GM boosts 4500 cutaway

May 1, 2008
General Motors' 2009 Chevrolet Express/GMC Savana 4500 commercial cutaway van features a new, stronger chassis that enables a 14,200-lb GVW with lower

General Motors' 2009 Chevrolet Express/GMC Savana 4500 commercial cutaway van features a new, stronger chassis that enables a 14,200-lb GVW with lower mass, giving it a payload rating of 9,100 lb.

The chassis — designed primarily for cargo bodies, along with those for school buses, shuttle buses, and ambulances — is offered with a gas V-8 and GM's 6.6-liter Duramax turbo-diesel V-8. With the new, strong frame and powertrains, the Express/Savana 4500 offers up to a 20,000-lb GCWR for towing and RV capability.

Some of the highlights include: reinforced frame assembly; new rear axle with reinforced housing, gears, and axle tubes; upgraded rear spring hanger bolt attachments and leaf-spring shackle assembly; high-capacity rear-spring assembly; upgraded front ball joint material; revised front and rear shock tuning; rear stabilizer bar; enhanced parking-brake system with thicker rear-brake rotors for improved heat dissipation; enhanced driveshaft hanger; higher-capacity radiator; and standard transmission cooler.

Greg Bilski, product manager of full-size commercial vans, said the frame reinforcements and other provisions for upfits were targeted to provide the most benefit with minimal impact on capability.

He said brackets added to the upper and lower portions of the frame's side-rail bulkheads provide reinforcing strength, as do kick-up reinforcements near the rear axle area. The body-in-white structure is also strengthened, with 10% thicker steel used in key areas, as well as additional spot welds and structural adhesive.

The 4500 chassis is available with a Vortec 6.0L gasoline V-8 or the Duramax 6.6L V-8 turbo-diesel. The emissions-compliant Duramax 6.6L was introduced as an interim change during the 2007 model year, and features enhancements that enable it to deliver reduced emissions using cleaner, federally mandated Ultra Low Sulfur fuel. It is rated at 250 horsepower and 460 lb-ft of torque.

The Vortec 6.0L gas engine, rated at 323 hp, features variable valve timing for enhanced performance and optimized fuel economy, and is based on GM's Gen IV small-block V-8 engine family that features deep-skirt cylinder block and cross-bolted six-bolt main bearing caps.

A Hydra-Matic HD 4L85E electronically controlled four-speed automatic transmission backs both available engines. It was designed for the heavy-duty use of commercial cutaway vans and features a brazed torque converter turbine, induction-hardened turbine shaft, five-pinion reaction and output gear carriers, and an improved overrun roller clutch.

All 4500 chassis (except school-bus applications) with the 14,200-lb GVWR and Duramax diesel engine receive a new, 57-gallon rear-mounted fuel tank that was designed with input from upfitters who wanted it mounted lower on the chassis, providing a flat mounting position for ambulance bodies and more.

The 57-gallon tank's fuel sender and all the fuel lines are upgraded to meet B5 bio-diesel performance requirements.

Bilski said the full-size van market in 2007 was “a little softer,” with 325,744 vans, a decline of 8.4%. With 140,400, GM's 43.1% market share stayed the same, but Bilski said GM increased its retail penetration by 1.4%, cutaway market share by 3.5%, and diesel penetration by 14%.

Two-mode hybrid

Dan Tigges, full-size truck product manager for Fleet & Commercial Operations, said GM's new two-mode hybrid will be released first on full-size products.

“A traditional one-mode hybrid typically has one torque-splitting arrangement and no fixed mechanical ratios,” he said. “Prius uses one electric motor and a continuous variable transmission, but that only provides hybrid benefit at low speed and it sacrifices payload and towing capability. GM's two-mode hybrid uses two electric motors combined with a fixed-gear, four-speed transmission. That allows us to get low-speed and high-speed fuel-economy advantages. There is no loss in capability or performance.”

While the vehicle is stopped, battery power provides accessories power, AC/heat, power steering, etc. At low speeds, the battery power alone drives vehicle at speeds up to about 30 mph. At mid-to-high speeds, the active fuel management four-cylinder mode is utilized to a much greater extent. The hybrid electric boost provides enough power to need only four cylinders at highway speeds. Tigges said the hybrid provides 50% city and 30% overall mpg improvement.

He said the two-mode hybrid Silverado/Sierra will have an identical powertrain to the Tahoe/Yukon hybrids, and it's available only on 1500 series Crew Cabs. Production starts November 17.

Also new for 2009: GM will add a 6.2L gas engine (Option L9H) to the LTZ/SLT half-ton Crew Cab models. The engine will have 403 hp and 417 lb-ft (Denali) and will add a six-speed automatic transmission. Crew cabs will be available with 5.3L, 6.0L, or 6.2L.

