When we’re in the market to upgrade turbochargers, we’re usually trying to solve a problem (EGT) or add performance (horsepower), yet still maintain good driveability (spool up). As many of you know, and for diesel newcomers who will soon find out, it doesn’t take long for fueling upgrades to overwhelm the factory turbocharger—on any of the Big Three’s diesel trucks. “Whether through programming that increases injector duration (on time), larger injectors, or both, the limitations of the factory turbocharger quickly surface,” says Nick Priegnitz, founder and owner of Calibrated Power Solutions. “The engine runs out of air as EGT and air intake temperatures rise, along with smoke. Initially, this negatively affects usability and versatility of your truck. Your turbo and even the engine itself could fail.”
For these reasons, Priegnitz designed and implemented a one-of-a-kind turbo test for truck owners entering the diesel performance aftermarket to replace their stock turbo. “We know there’s plenty of ambiguity in the buying process,” he says. “These tests cut through that and give buyers hard data to support their decision.” An ’07 Dodge Ram 2500 was used as the test truck, selected due to the wide variety of aftermarket parts available for the 5.9L common-rail Cummins. The tests focused on turbo lag time (spool up test), towing utility (EGT control with a simulated trailer), and peak power (maximum rear-wheel horsepower). All turbos were of fixed-geometry designs and ranged in size from 57 mm to 63 mm. Calibrated Power Solutions performed all testing on its state-of-the-art Mustang load cell chassis dyno, under controlled dyno cell operating conditions. The only changing variable was the truck’s turbocharger. As the parent company of Cummins-Tuner.com, CPS took the truck’s modifications into account when writing towing calibrations (for the spool and tow tests) as well as a performance calibration (for the peak power test) using EFILive software. No changes were made to either calibration once testing was underway to ensure the turbo was the only alteration to the truck’s configuration. The appropriate tune was simply uploaded to the truck’s ECU prior to each test.
What you are about to read are excerpts from the most comprehensive turbo test we’ve ever seen, and the complete report is available as a downloadable document at Cummins-Tuner.com. Throughout the process, three weeks of the company’s manpower was utilized, more than 40 gallons of fuel was consumed on the dyno, and, most importantly, the crew remained objective in their efforts to collect the following information.
The Test Mule
Year/Make/Model: 2007 Dodge 2500
Odometer: 160,000 miles
Engine: 5.9L I-6 common-rail Cummins
Transmission: 48RE four-speed automatic
Engine Modifications: A1 Technologies head studs, O-ringed cylinder head, 110-pound valvesprings, Scheid Diesel coolant bypass, S&B air intake and intake elbow, 5-inch stainless exhaust
Fuel Modifications: Exergy Engineering 45-percent-over (and 100-percent-over) nozzles, Exergy Engineering 12mm CP3, FASS 150-gph lift pump
Transmission Modifications: Goerend upgraded valvebody, Midwest Racing Converter triple-disc torque converter, torque converter manual lockup switch
Electronics: Engine and transmission tuning via SPADE programmer from Cummins-Tuner.com, Edge CTS monitor with 100-psi boost and drive pressure pickups, and expandable EGT probe
| 2007 Dodge Ram 2500 On Dyno
Obtaining the Turbos
In order to keep the test as real-world as possible, a member of Calibrated Power Solutions’ test team (posing as a consumer) called each turbo manufacturer anonymously. First, he specified that he owned an ’07 5.9L Cummins with a built transmission, custom tuning, and a fuel system. Then the turbo criterion was established: He’d like a direct bolt-in turbo that costs less than $2,000, can make a little more power yet won’t be too laggy, and can keep EGT down when towing. After each manufacturer made a recommendation it was recorded, and the next day each manufacturer was contacted and formally asked if they’d like to participate in this test. The catch was that they could only submit the turbo they recommended to the “potential” buyer the day before. All parties contacted agreed to participate. Read on for an up-close-and-personal look at each turbo involved in the test, including the stock unit, which we pitted against all five aftermarket turbos.
