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6NZ or Series 60

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I know Kevin and most others prefer the series 60, as do I. But, if you had a 6NZ in a Peterbilt, would you be better off rebuilding it with all the tricks, or find a series 60 to build and replace. I don't need yellow versus green arguments. I want an honest opinion. Cats cost more to build and generally don't get the mileage that a series 60 gets. But, which would provide the best Return On Investment.

Let me clarify my question. The truck is a 387 Peterbilt and fuel mileage is number one goal. What I was trying to get opinions on was this. If you had the choice, with similar modification, which motor would you choose? Please answer on the basis of fuel mileage and operating costs.

Your,

HWD, did you see my comment below about the two trucks to follow on fuel gauges? That will help you a lot with operating costs.

Chris Hileman,

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biker11566
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i have had cats an detroits,i believe they are both good engines an as for the cost to rebuild i dont believe there is much differance,i have rebuilt 1 cat an 1 detroit,sorry the cat was cheaper,if you drive the cat right you will get good fuel milage,i was getting 6.5 mpg with my cat pulling liquid,an i dont think would be worth changing all the wiring to put in a detroit

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Zachary Bell
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I like both as long as the Detroit was built before the advent of EGR. They're both great motors, and should have similar cost to rebuild. If you already have the CAT, I suggest rebuilding it instead of going and getting the DETROIT and having to get new wiring harnesses. It'll be worth your investment. If you spec the inframe kit right and do all the tricks (Pittsburgh Power ECM upgrade, OPS, MicroBlue, performance muffler, etc...) you'll get a fantastic truck that can pull your biggest loads AND get great fuel economy- even with a Pete 379 or KW W9xx.

Also, when it comes to truck engines, remember there is no replacement for displacement- a CAT C15 6NZ is a 15 liter, a Detroit Series 60 is a smaller engine (usually a 12.7 or 14.0 liter) so if you want to go with a Detroit for fuel economy, it's a good idea to spec a more aerodynamic truck along with the engine (the truck I would choose is an older (pre-2001) Volvo (like my WhiteGMC/Volvo W1A64T ES), but an older KW T800, KW T600, or Pete 377 (pre-2000) will be just as good).

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fivestartransfer
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I think its just a matter of math, and how much you want to spend. You should calculate what the cost of the rebuilt will be, including down time, on both engines and compare the numbers for both engines, I would think if you can afford to get the inframe kit with MicroBlue that would help get more efficient engine but the question is by how much and is it gonna be worth it. And once you have hard numbers for both options you may ask yourself if either one is worth putting the time and money into a Pete. If you are concerned with fuel economy, you may be better off getting an aerodynamic truck that gets good milage for the money you will spend on a series 60 or inframe. without knowing all the details of your operation and costs for each options, only you are able to make a logical decision.

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brandtgeiger
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I thought the 6NZ is that cat motor Bruce from Pittsburgh Power said if you ever find one get it. I never had Cat but remember them talking about one cat made was better then all the rest and not easy to find much more

I don't know if they are rare or not, seems like every logger or cow hauler on the west coast has one. LOL. Seriously though, I know a lot of people that have them in NorCAL.

Chris Hileman,

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dhshew
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I pull a bullwagon, mostly, with a 2000 Pete 377(3.70 rears, lp 24.5 rubber, no aftermarket stuff). Bought it used with a 12.7 series 60 with a 10 sp od behind it. Drive from speed limit (CA) to balls out (hey, it's a bullwaqon). Always got 5.8-6.1 on quarterlies. Inframed it at about 850K. Then the trouble began. After two more rebuilds in short order, jerked it out and dropped in a used no story 6NZ. It was clean and we set it at 550 hp with advanced parameters. Quarterlies since have been 6.3-7.3. Pulls 80K with little effort. Recently installed used low time 18 speed. SWEET. Geat for off-highway. No question, I would rebuild this engine when the time comes. Just my opinion. If you decide to switch engines, let me know. I'd be interested in your used 6NZ. See ya.

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Chris Hileman
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If you want a good comparison look up my truck and my friends truck on fuel gauges. My trucks name is "chris 350" and my friends truck is "ezmoney". We both run the same routes and haul the same loads, our trucks are spec'd close to the same, mine is a series 60, his is a 6NZ.

Edited by: Chris Hileman ( )

We both have Fleet Air Filters and OPS1.

Chris Hileman,

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jeremymacfarland
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Why does everyone on here think a Pete 387 is a non aerodynamic truck? I have a 01 387 with a 6NZ 475 hp 10sp 3.55 i have pitts power muffler fleet air filter and yokahoma ry617 tires all around. I get great fuel mileage. Last quarter average 7.95 pulling vans and refers. When I pulled a 7 car carrier from Boston to Miami for 3 years I averaged 7.5mpg I always weighed 65-70000 pounds. I'm on fuel gauges but only logged about 15 receipts I think my name is jeremymac on there.

I recently bought a 2000 international 9200 midroof. 12.7 430hp Detroit 10 speed direct drive 2.64 rears recap tires. My driver and I run in convoy now pulling belly dumps. Same speeds same weights at the same time. We fuel up together too. When we deadheaded the belly dump trailers to north Dakota I got 9.0mpg in the Pete he got 9.2mpg in the international. The difference was like 5 extra gallons. Since we have been here he continues to use a few gallons less than me every tank. But he also has a direct drive tranny pushes less air with the midroof and lower rolling resistance tires on his trailer.

I think the Detroit will do better light and empty but the cat will do better loaded heavy. It's close but I would stick with the cat since its in there and the return on investment on fuel cost alone would take forever. You can get great mileage out of that Pete with that 6nz.

Probably confusing 387 with a 389 would be my guess.

Cliff Downing,

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Mel Help
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I would go with the 6NZ Cat myself. I've never own a 6NZ Cat but I've own a 3406 B model Cat and the first electronic cat in 1990 which was 3406 then a E model Cat and now I have Series 60 I would take my E model back in heart beat. I don't dislike my Series 60 I have but would much rather have my Cat engine back.

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supercharged100
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you can't go wrong with either before emissions if you run california you'll need a 1995 engine,if you don't get either before emissions.i like cats,but that is a personal preference

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dynamo440
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HWD, What engine does your 387 have currently? i hav and 06 387 with an ISX that was inframed at 520k and never ran good after that. Now at 750k it has a cracked head again! I am seriously swapping to a 6NZ or series 60. Just wondering if you know what is involved in the swap.

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Your
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what about an N-14 celect plus cummins?

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Your
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The cost of the swap will change your mind. I swapped from an ISX to a 6NZ and the cost was way more than I anticipated. Your better off sticking with the Detroit because you will have better fuel mileage in the long run. And the overhaul will not be near as much as the swap.

Sorry went back and read your question. If you have a cat already I'm not sure the cost of the swap

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orourkesean15
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speaking as a cat man.stick with the cat.we rebuilt a 5EK 575hp at the flywheel 480 to the ground.2012 coronado first fuel up 5mpg,in heavy snow got stuck.not good trucking +14F idled.will not be satisfied until i get 8 mpg.fleet air filter on it's way.sending ecm to pittsburgh power in spring.stick with the cat.my other truck would have been below 5mpg

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