CA18DET Slow boost on stage 2 chip

Thread in 'Technical Questions' started by rocett, Jun 9, 2020.

  1. rocett

    rocett New Member

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    Hello everyone i got a problem with my 1991 S13 after instaling Stage 2 (Horsham) .

    For the chip i installed this stuff :
    1. New turbo pipes (60mm)
    2. new Air Filter (K&N RU-2820) with 127mm diameter ,and 76mm exit to the turbo.
    3. New T2860RS (hybrid) (Model 739548-5) :
    -Wheel: 53.90 mm
    -Trim: 76
    -A/R: 0.86
    -stock gate (7 PSI Internal Wastegate)
    4. Manual boost controller (Turbosmart Tee Boost) for making 1.0 bar (around 15 PSI).

    So now on the problem. My car is running nice and seems to be fine but i got boost a wayyy later than expected . I heard that 1bar on that turbo will come around 3300 - 3700 RPM even with the bigger 0.86 A/R on stage 2 cars , but mine hit 1 bar way over 4500 RPM on most of the gears , on 4th its even past 5000 RPM . The turbo is can be heard from 2500RPM and the car start to feel alive a little but till 3600 RPM i dont have more than 0.1 bar reading on the boost meter. On other hand i need to unscrew the boost controller alot to gain 1 bar , and even without the wastegate vacuum unplugged i cant read more than 1.0 bar of boost. I measure boost of the intake manifold (http://www.driftopia.com/images/uppermanifoldvacuumsmall.jpg with Number #3 on the pic) .

    The other noticable issue is that i hear strange noise from the turbo on low RPM (before boost) then it
    disappears, and its kind of like bearing rattling but the turbo is new and it was in perfect condition even after i head the sound and took it off to check the fins. Here is some video of the sound (ignore the fucked up gasket noise)



    Here are some 3rd gear pulls to see the problem (one with 0.5 bar , and another with 1.0bar):

    - 1.0 bar.

    - 0.5 bar.
     
  2. r3k1355

    r3k1355 Well-Known Member

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    You shouldn't be running that chip with that Turbo
     
  3. rocett

    rocett New Member

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    Okay that is my bad but isnt T2860RS in the T28 family or i'm wrong, i mean i know that this chip is for T28 but isnt that turbo a T28 ?
    Have i done something wrong with the chip build ?
     
  4. ludi

    ludi Active Member

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    The chip is for a T28, not for a GT2860RS with .86 Housing. Do you have a AFR-Gauge? I think your car run very lean on full throttle. For better boost response you should use a electrical boost controller like Blitz DSBC Spec R.

    Best Regards, ludi
     
  5. rocett

    rocett New Member

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    Okey, i dont have that gauge yet cuz i need to buy new wideband kit . What it the turbo that is called T28 then (rly i have no idea now) and what can i do to me save the T2860RS cuz i spend a lot of money for it and cant just trow it in the garage.

    Sorry if im stupid or sth its my first project car and even when i read i read hundreds of different comments on same stuff.

    upload_2020-6-12_11-8-31.
     
  6. thebe

    thebe Member

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    On Horsham website the stage 2 specs clearly state "t28 from s14" meaning the OEM "T28" turbo from s14 200sx. Your turbo is a completely different unit with different specs, wheel sizes etc so it won't work properly and by boosting it and driving hard on it you are probably going to destroy your engine. You might get away with baby driving it off-boost but Its not really advisable. Or fun.

    Right now 2 options come to mind:

    1. Get rid of the chip and get a tunable ecu and get your car properly tuned for your setup. Nistune is a good cheap option.

    2. Replace parts so you meet the Horsham chips specs precicely.
     
  7. Bolf

    Bolf Resident Nut Job.

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    fit a nistune or better , tune , and monitor

    currently that chip is doing more harm than good.
     
  8. Bolf

    Bolf Resident Nut Job.

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    also if your ca18 is rattling at around 2300 , don't use it anymore and have the bearings sorted
     
  9. r3k1355

    r3k1355 Well-Known Member

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    They're all the same family, but yours is much larger than the turbo you are supposed to be using.
    The Chip needs the OEM turbo off a S14, you can get away with the S15 turbo also as it's pretty similar in size.

    Thats the GT2560R
     
  10. rocett

    rocett New Member

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    Okey ty so much for the info , i got it now , i rly dont know much about turbo but i was told that the 2860RS was the best in the family for CA18DET till 300HP , and there wasnt big difference between turbine wheel like 10 mm (now i know its much) .

    May i ask if i want to fit Stage 3 will i get better results or i still need to fit GT2560R or are there any other turbos like TD04 or sth ?? (i'm asking because i neet to buy it new and in my country one new is 1.5x times of my monthly income)
     
  11. thebe

    thebe Member

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    If you want to get serious with tuning forget the generic "stage x" chips and get a decent tunable ecu, for example Nistune. Or whichever ecu you can get tuned somewhat near you. Then you can fit any turbo you want without having to limit yourself to said chips specs. There are plenty of good turbos that won't break the bank. For example for the price of a new Garrett you can propably get a new holset and a Nistune ecu.

    When tuning cars you cant really spend money better than on a decent ecu and a good tune. And they arent really even expensive when looking at the big picture
     
  12. rocett

    rocett New Member

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    Okey, thank you so much for the info , that help a lot and i rly need to change my priorities. :thumbs::worthy:
     
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