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    Pull-Off III
    Evolution of Power
    By Jim Bigley

    The evolution of Duramax 6600 power these past twelve months is nothing short of incredible. Four wheel drive burnouts while launching from a dead stop at 24,420-lbs combined weight, then cresting a 2-mile 6% hill at 84 mph is absolutely astonishing. This year's Pull-Off event gave everyone a much better idea of how far diesel performance has come.

    This was our third annual The Diesel Page Pull-Off event, which gave us another opportunity to evaluate both stock and modified diesel pickup performance. More than 50 trucks cycled through the parking area, and many more diesel owners saw the state-of-the-art in aftermarket diesel performance products.


    "Hood time" is always an important aspect of any diesel event. Discovering what others have done, and learning more about the various performance options are good ways to decide how to modify your own truck.

    The Diesel Page's new Duramax Power Project truck was on hand for everyone to see, and learn more about the Duramax 6600 installation. Look for this lightweight Chevy to establish new performance records for full-size diesel pickups.


    What is the Pull-Off? The very first TheDieselPage.com Pull-Off occurred on the evening of October 27, 1999, when GM brought new '01 Chevy & GMC Duramax/Allison powered prototypes here to Montana for us to compare to a 1999 Ford Powerstroke and 1999 Dodge ISB Cummins. Aside from dozens of 0-60 mph performance runs that first year, we also ran each truck up a local 6% grade with a 9,700-lb trailer to compare each truck's towing ability. That first event has become an annual tradition, by coordinating an annual truck pull using the same hill and similar weight trailers. We know that running a diesel pickup truck up a steep grade with a heavy trailer is the truest and best test of a diesel powertrain, and a stopwatch and calibrated speedometer help us to separate fact from fiction. Comparing towing power produced by GM, Ford & Dodge diesel pickup trucks is what the Pull-Off is all about, and owners of all three brands are always invited to attend. The story covering last year's event is now available in the 2001 Feature Articles volume.

    The Hill: The first section of the hill is a steep and unrelenting 6% grade that goes on for over a mile. As we've done for prior year hill-climbs, we began all runs from a dead stop at the 4-mile marker, near the bottom. About a quarter-mile past the 5-mile marker, the hill levels out a bit, then begins climbing again well before reaching the 6-mile marker. This allows for repeatable conditions from year to year, as well as being able to track performance trends over time.

    The same digital timer was used for every run, and a Honda Civic served as chase car, running interference and recording truck speeds. This removed as many variables as possible, and allowed for more accurate performance comparisons.

    The Trailers: This year we brought two trailers that would be used for the various classes of trucks. The "lighter" trailer is a 12K GVW car hauler that tipped the scales at a petite 10,460-lbs. The "Big Tex" tandem-dually gooseneck was loaded with concrete forms to a truck-grunting 16,270-lbs. We thought this huge load would be enough to keep the modified trucks below the speed limit on the loaded hill-climb. Boy, were we wrong!

    The first trucks to run this year were all 6.5TD powered. Chris Bigley's 6.5TD Project truck, John Kennedy's 1996, and Don Krake's 1994. Keep in mind that in 1999, the stock 6-speed manual transmission equipped Ford Powerstroke achieved 50-mph (4th gear 1.31:1 ratio) at the 1-mile mark while pulling a 9,700-lb trailer and the stock auto equipped 1999 Dodge Cummins managed to reach just 40-mph in 2nd gear. In addition, the pull this time was a little more difficult, in that the trailer was nearly 800 lbs heavier than the one used in 1999.

    Chris Bigley attended this year with his 6.5TD Power Project truck. Aside from routine maintenance, the engine, fuel injection system, turbocharger and transmission have been untouched for over 85,000 miles. The hill-climb this year would let us know if (or how much) the performance had changed after accumulating tens of thousands of hard trailer-towing miles. In 1999, the Project 6.5 reached 48-mph at the mile with a 9,700-lb trailer. This year, Chris's truck pulled the heavier 10,460-lb trailer past the first mile marker at 46-mph in 86-seconds, while running in 3rd gear (4L80-E direct). These times and speeds indicate that the performance hasn't changed much in the past three years, and that the durability built into the engine is now paying off.

    Member Don Krake, ran his stock 6.5TD Chevy K2500 up the hill as well. Don's truck pulled the 10K trailer up the 1-mile grade in 90-seconds and motored past the 1st mile-marker at 41-mph in 2nd gear. This was faster than the Dodge Cummins we used in the 1999 Pull-Off, and Don's 6.5 was pulling a heavier trailer.

