Editor's Note: In this article we will only look at the Duramax and its powertrain. At the time of this first drive the 2001 GM Heavy Duty trucks were 95% of the way through their design cycle. Some items on the trucks may yet be changed or modified. We do not yet have firm information related to pricing, warranties, etc. When GM issues announcements about these we will bring them to you ASAP.

Forum questions are answered in the right hand column.

The Battle Lines Have Been Drawn

Since 1993 General Motors and its troops have been fighting a losing battle at the heavy duty end of the pickup truck market. Left without adequate artillery to assault the Dodge and Ford positions, the General has had to make due with increasingly smaller pieces of the high ground where manufacturers battle it out for the bragging rights to claim who's truck is most powerful. The reason: underpowered and underperforming diesel engines.

Send word to the front because all that is about to change. The Duramax engine drives great!

Those Who Forget History...

GM drew upon lessons learned from the redesigned 1994 Dodge Ram and 1996 Ford F-150 to create the latest generation award-winning Silverado and Sierra twins that debuted as 1999 models but something had been definitely missing. Both the Dodge and Ford trucks offered powerful, next generation diesel engines which the GM models have lacked.

In 1989 Dodge went to its ally Cummins Diesel for help in creating a powerful diesel engine offering. It found it in the form of Cummins's strong and venerable inline six cylinder diesel that generated more torque than Ford or GM (400 lb. ft. vs. GM's 246 and Ford's 345 at the time of its debut). Combined with the latest generation Ram, sales have rocketed to just over 30% of the heavy duty diesel market.

Ford found an ally in big-rig maker Navistar and introduced a new generation of Power Stroke diesel engines in 1999 on its SuperDuty lineup of pickups. The Power Stroke was more fuel efficient and quieter than previous generations of Ford produced diesel engines. Ford has seen its share of the heavy duty market balloon to over 60%.

General Motors has been struggling on its own while watching its diesel engine market share fall from 20% back in 1994 to under 10% today.

GM has not had a new diesel engine to match the caliber of these fine Ford and Dodge engines since at least 1994. Six years ago General Motors introduced its in-house developed 6.5L diesel, and before that the last new GM diesel was the 6.2L way back in 1982 when it was sent to the frontlines.

Well, GM has learned from its own history, and the history of others, and is determined not to repeat it. This time around GM has chosen Isuzu Motors and Allison Transmissions as its allies in the heavy duty truck wars and to that end it has created, or should we say located, its latest diesel engine - the 6.6L Duramax 6600. GM's own Bruce Aileio states that, "Globally Isuzu is recognized as the premier diesel engine design company worldwide."


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The Great Debate - Maybe

Sure to be a point of contention for some heavy duty buyers is the Japanese origins of the Isuzu designed Duramax engine, but consider the following. The Duramax will be built and assembled in Moraine, Ohio at a joint GM / Isuzu facility known as Duramax Ltd. The Duramax uses Bosch fuel injectors of German manufacturing origin. The Allison transmission most Heavy Dutys will probably come with is from an American company and subsidiary of GM. The Allison team worked very closely with Isuzu during all stages of development even going so far as to fly Allison employees to Japan weekly for team meetings and engineering sessions.

We consider the Duramax to be a truly global diesel engine and after driving it we believe that folks are going to judge this diesel based on its class leading merits and not on issues related to engine origin.

If GM claims hold true, people who do judge this engine and dismiss it because of its design heritage do so at the peril of possibly missing out on an engine with very real economic benefits for those who use heavy duty trucks at work every day.

An Aerial View of the Duramax

We won't go into all the gory detail here about the 2001 Heavy Duty pickups and Duramax diesel. You can find our first look at the truck and its specifications from our previous coverage of the Duramax introduction.

At a high level the new Duramax is rated at a best-in-class 300 horsepower and 520 ft. lb. of torque.

The optional Allison automatic transmission is rated at up to 545 ft. lb. of torque and 375 horsepower. A six speed manual is standard. About their transmission Allison says, "Get All The Power You Pay For."

General Motors claims the Duramax has best in class fuel economy but official CAFE figures have not yet been released. Informal measurements show gas mileage to be up to 2 mpg plus over competitors' engines.

Lifetime durability is also claimed to be class leading with overall engine life expected to be well over 200,000 miles and 50,000 miles between transmission fluid changes.


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Driven to Win

Enough strategic overview and history lessons. On to the drive.

