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Thread: CA18DET Boost Spikes and Falls off

  1. #1
    Guest forpanos's Avatar
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    Smile CA18DET Boost Spikes and Falls off

    Hello everyone.!
    I have a 200SX S13 with a CA18DET. I have an aftermarket turbo back, free flow exhaust without a cat (70mm diameter), free flow filter, an Innovate SCG-1, turbosmart fuel pressure regulator and a aeroflow fuel pump.
    The car is not tuned, and has the stock intercooler, but afr's look good.

    My problem is that while I'm trying to achieve 0.85-0.9bar of boost (stock ca18det t25 turbo), midrange is perfect at 3.500-5.500rpms but as the revs go up, after 6.000rpms I'm hitting 0.4-0.5bars of boost. I've changed the actuator with an uprated one from hks but didn't do anything. Is there something I can check? or is it normal for a stock t25?

    Thank you in advance!

  2. #2
    Dorset & Hants Rep pointz's Avatar
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    You're running 0.9bar of boost through the stock small turbo, its going to drop off.

    Get a t28 or t28r on it, bin the likely leaking intercooler and get a tune.

    Afr may look fine but does your afr gauge tell you when the engines suffering knock?

    Sent from my SM-G960F using Tapatalk
    Last edited by pointz; 15-01-2021 at 07:40.

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    Guest forpanos's Avatar
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    I knew it's normal to drop off, but I wondered if that much amount (close to 0.4 bar) is normal. Knock isn't from bad afr's, high intake temps and low grade fuel? I'm running 100 octane on the car just to be safe. Thanks for your reply!

  4. #4
    Dorset & Hants Rep pointz's Avatar
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    Do a pressure test on the intercooler and pipework, these cars are 30 years old the intercoolers are prone to leaking.

    No knock isn't from bad afr necessarily

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    I've done a test up to 1 bar a couple of times. All good and no leaks. Is it normal to have such a drop off?

  6. #6
    Guest arry's Avatar
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    I'd say that's not unusual and is a factor of the turbo parameters and the restrictive wing mount intercooler. It's perhaps a little lower than I'd expect, but not by much.

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