Engine Horsepower

500 will get better economy and shave your time quite a bit over 400.

Very big deal if you run the mountains alot.

Nobody likes climbing donners at 20 mph in a 400 motor. The 515 I drove would do 35.

 

I don't think there is much difference between horsepower performance, at least not like people say it is.

I've driven trucks from 425 to 475hp. Not a HUGE range, but totally different performance.

The Cummins X15 475 had 2000ft lbs of torque. That thing would climb a brick wall hauling the building next door behind it. I used the long hill in IL on 57 north as my bench mark test. With this engine and just about grossed out near 80K, I was doing 47mph at the top of the hill. (The slowest the truck went assuming no traffic got in my way on the way up.)

The A26 had 450hp and was doing 32mph at the top of the same hill grossed out at the same weight. That's the EXACT same truck, International LT, 2019, as the Cummins truck.

2022 Cascadia with a DD15 at 450hp. Crested the same hill at the same weight doing 46mph. Basically identical to the Cummins with 25 less hp than the Cummins.

Now I drive a 23 Volvo 860 with a 13L rated at 425hp. When set in power mode, it pulls as hard as the Cascadia, and gets MUCH better mileage than all the other trucks do. I haven't been able to go up that hill yet as I haven't been that way in a long time, but judging from the performance on other hilly roads like 81 up through VA, it would do just as well. At max gross I've outpulled Peterbilts, Cascadias and many many KW's going up hills. So I KNOW they don't weigh more than me unless every one of them is flat out over gross weight, and I'm pulling their teeth out with 425hp and 13 liters.

Oh yea, the Cummins MAYBE got 7mpg. My Volvo can get 12 with a lightly loaded trailer, 15mpg bobtail. And it's by far the smoothest of all the trucks. Its nice because it will automatically adjust the drive mode to the driving conditions. If you set it to power mode, you get it, full rated HP and it comes alive. But once you crest the hill and don't need that, it reverts to economy and the mileage jumps up. Its really such a well built truck. Most reliable one too. Basically 115000 miles and no problems. Had to bring it to the shop once because at the factory they installed a wiring harness with a connector in a bind and our shop goes in and fixes that. Had several trucks do that. They fixed it in a couple of minutes 75000 miles ago and never looked back. My brand new Cascadia had 19,000 miles on it and had to be limped into a shop at 12mph. My two LT's BOTH left me in hotel rooms or at a Loves for 4-5 days for a failed DEF sensor that was out of stock. Had to limp BOTH into a shop at 5mph.

 

350 did the job for years, but it’s nicer to have it and not need it then need it and not have it, an underworked big motor will have a healthier life the. Working the bag off a small motor