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  1. #11
    Quote Originally Posted by mittens View Post
    that is not correct. A 2 bar map sensor can read up to 29.4 psi.... but atmospheric pressure is 14.7.. so a 2 Bar map sensors can only read 14.7 psi above atmospheric pressure/boost.

    a 3 bar is needed for 14.7- 29.4lbs above atmosphere/boost.

    look it up.

    that being said.
    When I read a tuner (Dean or Jesus whom ever) says they can tune it based on a 2 bar when the ski is pushing more then 14.7lbs of boost. I read it as "I will follow the linear graph I see with boost vs rpm and fuel needs (as boost and rpm are directly related) and will faten the tune appropriately to be close on anything above 14.7lbs."

    but the correct answer is to have a tune set up to add fuel for the air/boost it measures and not guess on the top end. Granted causes customers don't want to buy more parts and we want to go fast cheaper. But it is what it is.
    This is what I was getting at but said much better


  2. #12
    JESUS G's Avatar
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    Quote Originally Posted by mittens View Post
    that is not correct. A 2 bar map sensor can read up to 29.4 psi.... but atmospheric pressure is 14.7.. so a 2 Bar map sensors can only read 14.7 psi above atmospheric pressure/boost.

    a 3 bar is needed for 14.7- 29.4lbs above atmosphere/boost.

    look it up.

    that being said.
    When I read a tuner (Dean or Jesus whom ever) says they can tune it based on a 2 bar when the ski is pushing more then 14.7lbs of boost. I read it as "I will follow the linear graph I see with boost vs rpm and fuel needs (as boost and rpm are directly related) and will faten the tune appropriately to be close on anything above 14.7lbs."

    but the correct answer is to have a tune set up to add fuel for the air/boost it measures and not guess on the top end. Granted causes customers don't want to buy more parts and we want to go fast cheaper. But it is what it is.

    Well... You are about right....

    But but it's not necessary to run a 3 bar map sensor even if your boost goes over 20Psi. There is different ways to adjust the fuel, and yes , boost is related with the RMP and fuel, but also the TPS.

    In racing ( using aftermarket ECUs, Motec, Autronic, Vipec, etc....) many tuners use RPM vs TPS to set the ignition and fuel. So in the end is about to log everything and be sure you get the AFR you are looking for in every RPM range and situation.

    So using a 3 bar map sensor when you set the fuel : RPM vs Boost, could be more accurate than using a 2 bar map sensor.

    But if you are able to set the fuel also vs TPS and rescal the RPM axis, then you will get same results.... It's a fact, You could see that in any of the logs that we have.


    A different thing is, if you are running turbo. If for some reason , the boost regulator goes bad or wrong, and you get way more boost , then that will make you run very lean... probably it will stall at wot, due to lean conditions... But running supercharges, it's not a problem.

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  4. #13
    mittens's Avatar
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    Thank you very much for the response and info.

    tps would play a part as the less throttle but same rpm means boost can peak too. Also good to remember the maps are not single maps and are a combination of other maps as well. Weather is RPMs/ boost vs tps, vs fuel. Ect.

  5. #14

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    I was providing the conversion of bar to psi, which is correct. Not what the sensor reads. If I recall kpa is what MapEdit uses. Some MapEdit tuneup files have both 2 bar and 3 bar tables. You can tell the difference if you look at the KPA scale. This can be confusing as only one set is used. JesusG can remove the tables that you are not using.

    Robert




    Quote Originally Posted by mittens View Post
    that is not correct. A 2 bar map sensor can read up to 29.4 psi.... but atmospheric pressure is 14.7.. so a 2 Bar map sensors can only read 14.7 psi above atmospheric pressure/boost.

    a 3 bar is needed for 14.7- 29.4lbs above atmosphere/boost.

    look it up.

    that being said.
    When I read a tuner (Dean or Jesus whom ever) says they can tune it based on a 2 bar when the ski is pushing more then 14.7lbs of boost. I read it as "I will follow the linear graph I see with boost vs rpm and fuel needs (as boost and rpm are directly related) and will faten the tune appropriately to be close on anything above 14.7lbs."

    but the correct answer is to have a tune set up to add fuel for the air/boost it measures and not guess on the top end. Granted causes customers don't want to buy more parts and we want to go fast cheaper. But it is what it is.

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