Regarding an upfitter issue concerning an extended cab rear door that opens to 170 degrees and contacts bodies over 80” wide, he said a clip has been approved to limit the opening to 90 degrees. The clip (PN 25949918) has been designed and validated and can be dealer- or upfitter-installed.

He said the integrated trailer brake controller (JL1), which had limited availability at launch, is now available on all HD models.

Tigges said a higher FGAWR is required for Hyrail upfits on the 2500HD and 3500HD SRW. GM has added SEO 8W9, which will increase the FGAWR to 4500 lb on a two-wheel drive and 4800 lb on a four-wheel drive.

Providing a full-size pickup sales update, he said GM's total sales went down 2.4%, but its market share went up 0.2% to 40.2%.

E85 advances

Mike McGarry of GM's Advanced Propulsion Technology Strategy team said that global energy demand exceeds our current glide path for supply, with a 60% increase over 2003.

“That's going to be difficult to meet with oil itself,” McGarry said. “We're looking at biofuels, electricity, and hydrogen.”

He said GM has 11 vehicles that are E85-capable, which he says is “the best possible way to displace petroleum” at this point.” He said GM has 2.56 million E85-capable vehicles on the road, and has committed to have at least 50% of its production capacity E85-capable by 2012.

“E85 is a clean-burning, renewable resource,” he said. “We want to reduce dependency on foreign oil and help the US economy. E85 has even greater potential to reduce oil imports if 50% of all US vehicles were FFV (Flexible Fuel Vehicles). By 2030, we could displace 80 billion gallons of oil with ethanol.”

He said under the partnership between GM and Coskata — which uses proprietary microorganisms and patented bioreactor designs — ethanol will be produced for under $1 per gallon almost anywhere in the world, from a wide variety of inputs.

“We'll be able to make more than 100 gallons of ethanol from one ton of dry material,” he said. “It uses less than one gallon of fresh water per gallon of ethanol produced, compared with three to four gallons for ethanol today. It reduces greenhouse-gas emissions by as much as 84% compared to conventional gasoline and returns up to 7.7 times as much energy as is used in the ethanol production process.”

McGarry said B5 has been approved for use on 6.6L Duramax and all European diesels, and B20-capable cutaway vans and heavy-duty pickups are available via a special equipment option, but an industry-wide B20 standard is needed.

Medium-duty market share

Mike Eaves, product manager for medium-duty trucks, said GM's market share was unchanged at 17.8% during the industry 18% decline in 2007.

The Class 6 and 7 tilt cab industry of 5600 units was down 1.4% in 2007, but GM's T-Series LCF market share was up 1.4% to 21%.

Eaves said the 2008i Diesel Idle Shutdown Timer requires vehicles over 14,000 lb GVWR with diesel engines to automatically shut down after idling for five minutes in the park position and 15 minutes in the non-park position.

It's applicable to California and nine other states that follow California emissions. Exempt vehicles, including buses, RVs, and emergency vehicles, are excluded and do not have shutdown enabled. The shutdown feature cannot be programmed on or off. GM is using emission codes to select shutdown.

“Our recommendation is that you use YF5 on all orders for greatest flexibility,” he said. “Vehicles can be registered in all 50 states. Only use FE9 if vehicle registration is confirmed to be outside of the impacted states.”

He said the introduction of the Caterpillar C7 has been delayed because of “component-quality issues, particularly related to exhaust installation” at Flint, Michigan.

“We've had sporadic production to date,” he said. “We have not built as many as we would like, and customers have had to wait. We plan to build existing orders by June 2008.”

He said Caterpillar increased the price on April 1, and GM will pass on a $3300 increase to customers.

He also said GM and Isuzu are investigating the use of a fuel cooler for severe-service applications where there are high hp/torque load and prolonged use in a stationary application, such as fire trucks.

“The engine will de-rate power if the return fuel temperature exceeds the threshold,” he said.

Eaves also said that the last production of 8.1L gas in C6500/7500/8500 models is in September, “because this is a relatively low-volume engine application and there are emission changes that would be required, and we don't have the volume to support it. C4500 and C5500 gas models continue with the 8.1L.”

Eaves said 2008 model year ordering closed on February 22.

“We are investigating a production increase to satisfy the demand,” he said. “2008 orders that cannot be built will be rolled to 2009 MY.”

About the Author

Rick Weber | Associate Editor

Rick Weber has been an associate editor for Trailer/Body Builders since February 2000. A national award-winning sportswriter, he covered the Miami Dolphins for the Fort Myers News-Press following service with publications in California and Australia. He is a graduate of Penn State University.