    In addition to his '02 Chevy Duramax, John Kennedy also brought his 1996 6.5TD GMC to run this year with the other 6.5's. In addition to low compression pistons, John's 6.5 is balanced, has a DSG gear drive timing set, Spearco intercooler, a Peninsular high-flow turbocharger and lots of other enhancements. More than anything, seeing John's truck run the hill clearly demonstrated the benefits of a larger free-flowing turbocharger when run on a performance 6.5TD. John's 6.5 pulled the 10K trailer up the 1-mile grade in 81-seconds and powered past the 1st mile-marker at 48-mph in 3rd gear (direct). This is tremendous performance for an electronic 6.5TD!

    Rich Sarchet (Colorado Kid) attended this year with his 2002 GMC 2500HD Crew Cab Duramax ZF 6-speed 2WD truck. This was our first opportunity to evaluate and compare a stock 6-speed manual truck to a stock Allison equipped truck. Rich's truck produced a 4-mph and 4-second advantage over the 2003 stock Duramax/Allison we ran this year. It appears there is no disadvantage to shifting manually, given that a manual transmission generally absorbs less power than an automatic. Being 2WD may also help. Rich's truck pulled the 10K trailer up the 1-mile grade in 71-seconds and cruised past the 1st mile-marker at 58-mph, on the governor in 4th gear (1.31:1 ratio). This is the best speed yet for a stock Duramax 6600 powered truck.



    Duke Rose attended this year with his brand new 2003 GMC 2500HD Crew Cab Duramax/Allison luxo-truck. This truck gave us an opportunity to evaluate the performance of the '03 models, and see what if anything has changed. Duke's truck pulled the 10K trailer up the 1-mile grade in 75-seconds and blazed past the 1st mile-marker at 54-mph. This level of performance proves that from 1999 till now, the Duramax 6600 performance has remained constant. This is good news considering the tighter emissions regulations in effect today.


    Bill Heath's 2001 Dodge Hi-Output Cummins 6-speed pulled the 16K trailer past the 1st mile-marker at 57-mph and in just 79-seconds, then continued to accelerate to 78-mph at the 2nd mile-marker.

    Bill's Dodge was running Turbo-Master's Stage II program, which includes a computer module (extractor type), stepped exhaust system, air filter cartridge and EGT pyrometer gauge set.

    The Stage II program, sold and installed by Turbo-Master, is the most powerful yet well balanced performance package we've seen for the Dodge Cummins. This provides a big boost in power, yet is designed to operate within Cummins' exhaust temperature specs. Bill's Dodge ran the hill while producing very little smoke. Bill says a performance clutch will improve his Dodge's already impressive performance at our next Pull-Off. We're looking forward to it already!

    John Kennedy's 2002 Chevy 2500HD Crew Cab Duramax/Allison was the day's top performer. At 7400-lbs (we weighed it), this big truck flat scoots, whether loaded or unloaded. In addition to the weight of the truck and trailer, the loaded hill-climbs were made with 4 people aboard, which added yet another 750-lbs. At 24,420-lbs rolling combined weight, JK's truck charged to the 1st mile-marker in just 65-seconds and reached 64-mph, then flew past the 2nd mile-marker at an incredible 84-mph, accelerating hard every inch of the way.

    A humongus 5" exhaust system, a 120-hp power module, an experimental turbocharger modification and modified Allison were the primary motivators allowing the big Chevy to haul-ass. Always running with a backseat assortment of performance modules, his Tech II scan tool and other "secret" stuff, John spends a lot of time learning more about what works and what doesn't. He's got his Chevy cookin' - no doubt about it!


    John brought with him a wide selection of Duramax power modules, gauge sets and fuel treatment. Kennedy Diesel is an authorized dealer for most power products in use today by GM 6.5 and Duramax owners, and can help answer technical questions about their use and application.




    Also on display was the culvert sized 5" exhaust tailpipe. I can remember when the first 3" pipes became available, and how large I thought they were. You could lose small children in the five inchers!

    Thanks John, for taking the time to drive from Wisconsin to show us your products and your truck's impressive performance.


    What's in store for Pull-Off 2003? The availability of performance products for the Duramax 6600 has blossomed in just twelve months, and the diesel aftermarket is just now beginning to realize the performance potential of the Duramax. With aftermarket predictions of 800 Duramax horsepower in the very near future, the expectations are already building for Pull-Off IV. At our next annual Pull-Off, we'll make sure we have both an '03 Ford G2 6.0L Powerstroke and a new '03 Dodge HO Cummins to compare. The evolution of power is beginning to get real interesting...

    More Power!!!

    Authorized reprint from TheDieselPage.com
    Copyright © 2002 by TheDieselPage.com.