GM offered us five trucks to choose from during our test drive, which are listed on the right-hand side of this page. Three GM Duramax equipped Heavy Dutys, one Dodge Cummins and one Ford Power Stroke. The Dodge and Ford trucks were paired with similarly configured GM trucks for the sake of comparison.

Unfortunately we never had the chance to drive the Dodge Ram Cummins or its similarly equipped GMC Sierra Duramax counterpart.

We left the hotel where we stayed in Phoenix for the first of three 10 mile driving segments to a destination near the Salt River Recreation area in Arizona.

It seemed to us that General Motors set the tests up as fair as possible during the entire time, though there were some significant differences in truck setups between 'evenly matched' vehicles. These differences are described below.

Though supervised on the outbound portion with GM subject matter experts we were always in the driver's seat. We wanted to find our for ourselves with as little intervention as possible which truck would win this preliminary heavy duty shootout.

First Driving Segment - Level Road, City and Freeway Conditions

For the first segment we chose truck #5, the Ford F-350 Crew Cab 4x4 with its 7.3L Power Stroke, to help set a baseline.

For the purposes of the test the Ford was setup to tow its maximum payload which was a GCWR of 20,000 pounds. The GCWR was simulated by towing a trailer loaded with sand bags for weight and a large Plexiglas wind screen to simulate the aerodynamic drag of say a horse trailer.

When you first start the Power Stroke you note its a loud engine, distinctly diesel in tone. On the outside this was very apparent. Inside the cabin the sound is slightly quieter but always omnipresent. Stepping on the gas during a standing start cut the conversation to nil until we got to cruising speeds. Stepping on the gas at speed also created a significant amount of engine clatter.

The Ford took its time getting up to speed with its max payload. Stepping on the gas yielded some significant sound and fury but slow and steady progress relative to say a lightly loaded truck. To be expected of course, we know, but somehow you are left wanting for more performance. Some of this had to do with the relatively tall 4.10 axle ratio. Nice for quick accelerations.

You could feel the momentum of the payload behind you every tick of the speedometer upwards. Something we became acutely aware of as we got used to the heavy load.

At in-town speeds the truck felt good at 40-45mph. Quite comfortable to drive and change lanes. At stop lights though you quickly learned to add an extra hundred or so feet during braking maneuvers. Nobody likes to have a 20,000 pound Ford F-350 tap their rear bumper. The electric brakes proved to be pretty touchy - seemingly binary in operation (on or off with no in-between).

Entering the onramp of the freeway at about 15 mph from a left turn we quickly got up to highway speeds. On the freeway the Ford again handled well and had little difficulty in passing slower moving traffic.

We kept the truck in overdrive on the freeway and in drive on the surface streets of Phoenix.

Overall the F-350 seemed to be quite a capable hauler.

Second Driving Segment - Slight Incline, Two Lane Highway Conditions

During a quick ten minute pit stop we changed into truck #4, a Heavy Duty GMC Sierra 3500 Crew Cab configured simliarly to the F-350. The GMC Sierra was not at its maximum GCWR payload limit and unlike the F-350 the GMC HD was a two wheel drive truck with a 3.73 axle ratio.

Wow. There is a big difference here ladies and gentlemen.

The noise level of the Duramax while standing on the outside is something to marvel at. The Sierra was quieter than the F-350 but the biggest difference was between the Cummins and Duramax. It's just plain uncomfortable to stand near the Cummins too long at idle.

While parked we can claim to have accidentally tried to start the GMC Sierra when its engine was already idling - that's how quiet it was at rest.

The Duramax seemed to get up to highway speeds from a standing start much faster and significantly quieter than the Ford F-350 even with the smaller 3.73 axle ratio. Low end torque was always present. At 55 mph the Duramax had plenty of horsepower left in it at a touch of the pedal.

Though we didn't get to try it out as much as we would have liked, the tow/haul mode made things very pleasant while braking. No switching between drive or overdrive was necessary because the Allison transmission's ability to seemingly figure out the mass and momentum of the Sierra was as uncanny as GM described it. Upon touching the brakes for several seconds to slow down the tow/haul mode automatically downshifted to help control the deceleration. This was braking on a fairly level surface though. Others who tested the truck got a glimpse at the braking under more severe hilly conditions where it also seemed to excel.

We also didn't personally get to run the Ford F-350 and GMC Sierra HD side by side but were witness to several competitions between the two vehicles driven by other journalists.

