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2010 Duramax 4500 Diesel - Inside The 4.5L

Talking Diesel with the Man Behind the Motor

Photography by Courtesy of GM,

Diesel Power:
OK now we have a couple general questions. At the seminar, you mentioned that these 1/2-ton trucks may encourage a new group of customers to purchase a diesel vehicle. Tell us about that.

Charlie Freese:
The 6.6L V-8 Duramax has been extremely successful. Duramax was introduced in 2001 with a 310-hp and 520-lb-ft rating. At its introduction, General Motors only had a 1.1% share in the heavy-duty pickup market. Duramax and the Allison transmission established new performance and refinement benchmarks that changed many customer perceptions about diesels. Duramax soon captured one third of this important market. Since its introduction, Duramax routinely resets the bar for torque and power leadership. It now delivers 365 hp and 660 lb-ft of torque. Duramax has become a reason for purchase with many 3/4- and 1-ton truck customers.

We expect the new 4.5L V-8 Duramax can do the same thing for light-duty pickup trucks. Some customers don't need a 3/4-ton truck, but still need tow trailers and expect efficiency. The 4.5L Duramax that we showed today can match the original 310-hp and 520-lb-ft rating of the first 6.6L Duramax. It does this with 2.1L less displacement. Rated speed will be in the 4,000-rpm range with a broad torque curve. This gives the vehicle low-end, stump-pulling torque and high-speed operation that feels more gasoline-like. This is important because some buyers may not be accustomed to diesel engines. The diesel veterans will find they like it too. We continue to improve the 6.6L Duramax for those customers that require the biggest, most capable truck available. The 6.6L will serve the 2500 and 3500 pickups (Chevrolet Silverado and GMC Sierra), fullsize vans (Chevrolet Express and GMC Savanna), and commercial trucks (Kodiak and Topkick).

Diesel Power:
OK one last question. We're willing to bet that within a year of release, somebody will have one of your little 4.5L LMKs producing more than 600 hp. What do you think about modifications that take these engines to such an extreme level?

Charlie Freese:
We all enjoy the power and aggressive low-end torque modern diesel engines deliver. It can be appealing to test your skills at tuning these engines, and I personally understand the temptation. I grew up twisting wrenches in my dad's motorcycle and snowmobile shop.

Our customers are passionate about these diesel products. However, anyone who plans to modify their truck must understand the endeavor is risky. Subtle design features may be critically important to a part's function. People are still approaching me about the LMM exhaust cooler, thinking it is only a styling feature. These powertrains were developed after years of analysis and hundreds of thousands of test hours.

Component limitations were carefully mapped and balanced against all the design imperatives. The situation is even more complex with active aftertreatment devices on the vehicle. The onboard computer constantly compensates for the ambient environment, operating conditions, exhaust backpressure changes, and system temperatures. Seemingly simple modifications can severely compromise functionality. We didn't leave horsepower needlessly on the table.

Engine design is all about balancing competing design imperatives. Tampering with design or calibration parameters can cause catastrophic engine damage and void your warranty. If someone is willing to risk a $10K repair bill for a day at the track, then why stop at 600 hp?

Diesel Power:
Thanks so much for your time Charlie. We're genuinely excited about this engine and it looks like you did an excellent job designing it. We can't wait till they are in a production vehicle. Give us a call if you ever need us to drive one!

Charlie Freese:
You are welcome. It is always fun to talk about the product. We have a great engineering team working on this new engine. I am sure they will not let you down, and we may have some future surprises for you. Stay tuned!

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