| 2007 5 9l Cummins
Meet The Turbos (priced low to high)
Holset HE351CW (Stock)
Manufacturer: Holset
Price: $1,000
Sizing Specs: 58/58/.65
Turbine Housing Inlet Flange: T3
Wastegate: Internal
Description: All we can say about the HE351CW is that it works great at stock power levels, which is the power level it was designed to perform at. So from that standpoint, it’s a success. However, once more fueling is brought into the equation (disrupting the perfect fuel-to-air ratio the truck left the factory with), its small size begins to limit the performance potential of the engine, EGT can become worrisome, and the turbocharger’s long-term durability becomes questionable. While low-rpm performance is strong, the engine simply runs out of steam up top.
| Holset He351cw Turbo
Aurora 3000
Manufacturer: ATS Diesel
Price: $1,568 (downpipe included)
Sizing Specs: 57/64/.85
Turbine Housing Inlet Flange: T3 divided
Wastegate: N/A
Ease of Install: 4.5 of 5
Description: ATS Diesel’s tried-and-true Aurora 3000 has been on the market for years and performs well in Dodge, Chevy, and Ford applications. Its lack of a wastegate made it a cinch to install, and this aspect also helps keep the overall cost of the unit down. With a 57mm inducer, the Aurora 3000 features the smallest compressor wheel of any turbo in the test (including the factory unit). But while we suspected it would sacrifice some peak power when compared to the other turbos, we expected it to perform well in the spool up and tow tests.
| Aurora 3000 Turbo
Killer B
Manufacturer: BD Diesel Performance
Price: $1,638 (downpipe included)
Sizing Specs: 61.5/64/.80
Turbine Housing Inlet Flange: T3 divided
Wastegate: Internal
Ease of install: 3 of 5
Description: The Killer B turbo from BD Diesel has found a comfortable home in the ’03 to ’07 5.9L aftermarket. Based off BorgWarner’s popular S300-framed turbocharger, it offers good bang for the buck, a 360-degree thrust bearing for durability, and has been used in countless builds thanks to its ability to spool quick and support more than 600 rwhp. The Killer B’s one drawback was its large, diaphragm-style wastegate, which requires removal and reinstallation of the factory exhaust manifold in order to install it.
| Bd Diesel Killer B Turbo
Holset Cheetah
Manufacturer: Fleece Performance
Price: $1,847
Sizing Specs: 63/64/.65
Turbine Housing Inlet Flange: T3
Wastegate: Internal
Ease of install: 5 of 5
Description: Breaking the S300-based mold, Fleece Performance sent us something truly unique: the Holset Cheetah. This turbo begins life as a factory Holset HE351CW (the stock unit found on ’04½ to ’07 Dodge Rams), which Fleece performs the appropriate machine work on and fits with an oversized compressor and turbine wheel, before mounting its own wastegate actuator (which measures 3 mm larger than stock). It was designed to handle up to 650 rwhp and live at 45 psi of boost. Based on the factory turbo, this unit is as bolt-on as it gets.
| Holset Cheetah Turbo
Silver Bullet 62
Manufacturer: Industrial Injection
Price: $1,941
Sizing Specs: 60/73/.80
Turbine Housing Inlet Flange: T3 divided
Wastegate: Internal
Ease of install: 3 of 5
Description: Industrial Injection’s Silver Bullet 62 is an extremely popular turbo in the 5.9L segment. It was designed to handle multiple fueling upgrades and uses a relatively large turbine wheel to improve low-rpm efficiency, eliminate compressor wheel surge, and cool EGT considerably. Based on the S300 platform, the Silver Bullet 62 comes with a 360-degree thrust bearing for optimum durability, a polished compressor housing for cosmetic appeal, and the common 14cm turbine housing. Like the Killer B, however, its diaphragm-style wastegate required removal and reinstallation of the exhaust manifold during the install.
