DPF Challenge: ’07 vocational issues still being worked out

TORONTO — Diesel particulate filters (DPFs) are well understood by the engineering community, and after spending many million of dollars in testing, engine and truck makers have worked out exactly where they should be placed on a highway truck or tractor.

Packaging of the DPF is critically important because the temperature of the exhaust gas has to be precisely maintained. Equally important, there’s also back pressure to be accounted for.

So what’s a body builder to do?

The challenge in moving a DPF is maintaining the
right back pressure and exhaust gas temperature.

Unless we’re talking about a simple box van, chances are he’ll need to move the DPF somewhere, and it could well be going to a place the truck maker didn’t or couldn’t anticipate. There are many possible variations in the vocational world, after all.

That’s the challenge being faced by many custom fitters, including Quebec’s Simard Suspensions of Baie-Saint-Paul. Simard are veteran specialist manufacturers and much of what they do is to fit tandem steering-axle/suspension combinations to mean-looking trucks for the forest and the oil patch and other such rough places. Where to put the DPF?

In the case illustrated here, a Peterbilt with a dump body, the filter had to be moved back several feet to accommodate the rearmost front steer axle.

At this juncture, they hadn’t yet solved the problem of maintaining exhaust temperature or dealing with backpressure. Another potential issue is leakage.

Simard’s engineers are working with truck and engine OEMs to find the solution, and they’re 100 percent confident about getting there very soon.

But it’s a challenge that’s consuming a lot of engineer hours. So if you’re in the market for a truck with a one-off DPF packaging issue like this, make sure the homework has been done properly.

If it hasn’t, you could be faced with a particulate filter that needs frequent regeneration or kills fuel economy. Or more likely both.

— Be sure to check out this week’s feature, Full Steam Ahead, for a complete ’07 engine update.

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