From a standing start on flat and uphill roads the Duramax beat the Power Stroke no questions asked. Every time.

At highway speeds of 50 mph and side by side, the Duramax also handily pulled away from the Power Stroke each time. They were both quite dramatic presentations to help back the claims of General Motors.

This you almost have to see to believe.


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Third Driving Segment - Hilly, Two Lane Highway Conditions

For the third and final segment of our drive we chose truck #1, an unloaded GMC Heavy Duty 2500, 4 wheel drive, four door extended cab. We wound up calling this truck the hot rod.

We took off in this sweet black number. After previously driving two 20,000 pound DRW behemoths in the first two segments of the drive this SRW Heavy Duty was just begging to be driven - hard.

We were able to quickly prove that GM did indeed have a fuel cutoff on the engine to limit truck speed to around 95 mph on our truck.

Our apologies to the crew of GM's escort van that had been leading all of the trucks on our merry journey into diesel land. Good thing PickupTruck.Com folks know how to read a map and the GM folks had been kind enough to give us good directions to the last stop on our outbound journey.

If ever you were in the market for a light duty diesel truck to do your daily commuting in, this would be the truck. The engine had great response and gobs of torque and power without any payload. The interior was almost as quiet as a gasoline engine's interior at every speed except when totally mashing on the accelerator.

The Sierra's ride was very comfortable for an unloaded 4x4. In fact we thought it more comfortable than the 4x4 3/4-ton Silverado we had driven the day before in Los Angeles which was very similarly equipped but for its gasoline engine.

Coming Back from the Frontlines

After everyone rallied at the edge of the Salt River we were allowed to pair off and select a Heavy Duty to drive back in without any GM chaperones. We missed out on getting the black hot rod again - which we had hoped to take off-road - and got back into the red dually we had driven during the second drive segment. Before we left we were able to lose the trailer and its heavy load.

Driving the large Sierra back was pretty pleasant. The engine had lots of spare power now that it was free of the trailer.

Even though it was a two wheel drive truck, we did manage to take it off-road a little to get some good photos and video, which you will see in the coming weeks.

After such an exciting day at the frontlines a passenger even fell asleep in the truck - further proof of the quiet interior resulting from the Duramax's low NVH levels.

Aside from running into an apparent swarm of killer bees just before we got back to the hotel (honest, we swear - the swarm looked like a small black cloud) the drive to the hotel was low key. Nothing like having a Heavy Duty when facing those nasty little buggers.

Summing it All Up

In summary, GM appears to have taken the lead, if only momentarily, in the heavy duty truck wars. The new Duramax from Isuzu, Allison and GM is going to send shockwaves throughout the truck marketplace.

GM is sure to gain much of the ground it has given up while fighting alone now that it has teamed up with such capable allies as Isuzu and Allison. The new Heavy Duty trucks may even help Chevrolet once again capture the number one sales position from Ford in the pickup truck marketplace if the others are sleeping behind their walls.

Test Vehicles Driven

Truck #1 - Unloaded, No Trailer

Description:
2001 GMC Heavy Duty 2500, 4 Wheel Drive Extended Cab
Gross Vehicle Weight Rating:
9,200 lbs.
Gross Combined Weight Rating:
22,000 lbs.
Engine:
Duramax 6600
Horsepower:
300 hp @ 3100 rpm
Torque:
520 lb. ft. @ 1800 rpm
Transmission:
Allison 5-speed Automatic
Axle Ratio:
3.73 to 1
Weight Condition:
Curb, No Ballast
Trailer Weight:
N/A

Truck #2 - Loaded, No Trailer

Description:
2001 GMC Heavy Duty 2500, 2 Wheel Drive Extended Cab
Gross Vehicle Weight Rating:
9,200 lbs.
Gross Combined Weight Rating:
22,000 lbs.
Engine:
Duramax 6600
Horsepower:
300 hp @ 3100 rpm
Torque:
520 lb. ft. @ 1800 rpm
Transmission:
Allison 5-speed Automatic
Axle Ratio:
3.73 to 1
Weight Condition:
At GVWR, 9200 lbs.
Trailer Weight:
N/A