| Silver Bullet 62 Turbo
E.D. 63mm Billet S300
Manufacturer: Engineered Diesel
Price: $1,950
Sizing Specs: 63/67.5/.80
Turbine Housing Inlet Flange: T3 divided
Wastegate: Internal
Ease of install: 4.5 of 5
Description: Engineered Diesel builds custom turbochargers for mega-horsepower sled pullers and drag racers, so while the 63mm unit it submitted was the largest turbo in our test, it’s one of the smallest units it builds. The E.D. unit was also the most expensive turbo tested. Once again based on the proven BorgWarner S300, it features a billet-aluminum, six-blade, 63mm compressor wheel, and a 10-blade turbine wheel with a 67.5mm exducer. Its conventional (and simple) wastegate actuator made clearance issues a nonissue during install, and it bolted right up to the factory exhaust manifold.
| E D 63mm Billet S300 Turbo
Physical Dimension Comparison
(ascending compressor sizes)
Turbo:
Compressor inducer/exducer
Compressor blades
Turbine exducer/inducer
Turbine blades
Turbine housing
ATS Aurora 3000
57mm/83.5mm
7
64mm/73.5mm
11
.85 A/R
Stock HE351CW
58mm/85mm
7
58mm/65mm
12
.65 A/R
Industrial SB62
60mm/87.5mm
7
73mm/79.5mm
10
.80 A/R
BD Killer B
51.5mm/91mm
7
64mm/73.5mm
11
.80 A/R
Fleece Cheetah
63mm/91mm
7
64mm/73.5mm
11
.65 A/R
E.D. 63mm Billet S300
63mm/91.5mm
6
67.5mm/76mm
10
.80 A/R
Spool Up Test
A turbocharger’s driveability always boils down to how quick it can spool. For this reason, the spool up test was created. It’s designed to measure how quickly the truck can deliver the desired rear-wheel horsepower once the accelerator is depressed. The dynamometer’s dynamic load cell control was used to hold the engine at a constant rpm to accomplish this. Originally, the test was run at 1,700 rpm, with the time it took to go from 30 rwhp to 250 rwhp being recorded. However, only the Holset Cheetah, Aurora 3000, and the stock HE351CW were able to complete the test (the Killer B, Silver Bullet 62, and E.D. 63mm Billet S300 weren’t able to pull through the dyno load at this engine speed). So, a second spool up test was developed in order to accommodate each turbocharger involved in the test. Because of this, both target rpm and starting and ending horsepower goals had to be raised. The second test was run at 2,000 rpm, and the amount of time it took the truck to go from 60 rwhp to 300 rwhp was recorded. Each test was performed five times, consecutively, with the final three attempts being recorded and averaged for comparison.
| Bosst Gauge
In the 2,000-rpm data chart, you can see a wide variety in spool up time between the turbochargers. The top aftermarket performer was the Holset Cheetah, with the Aurora 3000 a close second. On the other hand, the Silver Bullet 62 and the E.D. 63mm Billet S300 both showed the downside of their larger turbine wheels, taking more than twice as long to spool as stock. There is clearly a correlation between the size of the turbine wheel and the spool up interval. All else being equal, a larger turbine simply takes longer to respond to throttle input, which can lead to extra smoke out the tailpipe while under the charger (pre-spool up) and general unresponsiveness.
| Once each turbo was installed, the entire system was pressurized to 30 psi to ensure there were no performance-hindering boost leaks.
Broadly speaking, spool up will suffer any time you install a larger, fixed-geometry turbo. This is evident in the stock turbo’s ability to spool much quicker than the fastest spooling aftermarket charger tested.
Spool Up Test 1:
1,700 rpm, 30 rwhp to 250 rwhp Cummins-Tuner.com Light Tow tune and 45-percent-over-stock Exergy injectors
Turbo:
Spool up time:
Stock HE351CW
2.142 seconds
Holset Cheetah
3.596 seconds
Aurora 3000
3.810 seconds
Killer B
N/A
E.D. 63mm Billet S300
N/A
Silver Bullet 62
N/A
N/A = turbo would not spool at 1,700 rpm
Spool Up Test 2
2,000 rpm, 60 rwhp to 300 rwhpCummins-Tuner.com Light Tow tune and 45-percent-over-stock Exergy injectors
Turbo:
Spool up time:
Stock HE351CW*
0.839 seconds
Holset Cheetah*
1.426 seconds
Aurora 3000
1.493 seconds
Killer B
1.552 seconds
E.D. 63mm Billet S300
1.808 seconds
Silver Bullet 62
2.056 seconds
*Due to time constraints, the Holset Cheetah and factory HE351CW were not physically tested in the 2,000-rpm spool up test. Their comparison data for the 2,000-rpm spool up test is an estimate calculated by normalizing the data to the ATS turbo, which was run in both the 1,700-rpm and 2,000-rpm test.
