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Navistar and Workhorse Display 3 Chassis Products, MaxxForce 7 Featured

Posted 12-17-2009 at 12:17 PM by DriVer
Updated 01-03-2010 at 09:03 AM by DriVer

Workhorse Display 2010 RVIA Exposition

While attending the 2010 RVIA exposition one of the displays that I did not want to miss was the Workhorse exhibit in Booth 3308. In the display were many familiar faces including Bill Walmsley, Alan Stegich and others. The exhibit shares space with a Navistar DURAStar cab and chassis and I was able to speak with the Navistar representative Michael Satlak who is the Medium Truck Marketing Manager.

The Workhorse W24 Motorhome Chassis

Mike told me all about the DURAStar and how it is configured for RV use. The truck shown in the display was powered by a 300HP / 860 lb/ft Torque Navistar DT engine as it referred to now days. Although the demo chassis had 24 inch tires on it Mike said that they could swap the tires for 19.5 inch ones for use in RV applications.

The Workhorse W20D Chassis

The DURAStar is completely configurable from use of conventional springs to an air ride suspension. The weight carrying capacity ranges from 17,800 all the way up to 54,000 pounds. This vehicle also may come with 4x2, 4x4 or 4x6 drivetrain configurations and may be equipped with an Allison automatic, Eaton or an Eaton “Ultrashift” automated transmission. The wheel cut on this vehicle is 50° so it highly maneuverable. The brakes on this unit were 4 wheel hydraulic disks with 4 channel ABS. Traction control is available and so are air drum brakes. International’s multiplexed electrical system is called “Diamond Logic” and it can feature up to a 320 Amp alternator with 4 chassis batteries.

One of the RV manufacturers currently building on this chassis is Gulfstream and they feature a model called the “SuperNova.” The SuperNova is built as a Super B more like a Supreme B than anything else I can call it.

2010 Conquest SuperNova

Some of the features of the SuperNova are:

·International 4200 Diesel
·DT 365 300 HP Turbo Diesel Engine
·Heavier Duty 2500 Series Allison 6 Speed Transmission
·140 gallon Fuel Tank
·150 gallon water tank
·25,900 GVWR
·33,000 GCWR
·The 40 foot Model 6400 Features a Full Wall Slideout

SuperNova Model 6400 "Grand Hotel"

Workhorse Custom Chassis of Union City, IN brought 2 display chassis to the show, the veritable workhorse of the RV gas powered world, the W24 and the newly released W20D MaxxForce7 front engine diesel motorhome chassis. For 2010 the W24 hasn’t changed much at all cosmetically as Workhorse continues on the reputation that customers have enjoyed for so many years with the W24. The 8.1L GM Vortec engine continues to be featured in all W Series chassis. The industry leading Allison MH1000 6 Speed transmission is used in the W20 & W22 model while the W24 utilize an MH2000 6 Speed transmission.

W24's Allison 2000 Series 6 Speed transmission, driveline brake drum, dual exhaust, Wabco ABS computer and Bilstein shocks are seen in this photo.

This legacy power train combination provides its owners with 2nd to none performance on the highway and byways of the US. The GM 8.1L Vortec continues to impress owners with its long stroke stump pulling power and matched to the Allison transmission gives owners excellent performance and good fuel economy.

Workhorse continues to build from 16,000 lbs of GVWR all the way up to 24,000 lbs of GVWR on front gasoline powered chassis. Robert Bosch twin piston 66mm hydraulic calipers are fitted all the way around on W20 & W22 while the W24 continues to use Arvin Meritor “Quadraulic” 4x70mm Piston units. W20 through W24 brakes are provided stopping power from a Bosch Hydro-Max brake booster. The rotor sizes on the W20-22 are 15.0 inches by 1.44 inches and the size of the W24’s rotors is 15.375 x 1.54 inches. The W20, W22 & W24 Series motorhomes feature 4 wheel, 4 channel, 4 sensor ABS systems. All W20 to W24 motorhome chassis have a 50° wheel cut and Stabil-Ride suspensions with Like Air Springs and Bilstein Gas-Charged mono tube shock absorbers.

