Cat 350 HP vs Cummins 360 HP

[LaWandaJo]

I am looking to move up to a larger coach. Currently have a National RV Tropi-Cal 370 with a C-7 Cat 350 Turbo. I'm looking at a Tiffin Phaeton 42 with a Cummins 360 HP. My question is, does the Cummins have more torque? My Tropi-Cal bogs down to a crawl & over heats when pulling up a mountain towning a car hauler trailer with car. Any advice is always appreciated.

Michael Swinea

Pegram, TN

[bobbyks]

I had a Cat 350 in a 40' Damon, now own a 45 ' Mandalay with 425 Cummins towed 4 WD Jeep Wrangler with both, the Cummins was much better in Mtns. and flat land travel and performed better. I never had any problem with the Cat engine but I like the Cummins better.

[BillO]

I suggest that you probably need to do a little research with Cummins (or other Tiffin owners with comparable power plants) to find out specifically which engine is in that Phaeton and what torque it produces. If you have a specific Phaeton in mind, then a quick call to Cummins with engine model and serial number should give you the torque. You can do the same with your CAT engine at the CAT hotline and compare the two, making allowance for differences in MH weight.

The engine makers play so many games that horsepower isn't much of a measure (i.e. smaller displacement and torque at higher RPMs yields the same HP as big displacement/torque at low RPM). They can also rate the same engine in a range of HP without significantly changing the torque. I took a quick look at the Cummins MH page here and see a couple different engines that could be rated at 360 HP with torque between 800 (ISB) and 1050 (ISC) lb-ft. The ISB would be at the high end of HP rating as would the older ISC. The newer ISC8.3 (EPA 2010 rated) would be at the lower end of potential HP rating.

I couldn't find a similar page for CAT engines, but a brief internet review suggests that your C-7 CAT is at the high end of HP range and similar to the ISC (the older one I'm guessing).

Just by way of illustrating the HP fallacy, my old coach has a CAT 3176 (loosely, the grandad of the C-12) that is also rated at 350 HP, but produces almost 1400 lb-ft of torque. From the stats that I've seen, newer Cummins MH engines need to be in the 450+ HP range to match that torque. That results from the fact that my engine is an older big block at the lower end of potential HP ratings that went up to around 400.