Pusher Intakes Compound Turbo Wrap-Up: How Did It Do On The Dyno?

All good things must come to an end, as they say. Working together with Pusher Intakes, Edge Products, BorgWarner, MAHLE, Exergy Performance, Valair, and other companies, we have finally put the finishing touches on this truck to give it a finale befitting a heavy-duty tow rig.

When we last checked in on the big red Dodge, owned by Rob Blanton of Warfighter Made, we talked about the steps for installing the Pusher system, turbochargers, and other components. Now, it’s time to settle in and see how the truck did when put onto the dyno and given the flogging it needs to gauge its performance. Without further ado, let’s dive in and see how it all turned out.

A Bump On The Way To Greatness

The truck was doing fine for a while after the installation of all of our components. Fueling, transmission shifts, boost, all parameters were reading normal. But it all it took was one bad dyno run for things to go haywire.

One thing to remember is that in all of this upgrading and outfitting, the Dodge was still running on its old stock turbo and intercooler, which up to that point had been performing okay, albeit showing its age. There were a few dyno runs that were not up to snuff as far as what we wanted, and that required talking back and forth with the tuner and dyno operators to nail down problem areas.

In one fateful dyno run, the truck's stock turbo let go, and we could tell from the gray smoke that we were in trouble.

At the back of our minds, we all had our inklings that it might be the turbo and intercooler to blame, but we didn’t want to admit defeat. We kept thinking it might be the tune, or something with the dyno procedure, that was causing the EGTs to be too high or the boost to be too low, or some such.

And then… it happened.

After nearly 250,000 miles of hard use and towing, the Holset turbo let go in the worst way possible. In a fraction of a second at extremely high RPM, the turbine wheel said “No more!” and detached from the shaft, starting a chain of unfortunate events.

The high-pressure exhaust pipe, having to contain a deadly spinning impeller blade, suffered some bumps and bruises as the tiny shuriken sped up and into the BorgWarner turbo. Here, it chipped the flange of the bigger turbo, and then went flying into its compressor wheel, shredding the fan blades. Then there was the oil, which was flung throughout the system and made its way into the intercooler, likely bringing metal particles along for the ride.

The main culprit was this impeller wheel from the stock turbo.

In short, a blink of an eye was all it took for the big red Dodge to come to a complete stop. Gray smoke billowed out of the back as the dyno wound down and we all knew something was wrong. The disassembly showed the extent of the damage done, and what all needed to be replaced; namely, the intercooler, its boots, and then both turbochargers.

That little wheel did a lot of damage once it came loose.

Fixing The Truck=Picking Up A Phone, Not A Wrench

Things were in a sorry state of affairs for a while. The truck had to sit for a few weeks while we spoke with our contacts in the aftermarket.

But before long, we had the solutions in hand. BorgWarner sent us a replacement turbo, and MAHLE took care of our stock turbo. We even reached out to Rock Auto and secured a replacement intercooler, along with a set of new boots.

The new replacement stock turbo from MAHLE was a must to get our truck back on track.

We chatted with MAHLE to learn more about their remanufactured turbo side of the business. “We match the OE quality, and whether they’re new or remanufactured, we offer the same warranty as well,” said MAHLE’s Kyle Sexton. “If there’s too much damage to the housing, it won’t get reused. But everything from the bearings, to the impeller, to the seals and so forth is all replaced and checked for integrity. We source our remans from directly from the companies that manufacture them for OEMs, be it Garrett, BorgWarner, Holset, and the rest.”

A new intercooler and set of boots from Rock Auto was essential, too.

Rock Auto, meanwhile, does not manufacture its own parts for sale, but its name is legendary among gearheads for the vast inventory of parts they sell for practically any make, model, and year one can think of. With service and dedication stretching almost 20 years, Rock Auto has made its mark on the automotive hobby and was indispensable in helping us get the big red Dodge back up and running.

Now We Can Pick Up A Wrench

We got to work right away with the parts, hoping to restore the Big Red Dodge to her former glory. We laid out the parts on the shop floor, made sure we had everything, and got to work.

One of the first steps was disassembly of the stock turbo. We had to take off the old oil drain tube and attach it to the replacement MAHLE turbocharger, and also force out the double-sided bolts to mount the turbo in the engine bay. We installed the turbo into place and then turned our attention to the intercooler.