The Vortec 8.1L engine will see its career come to a close in model year 2010 as these engines are exhausted from inventory.

Building the D Models was relatively straight forward. Using the reliability of the W20 the W20D was created and launched in 2008. In model year 2009 the W20D continues delivering excellent performance with its 230HP 620lb/ft Navistar MaxxForce 7 turbo charged diesel engine. The front axle rating is 7,500 lbs and the rear axle is rated at 13,500 pounds. The W20D motorhome chassis is mated to an Allison 6 Speed MH1000 transmission which delivers excellent fuel economy due to its 2 over drive gears and its economy geared Dana S110 3.88 rear axle.

The Bosch Automotive Proving Grounds (BAPG) in Flat Rock, MI operates as an independent vehicle testing and development service supplier to all vehicle and component manufacturers. In recent testing the W20D delivered an amazing 13.2 mpg.These tests were conducted using a 32-foot Four Winds Serrano motorhome loaded to the maximum GVWR of 20,500 lbs.

The W20D's cool pack, auxiliary cooling fans and assortment of transmission, oil and charge coolers are shown. The coolant recovery tank, Bosch Hydro-Max, power steering pump and air filter box are also visible.

In model year 2010 and beyond the Navistar MaxxForce 7 used on the Workhorse W20D has received an upgrade, a 2nd turbo charger. Nestled in within the plumbing and on top of the engine, the twin turbos provide both a low speed and sequentially a high speed boost. Adding a 2nd turbo provides for better combustion efficiency and helps assure the low emissions provided by the Advanced EGR system.

In recent press we have seen where, “Drivers will also immediately notice that MaxxForce 7 is quiet. The noise level measured at 68.9 dBA in a low idle test. A high-pressure common rail fuel system, piezo actuated fuel injectors and a block and head design with a single-piece nodular iron bedplate are among the features that contribute to reduced noise and vibrations, a key to the MaxxForce 7’s front-engine application.”

View from the rear of the Navistar 6.4L turbo diesel engine showing the outlet pipe and plumbing coming in from the charge cooler. New for 2010 and beyond is going to be a 2nd turbo charger.

I have heard the MaxxForce 7 on the bare chassis and it is indeed as quiet as they claim it to be. Market trends are telling the builders that smaller is better and that’s where Workhorse is dedicating a good amount of attention. Surveys have shown that motorhome buyers are trending downward toward 30 to 35 foot in length vehicles (or less) and this trend does not appear to be losing ground. In speaking with a number of different manufacturer representatives a lot of energy is being dedicated to smaller units.

As seen in the 4Winds Serrano the doghouse does not protrude excessively into the cockpit area. Access to the seats was quite easily accomplished.

The W20D is fitted with a Bosch Hydro-Max brake booster and Bosch disk brakes on all four corners like the W20 and W22 Series. The anti-lock brakes are a 4 wheel, 4 channel, 4 sensor system controlled by a Kelsey Hayes ABS computer.

The W20D is available in chassis in 3 lengths, 190, 208 and 228 inches. The frame is a constant section rail whose dimension is 9.625 x 3.0 x .25 inches with a section modulus of 10.13 cu inches made from 50,000 psi tensile strength steel. The “Stabil-Ride” suspension is used as are air auxiliary “Like-Air” springs, a 2.5 inch stabilizer bar, and Bilstein mono tube gas-charged shocks absorbers. The W20D feature Goodyear 245/70R 19.5 tires which are provided on steel wheels. The W20D chassis has a 50° wheel cut for increased maneuverability.

Shown is the Kelsy Hayes ABS computer which is in command of a 4 wheel, 4 channel, 4 sensor system. At the four corners Bosch twin piston calipers provide the stopping power to the W20D's 15 inch rotors.

