So our DP sold and we are shopping for our "upgrade". Engine size is one of the things we want to improve. I see the following in an ad:"THE 8.3 LITER CUMMINS 360 HP ENGINE HAS BEEN RE-RATED TO 425 HP AND GETS 2 MPG BETTER FUEL ECONOMY. "Can anyone shed some light on this? What is done to magically change the HP other than some creative typing?As always, thanks in advance.

I'm sure they added a "chip" to increase HP. On my ISM, which is rated at 500HP the chip increased the HP to just a tad over 525HP. Did it change anything..? Well it lightened my wallet a bit but no noticeable change in power or mileage....Dennis

LongWeekends wrote:So our DP sold and we are shopping for our "upgrade". Engine size is one of the things we want to improve. I see the following in an ad:"THE 8.3 LITER CUMMINS 360 HP ENGINE HAS BEEN RE-RATED TO 425 HP AND GETS 2 MPG BETTER FUEL ECONOMY. "Can anyone shed some light on this? What is done to magically change the HP other than some creative typing?As always, thanks in advance.More than likely, a "BANKS" programer, that changed the fuel schedule to allow lower fuel flow at low power settings, and more fuel flow at max power.

I have an Edge on a Duramax, increased by 40 hp and fuel mileage went from 13.5 ety to 17-19 ety and 10.8 loaded at 67 MPH and GVW 20000 lb.

If you want 425 HP, look for the 8.9L ISL. Without changing the injectors and the turbo a 8.3 is already pushing it's max at 360. In PU's much of the mileage increase by a chip is done by increasing the tire size in the computer... making it LOOK like you've gone more miles than actual.

Ivylog wrote:If you want 425 HP, look for the 8.9L ISL.Another vote for the ISL. Ours is rated per factory specs at 400HP, but can be chipped easily to 450HP.

HP question on a Cummins 8.3 | Good Sam Community

prstlk
Explorer
Feb 05, 2016
Chipped rigs can also be worth less on trade in or outright sale. Some of us have concerns about reliability. I'd take a box of donuts to your local cummins dealer and ask some questions 360 to 425....thats sounds to good be true.
barmcd
Explorer
Feb 05, 2016
I don't think an 8.3 can reliably put out 425 hp. That doesn't mean this particular engine might be unreliable. It might not be putting out 425 hp.
tinkerer
Explorer
Feb 05, 2016
One thing to remember when you do anything to increase the hp of your motorhome you will increase the heat the engine produces and if the radiator remains the same size you could overheat your engine which can be detrimental.
sch911
Explorer
Feb 05, 2016
Ivylog wrote:
If you want 425 HP, look for the 8.9L ISL.

Another vote for the ISL. Ours is rated per factory specs at 400HP, but can be chipped easily to 450HP.
Ivylog
Explorer III
Feb 05, 2016
If you want 425 HP, look for the 8.9L ISL. Without changing the injectors and the turbo a 8.3 is already pushing it's max at 360. In PU's much of the mileage increase by a chip is done by increasing the tire size in the computer... making it LOOK like you've gone more miles than actual.
Passin_Thru
Explorer
Feb 05, 2016
I have an Edge on a Duramax, increased by 40 hp and fuel mileage went from 13.5 ety to 17-19 ety and 10.8 loaded at 67 MPH and GVW 20000 lb.
Tom_Barb
Explorer
Feb 05, 2016
LongWeekends wrote:
So our DP sold and we are shopping for our "upgrade". Engine size is one of the things we want to improve. I see the following in an ad:

"THE 8.3 LITER CUMMINS 360 HP ENGINE HAS BEEN RE-RATED TO 425 HP AND GETS 2 MPG BETTER FUEL ECONOMY. "

Can anyone shed some light on this? What is done to magically change the HP other than some creative typing?

As always, thanks in advance.

More than likely, a "BANKS" programer, that changed the fuel schedule to allow lower fuel flow at low power settings, and more fuel flow at max power.
Executive45
Explorer III
Feb 05, 2016
I'm sure they added a "chip" to increase HP. On my ISM, which is rated at 500HP the chip increased the HP to just a tad over 525HP. Did it change anything..? Well it lightened my wallet a bit but no noticeable change in power or mileage....Dennis

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