they say is the ultimate in HE351 performance for the stock injector and stock CP3 common rail Cummins market when it comes to complete drop-in replacements.

3 HT Turbo has been casting their line of stainless steel exhaust manifolds for some time now. Cast as a one-piece unit, the stainless material can withstand much higher temperatures and resist the cracking and warping that stock manifolds are known for. Since the turbo swap is done easiest by removing the turbo and manifold as an assembly, this is the perfect time to upgrade both.

The compressor-side upgrade pulls quite a bit more air from the intake system and compresses it before feeding it through the intercooler to the intake manifold and cylinders. The additional airflow helps to burn the extra fuel being commanded by the performance tuner, which helps efficiency, power and EGT. Once that fuel and air have been combusted inside the cylinder, the exhaust flows through the new stainless steel exhaust manifold and through the upgraded turbine section of the HE351 turbo. By using a larger-than-stock turbine wheel with a smaller fin count, a major restriction is removed from the exhaust side of the turbo, helping reduce back pressure which also helps with the engine’s efficiency, power and EGT. The unique turbine wheel profile, while helping to reduce back pressure, still spools close to stock, so there should be no fear of additional lag time or a lazy low end, which makes this the perfect option for a daily driver and towing application.

Installation and Testing

With a bed full of parts ready to be installed, the test vehicle was taken to Edge Products in Ogden, Utah, to be tested on their in-house chassis dyno. HT Turbo wanted to have hard data to prove the performance and EGT reduction potential from this package, and by making back to back to back dyno runs after the installation of each individual part, we’d have the numbers to back their claims of better power with lower EGTs. Along with the Airflow For Tow parts being installed, the 2005 Ram would also be outfitted with an Edge Evolution CTS tuner to make sure the engine could take full advantage of the increased airflow by adding the needed fueling and timing through enhanced ECM calibrations of the tuner.

TEST VEHICLE:

Our test vehicle was a 2005 Dodge Ram 2500 5.9L CR Cummins with 4-inch turbo back MBRP exhaust, Airaid intake, AirDog fuel lift pump, RKL Diesel 48RE auto transmission, 285/75/R17 Hankook ATM tires, and 3.73 gears.

4 In certain model year trucks, Dodge actually equipped the 5.9L Cummins with a plastic end tank intercooler, which is prone to cracking and leaking, especially in heavily used or high-boost applications. HT Turbo offers a direct-fit intercooler for the 2003-09 Cummins that not only uses much sturdier polished cast end tanks, but a much more efficient and thicker core for better charge air temperature control, which equates to better power and cooler EGTs.

5 While upgraded intercooler boots and clamps are an option with all HT Turbo intercoolers, in a stock application such as this, the original boots can be reused, assuming they’re still in good condition and haven’t been subjected to extreme heat or excessive oil residue which can cause them to crack or swell, leading to unwanted boost leaks.

6 The intercooler installation really couldn’t be simpler and can be completed in well less than an hour with just basic hand tools. Loosening the intercooler boots, removing the A/C condenser and swinging it aside, then just removing the upper mounting bolts attaching the intercooler to the core support is all there is to it.

7 With the stock cooler out of the truck and sitting on the floor placed next to the HT Turbo cooler. you can clearly see the difference in both core thickness and height. The larger core is much more efficient at passing large amounts of air from one side to the other while maximizing that air’s temperature loss before entering the intake manifold and cylinder head. At this point, you’ll need to transfer the factory mounting bushings from the stock piece to the HT Turbo cooler before final installation.

8 With the polished HT unit slid down into the factory location, the original mounting bolts can be installed at the core support and the factory intercooler tubes reinstalled and clamps tightened. The new core is supplied with four new mounting bolts for the A/C condenser, which may need to have the mounting brackets repositioned depending on model year. These brackets are attached to the A/C condenser with small Torx bit-style bolts, and have multiple mounting holes along the condenser. On our 2005 test truck, the lower brackets needed to be repositioned one hole higher to fit the new HT Turbo cooler. We should also note that with our truck, the taller intercooler caused an interference problem with the bumper mounting bolts that just required us to flip them around. Basically requiring us to put the heads of those bumper bolts on the inside of the frame rails versus the outsides (a simple five-minute fix).

Wanting to get the most realistic before and after power and EGT numbers, it was decided that the complete install could be done while still strapped to the chassis dyno at the Edge Products headquarters. With the intercooler being a simple 30-minute install and the turbo/manifold swap only taking about two hours, the complete job including, time for pictures and dyno runs, only took the better part of an afternoon.

Baseline Numbers

To get good baseline numbers, the 2005 Dodge made three consecutive runs with the stock programming, stock intercooler and stock turbo system before any parts were added. The test vehicle was already equipped with an Airaid intake, MBRP turbo back exhaust, AirDog fuel lift pump and a built transmission with triple-disc torque converter. With a large industrial-sized fan blowing air onto the front of the truck, after averaging the three baseline runs together, power numbers came out to 320 hp and 601 lb/ft of torque to the rear tires, with peak EGTs averaging 1,333 degrees. Again, this is with the factory Dodge programming, no tuner installed.

