International's HT 570
Tom Berg
Equipment Editor
The January '04 exhaust emissions regulations were a high hurdle for all diesel builders, including International Truck & Engine. It designed what amounts to a brand-new engine, the VT 365 (also sold by Ford as its Power Stroke) for lighter-duty trucks, and early this year announced major revisions to its inline 6-cylinder diesels, the DT 466 and HT 570 (formerly the 530).
Both engine series get an electronically controlled variable-geometry turbocharger whose vanes adjust to optimize boost across the operating range; cooled exhaust-gas recirculation to reduce EPA-regulated oxides of nitrogen; and a Generation 2 electro-hydraulic fuel system, a common rail design with internal high-pressure lines and smaller injectors that provide room for four valves per cylinder for a complete mix of fuel and air.
Optional on the 466 and 570 are newly developed Diamond Logic exhaust and engine brakes. The exhaust brake uses the turbo's vanes to introduce back pressure, and develops up to 120 retarding hp in a 466 and 230 hp in a 570. To that the engine brake adds hydraulically actuated valve action on all six cylinders to increase compression. It makes up to 250 retarding hp in a 570, International engineers said.
SHOWING 'EM OFF
In late May, International executives showed off the new engines in new trucks and tractors at the Texas Motor Speedway north of Dallas. The 466 is used mostly in 4000 models while the 570 is employed in the 7000 severe-service trucks and 8000 series highway tractors. Most of the 200 dealer people and customers at the event competed for individual driving time, so I stayed late to spend an extra hour with one vehicle, the 7500 dump truck pictured here.
The moderately loaded 10-wheel dumper had an HT 570 with the exhaust/engine brake, and ran through an Eaton Fuller 13-speed transmission. I took several trips over a rough and dusty off-road course and a spin around the speedway's perimeter road at moderate highway speeds to get a feel for these components.
The HT (high-torque) 570 (its displacement in cubic inches) was rated at 340 hp and 1,150 lb.ft of torque — pretty healthy for a 9.3-liter diesel, and right in the same league as Caterpillar's C9 and Cummins' ISL, which are not offered in this truck model (though bigger Cat and Cummins power is installed in heavier Internationals). With a higher capacity cooling package, the HT 570 will eventually grow to 370 hp and 1,450 lb.ft, engineers said.
Low-end boost from the VG turbo and the extra 50 cubic inches over the old 530 made the 570 feel more like a 10-liter engine. It was pleasingly lively as I rowed through the gears while trundling through the off-road course. Coming out of corners it would accelerate from 900 RPM with little vibration and it felt strong from the 1,100-RPM torque peak on up to its 2,200-RPM limit. Because it behaved like a big-bore engine, I usually upshifted at 1,800 or less.
While watching other trucks being driven during the course of the day, I noticed that smoke puffed out of their stacks while their 466 and 570 engines idled and sometimes during gear shifts. A later query to International's Engine Division got me the explanation that these engines were pre-production versions tuned for the proper advertised performance, but some weren't yet certified for emissions. Engines now coming off the assembly lines should be visibly smokeless.
THREE-LEVEL RETARDING
The Diamond Logic exhaust brake feels and acts somewhat like a Jake Brake, and the two dash-mounted rocker switches are also familiar: one for on-off, and the other for retarding levels 1, 2 and 3. Those three positions don't run the valves of two, four or six cylinders, as does a Jake, but brings the vanes of the variable-geometry turbocharger into play and adjusts their angle. So it's not a one-third, two-thirds action at levels 1 and 2, but more like 30% and 70%, an engineer explained.
This is due to the brake's function, which starts with valve action that heightens compression, then engages the turbo to build back pressure. There's no valve popping as with a Jake and no "potato in the pipe" muffling as with an exhaust brake, either. In fact, there's little sound at all. Engineers claim it's quieter than the sound of the engine idling. I didn't have a decibel meter to verify that, but it really is almost whisper quiet, and might allow drivers to sneak its use in places where engine brakes are banned.
Some people at this event thought that signs which specifically forbid use of "Jake Brakes" would legally allow use of this device. Maybe and maybe not. Most signs actually say "Exhaust Brakes Prohibited," but I doubt that police officers will hear the Diamond Logic brake operating, and use does save the service brakes for more serious situations.
The engine/exhaust brake will be helpful on long downgrades, but there aren't any of those on the grounds of the speedway. All I could do is engage the brake on level pavement and let it pull down the truck's speed, as a driver might do in heavy traffic. The Diamond brake worked gently in this engine and in a DT 466 I drove earlier, and maybe its quietness masks its power.
Brief drives of other DT 466-powered trucks were underwhelming because they seem to drive pretty much like the predecessor 466s. They were smooth and quiet, and promise to be willing and long-lived performers like all 466s, which first appeared in the 1970s. If the new 466 and 570 work as well, they will be good tools for their owners and maintain the historically high resale value of International trucks.
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