The engine’s electrical system is powered by a single 950 CCA maintenance free battery and a 145 Ampere alternator. The chassis is provided with a 40 gallon capacity fuel tank.

The only downside if there is one in my opinion is the 40 gallon fuel tank. It was most likely considered that the quantity of fuel multiplied by MPG would allow the average RV’er to cruise all day long or approximately 500 miles a day. I expect that the use of a 40 gallon fuel tank would also yield less of a weight penalty on a lightweight coach as well.

This is the "New" Navistar MaxxForce 7, 6.4L twin turbo V8 with Advanced EGR. The chassis is absent a urea tank and offers owners less things to worry about. The engine's technology is completely 2010 emission compliant.

This isn’t a really a bad decision or poor gauge of RV’ing habits because as for me, I will comfortably drive 300 miles a day and that about all I really want to do. That said, some people that live in their vehicles for extended periods have needs other than driving and one of those is generator staying power. Motorhome owners don’t like to pull up stakes to go to fuel up when they are on a long term stay for instance in the desert at Quartzsite in the winter season. Anything that can extend that stay in one place is going to be much appreciated by owners considering buying a W20D.

The Workhorse W20D has a 3 year 36,000 mile bumper to bumper warranty, a 3 year 150,000 mile powertrain warranty and FREE transferable 3 year 36,000 roadside assistance. The “Transynd” filled Allison transmission has a 5 year 200,000 mile warranty. For more information about the W20D see the “products” tab on the website.

For more information about the MaxxForce 7 engine and Advanced EGR see the website on Navistar's
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  1. Old Comment
    max49's Avatar
    Looks like a really nice Rig!
    Posted 12-17-2009 at 08:44 PM by max49 max49 is offline
    Updated 12-17-2009 at 08:51 PM by max49
  2. Old Comment
    Bob (WA0MQE)'s Avatar
    Regarding the 40 gallon fuel tank. To me a larger tank should be included. It's not so much about how far I can drive before refueling. It's the fact that with a large fuel tank I don't have to go through the issues of refueling so often. Negotiating gas pumps with a large vehicle, especially while pulling a toad, is a real pain. Although in the case of the diesel one can hit the truck pumps which is a plus.
    Posted 12-18-2009 at 05:28 AM by Bob (WA0MQE) Bob (WA0MQE) is offline
  3. Old Comment
    Fred and Bonnie's Avatar
    DriVer, with the supply of 8.1L engines running out in 2010, does this hail the end of larger gas units from WCC?

    Posted 12-20-2009 at 10:58 PM by Fred and Bonnie Fred and Bonnie is offline
  4. Old Comment
    DriVer's Avatar
    Originally Posted by Fred and Bonnie View Comment
    DriVer, with the supply of 8.1L engines running out in 2010, does this hail the end of larger gas units from WCC?
    Fred, There's thread at the moment running in the Workhorse Forum that shows that the "last" 8.1L has already been made and retired to a GM museum.

    Workhorse will continue making large rigs throughout 2010 I expect however I believe that a big push has already been applied in the direction of front diesel power. Does this strategy allude to the death of BIG rigs that are front engine powered from Workhorse? I'm not certain it does. Most likely in the next few years that answer will be more visible to all of us but absent a crystal ball, I can't be sure. Currently there is an option for a W22D which will put a Workhorse in its most popular GVW rating and will still be front engined.

    FCCC's FRED will continue in the 26,000 GVW class and in Ford gas they have a 26,000 pound GVW chassis as well.

    The revival of the Workhorse UFO with a MaxxForce 7 engine in the 26,000 pound GVW range could level the playing field in regard to GVW. The UFO is one of my favorite rigs to drive and I think they've got something there that just needs a bit more time and market to come back on-line.

    Thanks for the question.
    Posted 12-21-2009 at 06:27 PM by DriVer DriVer is offline
    Updated 12-21-2009 at 06:31 PM by DriVer
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