9 While the factory HE351CW turbocharger works okay in a mildly modified application, EGTs while towing and drive pressures at higher boost levels can get a little out of hand. The factory exhaust manifold is also prone to warping and cracking due to the extreme temperature fluctuations they’re constantly going through. The modified stock HT Turbo Stage 2.5 and stainless steel manifold can help improve durability, while giving you a more usable power band while towing by dropping your EGTs and allowing you to use the power you already have without having to let out of the throttle on those long grades.

10 While a little more complicated than the intercooler install, removing the factory turbocharger can be done in just a matter of hours. The tech doing the work on this test truck prefers to pull the turbo and manifold as an assembly. You’ll need to remove all the turbo connections, which include the air intake, intercooler charge pipe, exhaust downpipe, oil feed line, oil drain line, and wastegate control harness. With those pieces disconnected or removed, you can then remove the exhaust manifold bolts and studs, and lift the system up and out of the engine bay.

Intercooler Results

With the baseline runs completed, the new High Tech Turbo high-flow cast intercooler core was installed in place of the factory unit. Running the stock ECM tuning again, three more dyno runs were made with the numbers averaged together for final results. At 322 hp and 598 lb/ft of torque, power numbers stayed pretty consistent with the baseline runs, which we had predicted. The intriguing part was that exhaust gas temperatures did show a significant drop peaking at just 1,283 degrees. With a solid 50-degree drop with no change in tuning or boost pressure, this data helped prove the larger than stock cooler can be quite effective, even in a bone-stock application.

Edge Evolution Level 1

The next part of our testing was to install and download the Level 1 Tow program from the Edge Evolution CTS tuner into the ECM to see what improvement could be had with some mild fueling, timing, and engine calibration changes. Edge markets this tune as a 55-hp tune safe for heavy towing. Once the download had completed we again made three consecutive runs, which averaged out to 390 hp and 768 lb/ft of torque, a gain of 68 rear-wheel horsepower and 170 lb/ft of torque. Like our intercooler results, we were once again completely baffled by our peak EGT results, which actually dropped from the stock ECM runs more than 100 degrees to just a peak of 1,170 degrees on the pyrometer gauge. Normal thinking would leave you to believe that with more power, the additional fuel being injected would cause EGTs to rise, but this shows that with the right programming changes, you can actually see safe usable power increases. More power and less EGT while towing sounds like a win-win situation to us.

11 Since the new Stage 2.5 is nothing more than a rebuilt and upgraded stock turbo, you’ll be reusing the factory oil feed and drain lines. With the stock turbo on the bench, you can remove these pieces. A new drain tube gasket and oil feed-fitting O-ring is supplied with the High Tech Turbo. You’ll also need to transfer the large exhaust outlet elbow from the factory turbo to the new piece. Don’t worry, there’s a small dowel pin to locate this elbow in the correct orientation on the new turbo when you install it.

12 Since the HT Turbo stainless exhaust manifold is cast as a universal piece to fit any 2003-07 Cummins and T3-style turbocharger, when being used in conjunction with a stock or modified stock HE351 turbocharger, the turbine housing will need to have the two threaded holes drilled out. The new High Tech Turbo manifold is tapped to accept mounting studs, so you’ll have no way to tighten a bolt into both the threaded manifold and its mated turbine housing. By drilling out the two threaded holes on the turbo’s exhaust housing, it can be easily slid off the manifold mount studs and snugged down.

Turbo and Manifold

The fourth part to our installation and data-collection process was the installation of the new 64mm Stage 2.5 HE351CW turbocharger and stainless steel exhaust manifold. Since High Tech Turbo markets these parts as “the complete towing performance package,” we opted to leave our Evolution tuner in the Level 1 Tow file. By doing this we could better compare power and EGT differences to those produced by the stock turbocharger in the truck’s current configuration. The install took just a matter of an hour or two and was a complete bolt-in replacement with no modifications to the truck or engine bay required. The factory exhaust downpipe, intercooler plumbing and existing intake system mounted right up.

Once getting the truck back up and running and driving on the dyno rollers for a few minutes to check for oil and exhaust leaks and get the engine back up to operating temperatures, three full dyno pulls were made. Again, taking the average of all three runs to account for heat soak and any variations, horsepower and torque numbers jumped yet again, even without adding additional fuel and tuning. Jumping from the previous 390 hp to 405 hp with torque coming up to 785 lb/ft, the new turbo and manifold combination showed a modest 15 hp and 17 lb/ft torque improvement Best of all, the power band and torque curve followed right along with the stock curves, telling us that low-end spool-up remained virtually the same, so the fear of additional turbo lag while towing shouldn’t be an issue.

