3500 Work Truck: 322hp Why?

QUIKAG · July 10, 2011

A buddy got a new 3500 work truck with a flat bed and it has a 322hp 6.0. What is the difference between this engine and the other 6.0 engine in other 3500 trucks that make 360hp? What are the differences and why does GM have a derated engine in the work trucks?

Zembonez · July 10, 2011

Possibly a cam difference biased toward torque? I'm only guessing here. A lot can also be done by tuning the electronics.

Doug_Scott · July 10, 2011

A buddy got a new 3500 work truck with a flat bed and it has a 322hp 6.0. What is the difference between this engine and the other 6.0 engine in other 3500 trucks that make 360hp? What are the differences and why does GM have a derated engine in the work trucks?

HP is a number derived from torque, rpm and a constant number (5252). The 3500 shows HP at 4400rpm, the 2500 shows HP at 5400 rpm. Given that both have the same torque at 4200 (380), I would think both engines will also have the same HP 200 rpm later. I think you will find they are just rating the HP at a lower RPM for some reason on the 3500.

MS3DALE · July 10, 2011

All 3500's get the reduced HP and TQ.,where as the 2500's it depends on if you have the bed-delete option or not....

Heres the descrition from the 2011 truck order guide for the 2500's....

L96 Vortec 6.0L Variable Valve Timing V8 SFI (360 hp @ 5400 rpm, 380 lb-ft of torque @ 4200 rpm) with (E63)

fleetside pickup box; (322 hp @ 4400 rpm, 380 lb-ft of torque @ 4200 rpm) with (ZW9) pickup box delete.

On the 2500's it doesn't have anything to do with the fact if its a "work truck",It depends on if the truck was ordered as a chassis-cab or "bed delete" (RPO "ZW9") option,it has to do with emissions and federal regulations.

Same way with the new Duramax's,If you get one in a regular truck with a bed it has 397hp and 765 lb-ft tq.

If you get one in a chassis-cab it has 335hp and 335hp and 685 lb-ft tq.

tanked_darren · July 10, 2011

All 3500's get the reduced HP and TQ.,where as the 2500's it depends on if you have the bed-delete option or not....

Heres the descrition from the 2011 truck order guide for the 2500's....

L96 Vortec 6.0L Variable Valve Timing V8 SFI (360 hp @ 5400 rpm, 380 lb-ft of torque @ 4200 rpm) with (E63)

fleetside pickup box; (322 hp @ 4400 rpm, 380 lb-ft of torque @ 4200 rpm) with (ZW9) pickup box delete.

On the 2500's it doesn't have anything to do with the fact if its a "work truck",It depends on if the truck was ordered as a chassis-cab or "bed delete" (RPO "ZW9") option,it has to do with emissions and federal regulations.

Same way with the new Duramax's,If you get one in a regular truck with a bed it has 397hp and 765 lb-ft tq.

If you get one in a chassis-cab it has 335hp and 335hp and 685 lb-ft tq.

Why?

edit: nevermind

MS3DALE · July 10, 2011

Yeah I don't quite understand it all myself Darren,I was just told it had to do with certification for emissions,and something about how if a truck is built as a chassis-cab they (GM) don't know what bed or body is going to installed on the chassis,therefore they have to de-rate the engines hp/tq output,again why I don't know quite all the details.

QUIKAG · July 11, 2011

Thanks for the info. I wonder what power the derated engine makes at the same rpm as the advertised 360hp model. I wonder if it's 360 too but they report at the lower rpm for some regulation reason? The 380 torque being the same at the exact same rpm on both the regular and derated engine certainly raises eye brows.

markw8 · July 11, 2011

I would wager that durability is the reason for the derating. Most of these go into commercial use. Companies want them to last, not be fast. They likely would have less overall warrenty claims.

Mark

C/K Man · July 12, 2011

A buddy got a new 3500 work truck with a flat bed and it has a 322hp 6.0. What is the difference between this engine and the other 6.0 engine in other 3500 trucks that make 360hp? What are the differences and why does GM have a derated engine in the work trucks?

HP is a number derived from torque, rpm and a constant number (5252). The 3500 shows HP at 4400rpm, the 2500 shows HP at 5400 rpm. Given that both have the same torque at 4200 (380), I would think both engines will also have the same HP 200 rpm later. I think you will find they are just rating the HP at a lower RPM for some reason on the 3500.

That is correct. The difference is at what r.p.m.. For some reason, horsepower ratings are taken at a different r.p.m. for trucks over a certain G.V.W.. The engines are the same. Same thing with the Ford 6.2L in an F-350.

pm26 · July 12, 2011

Also, the Duramax engine is offered in Chevy Express 2500 and 3500 series vans, but it has much lower HP and torque ratings than in the pickups. This may be due to the fact that they do not use the Allison transmission in the vans (not sure about that though) and the transmission they use is not rated for the almost 800 ft-lbs of torque that Duramax puts out as installed in the pickups. It is easy to derate the engine just by tuning and lowering the fuel flow rate.