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NCT smoke test vs rev limiters.

  • 27-07-2018 08:46PM
    #1
    CiniO
    Registered Users, Registered Users 2 Posts: 16,041 ✭✭✭✭


    I started wondering how do they go around that.

    NCT during smoke test on diesel cars need to rev them to high RPM (near red zone).
    But many modern cars have rev limiters, which f.e. don't allow to rev engine higher than 2500 or 3000rpm on neutral even if you press accelerator pedal to the floor.

    How does NCT deal with that?


Comments

  • #2
    ION08
    Registered Users, Registered Users 2 Posts: 2,525 ✭✭✭ION08


    I dont think redlining the car is a requirement. Usually only up to around 2000 to 3000rpm

    Edit: “Where a vehicle’s engine speed is limited when the vehicle is stationary, the smoke test may be carried out at the restricted rpm“

    Ahh the wonders of the internet :D


  • #3
    10-10-20
    Registered Users, Registered Users 2, Paid Member Posts: 10,008 ✭✭✭✭10-10-20


    I think that the petrol versus diesel test-method differs, with the diesel being brought up to the max-RPM (where diesel will simply not over-rev) and perhaps petrol is only brought up to ~3000 RPM, as pointed out above. I know that they do not red-line the petrols, but you have to sign a disclaimer about the diesels (due to the RPM's).
    My Alfa 156 was so damn smokey before I treated it with Dipetane that it filled the hall with dense smoke and the test-technician had to turn on the air extraction system for about 30 seconds to clear it. All of the other test-technicians backed away and laughed. Who knew that would have failed the NCT...?


  • #4
    almostover
    Registered Users, Registered Users 2 Posts: 3,423 ✭✭✭almostover


    CiniO wrote: »
    I started wondering how do they go around that.

    NCT during smoke test on diesel cars need to rev them to high RPM (near red zone).
    But many modern cars have rev limiters, which f.e. don't allow to rev engine higher than 2500 or 3000rpm on neutral even if you press accelerator pedal to the floor.

    How does NCT deal with that?

    If you turn off the traction control on my 2009 Passat tdi you can review the b*ll*cks off it! Not sure do the NCT testers do this?


  • #5
    mikeecho
    Registered Users, Registered Users 2 Posts: 5,520 ✭✭✭mikeecho


    10-10-20 wrote: »
    .......but you have to sign a disclaimer about the diesels (due to the RPM's).......

    I had my diesel tested last week.. and I didn't sign any form.

    The revs aren't limited by speed, so the tester could rev to the red line if he wished.

    Btw. . The smoke test result was 0.01, the max allowed was 1.5


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