Engine Ratings - Chassis Cab Vs. Pick Up

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Aug 6, 2010 | 02:02 PM

blueheron

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Joined: Feb 2004

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From: St. John's Newfoundland

Engine Ratings - Chassis Cab Vs. Pick Up

According to the specs. on page seven of the Coffee table Book:
Diesel Technician Society

The engine in the chassis cab is rated
at 300 hp @ 2800 rpm and 660 ft.-lb. @ 1600

while the pick up is rated
at 390 hp @ 2,800 rpm and 735 ft.-lb. @ 1,600 rpm

Please pardon my ignorance, but what is different about the engines which produces the different ratings? I dare say it's in the software, but what is it that the software does?

Aug 6, 2010 | 02:13 PM

jfritz_drfritz

Mountain Pass

Joined: Dec 2009

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From: Regina, Saskatchewan

Quote:

Originally Posted by blueheron

fundamentally it comes down to the emissions certification process. It would seem that the chassis cabs model follow a more stringent emissions certification process. My understanding is that because of the variable configuration that a chassis cab could have once it leaves the factory, the tuning must be conservative enough that the emissions requirements are met however the truck is used. Thus the lower state of tune allows a large safety margin for emissions compliance.

Aug 6, 2010 | 10:06 PM

BrockwayMT

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Another concern in addition to emissions is duty cycle. Chassis cab truck is expected to work at a higher load at a given percentage of time. Or spend a higher percentage of time above a given load level.

The 400hp and 800 lb-ft in a pickup is not sustainable for a long period. The engine components won't hold up and the cooling system can only hold that level of power for so long.

Duty cycle is why you see lower specific power outputs in higher duty cycle applications. 400 hp from 6.7 liters is great but only in small doses. A modern 400hp truck engine is around 9 or 10 liters at typically 1800 or 2100 rpm. Before electronic controls 400hp would probably be 14 liters (in a 4 stroke). But this 10 liter truck engine can sustain a higher percentage of it's rated power for a longer period of time. It also has a much larger radiator to support this duty cycle.

Aug 7, 2010 | 11:11 AM

Smokin_cache

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So my chassis cab was just delivered. Will my truck be upgaded to the specs of 400 and 800?

Aug 7, 2010 | 11:21 AM

PowerStrokeHD

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Quote:

Originally Posted by blueheron

As you would expect the software is different, but the biggest difference is the turbo set-up. The pickups use a single-sequential turbo while the chassis cabs use a single-stage turbo.