Truck #3 - Loaded, No Trailer

Description:
2000 Dodge Ram 3500, 4 Wheel Drive Extended Cab
Gross Vehicle Weight Rating:
11,000 lbs.
Gross Combined Weight Rating:
20,000 lbs.
Engine:
Cummins I6, 5.9L V8
Horsepower:
215 hp @ 2700 rpm
Torque:
420 lb. ft. @ 1600 rpm
Transmission:
4-speed Automatic
Axle Ratio:
4.10 to 1
Weight Condition:
9,200 lbs.
Trailer Weight:
N/A

Truck #4 - Loaded, Trailer

Description:
2001 GMC Heavy Duty 3500, 2 Wheel Drive Crew Cab
Gross Vehicle Weight Rating:
11,400 lbs.
Gross Combined Weight Rating:
22,000 lbs.
Engine:
Duramax 6600, 6.6L V8
Horsepower:
300 hp @ 3100 rpm
Torque:
520 lb. ft. @ 1800 rpm
Transmission:
Allison 5-speed Automatic
Axle Ratio:
3.73 to 1
Weight Condition:
10,500 lbs.
Trailer Weight:
9,050 lbs.
Total Weight:
19,550 lbs.

Truck #5 - Loaded, Trailer

Description:
2000 Ford F-350 SuperDuty, 4 Wheel Drive Crew Cab
Gross Vehicle Weight Rating:
11,000 lbs.
Gross Combined Weight Rating:
20,000 lbs.
Engine:
Power Stroke 7.3L V8
Horsepower:
235 hp @ 2600 rpm
Torque:
500 lb. ft. @ 1800 rpm
Transmission:
4-speed Automatic
Axle Ratio:
4.10 to 1
Weight Condition:
10,500 lbs.
Trailer Weight:
9,050 lbs.
Total Weight:
19,550 lbs.

PUTC Questions and Answers

Q: Now that diesel is near $2/gallon, how does the Duramax compare with competitors trucks?
A: The engine and trucks we drove are part of GM's unregulated fleet meaning that no CAFE figures can be released with regards to the trucks we drove.

There are no official mpg stats yet from GM and we did not have the opportunity to check the fuel economy ourselves during the drives. The drivetime was too short for each vehicle to try and make an accurate fuel economy estimate.

GM claims fuel economy is 15-20% better than the current 6.5L turbo diesel.

Q: How much will the Duramax combo add to the cost?
A: Pricing figures have not been released yet from GM

Q: When will pricing be announced?
A: Pricing should be announced just prior to launch around August or September.

Q: When will non-fleet customers receive their trucks:
A: Sometime this fall

Q: Will there be adequate tech support at dealerships when deliveries start?
A: GM was not able to address this

Q: When can we officially place an order?
A: Expect to be able to place an order most likely in the May / June timeframe when most other 2001 GM models orders can be placed.

Q: What will the official warranty be?
A: This point is still being kicked around at GM. GM recognizes that both Ford and Dodge offer warranties that in some aspects go beyond normal trucks and GM will be offering a similar warranty option.

Q: When will we see the trucks at dealers?
A: Around the late fall

Q: Is 300 Horsepower and 520 ft. lb. of torque official?
A: Yes, those are official figures

Q: How much taller is the new model than previous?
A: We are researching this and hope to have an answer soon

Q: Will the HD Duramax with an Allison transmission and four wheel drive be able to be towed behind an RV?
A: Yes, you will be able to tow both the four wheel drive Allison automatic and manual transmission trucks. For two wheel drive HDs you would need to pull the drive shaft first before towing.

Q: What are the gross axle weight ratings?
A: The SRW 2500 is 9,200 lbs. and the DRW 3500 is 11,400 lbs.

Q: What is the spring capacity?
A: We are researching this and hope to have an answer soon

Q: How much does the Duramax weigh?
A: The Duramax 6600 weighs only 836 lbs. thanks to the use of aluminum in key components like the cylinder heads, crankcase, accessory drive brackets, intake manifold and flywheel bell housing.

Q: How big is the Duramax?
A: The Duramax is the shortest engine in its class at 34.5 inches long.

Q: What was the percentage grade of the hills the tests were performed on?
A: The percentage grade varied quite a bit. On the second portion the grade varied between 2% to 4%. On the third portion the grade started at 4% and peaked at 6%.

Related Links

First Look: 2001 GM Heavy Duty Trucks

Dodge Diesel Pickup Trucks: 1989 to 1993

The Ford Diesel Page

The Dodge Turbo Diesel Registry

The 6.2 / 6.5L Diesel Page