6NZ vs 3406E

Discussion in 'Trucks [ Eighteen Wheelers ]' started by areelius, Sep 27, 2013.

  1. areelius

    areelius Light Load Member

    Nov 9, 2012
    Temecula Ca
    Can someone explain the differences in a 6nz and a 3406E. What years they were used and the minimum and maximum horsepower ratings? Also durability differences. I am considering buying a CAT powered truck and I want to get the best engine available.
  2. fuzzeymateo

    fuzzeymateo Heavy Load Member

    May 20, 2013
    There's some threads on here specifically about the 3406e and 6nz. Both very good engines from what I read. I believe the 6nz came after the 3406e sometime around 2002? Could be wrong on that though. Keep in mind that these are both pre-emissions engines and you won't be able to run them legally in the state of CA.
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  3. superhauler

    superhauler Super Crusty

    Jan 30, 2010
    both are virtually the same. the 6nz's have a better gasket setup on the front and rear structures. 2ws's are a strong block. 1lw's are a good one 5ek's ok as long as you don't go wild with them. but in cali good luck with carb.
    Oxbow, CbarM and areelius Thank this.
  4. ModZZilla

    ModZZilla Bobtail Member

    Sep 22, 2013
    6NZ used in 2000 year trucks, 15.8L, single turbo, 70 pin ecm, some say the best truck engine ever built.
    3406E used from 1993 to 1999 year trucks, 14.6L or 15.8 on 600hp models, 40 pin ecm to 1998, 70 pin in 1999. also very good engine.
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  5. poppapump1332

    poppapump1332 Road Train Member

    Jan 2, 2010
    Although isx cummins is best available in today's market the 3406e would be my choice good motor except for fuel mileage.
  6. bull hauler

    bull hauler Medium Load Member

    Apr 23, 2012

    Have to disagree mate on bad mileage, im at 6.5 mpg with my 1995 5ek 3406e, and im pretty confident im gonna b close to 7 after my last mod gets done this weekend. IF u get them tuned up right they have good power and can get good mpg. Before i did any mods it was 5.4 stock

    A bud has 6nz and refuses to do any aftermarket mods to it and cant get better than 4.8, if u get a stock one be prepared to throw some $ at it to get er runnin like u want.

    I wouldnt sell my truck for any amount of money, i will keep rebuilding over and over
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  7. BigJls1

    BigJls1 Medium Load Member

    Dec 25, 2012

    pretty sure the 6nz was also a 14.6 and the 7cz was the 15.8L (c16), but hey throw it out like its a fact!.
    Oxbow, insertnamehere and Cetane+ Thank this.
  8. underpsi

    underpsi Road Train Member

    Sep 18, 2008
    Toronto, Ont
    6NZ is a 14.6L. 3406E's were used in the 2000's. 40 pins in the 99 and 70 pins introduced in 99 as well.

    3406Es are prefix's 5EK (14.6L), 6TS (14.6L), 1LW (14.6L), 5DS (15.8L) all 40 pin ecms. 2WS (14.6L), 1MM (15.8L) 70 pin ecms.
    C15s are prefix's 6NZ (14.6L), MBN (14.6L), 7CZ (15.8L) all 70 pin ecms
  9. j-dawg

    j-dawg Light Load Member

    Dec 21, 2011
    Oil town, Ab
    This is the kinda thread that makes truckers report so great. Guys helping each other. Awesome
    Nolelover61 and blade Thank this.
  10. Mr. Haney

    Mr. Haney Road Train Member

    Dec 17, 2008
    The 435 to 550 Hp engines in both the 3406E 14.8L and C-15 6NZ are very similar in internal parts from the 1LW serial number to the 6NZ. The 3406E 5DS and 1MM, along with the C-16 7CZ are identical in internal parts. The 1MM 15.8L 3406E and 2WS 14.8L 3406E went to the newer electronics know as ADEM II or 70 pin ECM. Otherwise they are basically the same engine as the earlier 40 pin 1LW 14.8L and 5DS 15.8L engines

    The main difference between these engines is Cat changed the gasket sealing of the oil pan, front structure cover and flywheel housing to facilitate less oil leaks over the life of the engine. The 3406E started having engines leak oil at the front structures after they had 750,000 miles on them. By a 1.3 million they need to be rebuilt to stop the oil from running out of them. There were also some gear changes under the front cover to help longevity on the C-15/C-16. But the main internal parts to build Hp are basically the same for these engines. Different Hp,lower levels on the earlier engine usually had smaller turbos then a 550 Hp engine would. I don't remember the serial number break on the 6NZ, I think it was 6NZ5400 and higher. Whether it was a 435 or a 550 they use the same turbo, so they had all of the same hardware, the only difference was the file in the ECM. CAT did this to make it easier on their inventory requirements and for the customer to be able to uprate at little expense.
    Oxbow, Nolelover61, MTownZ and 13 others Thank this.
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