Tow Test
To find out how well each turbo could control EGT across a wide range of engine speeds, a grueling towing scenario was simulated. This was done by measuring the truck’s maximum achievable horsepower output while staying at a predetermined limit of 1,200 degrees. After each test’s target engine speed was achieved, the dyno’s dynamic load cell braking was applied to hold rpm steady, and the accelerator was depressed until EGT stabilized at 1,200. Test speeds included 1,400, 1,700, 2,000, 2,300, 2,600, and 3,000 rpm for each turbo. Between each constant rpm test, the truck’s coolant temp was allowed to cool back down to 185 degrees to avoid cooling fan engagement (which can rob as much as 20 to 30 hp), and ambient air in the dyno cell was allowed to return to the temperature the test started at. Each test was concluded before coolant temp reached 205 degrees. This test was akin to towing a 15,000-pound trailer up a 4 percent grade.
| Useable Hp Vs Operating Rpm Graph
While we expected most of the turbos to outperform the factory Holset across the board, that simply wasn’t the case. In fact, the stock turbo was well above the curve at the lower rpm test points (1,400 and 1,700 rpm, respectively), and it showed the ability to lug at low rpm without pushing EGT into unsafe territory. However, once rpm started to climb, most of the aftermarket turbos began to surpass it. The Killer B and the E.D. 63mm Billet S300 edged out the stock unit slightly at 2,000 rpm, while the Silver Bullet 62 and Aurora 3000 started to pull away from the field. Surprisingly, the quick-spooling Holset Cheetah was the only turbo that couldn’t outmatch the stocker, in terms of horsepower, at 2,000 rpm.
| The tow test was the most time-consuming portion of the shootout. Here you can see what kind of numbers the Holset Cheetah was putting up during the 2,300-rpm test (making 290 hp, 657 lb-ft of torque, and 28 psi of boost at the 50-mph target speed).
The 2,300-, 2,600-, and 3,000-rpm tests represent a point where the driver would drop out of Overdrive and try to accelerate (or maintain his or her speed) on a grade using direct drive, Third gear in our case. All aftermarket turbos were outpacing the stock unit at this point, with strong performances from both the Silver Bullet 62 and the Aurora 3000. Between the 2,600- and 3,000-rpm tests, the E.D. 63mm Billet S300’s larger compressor size is evident and it outperforms the Aurora 3000.
Tow Test: (Peak horsepower sustained without exceeding 1,200 degree EGT)
RPM:
1,400
1,700
2,000
2,300
2,600
3,000
Average Usable HP:
MPH (Drive):
30
36
44
50
56
65
Silver Bullet 62
110 hp
145 hp
296 hp
350 hp
360 hp
345 hp
268 hp
Aurora 3000
127 hp
160 hp
300 hp
333 hp
340 hp
306 hp
261 hp
E.D. 63mm Billet S300
112 hp
150 hp
275 hp
308 hp
332 hp
333 hp
252 hp
Stock HE351CW
145 hp
219 hp
270 hp
291 hp
288 hp
237 hp
242 hp
Killer B
110 hp
145 hp
275 hp
307 hp
308 hp
285 hp
238 hp
Holset Cheetah
105 hp
150 hp
250 hp
297 hp
300 hp
252 hp
226 hp
Cummins-Tuner.com Tow tune and 45-percent-over-stock Exergy injectors
Test performed in Third gear with the torque converter locked
Peak Power Test
No turbo shootout would be complete without comparing raw, maximum horsepower data. The fact that CPS was using the same truck with the same tuning, and performing the test on the same dyno, makes this the first time these turbos have ever been pitted against each other in a controlled environment. To get the most out of each turbo, the truck was run at full throttle against the dyno brake. Each dyno pull had a start rpm, meaning horsepower was allowed to peak before starting a timed acceleration interval. The dyno’s computer dynamically altered the load placed on the truck to ensure every run lasted exactly 7 seconds, and the test concluded once the end rpm was achieved. Due to their ability to spool at low rpm (and because the other turbos couldn’t), only the stock Holset, Aurora 3000, and Holset Cheetah were tested from 1,700 rpm to 3,200 rpm. The Killer B, Silver Bullet 62, and E.D. 63mm Billet S300 were tested from 2,000 rpm to 3,200 rpm. In addition to collecting peak horsepower and torque numbers, maximum EGT, boost, and drive pressure values were also recorded.
