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Thread: OverBoost on Track + Just in Case Questions

  1. #1

    Default OverBoost on Track + Just in Case Questions

    Took the car to Laguna Seca yesterday. Everything was fantastic, and given that I don't run the car at WOT that often on street the car felt FAAASSST.

    Checking the video logs, Boost seems to surge to 1.5Bar then taper to 1.3-1.4. I couldn't hear any knocking, temps stayed consistent, and the car was full of 101 Octane. I think luckily there's no long term harm (knock on wood), but not I can't find the source of the overboost itself. No vacuum lines missed, no obvious wastegate malfunction. The car was recently tuned by Troy, and not a single Dyno hickup that day, so a bit confused here - any other sources to check for? The car did need a jump start in the morning (needs a new battery) but I wouldn't think any ECU settings could have changed.

    Additionally, if I did do long term damage - what's the best source for a new AER crate engine? Anyone still have a supply of these sitting around for reasonable cost? I'm likely to want a spare given I'll remove and retouch the engine bay frame and apply new heat-coatings.

    - Chris

  2. #2
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    i have motors in stock

  3. #3
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    In reply to Mr. Gafernandez, please tell us more about your motors. What state are they? Are they similar to or better than that of the AER prepped motors? And lastly, what is your price for a ready to bolt in unit? Thank you.

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    Do you have an adjustable boost controller? Probably yes if your car is tuned.

    If so, it probably has a setting to level out the boost called 'spike stop' or something similar to prevent transient over pressure while building boost. You can play around with my boost controller quite a bit, but I found that problems get worse the higher boost you run. I have nearly zero boost spike at my current setting (0.92 Bar). I dialed it back for pump gas and have had no issues. You also need a blow off valve it you are routinely running that much boost and closing the throttle abrubtly such as on the track. You will get turbo stall and pressure spikes if you don't have one plus turbos won't stay spooled up for next time on gas so you'll have more lag.

    Another issue may be the pressure/vacuum tubing length from manifold to sensor (if it goes to a remote sensor, if sensor is right on manifold and then no issue). If tubing is long and narrow, it acts to delay pressure changes at the controller which can also lead to transient overboost until pressure evens out at whatever max boost is. I can actually have some boost oscillation on my car at the boost you are running with WOT due to this. If the tubing is kinked in any way on the way to controller/sensor it will also have this effect.

    be careful with that much boost routinely. If you need it, run it... but if it is just for fun I would back off a tad to make everything last a bit longer even if it runs fine.

    As an aside, you car is probably dialed in fine and the boost spike you have is probably normal for the tuning. You may not be able to tune it any better than what you have even if you mess with the boost controller.
    Last edited by esrandl; 11-26-2018 at 06:07 PM.

  5. #5

    Default

    Quote Originally Posted by esrandl View Post
    Do you have an adjustable boost controller? Probably yes if your car is tuned.

    If so, it probably has a setting to level out the boost called 'spike stop' or something similar to prevent transient over pressure while building boost. You can play around with my boost controller quite a bit, but I found that problems get worse the higher boost you run. I have nearly zero boost spike at my current setting (0.92 Bar). I dialed it back for pump gas and have had no issues. You also need a blow off valve it you are routinely running that much boost and closing the throttle abrubtly such as on the track. You will get turbo stall and pressure spikes if you don't have one plus turbos won't stay spooled up for next time on gas so you'll have more lag.

    Another issue may be the pressure/vacuum tubing length from manifold to sensor (if it goes to a remote sensor, if sensor is right on manifold and then no issue). If tubing is long and narrow, it acts to delay pressure changes at the controller which can also lead to transient overboost until pressure evens out at whatever max boost is. I can actually have some boost oscillation on my car at the boost you are running with WOT due to this. If the tubing is kinked in any way on the way to controller/sensor it will also have this effect.

    be careful with that much boost routinely. If you need it, run it... but if it is just for fun I would back off a tad to make everything last a bit longer even if it runs fine.

    As an aside, you car is probably dialed in fine and the boost spike you have is probably normal for the tuning. You may not be able to tune it any better than what you have even if you mess with the boost controller.
    Found the issue. Those vacuum boost hoses were dead tight on either end, but the center of the hose had become brittle and cracked from all of the heat-cycling. Boost problems solved and now back to 1.1 BAR per Troy's original Tune. Replaced both hoses with new hose and retightened all clamps.

    Thanks -
    - Chris

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    Jimbo986
    They are ARE motors that have rebuilt nothing better, Just new pistons, rings, oil pump, timing chain, bearings, and gaskets, Fresh Long block ready to install. Price is $5700 plus shipping. I always have one ready to go

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    Nice, thank you. I just PM you my phone and email. I could be interested in one of those guys if you are willing to sell.

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