Does anyone know why the chassis cab motor is derated?
Is it just electronic tune or hard parts? Getting ready to replace my 7.3 chassis and noticed the 100HP missing in ratings for CC trucks .

 

its just in the tune i am running h&s on mine and i have a 350 cab and chassis it on stock tune as in the 400 800 is alot more power then the one it came with ive got 43,000 miles on it to nothing major has went wrong but thats the only way u can get the 400 800 out of a cab & chassis

 

Only Ford knows for sure but this link has some insightful info that explains the differences between how a chassis/cab and light duty truck are certified.
Emission Standards: USA: Heavy-Duty Truck and Bus Engines

Here is an excerpt from that page...

Current federal regulations do not require that complete heavy-duty diesel vehicles be chassis certified, instead requiring certification of their engines (as an option, complete heavy-duty diesel vehicles under 14,000 lbs can be chassis certified). Consequently, the basic standards are expressed in g/bhp·hr and require emission testing over the Transient FTP engine dynamometer cycle (however, chassis certification may be required for complete heavy-duty gasoline vehicles with pertinent emission standards expressed in g/mile).

In a nutshell...
Cab and chassis engines are certified on a chassis dyno called Urban Dynamometer Driving Schedule (HD-UDDS) sometimes referred to as "Cycle D". Standards are expressed in g/bhp x hr

Pickup engines are not required to be certified on a chassis dyno so they are most likely measured on an engine dyno, however this appears to be irrelevant since brake horse power isn't considered part of the equation That method is called Federal Test Procedure-72 sometimes referred to as LA-4 Cycle. With this method, emissions are expressed in only g/mile.

In addition, the duty cycle is different between the two methods. The cab and chassis dyno test has a much longer initial duration where the LA-4 cycle is broken into two segments with a 10 minute break between the two. So, I figure all this means that Ford can rate the pickup engines much higher because their duty cycle during emissions testing is much lower AND they have the luxury in only needing to meet a gram per mile requirement vs the much stricter g/bhp·hr calculation.

I will be the first to admit that I don't completely understand the regulations or motives so I am really just sharing what I've learned so far. (much more to digest still....) From what I can tell so far, the emissions regulations can be a bit of a double edged sword in the sense that Light-Heavy Duty Diesel engines (non chassis cab pickups) do allow for less stringent emissions standards at the cost of being forced to comply with MDPV (Medium Duty Passenger Vehicle) compliance regulations (on board monitoring systems). I can only presume this is the main reason for the "Drive to Clean" messages and ultra touchy DEF sensors that have been a nuisance so far to date.

According to my local dealer of fleet vehicles...the cab and chassis trucks are much less touchy regarding regens and DEF faults and even have the ability for some driver controlled regen functions. I am not sure what that is exactly because we haven't carried the discussions that far (yet...).

 

there are a few different parts too. like the Turbocharger is the first one to come to mind.

 

That would answer alot if the turbo is different. Also great to know about the H&S controller.

 

Actually as far as parts are concerned, the turbocharger is the only item that Ford shows as different to my knowledge. The other differences relate to exhaust configuration. The narrow-frame (chassis-cab) exhaust starts with DOC - DPF - SCR while the pickup configuration is DOC - SCR - DPF.

The former configuration is designed for improved passive regeneration necessary for extended idling in California. The latter (I think) slightly reduces DEF consumption but requires more frequent active regeneration. Frankly, I don't see any reasons other than maybe physical under-chassis layout constraints for making the truck configuration different from the chassis-cab which is clearly a better (typically used in commercial trucks) approach where fuel economy and low emission are key constraints.

 

Shake-n-Bake hit the nail on the head. Engine dyno testing vs. chassis dyno testing. There is usually a 15 to 20 percent loss of output on a chassis dyno due to the parasitic loss of drivetrain components; transmission, driveshaft, rear axle gears, and tire slippage. The engine is actually using some of it's power just to turn all that weight.
The only major 'parts' difference is the single stage turbo used on the CC trucks. Plus the programming in the PCM is probably a bit different due to the 'heavy duty' use most CC trucks will see.
I looked up H & S Performance and found where they had dyno'd a 2011 Ford and the dyno numbers for a stock truck are about 15 percent less than the factory ratings. Pretty accurate when you consider how controlled the factory dyno sessions must be.