| It’s important to understand that everyone won’t see the same peak horsepower numbers CPS saw on the dyno unless they’ve made similar fueling, tuning, and transmission modifications to their truck. Choosing a turbo simply because it’s capable of making 650 hp won’t do you any good if you’ve only got 500 hp worth of fuel.
Each turbo was tested three times to verify its consistency, and at the conclusion of each test, the truck’s coolant temperature was allowed to return to 185 degrees before making another run. After all turbos were tested with the 45-percent-over-stock injectors and three of the six test units produced the same power number (648 hp), Calibrated Power Solutions determined that these turbos might require more fuel to achieve their peak number. The company concluded that a three-way tie between the Killer B, Silver Bullet 62, and E.D. 63mm Billet S300 not only proved that 650 hp is the rough power limit of 45-percent-over-injectors (regardless of turbo size), but that they should also be tested with larger, 100-percent-over-stock injectors in the engine. This second test was conducted to make sure the horsepower limit was reached for every turbocharger. During the second test, the E.D. 63mm Billet S300 picked up an additional 40 hp, the Silver Bullet 62 gained 16 hp, and the Killer B made the same 648 hp it had before.
Peak Power Test Results
Cummins-Tuner.com Max Effort tune
Turbo
Peak HP
Peak Torque
Peak EGT
Peak Boost
Peak Drive Pressure
Injector Used
E.D. 63mm Billet S300
688 hp
1,566 lb-ft
1,516 degrees
50 psi
64 psi
100% over
Silver Bullet 62
664 hp
1,592 lb-ft
1,540 degrees
51.5 psi
63 psi
100% over
Killer B
648 hp
1,534 lb-ft
1,570 degrees
49.5 psi
67 psi
45% and 100% over
Holset Cheetah
638 hp
1,435 lb-ft
*
53 psi
*
45% over
Aurora 3000
583 hp
1,404 lb-ft
1,530
43 psi
56 psi
45% over
Stock HE351CW
572 hp
1,339 lb-ft
*
43 psi
*
45% over
Test performed in Third gear with the torque converter locked
* = Data logger malfunction
The Verdict
ATS Aurora 3000
Spool Up Test: Third Place
Towing Test: Second Place
Peak Power Test: Fifth Place
The Good: Great towing turbo, responsive, best price
The Bad: Limited peak power ability due to its size
Manufacturer’s Rebuttal (Clint Cannon): “The Aurora 3000 is designed to be a streetable turbo that shines while towing. The turbo supplied for this test was equipped with a .85 A/R exhaust housing, but if quicker spool up is desired, we have a .76 A/R exhaust housing option. Of course, we can also improve on the peak power number by stepping up to the Aurora 4000, which maintains strong towing performance while improving on the peak power number. The ATS turbo lineup represents one of the few aftermarket companies that designs, casts, and builds turbochargers from start to finish, in-house.”
| Ats Aurora 3000 Turbo
BD Diesel Performance Killer B
Spool Up Test: Fourth Place
Towing Test: Fifth Place
Peak Power Test: Third Place
The Good: Strong bang for the buck, offers respectable performance in every category
The Bad: Required removal of the stock exhaust manifold during installation, wastegate adjustment needed in order to maximize peak power number (otherwise we were stuck at 615 rwhp)
Manufacturer’s Rebuttal (Brian Roth): “The Killer B is designed as a strong bolt-on turbo for a street-driven 5.9L that’s after performance and driveability. While failures are very rare, I would still caution users to only adjust their wastegates if necessary. We offer a wide range of turbochargers on either side of the Killer B. If the goal is quicker spool up, the Super B would be the choice. On the other hand, the Super B Special and Track Master turbos are geared more toward the ‘peak performance’ crowd.”
