6NZ or Series 60

they just call the 6nz and mbn a C-15, rounded the number up.

 

I have owned and driven both.
I think the Detroit is smoother and I like the way the throttle feels. Kinda reacts like a mechanical engine.
Plus, the cruise is right on the money. No real variance going up and down hills. Smooth increase and decrease of power .

My Cat 6nz has 1.1 million miles. Bought it new . Had a blown head gasket and cracked head fixed under warranty. Otherwise, almost nothing. A turbo and a bad oxygen sensor ( both at around 900,000 miles.
Cat parts are said to be expensive, but I wouldn't know, because I've hardly bought any.

I wouldn't pay $12k extra for the Cat. I would be perfectly happy with a Detroit. But I like a Detroit.

If I bought a glider with a Detroit, I personally would gear it lower than a Cat. Imo, the Detroit needs to turn some rpm to give adequate power, and will still give decent fuel economy. I think I would gear it to turn about 1500 rpm at my typical cruising speed ( about 65 mph.). It would save alot of downshifting.
My Cat has 3.55 rears with an 18 speed that has a pretty tall overdrive. But it has plenty of torque to pull. But I still do some downshifting.
The people I met in the past that were unhappy with Detroit power usually had 3.55 rears with the 12.7.
My old truck had 3.90 rears with my Detroit and pulled great, but wasn't geared to run fast, but would outpull alot of trucks. Plus, not much downshifting.
I guess I don't like downshifting. Maybe I'm lazy.
I enjoyed my low geared Detroit powered truck better.

 

I had a 2000 FL Classic years ago that had a 12.7 in it with 3.58's, that thing would keep up with a 475 1850 Cat until we hit about 40 mph, then he would slowly walk away from me.

 

I park my truck at a local truck shop they work on all kind of equipment from farm trucks to well drilling rigs. The shop can hold 12 trucks. At any given time there will be 4 to 5 cats with bad head gaskets and 1 to 2 being rebuild it just amazes me on the number cats that fail. The owner loves cats they make him tons of money. Really he just rebuild the first ISX cummins of the year last week. This week two cats for oil coolers another for a head gasket one with bad ecm and finally one being rebuild. The best or the one you never see detroit all makes and years. I have been parking here over 3 years it my unofficial study and there is one motor that beats all other for shop time is cat.

 

I guess us guys who never really have issues with them must have unicorn CATs.

 

The only problems I ever had with two I owned were 1 IVA on each and an oil pressure sensor on one. The first one (2005) went just a hair over a million miles before needing inframed. That being said, I always liked the way a Series 60 drove better, and it always got better mileage than the 05 doing the same thing.

 

Our experience has been the opposite. The Cats give little trouble, two of them turned a million miles last year, the one has never been touched other than oil changes and a valve adjustment at 500k.

We also have 4 trucks with the 12.7 Detroit's. All are less than 500,000 mile trucks. One is in the shop getting a rebuild right now, and another just went in today for a turbo. And I think every one leaks oil

 

Detroits always leak oil. And if they arent it means they are out of oil. But then again all my experience is with the 2 strokes. Lol

 

I found them to be honest and straight forward with me. They did as they said they would and were nice people to work with.

 

Before dealing with Fitzgerald and their beautiful rattle can rebuild (pulling a junk engine out of a junk yard truck, painting it, sticking it in your new glider, then blessing you with a warranty to make you feel good). I would look to Harrison for your glider needs. Or D&B if you're looking for a cat. Just looking out for your sanity and pocket book.