13 Once drilling out the turbocharger’s threaded turbine holes, it can be installed onto the stainless one-piece manifold. A new gasket is supplied with the manifold to seal the mating surface to prevent any exhaust leaks once the truck is back up and running. The manifold will also include all new gaskets to be placed between its six inlet ports and the cylinder head.

14 Here you can see the new turbine wheel profile High Tech Turbo uses in the Stage 2.5 to improve exhaust flow and help expel spent exhaust gases and lower drive pressures under hard load. The larger than stock wheel can not only move more exhaust compared to the stock turbine wheel, but its 10-blade design removes some of the restriction, helping lower exhaust gas temperatures and back pressure without sacrificing low-end response and spool-up.

15 The passenger side of our 5.9L Cummins engine looks rather lonely and bare without the manifold and turbocharger hanging off of it. Luckily, the new HT Turbo pieces will bolt right back into place just like the OEM pieces would. The new exhaust manifold will reuse most of the original mounting hardware; just don’t forget to install the gaskets between it and the cylinder head.

16 After dropping the complete turbo/manifold assembly back into place, we just need to reinstall the manifold bolts and hook up all the factory lines and hoses. Be sure to follow the instructions for proper torque specs on the manifold bolts, which will require a second “retorque” once the engine has been run through a couple of hot cycles.

While power improvements are always nice to see, with a package like this engineered specifically for towing, it’s the usable power we like to see and this usually equates to how controllable the EGTs are. With a peak of just 1,069 degrees in the Tow program, EGTs are down another 100+ degrees, which means the system now runs more than 250 degrees cooler than stock, all while producing 85 additional horsepower.

Edge Evolution Level 4

While the installation of all our test products had been completed, the true motorhead and horsepower junkie within all of us came shining through as it was decided some dyno runs in Edge’s most extreme tune on the Evolution were in order. Boost pressures had been limited to 32 psi with the use of the turbocharger’s wastegate controlled electronically with the Edge programming in the Tow file runs. In the Extreme file, the more aggressive fueling curves and timing tables allow for more boost pressure to be run through the engine, peaking at 38 psi on all three dyno passes.

When the first dyno pass showed 549 hp and 1,186 lb/ft of torque, it was thought there was a glitch with the dyno or computer system, as those are extremely strong numbers for a stock injector and stock CP3 truck, especially with a stock frame-sized turbocharger still equipped. The two follow-up runs, however, showed a consistent 550 hp and 548 hp, proving the first run was no fluke. Just as a side note, EGTs in the Extreme file peaked at 1,428 degrees, which is starting to get on the warm side of things, but is only 100 degrees hotter than the original base runs were (1,333 degrees) in pure stock form. That’s 230 additional horsepower and 577 additional lb/ft of torque with less than a 100-degree increase in exhaust gas temperatures.

17 Our 2005 Cummins had already been equipped with a high-flow 4-inch MBRP exhaust, Airaid intake and AirDog lift pump, and had just recently undergone a complete transmission overhaul, so with the new HT Turbo pieces installed and an Edge Evolution CTS tuner, the Airflow For Tow package could really be pushed to its limits on the chassis dyno and out on the street.

18 On the chassis dyno at Edge Products of Ogden, Utah, running the Evolution CTS Level 1 Tow file, the new HT Turbo package really showed its true potential for a towing application. At more than 400 rear wheel horsepower and just a peak of 1,056 degrees of EGT, this combination of parts should be more than enough to keep just about any load moving down the highway without worry of melted pistons and downshifting gears over long, steep grades. The broad power and torque curves show the system’s quick low-end response and strong top-end pull.

19 Bumping things up to the Edge Evolutions Extreme program, we were able to find the limits of the factory injectors and CP3 injection pump system. With the 64mm Stage 2.5 turbocharger pushing air through the high-flow intercooler, power output jumped to an impressive 550 hp and 1,177 lb/ft of torque. That’s more than a 250-hp improvement while only running 100 degrees hotter than the stock system ran with the factory ECM tuning.

In the end, with 400 rear-wheel horsepower on tap in a Tow file, with ultra-cool EGTs and next to no smoke out the tailpipe, the HT Turbo Airflow For Tow package can turn just about any mildly modified 2003-07 Cummins into the ultimate tow rig. With just a few hours of wrench time, the addition of the Airflow For Tow package and Edge Evolution CTS Tow tune resulted in an additional 85 rear wheel horsepower and more than a 250-degree drop in EGTs.

While the data we collected was just taken on a chassis dyno, later testing on the street has backed up its real world driving characteristics with quick low-end spool-up and a strong, broad power band. Depending on the particular Evolution program chosen, the truck can have extremely drivable and tame commuting to and from work characteristics, while still having more than enough grunt to break tires loose on command and put that arrogant late model Camaro or Mustang owner way back in your rear view mirror. DW

SOURCES

High Tech Turbo
801-304-0700
www.ht turbourbo.com

Edge Products
888-360-3343
www.edgeproducts.com

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Pinaki Bhattacharya

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