| Bd Diesel Performance Killer B
Fleece Performance Holset Cheetah
Spool Up Test: Second Place
Towing Test: Sixth Place
Peak Power Test: Fourth Place
The Good: Responsive, subtly impressive peak power number, easiest to install
The Bad: Lowest usable horsepower while towing heavy, best suited for a lightly loaded truck
Manufacturer’s Rebuttal (Chase Fleece): “This is a stock turbo on steroids. If you’re towing a boat or lighter load and want great driveability, then this is a great upgrade. It really shines on spool up. It’s able to spool earlier in the rev range during dyno tests, coming to life at 1,500 rpm during our in-house testing.” Fleece states there is an 8 percent difference between the Calibrated Power Solutions dyno numbers and the numbers they report. This statistic is meant to help with comparison, not to suggest one dyno is right or wrong.
| Fleece Performance Holset Cheetah Turbo
Industrial Injection Silver Bullet 62
Spool Up Test: Sixth Place
Towing Test: First Place
Peak Power Test: Second Place
The Good: Impressive ability to control EGT while towing, solid peak power performance
The Bad: Required removal of exhaust manifold during installation, slow spool up, appreciates being above 2,000 rpm
Manufacturer’s Rebuttal (Brady Williams): “The Silver 62 is built to be a strong, reliable towing turbo. One turbo can’t do it all; that’s why Industrial Injection maintains a wide selection and continuously tests new products. On either side of the Silver Bullet 62 are the Silver Bullet 66 (more to the racing side), and the Phat Shaft 62/70 (which offers much quicker spool up). Industrial Injection continues looking to the future, and testing is going well on the new BorgWarner EFR (engineered for racing) products.”
| Industrial Injection Silver Bullet 62 Turbo
Engineered Diesel 63mm Billet S300
Spool Up Test: Fifth Place
Towing Test: Third Place
Peak Power Test: First Place
The Good: Easy install, most horsepower, mid-pack tow test finish despite being the largest turbo
The Bad: Second to last in spool up, requires more rpm while towing
Manufacturer’s Rebuttal (Chris Beardsley): “I appreciate this test being performed the way it was. The method is far and away more substantial and fair than anything I’ve seen before. Our Billet 63mm turbo gets rave reviews from people who buy it. For operating between 625 and 650 hp, I’d suggest keeping this turbo. If a guy is running 650 to 700 hp I would step him up to a larger turbine wheel, and when running more than 700 hp it would be smart to step up on the compressor. This turbo ships with the wastegate set at 52 psi. I recommend not exceeding 52 to 54 psi.”
| Engineered Diesel 63mm Billet S300
Conclusion
If we’ve learned anything from this shootout, it’s that no magical, fixed-geometry turbo exists that can top the list in all three categories (driveability, towing, and peak performance). You might get a turbo that can do two out of three things well, but unfortunately, you still can’t have your cake and eat it, too. For example, you can choose a charger that spools quick, cools EGT, and tows well, such as the Aurora 3000. But due to its small size, much will be left to be desired in terms of all-out horsepower. On the other side of the spectrum, you can have a turbo like the Silver Bullet 62, which makes great peak power and tows surprisingly well for its larger size—but comes with the tradeoff of being noticeably laggier.
In the end, each turbo has its high marks, along with at least one drawback. This was true for every aftermarket turbo tested. But that’s what happens when you venture past stock power levels—something is always sacrificed. If you’re in the market for a larger turbo, it’s important to be honest with yourself, the modifications you’ve already made, and the way you use your truck. The only winner in this shootout is the turbo you decide is best for your own personal setup, based on the data presented. It’s our hope that this test will aid you in your pursuit of the perfect turbo for your specific needs.