The new MAHLE turbo was prepped and then installed in the engine bay.

The intercooler required taking out the A/C condenser, which mounts in front of the intercooler. Removing it entirely from the truck was not an option, as it would have caused a leak and led to more problems, so we were careful when setting it down. We decided to save ourselves a headache and installed the intercooler with the boots already attached, and lined everything up before securing the boots to the rest of the cooling system with hose clamps. Up top, the intake horn was decoupled and given a new boot as well before being reinstalled.

The second turbo, the BorgWarner SX400, was now up. We compared the clocking orientation of the old one against the new one and matched them up, and then tightened the V-band clamp. We applied anti-seize to the bolts and then completed the installation of the turbo. After attaching all of the lines and securing the intake tube and air filter, we were wrapped up. We started the engine and found no leaks or undue noises, and that was that.

The intercooler system was complete with new boots, and went in perfectly where the old one used to be.

Dyno Time

With new turbos and intercooler installed, the Cummins was ready to rock.

It was with no small amount of tension that we anticipated the next dyno session. After what happened last time, we were careful to make sure that everything went smoothly. It was bittersweet; the truck had no major malfunctions, but the results were not the best we could achieve. Rob, the truck owner, had made sure to put 500 miles on the truck to break in the turbos before doing any towing – it was his personal work truck, after all – so we knew we were good there. Nonetheless, we had to keep trying to get the power curve and drivetrain parameters (EGTs, fuel rail pressure, etc.) in line with what the system could achieve in optimum settings.

What followed was several weeks of dynoing and re-dynoing the truck, with much discussion over dynoing methodology, tuning options and troubleshooting, and time passing. We finally made the decision to have Dynojet drop by to do a calibration and check-up on the dyno, and got their blessing to try the truck out. We strapped the big red dually down for what we hoped would be its final pass.

As it turned out, everything went smoothly. And what of the results?

Below, you’ll see what we made on the dyno while using the Race tune. Compared with what we were making before all of this started, it was a stark contrast and massive improvement. You can see the difference we achieved with the before-modification dyno graph (on a stock tune, of course).

Some salient tidbits from the graph present themselves right away. For starters, the powerband starts higher at 1,500 rpm; an increase of over 20 horsepower, from 80 to 100. From there, the curve does a steady uptick to about 2,100 rpm, where it shows the ever-irritating dip that we could never figure out.

It finally reaches peak power at around 3,100 rpm, where we saw a maximum of 616.83hp and 1,044.13 lb-ft of torque; this blew the old performance numbers out of the water, at a mere 234.72hp and 425.48 lb-ft of torque. Put into percentage figures, our fully upgraded Cummins was making 263 percent more horsepower and 245 percent more torque. With more than a twofold increase in power, factoring all of the upgrades we did – new turbos, new injectors, new clutch, new CP3, a lift pump, and more – this was a magnificent boost to the Cummins’ performance.

From the outside, the truck looks no different than it did at the beginning. But deep within beats the compound-turbo, 1,000-lb-ft-of-torque heart of a reinvigorated workhorse!

It was also during this pull that we did a data log to try and suss out what the engine was undergoing during that high-demand situation. As it turned out, it was going through a lot. We saw the EGTs reach a high of 1,456º F, which, although dangerous for extended periods of driving, was perfectly acceptable for an engine that we made run on its absolute highest level for a dyno pull. The truck would be running on a Tow or Stock tune most of the time, anyway, and Rob would have his trusty CTS2 to keep him apprised of the engine’s goings-on no matter what.

We’re very pleased with how the Pusher compound turbo system came together on this project and helped out a veteran making a difference in his fellow soldiers’ lives. To date, Rob has gotten a great deal of use out of his rig, and makes the most out of those turbochargers wherever he goes. We would like to thank Pusher Intakes and Pela Motorsports for their cornerstone involvement in this project, as well as the support we received from Edge Products, Exergy Performance, Valair, FASS Fuel Systems, BorgWarner, MAHLE, Rock Auto, and ARP.

Article Sources

About the author

David Chick

David Chick comes to us ready for adventure. With passions that span clean and fast Corvettes all the way to down and dirty off-road vehicles (just ask him about his dream Jurassic Park Explorer), David's eclectic tastes lend well to his multiple automotive writing passions.
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