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Thread: Warm Air Intake

  1. #61
    Administrator Daox's Avatar
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    I have fully removed my mail slot (upper) grill block. This seems to have lowered intake temps down to 100-120 which is just about perfect I think.


    Custom Mirage products: Cruise control kit, Glove box light, MAF sensor housing, Rear sway bar, Upper grill block

    Current project: DIY Nitrous oxide setup for ~$100

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        click to view fuel log View my fuel log 2015 Mirage DE 1.2 manual: 47.2 mpg (US) ... 20.1 km/L ... 5.0 L/100 km ... 56.7 mpg (Imp)


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    I don't run any upper block in the summer...and I even have some of my lower open so I can get a little airflow over my AC condenser.

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        click to view fuel log View my fuel log 2015 Mirage ES 1.2 manual: 52.2 mpg (US) ... 22.2 km/L ... 4.5 L/100 km ... 62.6 mpg (Imp)


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    Quote Originally Posted by Fummins View Post
    I'm not sure if this has been mentioned yet... To control the temperature you could try a valve like this Attachment 10367
    And control it with a simple heater control dial like this Attachment 10370Attachment 10368. Or get real fancy and try to make it all automatic by a temperature switch and electric heater valve.
    I wish the attachments on some of these older posts would work...

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    Quote Originally Posted by Daox View Post
    Well, the WAI I've been running is REALLY working well lately. Here is a shot of one of my recent trips. The intake air temp is up to 150F. A later trip in the day actually got up to 170F. This is too warm IMO. The power loss was very real which is what we're going for, but this was a bit too much.

    Attachment 14751
    As long as the engine produces enough power for your needs what are the downsides with trying to maximize intake air temperature? Isnt the reduction in power and throttle response the goal? because you are trying to reduce pumping losses by decreasing the vacuum created in the intake manifold.

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    Fifteenwindow already pointed out that warm air is less dense, meaning less O2 which equates to a leaner mixture required which reduces output. Flyers use techniques called "power recovery" to compensate for loss of power which requires leaning the mixture. This leaning would be done by the ECU via MAP sensor, ambient temp sensor and O2 sensor.

    In essence, what you have accomplished is to raise the density altitude with your WAI and reduced the power out of the engine. You may see a mpg increase because of the leaning mixture but you WILL be suffering a power decrease.
    Karl

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    Quote Originally Posted by CROSSBOLT View Post
    Fifteenwindow already pointed out that warm air is less dense, meaning less O2 which equates to a leaner mixture required which reduces output. Flyers use techniques called "power recovery" to compensate for loss of power which requires leaning the mixture. This leaning would be done by the ECU via MAP sensor, ambient temp sensor and O2 sensor.

    In essence, what you have accomplished is to raise the density altitude with your WAI and reduced the power out of the engine. You may see a mpg increase because of the leaning mixture but you WILL be suffering a power decrease.
    I understand that a power decrease will occur. But I do not think it is from leaning the mixture. It takes a certain amount of power to make the car move, if the intake air is warmer the driver will simply depress the gas pedal further. I think the fuel savings is from a reduction in pumping losses caused by the throttle body being wider open to let more air in creating less of a vacuum. My question was at what point would you want to stop warming up your intake air?

    If the intake air was so warm that the car would always operate near wide open throttle would that be better or worse for fuel economy?

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    Administrator Daox's Avatar
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    Mohammad is correct in his thinking on how it works with the reduction of pumping loss and reducing intake manifold vacuum. The O2 sensor in cars prevents them from running lean for emissions purposes.

    One problem with getting air too warm is ignition timing. At some point (which could only be found via testing, and I would imagine is highly variable) the air gets too warm and ignition timing will need to be retarded. The air will get too warm and cause pinging. This causes ignition timing to be less than ideal and reduces engine efficiency. This is why you see efficiency loss on brake specific fuel consumption maps at high engine loads, but at ideal RPMs. Ignition timing is pulled to prevent engine knock / pinging / damage as the intake charge (of fuel and air) gets too hot.

    Another factor that may happen before that would be softening your intake system's plastics... I think the intake plastics are mostly polyurethane (though I haven't checked), and according to google it starts to soften at around 200F / 93C. I think there may also be some ABS components (in sensors likely) and its service temperature is 176F / 80C. I would want to stay below that point.

    Which of these is a larger factor? I am unsure. My best guess is you could probably run 150F intake air safely and still see MPG gains, but I can't be sure of it.
    Custom Mirage products: Cruise control kit, Glove box light, MAF sensor housing, Rear sway bar, Upper grill block

    Current project: DIY Nitrous oxide setup for ~$100

        __________________________________________

        click to view fuel log View my fuel log 2015 Mirage DE 1.2 manual: 47.2 mpg (US) ... 20.1 km/L ... 5.0 L/100 km ... 56.7 mpg (Imp)


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  10. #68
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    This is taking on the same flavor of the old "higher octane" discussions.


    Karl

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